root@chels-5f46dc6b67-7tct5:/data/home/AlphaPose# sudo apt install update-manager-core Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt --fix-broken install' to correct these. The following packages have unmet dependencies:  cuda-drivers : Depends: nvidia-418 (>= 418.126.02) but it is not going to be installed  libcuda1-418 : Depends: nvidia-418 but it is not going to be installed  nvidia-418-dev : Depends: nvidia-418 (>= 418.126.02) but it is not going to be installed  nvidia-opencl-icd-418 : Depends: nvidia-418 but it is not going to be installed  update-manager-core : Depends: python3-update-manager (= 1:18.04.11.13) but it is not going to be installed                        Depends: python3-distro-info but it is not going to be installed                        Depends: ubuntu-release-upgrader-core (>= 1:18.04.9) but it is not going to be installed E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution). root@chels-5f46dc6b67-7tct5:/data/home/AlphaPose# apt --fix-broken install Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following additional packages will be installed:   nvidia-418 The following NEW packages will be installed:   nvidia-418 0 upgraded, 1 newly installed, 0 to remove and 113 not upgraded. 8 not fully installed or removed. Need to get 97.9 MB of archives. After this operation, 410 MB of additional disk space will be used. Do you want to continue? [Y/n] y Get:1 http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1404/x86_64  nvidia-418 418.126.02-0ubuntu1 [97.9 MB] Fetched 97.9 MB in 1s (67.1 MB/s)      debconf: unable to initialize frontend: Dialog debconf: (No usable dialog-like program is installed, so the dialog based frontend cannot be used. at /usr/share/perl5/Debconf/FrontEnd/Dialog.pm line 76, <> line 1.) debconf: falling back to frontend: Readline (Reading database ... 128611 files and directories currently installed.) Preparing to unpack .../nvidia-418_418.126.02-0ubuntu1_amd64.deb ... Unpacking nvidia-418 (418.126.02-0ubuntu1) ... dpkg: error processing archive /var/cache/apt/archives/nvidia-418_418.126.02-0ubuntu1_amd64.deb (--unpack):  trying to overwrite '/usr/lib/x86_64-linux-gnu/libGLX_indirect.so.0', which is also in package libglx-mesa0:amd64 20.0.8-0ubuntu1~18.04.1 Errors were encountered while processing:  /var/cache/apt/archives/nvidia-418_418.126.02-0ubuntu1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)  How should I fix this? Can't install the update manager.

For example:  $ sudo apt-get install curl Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: bsh : Depends: libjline-java but it is not going to be installed groovy : Depends: libjline-java but it is not going to be installed rhino : Depends: libjline-java but it is not going to be installed E: Unmet dependencies.   Try 'apt-get -f install' with no packages (or specify a solution).   I get the same or similar errors when I attempt to install clojure1.3, leiningen, and several other packages.   When I try the suggestion made in the error message, this is what happens:  $ sudo apt-get -f install  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following packages were automatically installed and are no longer required:   diffstat linux-headers-3.2.0-26-generic linux-headers-3.2.0-26 dh-apparmor dkms html2text libmail-sendmail-perl libsys-hostname-long-perl Use 'apt-get autoremove' to remove them. The following extra packages will be installed:   libjline-java Suggested packages:   libjline-java-doc The following NEW packages will be installed:   libjline-java 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 23 not fully installed or removed. Need to get 0 B/72.0 kB of archives. After this operation, 129 kB of additional disk space will be used. Do you want to continue [Y/n]? Y (Reading database ... 226243 files and directories currently installed.) Unpacking libjline-java (from .../libjline-java_1.0-1_all.deb) ... dpkg: error processing /var/cache/apt/archives/libjline-java_1.0-1_all.deb (--unpack):  trying to overwrite '/usr/share/java/jline.jar', which is also in package scala 2.9.2-400 Errors were encountered while processing:  /var/cache/apt/archives/libjline-java_1.0-1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1)  $ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  bsh : Depends: libjline-java but it is not installed  groovy : Depends: libjline-java but it is not installed  rhino : Depends: libjline-java but it is not installed E: Unmet dependencies. Try using -f.


The wikipedia page for divisibility rule for 7 has an interesting method. Which I am elaborating and generalizing.  let a number N. Make pairs of the number starting from right. find remainders for each pair. let remainders be R0,R1,R2,R3.. . Then the number N is divisible by 7 if R0X2^0 + R1X2^1+R2X2^2+R3X2^3... is divisible by 7. eg 194,536: 19|45|36 ; (5x4) + (3x2) + (1x1) = 27, so it is not divisible by 7 204,540: 20|45|40 ; (6x4) + (3x2) + (5x1) = 35, so it is divisible by 7 1,655,598: 1|65|55|98 ; (1x8) + (2x4) + (6x2) + (0*1) = 28, so it is divisible by 7 can this be proved? the system may give easier results if we take negative remainders(in case remainders are 5,6 we can take remainder as -2,-1)

I have seen other criteria for divisibility by 7. Criterion described below present in the book Handbook of Mathematics for IN Bronshtein (p. 323) is interesting, but could not prove it. Let $n = (a_ka_{k-1}\ldots a_2a_1a_0)_{10} = \displaystyle{\sum_{j=0}^{k}}a_{k-j}10^{k-j}$. The expression $$ Q_{3}^{\prime}(n) = (a_2a_1a_0)_{10} - (a_5a_4a_3)_{10} + (a_8a_7a_6)_{10} -\ldots  $$ are called alternating sum of the digits of third order of $n$. For example,  $$ Q_{3}^{\prime}(123456789) = 789-456+123=456 $$ Proposition: $7 | n \ \Leftrightarrow \ 7 | Q_{3}^{\prime}(n)$.  proof. ??  Thanks for any help.


The Community user has badges on  and  .  While they are partially hidden, they are still visible, and they are also visible in the .  I guess this is partly because these sites have been imported in the SE network, not been created through the Area 51 process.

Apparently, .  How the heck did that happen?


All the other horcruxes were hidden and guarded carefully and with a lot of thought as to where they were hidden. It seems odd to me that the diary was given to the someone to keep safe. Even if he needed someone to use it to open the chamber of secrets ... It still seems a big risk.  Why was the diary given/entrusted to Malfoy Snr? Voldemort, who works alone, trusts something such as his diary horcrux to a person to keep safe. That seems to be a bit odd to me.

In the Harry Potter movies, Voldemort made the Horcruxes and hid them in different locations, but he hid two of them in the same place: Hogwarts.   Tom Riddle's diary in the Chamber of Secrets; Ravenclaw's Diadem in the Room of Requirement;   Is there some explanation in the book of why he leaves these two in the same place?


To give some context, A person believes somethings (for example religious practices) but if someone tries to prove that those beliefs are wrong, the person gets into defensive mode - and can even burst with anger or get ready to fight. So, this is a person who wants to protect his/her beliefs and if someone shares their beliefs he/she thinks that they are attacking their personal beliefs. This person doesn't want to change their beliefs. They protect them with their life if needed. FYI, in this context, belief is different than knowing things. We know we have two hands but don't believe it.  What is the word for such a person? (I don't think it is believer)

What is the word when someone considers any questioning of their view to be a moral failing or blindness of the questioner?   I'm thinking of a bottom up, community driven acceptance of a view or analytical model. I can think of a few examples in the current public conversation but I don't want to name them for fear of politicising the question.   'Dogma' may just be the word, but perhaps'dogma' suggests a 'Truth' mandated by locus of power rather than the crowd wisdom I have in mind. An example of dogma would be the biblical creation story where it is held to be true through reverence for its source.


Roughly what purpose does the word "cut" serve in the sentence "cut me some slack"?  I have a guess as to what this word means in that sentence. English is actually my second language; my first was Polish.   So in literal translation from a common Polish phrase "to cut yourself a nap" means that you basically have yourself a nap.   So coming from that, I assume that to "cut" in the  sentence in question means to just give/have yourself some slack (If you give yourself slack, you're gonna have slack is what I mean by "have yourself some slack").   Would this be an acceptable interpretation?

Teenagers. All the literature tells you one thing and one thing only – that  whatever they are doing, give them a break, cut them some slack, it's normal.      From the novel, Apple Tree Yard   I'm curious about the origins of . I know slacks are American English for trousers or pants, and a slacker is a lazy person. But what is a slack and how does one "cut" it?


My book says that if functions $f$ and $g$ are both onto then $f\circ g$ and $g\circ f$ may or may not be onto.   Why is this so? Would someone please help me understand this, maybe with an example or diagrammatically? My book states that$  f\circ g$ and $g\circ f$ may or may not be onto. I think this might be related to the domains and codomains of g and f which may not be equal. I am aware that there is a similar looking question and therefore I'm clarifying mine. With respect to the domains and codomains would someone please explain why the composite functions may or may not be onto?

Suppose $f: A \to B$ and $g: B \to C$ are both surjections.  Since $f$ is surjective, then for every $b \in B$ there exists $a \in A$ such that $f(a)= b$.  Since $g$ is surjective, for every $c \in C$, there's  $b \in B$ such that $g(b) = c$. Then $g(f(a)) = g(b) = c$.   Would this work?  edit; I didn't realize there are similar questions on this site. Don't mind if this post is deleted.


I created two blender scripts :  a MeshCleaner : that cleans the meshes for my glb file a HierarchyCleaner :  that cleans the hierarchy for my glb files  To clean the code , i added an IOHandler for reading and writing glb files so i can reuse the IOHandler in both the MeshCleaner and the HierarchyCleaner . When running one of the scripts i run blender in the background  MeshCleaner.py  import bpy from .IOHandler import import_gltf_file , export_gltf_file , read_filename  def remove_default_cube ():     objs = bpy.data.objects     objs.remove(objs["Cube"], do_unlink=True)      def clean_heavy_gltf_file(filename):     import_gltf_file(filename)     export_gltf_file(filename)  if __name__=="__main__":     remove_default_cube()     filename = read_filename()     clean_heavy_gltf_file(filename)    HierarchyCleaner.py  import bpy from IOHandler import import_gltf_file , export_gltf_file , read_filename from MeshCleaner import remove_default_cube  def clean_hierarchy():     objs = bpy.data.objects     nodes=objs.values()     print(nodes)     for node in nodes :         if(len(node.children)==0):             node.name=node.data.name      def correct_file(filename):     import_gltf_file(filename)     remove_default_cube()     clean_hierarchy()     export_gltf_file(filename)   if __name__=="__main__":     correct_file()   IOHandler.py:  import bpy import sys  def import_gltf_file(filename):     bpy.ops.import_scene.gltf(filepath = filename)  def export_gltf_file(filename):     bpy.ops.export_scene.gltf(filepath = filename)  def read_filename():     filename=sys.argv[4]     return filename  I run the code using sh scripts running : GLB_FILE=$1 ;  blender --background --python HierarchyCleaner.py $GLB_FILE ;  or GLB_FILE=$1 ;  blender --background --python MeshCleaner.py $GLB_FILE ;  when trying to run the code i have an ImportError stating that there is no such module as IOHandler . all the scripts are within the same directory . Is there a way to make this work and  ?

The path for the Python executable used in Blender (up to 2.79) is not configurable.  I looked around and did not find a consistent way to be able to use custom  3rd party Python modules without installing then directly in the O.S. Python.  This would work, although not the ideal solution, but then I had issues with that in Linux, as running pip install system wide adds the modules to /usr/local/lib, but /usr/local is not the in the PYTHONPATH when Blender is started.   An active Python virtualenv - Python's own way of isolating 3rd party modules is ignored by Blender - as the way to activate a virtualenv is simply using it's Python binary (in a different Path than the one used by Blender).


Can we able to disable the Windows 10 automatic update by disabling the wuauserv in services.msc? And also please confirm whether disabling the wuauserv will affect the system?

We've upgraded some machines to Windows 10 and realized there were some updates which updated as required. However, I realized there was no option available to stop the download similar to that on Windows 7 and 8.1. The only way I could stop the download was to stop the Windows Update service.  My question is does anyone know of a way to stop auto updates or is stopping the service is the only solution?


I'm trying to set up file transfer via FileZilla and it doesn't seem to matter what details I put in, I always get the following error:     Status:       Connection attempt failed with "ECONNREFUSED -   Connection refused by server". Error:         Could not connect to   server   My Dad has tried on his computer (with FileZilla on Windows) and it connects and everything is fine.. When I try on mine with all the same details that he put in, it comes up with that error.  I read that a firewall might be blocking it so I double checked and my firewall through system preferences and it is off.  Anybody know why this might be???  Additional info:  Macbook Pro running OS X El Capitan version 10.11.6  FileZilla version 3.23.0.2


I just received my (passing) grades for my last remaining courses for my BSc. I’ve completed all my requirements, but the next convocation ceremonies don’t take place until Summer 2018. Likewise, I don’t think I will receive my diploma (the physical, official certificate) until then. Usually when a résumé says “degree expected in ____”, it reads along the lines of: “I’m not done yet, but if things pan out, I’ll hopefully be done by then“.  This is not my case, so in my résumé, how can I communicate across that I expect to receive my diploma in Summer 2018 as a matter of certainty?  Am I justified to use the term graduated? If so, should I say I graduated December 2017 (when I finished my requirements) or Summer 2018 (when convocation occurs)?

I have completed all the requirements for an M.S. degree and have filed the appropriate paperwork. All I have left to do is walk at the end of this semester. I want to put this on my CV, but it seems appropriate to differentiate it from my Ph.D., which is (only) "In progress", and another M.S. which I completed a few years ago.   How should I express this on my CV? Should I say "Anticipated" or "Expected", with the date?   My question is different than  because that question asks about a degree that was entirely incomplete, unawarded, and is not likely to ever be awarded. In my situation, the degree needs only to be formally awarded.


I'm making a bee game and so far its all been going well until i've tried to add my bee character where i've stumbled across a problem. The problem is it doesn't add my characater into the stage so I cant see my bee character and I dont know why? I'm not sure what the problem is the code seems to be fine to me and i've asked some of my friends and they don't why it breaks either?  i get this error  :  Caused by: java.lang.NullPointerException     at myFirstGame.GameObject.update(GameObject.java:20)     at myFirstGame.BeeCharacter.update(honeyBee.java:88)     at myFirstGame.BeeCharacter.<init>(honeyBee.java:79)     at myFirstGame.Factory.createCharacter(honeyBee.java:109)     at myFirstGame.honeyBee.start(honeyBee.java:65)   my beeClass   package myFirstGame;  import java.util.ArrayList; import java.util.Random;  import javafx.animation.AnimationTimer; import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.canvas.Canvas; import javafx.scene.canvas.GraphicsContext; import javafx.scene.image.Image; import javafx.scene.layout.Pane; import javafx.stage.Stage;  public class honeyBee extends Application {      GameObject gameObject;     GraphicsContext gc;     Stage stage;     Canvas canvas;     Image img;     Factory Factory;        ArrayList<GameObject>characterList = new ArrayList<GameObject>();     Random rnd = new Random(System.currentTimeMillis());     int count = 0;      AnimationTimer timer = new AnimationTimer() {          @Override         public void handle(long now) {             // TODO Auto-generated method stub             gc.drawImage(img, 0, 0, canvas.getWidth(), canvas.getHeight());             for(GameObject obj : characterList) {                 obj.update();             }          }     };      public static void main(String[] args) {         // TODO Auto-generated method stub         launch(args);     }      public void start(Stage stage) throws Exception {         stage.setTitle("HoneyBee");         Pane root = new Pane();         Factory = new Factory(gc);         stage.setScene(new Scene(root, 780, 580));         stage.setResizable(false);         stage.show();           canvas = new Canvas(800,600);         gc = canvas.getGraphicsContext2D();         img =new Image("res/1.png");         gc.drawImage(img, 0, 0, canvas.getWidth(), canvas.getHeight());         root.getChildren().add(canvas);           //gameObject.timer.start();         characterList.add(Factory.createCharacter("bee", 30, 30));          timer.start();     } }  class BeeCharacter extends GameObject{      double dx=1;      public BeeCharacter(GraphicsContext gc, double x, double y) {          super(gc, x, y);         img = new Image("res/bee.png");         update();     }      public void update() {         x+=dx;         if(x>800 || x<0) {             dx=-dx;             y+=20;         }         super.update();     } }  interface FactoryIF {     GameObject createCharacter(String start, double x, double y); }   class Factory implements FactoryIF {      GraphicsContext gc;      public Factory(GraphicsContext gc) {         super();         this.gc = gc;     }     @Override     public GameObject createCharacter(String start, double x, double y) {         // TODO Auto-generated method stub         if(start.equals("bee"))              return new BeeCharacter(gc, x, y);         else             return null;     }  }   my GameObject class   package myFirstGame;  import javafx.scene.canvas.GraphicsContext; import javafx.scene.image.Image;      class GameObject {     protected Image img;     protected double x, y;     protected GraphicsContext gc;      public GameObject(GraphicsContext gc, double x, double y){     this.gc=gc;     this.x=x;     this.y=y;     }      public void update(){      if(img!=null)         gc.drawImage(img, x, y, 30, 30);     }   }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I did:  pm disable com.android.systemui   I get:  pm list packages -d package:com.android.systemui   So it is disabled. Still I get:  ps | grep systemui                                             u0_a71    2053  1183  462960 27552 ffffffff 40089a40 S com.android.systemui   so it is still running, even if I kill it, it restarts! How can it both be running and be disabled at the same time?

I've noticed that apps (such as Google Contacts Sync) that have been disabled using the stock Android (KitKat) app manager still show up as running when using process observer tools.  This is true even after the device has been rebooted.  Why are disabled apps still running?  Is there an effective (and safe) way to actually disable them?  Solutions requiring root privileges are acceptable.   (Note that for the specific example above, you can tell Android not to sync your contacts, but it still runs the Google Contacts Sync process.  But let's not dwell on that example... it's just an example.)


In Avengers: Endgame, is the snap simply dramatic, or does the wielder of the Gauntlet needs to follow this ritual to actually activate it?

In the scene on Titan with Doctor Strange in Avengers: Infinity War, Thanos said,     With all six Infinity Stones, I will simply snap my fingers and it would all cease to exist.   Then again, in the very first scene with Thor and Loki, when Maw gave Thanos the Space Stone, he said that no one has ever worn two Infinity Stones together.   So how come Thanos knew about the power of the Snap? Because as Wong puts it to Tony, the Big Bang hurled the six Infinity Stones across the universe.   So if no one had collected all the six stones before Thanos, then how did he know about the ability to "Snap"?


Many of the solutions to prevent windows 10 from doing their auto reboot updates are not working anymore. The solutions posted here:   No, this question is not a duplicate. Hence: "It's 2019"    Are outdated and just a waste of time for everyone to try as they do NOT work anymore. It's 2019, what tricks does Microsoft have up their sleeves to force an auto shutdown update?  Many people seeking help want to disable updates completely. Not just auto reboot. Please do not post answers that only disable auto reboot. Alot of the times when windows update with new patches, it removes certain programs that it deems unnecessary. In my case it constantly removes my work's vpn software. wtf!? I just want to disable updates completely!  What are the latest ways of preventing further updates on Windows 10? Home and Pro versions. Solutions that don't need to install software would be best, but also installing 3rd party software can be possible too for the non-tech savvy.

Windows 10 lets you 'schedule' a reboot for later. I want to disable it.  Evidently Windows scheduled itself for a reboot last night when I wasn't looking and just closed everything I had been working on the night before.  I reboot on the regular; I don't need Windows to do that for me.  Can I disable it completely? I don't mind if it downloads everything, and then says "hey, you should reboot," but it should never reboot itself, ever.  I'm using the "Pro" edition of Windows 10.


My goal is a dual boot Linux/Windows 7 PC. It already has windows 7 on drive C, on a 3Tb drive.  I first defragmented this drive, then shrink the drive c partition to the maximum allowed.  The drive is now 1037.17 Gb, but only 42.9 Gb is used space. I only want to use 120 Gb for windows.  When I try to shrink it, after also defragmenting, the system says:     Size available shrink space in MB:  0   I've made a system backup to an external drive and a DVD repair disk.  Can I just trash this partition and restore it to a newly created 120Gb partition?

I have just bought an HP laptop with Windows 7 (64 bit). It has a 500 GB HDD with three partitions: a small hidden system partition, a 12 GiB HP recovery partition, and a 450 GiB C: boot partition.  I would like to split this large C: partition into two partitions, leaving only 100 GiB for the system, and giving the rest to a new data partition.  Although the Windows built-in Disk Management utility has an option to shrink the bootable partition, it only allows me to shrink it roughly by half, even though only 20 GiB on the partition is used. As far as I understand, system unmovable files lie in the middle of the partition, preventing Disk Management utility to do what I want.    And since new HP laptops don't come with OS installation disks (they only allow you to create recovery disks yourself), I can't just repartition HDD and then reinstall OS.  So, is there a way to shrink the C: bootable partition and preserve Windows 7 working?  P.S.: I have tried to use the third-party  utility, and after shrinking the partition, Windows 7 stopped booting, with a . System recovery didn't work, and I had to do factory recover. Since this is a long process, I would like to avoid doing it again :) So, please, suggest only proven solutions.


The machine has a Broadcom 802.11ac network adapter with Intel Ethernet Connection I217-LM. Works fine in W10, but nothing when trying to install Ubuntu 18.04. Is there a way making 18 work or should I change to another version?

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


How to install 32-bit libraries to run Second_Life_3_8_2_303583_i686 on a 64-bit 16.04?  gaius@gaius-HP-Pavilion-dv6-Notebook-PC:~$ sudo apt-get install lib32ncurses5 Lettura elenco dei pacchetti... Fatto Generazione albero delle dipendenze        Lettura informazioni sullo stato... Fatto lib32ncurses5 is already the newest version (6.0+20160213-1ubuntu1). 0 aggiornati, 0 installati, 0 da rimuovere e 0 non aggiornati. gaius@gaius-HP-Pavilion-dv6-Notebook-PC:~$   gaius@gaius-HP-Pavilion-dv6-Notebook-PC:~$ sudo apt-get install lib32z1 Lettura elenco dei pacchetti... Fatto Generazione albero delle dipendenze        Lettura informazioni sullo stato... Fatto lib32z1 is already the newest version (1:1.2.8.dfsg-2ubuntu4). 0 aggiornati, 0 installati, 0 da rimuovere e 0 non aggiornati.

I installed Ubuntu 14.04 and the current Android development SDK, which contains 32-bit executables. I found that I cannot run those 32-bit binaries. Trying to start them from bash gives me an error: $ ./adb bash: ./adb: No such file or directory  It is there though: $ ls -al ./adb -rwxrwxrwx 1 thomas thomas 1231255 Jan 17 13:31 ./adb $ file ./adb ./adb: ELF 32-bit LSB  executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.8, not stripped.   Same symptom for all the other 32-bit tools in the Android SDK. In olden days one could just install 32-bit libraries on 64-bit Ubuntu to get 32-bit support, but that does not seem to work anymore. How do I run 32-bit apps on a 64-bit Ubuntu distribution?


I have a problem with nodes in scheme. I need type a node where will be text "Banka melovskych filtru". Each word on a special line with center align.

How can I insert a line break in a TikZ node? Simply putting \\ where I want the break doesn't work (see MWE).  Is there a way to make lines break automatically at some specified width?  And can I control the alignment of the text (left, right, centered, justified)?  \documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \node {First line\\second line}; \end{tikzpicture} \end{document}


Two stars of masses $M$ and $2M$ move in circular motion about their common centre of mass. Which of the following statements is true? A.    Both stars move with the same radius. B.    Both stars move with the same speed. C.    Both stars move with the same angular velocity. D.    Such a motion is not possible.  Since the gravitational force contributes to centripetal force of the rotation, consider mass $M$, we have $$\frac{2GM^2}{R^2} = \frac{Mv^2}{R}$$ where $R$ is the distance between the two masses. I have no idea how to show they have the same angular velocity.

In a binary star system, two stars $A$ and $B$ follow circular orbits, of radius $R$ and $r$ respectively, centred on their common centre of mass $O$. The mass of star $A$ is $M$, and that of star $B$ is $m$. I am having trouble with the following problem:  Explain why the period of rotation of star $A$ is equal to the period of rotation of star $B$.   By using Kepler's Third Law, we know that $$r^3\propto T^2.$$ In this question, however, we want to show that they are the same. How should I approach this question? I only notice that the two stars are always on the straight line joining them and the centre $O$.


I am currently trying to convert some vb into c# and in the vb code I have the following line:  If DateTime.TryParse(txtExpirationDate.Text, Nothing) = False Then  _isValid = False   Which, with my extremely limited knowledge of vb, I think should read in c# as:  if (DateTime.TryParse(txtExpirationDate.Text, null) == false)         _isValid = false;   However visual studio is telling me that I have invalid arguments:     The best overloaded method match for 'System.DateTime.TryParse(string, out System.DateTime)' has some invalid arguments      I was wondering if anyone would be willing to help me out. What am I doing wrong? Is this even possible in c# and if so how would I do it?

I'm making a call:  myResult = MakeMyCall(inputParams, out messages);   but I don't actually care about the messages.  If it was an input parameter I didn't care about I'd just pass in a null.  If it was the return I didn't care about I'd just leave it off.    Is there a way to do something similar with an out, or do I need to declare a variable that I will then ignore?


Prove that the following statements are equivalent:   If $A$ is a non empty set, there exists a function $f:\mathcal{P}(A) \setminus \{\emptyset\} \rightarrow A$ such that $f(X) \in X$ for every $X \in \text{dom}(f)$. Every non empty family $\mathfrak{F}$ of sets such that any two distinct sets of the family are disjoint has a set $X$ such that $|X \cap F|=1$ for every $F \in \mathfrak{F}$.   Now, this is how I've done $1 \Rightarrow 2$:  We notice that for every non empty family $\mathfrak{F}$ of disjoint sets we have that: $$\mathfrak{F} \subseteq \mathcal{P} \left(\bigsqcup _{F \in \mathfrak{F}} F \right) \setminus \{\emptyset\}$$ If we set $A=\bigsqcup _{F \in \mathfrak{F}} F$, we have (for hypotesis) a function $f$ such that $f(Y) \in Y$ for every $Y \subseteq A$. So, in particular, we have that $f(F) \in F$ for every $F \in \mathfrak{F}$, and also that $f(F) \notin F'$ for every $F' \in \mathfrak{F}$ such that $F' \neq F$. So, if we consider the set $X=\{f(F) \mid F \in \mathfrak{F}\}$, we obtain the thesis.  For $2 \Rightarrow 1$ I really don't know what to do. Any suggestions?

This is the first part of the first half of the a proof in the Axiom of Choice. The proof that the Axiom of Choice is equivalent to the choice function. REsources: Keith Devlin's Joy of Sets: pg. 58. F.R. Drake and Singh Intermediate Set Theory: pg. 110).   I am confused on proving disjointness and will ask further questions of proof once I get this first part v. clear for myself.   AC1: Let $\mathcal F$ be a family of pairwise disjoint, non-empty sets. Then there is a set $\mathcal M$ that consists of precised one element from each member of $\mathcal F$  AC2: For every family $\mathcal F$ of non-empty sets, there is a choice function $\mathcal f$. (I.e. $\mathcal f(X)$ is a member of X, for each X in $\mathcal F$.   Disjointness: Two sets are disjoin if Q $\cap$ R = $\emptyset$. Meaning that they have zero elements in common. These sets do not overlap.   Show: AC1 $\leftrightarrow$ AC2   (1) ($\rightarrow$) Let $\mathcal F$ be a set of nonempty sets.   (2)For each X $\in$ $\mathcal F$, let $X^*$ = (X $\times$ {X}) = {(x, X) | x $\in$ X})  (3) Show Disjointness.  An outline of how book proves  disjointness:  (a) if u = {(X $\times$ {X}) | x $\in$ X} then u is of the form $\lt  z, t \gt$ where z = X and t=x, i.e. x $\in$ X.   (b) then if u $\in$ ({X} $\times$ x) $\cap$ ({Y} $\times$ Y) $\rightarrow$ u = $\lt z, t \gt$ with z = X and z=Y, i.e. X=Y. Which means ({X} $\times$ x) = ({Y} $\times$ y).  Questions: (1) Apparently we cannot prove disjointness in $\mathcal F$ but must prove in a different set. If so, why is that?  (2) why is the case that if u $\in$ ({X} $\times$ X) $\cap$ ({Y} $\times$ Y) then z =X and z=Y? I am not following that step at all.   (3) why does the axiom of choice have to do with ordered pairs? Why are we setting X $\in$ $\mathcal F$, let $X^*$ = (X $\times$ {X})?    Thank you!


I want to change this loading screen background (the purple one), without changing the whole animation, just the purple background, without software, How can I do it ?    I have found the files under  /usr/share/plymouth/themes   and that I should save the file and run the following command.  sudo update-initramfs -u   But what are the needed lines to do add in the files ?

With regards to Plymouth --  Are there alternative boot screens available?  What's the easiest way to change the boot screen?


What is the use of CDATA inside JavaScript tags and HTML?  <script type="text/javascript">  // <![CDATA[  // ]]> </script>

Are CDATA tags ever necessary in script tags and if so when?  In other words, when and where is this:  <script type="text/javascript"> //<![CDATA[ ...code... //]]> </script>   preferable to this:  <script type="text/javascript"> ...code... </script>


I'm a stock market trader and at the end of every trading session I have some files to download from stock exchange website, how can I write a code in python or in any other language to download a file and perhaps schedule it for downloading..?

I have a small utility that I use to download an MP3 file from a website on a schedule and then builds/updates a podcast XML file which I've added to iTunes.  The text processing that creates/updates the XML file is written in Python. However, I use wget inside a Windows .bat file to download the actual MP3 file. I would prefer to have the entire utility written in Python.  I struggled to find a way to actually download the file in Python, thus why I resorted to using wget.  So, how do I download the file using Python?


I posted this suggestion earlier in  at the Portuguese Stack Overflow Meta, and they suggested that I post it here.    Currently, the tab shows the number of new questions:        Wouldn't be more useful to have the number of notifications instead?  In the Meta questions linked above, @Bacco suggested it would be a nice idea to have a mixed format:     (Questions|Notifications) Stack ...   In this case, if there no new notifications or questions, it would be shown a 0:     (0|2) Stack ...   or   (2|0) Stack ...     Another alternative: let the user choose if he/she wants to see the number of questions or notifications.  What do you think, friends?

I'm usually running many different StackExchange sites in Firefox using tabs (using ReloadEvery to update every 5 minutes).  Right now to check for activity, I have to manually click on the tab to see if the envelope is lighted.  How about making the icon on the tab i.e. the title text change in some way, denoting that you have activity on the page?  We already add a message count for the chat tabs, so this shouldn't be very complicated.  Possible Example:


It's easy to prove $x^2+1$ is never divisible by $4k+3$ primes. I know a non-constructive proof for existing $x$ so that $p|x^2+1$ for $4k+1$ primes. is there any constructive one?

I came across this problem and I believe Lagrange's theorem is the key to its solution.  The question is:     Let $p$ be an odd prime. Prove that there is some integer $x$ such that $x^2 \equiv −1 \pmod p$ if and only if $p \equiv 1 \pmod 4$.   I appreciate any help.  Thanks.


I had an interview today (my first one) for a teaching stream position at a college, and I'm unhappy with a couple of my answers.  Should I just consider the matter closed and send a follow-up email to the committee thanking them for their time? or is it appropriate to include a few remarks and/or clarifications about the questions that I wish I answered differently?  Appreciating any advice.  Thanks!

I didn't do well in a part of a technical interview for a master's program, which was a question in the field X.   The most important subfield of my major for that program is X and X is not particularly my strength, because I took more advanced courses in other subfields during the last two years of my undergrad. But that is exactly why I want to do that master's program. I've had the necessary elementary courses in the field X, but did not go deeper in those topics, simply because there is not enough time to take all the helpful and good courses as an undergrad. That's why I decided to take some other courses as an undergrad and leave advanced courses in X for my graduate degree. I also want to do a Ph.D. after my master's and the field I want to do my Ph.D. is quite directly related to the master's degree I was interviewed for and involves a great deal of X.  To me, it makes perfect sense to apply for a master's program in a field that I'm not strong in, because otherwise, I wouldn't need to take more courses in that field and I will learn whatever I need, quite easily, through self-study. Is it a good idea to email the admission committee (or the professor who interviewed me) and explain this to them now? (Please keep in mind that I could have mentioned this point in my SOP, but I didn't. Probably a bad decision...)


What is the difference between these two sentences?   Kate watched TV a lot when she was sick last year. Kate watched TV a lot while she was sick last year.

But you can't find anything while you're crying.   But you can't find anything when you're crying.   I'll tell you about it while Frank saddles the horse.   I'll tell you about it when Frank saddles the horse.     When should I use when, and when while? Are these sentences correct?


My son is writing an essay about a dead hero. Most of the verb tense he used is in the PAST, as in, "He was a clever hero." To be consistent, he wrote, "He was an inspiring hero." However, it got me thinking if it would be better to say, "He is an inspiring hero," because he still continues to inspire others even after his death.

I have a basic grammar question about the past tense. If I met a guy yesterday, which tense should I use about his name today?  For example,     "Yesterday I met a guy, his name is/was John."


I couldn't find the Belgian keyboard layout during Ubuntu 20.04 install, the option seems to be missing (some "belgien" layouts are listed, they're not what I need). The workaround is to execute the command sudo setxkbmap be at startup. Of course I'd like to automate this hassle. I've tried putting the command (both directly and as a (tested) script) in crontab, preceded by @reboot through sudo crontab -e. The cron log lists this script so I suppose it has been executed, however, on startup the correct keyboard layout had not been loaded. I thought that perhaps it got overruled afterwards by system settings, but adding a minute of sleep did not work either. Neither does evoking crontab -e as regular user. Nor doing something like @reboot root /path/to/script.sh. I've looked at anacron, but that one doesn't seem to be promising more control at startup either. I've also tried putting the script in /etc/profile.d/. This breaks the system. Using ~/.profile appears not straightforward either for that matter, with reportedly inconsistent behavior. Listing bash /path/to/script.sh in startup application preferences, too, is ineffective. So do I really need to create a systemd service just for this? It seems like such a complicated ordeal for just changing the bloody keyboard layout..

I'm in Belgium (french part) and I cannot find the proper keyboard layout in Settings > Region and Languages > Input Sources.  the closest I found is the french (AZERTY) one but for the symbols such as ! and _ it's not the same keys...  what can I do to solve it ?  Thank you.


I am trying to send a google login link in email body, but it always marks as spam.  The reason which i've found only is accounts.google.com, even though the 'google.com' also not. When i put account. in start of this; it goes to spam otherwise everything works perfect.  See the link and email body below.  $google_link='accounts.google.com/o/oauth2/auth?response_type=code&redirect_uri='.$site_url.'&client_id='.$client_id.'&scope=email+profile&access_type=online&approval_prompt=auto';    $html.='
           Click here
               ';  wp_mail( $email_address,subject, $html, $headers);   Question: Is there any way to encrypt this URL in email body to send and it works proper in email/gmail inbox?   Is there any other way to avoid the email going to spam like marking specific email by it's subject using any third party mail sending tool?

This is a tricky one and I've always relied on techniques, such as permission-based emails (i.e. only sending to people you have permission to send to) and not using blatantly spamish terminology.  Of late, some of the emails I send out programmatically have started being shuffled into people's spam folder automatically and I'm wondering what I can do about it.  This is despite the fact that these particular emails are not ones that humans would mark as spam, specifically, they are emails that contain license keys that people have paid good money for, so I don't think they're going to consider them spam  I figure this is a big topic in which I am essentially an ignorant simpleton.


In reference to  explanation:  This is particularly useful in the case when a struct is a header for a variable-length object. This is exactly my case. Furthermore, I am concerned with the alignment of my structs in the heap.  In this case, I still really do not understand what's useful about zero length arrays. How are they related to this particular situation?  EDIT:  Is it that I can put as much "data" as I want in there?

I am working on refactoring some old code and have found few structs containing zero length arrays (below). Warnings depressed by pragma, of course, but I've failed to create by "new" structures containing such structures (error 2233). Array 'byData' used as pointer, but why not to use pointer instead? or array of length 1? And of course, no comments were added to make me enjoy the process...  Any causes to use such thing? Any advice in refactoring those?  struct someData {    int nData;    BYTE byData[0]; }   NB It's C++, Windows XP, VS 2003


I am trying to read content of Word file. I used code below but it is giving warning as Warning: fread() [function.fread]: Length parameter must be greater than 0  $filename=$file->getFilename(); $ext = pathinfo($filename, PATHINFO_EXTENSION); if($ext=='docx') { $fname = fopen($filename, 'r'); if (is_readable($filename))  { $content = fread($fname,filesize($filename)); echo $content; }  else  { echo 'The file is not readable.'; } fclose($fname); }

Is it possible to read and write Word (2003 and 2007) files in PHP without using a COM object? I know that I can:  $file = fopen('c:\file.doc', 'w+'); fwrite($file, $text); fclose();   but Word will read it as an HTML file not a native .doc file.


I have a large data set with several columns. One of columns are continous and another one is categorical. Can you find the correlation between those columns?

I have a nominal variable (different topics of conversation, coded as topic0=0 etc) and a number of scale variables (DV) such as the length of a conversation.   How can I derive correlations between the nominal and scale variables?


I need to prove that $e^x>x+1 \forall x\ne 0$.  Any ideas of hints about how to begin? I don't have any idea except the graphical way.

The elementary but very useful inequality that $1+x \le e^x$ for all real $x$ has a number of different proofs, some of which can be found online. But is there a particularly slick, intuitive or canonical proof? I would ideally like a proof which fits into a few lines, is accessible to students with limited calculus experience, and does not involve too much analysis of different cases.


I have just installed Ubuntu 14.04 on my toshiba laptop along side Windows 7. When the menu comes up to choose which OS to boot into, I can easily boot into Windows 7. I cannot successfully boot into Ubuntu. All I get is a blinking cursor on a black/purple screen.  I attempted the nomodeset trick, which was a bit more successful. I got a screen with a lot of code, but then it stopped with a blinking cursor at the bottom and wouldn't load anymore.  As a last resort, would returning my laptop to factory settings get rid of linux and the partitions made to the drive? I already did this to my laptop when it was just windows, which is why I thought I might as well try to add Ubuntu. But it's a lengthy process, and if it won't get rid of the partitions and ubuntu, I won't bother.  I appreciate any help ~many thanks

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


The temperature $T(x)$ at each point $x$ on the surface of Mars (a sphere) is a continuous function. Show that there is a point $x$ on the surface such that $T(x) = T(-x)$. Hint: Represent surface of Mars as $\{x \in \mathbb{R}^{3} : \|x\| = 1 \}$.  There is another post similar to this, but it only gives a hint and I didn't find the hint any more helpful. So here is my attempt:  Possible useful definition:          A path in $S \subset \mathbb{R}^{n}$ from $a$ to $b$, both points in $S$ is the image of a continuous function $\gamma$ from $[0,1]$ into $S$ such that $\gamma(0) = a$ and $\gamma(1) = b$.      Attempt:  let $f(x) = T(x) - T(-x)$.  What I envision myself wanting to do is using the existence of a path by somehow saying let $\gamma(0) = 0$ and $\gamma(1) = x$. My reasoning for this is that I somehow want to use the hint that $\|x\| = 1$. From here something should work out where $f(x) < 0$ and $f(x) > 0$ over some interval and apply IVT over this interval and I would get my equality.  Now trying to formalize this is where I am having trouble.....Is this the right idea?

I want to prove the Borsuk-Ulam Theorem:  For every continuous map $f:S^2\rightarrow \mathbb{R}^2$ there exist a pair of antipodal points $x$ and $-x$ in $S^2$ with $f(x)=f(-x)$  I did google search and I got the following hint: My Efforts I know there is quotient map $q:S^2\rightarrow RP^2$ and by property of quotient maps any continuous function from $S^2$ will factor through $q$, so I get a map from $\tilde{f}:\mathbb{R}P^2 \rightarrow \mathbb{R}^{2}$ I have inclusion map, $i:\mathbb{R}^2-\{0\} \rightarrow \mathbb{R}^2$. I have quotient map, $q': \mathbb{R}^2-\{0\}\rightarrow RP^1$. So I get a map $\tilde{i}:RP^1\rightarrow \mathbb{R}^2$ How should I proceed from here ? I am not able to construct a map from $RP^2$ to $RP^1$ For the next step, I think I have to use the fact that $\pi_1(RP^2)=\mathbb{Z}/2\mathbb{Z}$ and $\pi_1(RP^1)=\mathbb{Z}$


Suppose I have an unconstrained generic method that works on all types supporting equality. It performs pairwise equality checks and so works in O(n2):  public static int CountDuplicates<T>(IList<T> list)  {     /* ... */  }   I also have a constrained generic method that only works with types supporting sorting. It starts from sorting the list in O(n log n), and then counts all duplicates in one pass:  public static int CountDuplicatesFast<T>(IList<T> list)      where T : IComparable<T>  {     /* ... */  }   So, a caller can choose to invoke the fast method if it is statically known that the type of elements of the list supports ordering.  It might happen that the caller itself works with generic IList<T> where T is unconstrained, so its only option to invoke the first (slow) method.  Now, I want the first method to check at runtime if the type T actually implements the interface IComparable<T> and if so, invoke the fast method:  public static int CountDuplicates<T>(IList<T> list) {     if (typeof(IComparable<T>).IsAssignableFrom(typeof(T)))     {         return CountDuplicatesFast(list);     }     else     {         /* use the slow algorithm */     } }   The problem is the compiler rejects the invocation CountDuplicatesFast(list):  error CS0314: The type 'T' cannot be used as type parameter 'T' in the generic type or method 'Program.CountDuplicatesFast<T>(System.Collections.Generic.IList<T>)'. There is no boxing conversion or type parameter conversion from 'T' to 'System.IComparable<T>'.  Is it possible to persuade the compiler to trust me that I know what I am doing, and to skip the constraint check?

What's the best way to call a generic method when the type parameter isn't known at compile time, but instead is obtained dynamically at runtime?  Consider the following sample code - inside the Example() method, what's the most concise way to invoke GenericMethod<T>() using the Type stored in the myType variable?  public class Sample {     public void Example(string typeName)     {         Type myType = FindType(typeName);          // What goes here to call GenericMethod<T>()?         GenericMethod<myType>(); // This doesn't work          // What changes to call StaticMethod<T>()?         Sample.StaticMethod<myType>(); // This also doesn't work     }      public void GenericMethod<T>()     {         // ...     }      public static void StaticMethod<T>()     {         //...     } }


I've been tasked with migrating a database and I want to figure out how much resource in terms of CPU and IO does that database need before migrating it.  The target server to which the database is planned to be moved to is critical and I want to figure out if the target server can handle the load that the new db brings. Things which I am considering   Use plan cache to find the IO and CPU, but I am not sure how to translate to real CPU and IO usage on the server. Use profiler/extended events to track activities on the DB.  NOt sure how to translate it to real CPU / IO usage   What is the normal things to do in such situation?  Cheers

We currently have several shared SQL Server servers and instances in our organization. They are going with a different architecture where business units will get their own SQL Server instances. We have SQL Server 2008R2.  In the past, databases were put on servers in a more or less random fashion -- business use and disk space were the main drivers.  I've been tasked with coming up with a plan for allocating our 50+ databases across 3 servers (one instance per server). My criteria for divvying them up is as follows:   Business critical db's should be spread across the servers. i.e. avoid lumping a bunch of business critical db's all one server.   For the remainder of the non-mission critical db's, consider: a. Disk space usage b. I/O usage -- memory, CPU, etc.     1 and 2a are easy for me to figure out. I know how to get data file sizes.   My question is with that last bit - 2b. I do not know how relevant this is, what specific stats to look at, or how to get them.   Frankly, I'm not 100% sure how to phrase this question! I think I basically want to know is, "How 'busy' is this db -- however you define 'busy'?" Or maybe, "How does this db impact the performance of the server?"  I mean, disk space is important -- but it could (in theory) have a ton of rows or binary objects in there that are not written very often, so it has little impact on the performance of the server. I think I would want to know how much impact a db within a date range.  Is there a way to get these kind of general stats? I'm not looking for expensive queries, detailed user stats, or query optimization here. I'm aware of the SSMS reports, but they seem to be more real-time. The end goal is to divide up our current databases into evenly balanced buckets, and I would think performance is one way to do that.  Thoughts? Wisdom? Any other ideas on how to divvy up the db's?  Thanks! Tom


When I try to create or edit a tag wiki, I don't see the edit toolbar, neither do I see the preview below the post:    When I attempt to load an editing form for a post, it briefly shows like this, but then the toolbar and preview load properly. However, when loading an editing form for a tag wiki, it remains stuck at this state. I see the following in my JS console:   "showLowRepImageUploadWarning"in e.imageUploader||(e.imageUploader.showLowRepImageUploadWarning=e.showLowRepImageUploadWarning  Invalid operand to 'in': Object expected  Using Microsoft Edge.

Toolbar options are not displaying in  page About me section.  Issue can be reproduced in all the Stack Exchange sites.        Seeing the following error in Google Chrome console:     Uncaught TypeError: Cannot use 'in' operator to search for 'showLowRepImageUploadWarning' in undefined   at new StackExchange.MarkdownEditor (wmd.en.js?v=50f41773693e:2)


This might sound like a stupid beginner question, but... I have been using LaTeX for years and have always been looking for the exact type of font used in many econ papers, .    Some friends from the econ field told me this is just Latex's compute modern or Latin modern font (the latter gives your font a thicker, more accentuated look) or maybe some variants of times new roman. I have tried all of them on my PC (with WinEdt) and Mac (with TeXwork), but the output just don't look right.   Could anyone tell me what's the type of font in that paper and which package-if needed-should I mention in the preamble?  Thanks.

Is it possible to identify the font used in a specific document/picture?  Answers to this question should identify:   Possible methods to do this (perhaps one answer per method) and adequately describe how to use it (as opposed to merely stating it); Ways of finding the identified fonts, if possible (free or not); and Any prerequisites associated with the method used, if required (for example, "In order to use method X, your document has to be in format Y").   This question is meant as an FAQ, based on an . Its aim is to facilitate the community with the general procedures involved in font identification. Similar cases are solved on a per-usage basis on 's  tag.


I need to add a new directory to my PATH so that SublimeText can find it. I assume this should be added to either .bash_profile, .bashrc, or .profile.   Which one should I add it to?   .bash_profile already has:   export PATH="/home/josh/.rvm/gems/ruby-2.1.5/bin:/home/josh/.rvm/gems/ruby-2.2.0/bin:/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:$PATH"   in it.  .bashrc and .profile both have:  export PATH="$PATH:$HOME/.rvm/bin"   in them.   Should I have all of these in just one of the files and do multiple 'export' statements just get chained together when processed, even if from different files?

Is ~/.bashrc  the only place to specify user specific environment variables, aliases, modifications to PATH variable, etc?  I ask because it seems that ~/.bashrc seems to be bash-only, but other shells exist too…


I need to prove that the language of $0^n1^m$ is irregular if $n$ and $m$ are coprime. (Or to disprove that)  My attempt at this was to use the pumping lemma, and I've gotten $0^{n+(k-1)i}1^m$ after pumping, where $0<i\leq n$. If I'm correct, I only need to prove that $$\forall n,m : gcd(n,m)=1 \ \ \forall i\in\mathbb Z: 0<i\leq n \ \ \exists k\in\mathbb Z : gcd(n+(k-1)i, m)\not=1$$ However, I do not follow how this can be proved.

Let $L=\left\{0^i 1^{j} \mid \gcd(i,j) = 1\right\}$ I want to prove that this is not a regular language, but I am having trouble finding a string I can pump resulting in the string not being in the language. Ideally, rather than a full solution, I'd like suggestions for a string that I could use in this proof. I've played with the idea of setting $j = 2$ and $i = 2n+1$, but I don't think that would work.


$a\in\Bbb{Z}[i]$ is an irreducible element such that $a$ divides $p$ ($p$ is a prime number such that $p \equiv 1 \pmod 4$). Then show that $N (a) = p$.    $N (\alpha) = a^2 + b ^ 2$ with $\alpha = a + ib$  Does somebody know the proof of that ?

Let $\pi \in \mathbb{Z}[i]$ irreducible and $\pi$ divides $p$ ($p\in\Bbb Z$ prime). Then show that $N(\pi)=p$.   ($N(\alpha)= a^2 +b^2$ where $\alpha = a+ib$.)


I made an Interactive animation by using Flash. But my clients wants an HTML version. And all they need is to play it in IPAD. My question is, Does anybody know how convert from SWF to HTML5 and transfer to IPAD? The file size is like 30MB.

My website has a number of instructional videos that would be very helpful to be viewable on an iPad.  The video player is SWF, and the video itself is FLV.  Questions:   Can I replace the flash player swf app with a different container that will play the FLV video content? Or... Do I have to also re-encode the video to a different format? ... and what would that format be?


Evaluate the limit: $$ \lim_{n \to \infty}e^{-n}\sum_{k = 0}^n \frac{n^k}{k!} $$ It is not as easy as it seems and the answer is definitely not 1.  Please help in solving it.

I'm supposed to calculate: $$\lim_{n\to\infty} e^{-n} \sum_{k=0}^{n} \frac{n^k}{k!}$$ By using WolframAlpha, I might guess that the limit is $\frac{1}{2}$, which is a pretty interesting and nice result. I wonder in which ways we may approach it.


I am trying to make a crown molding with bezier curves where I make a path along the wall, and then in Bevel object, selecting a profile of the molding that I made with another bezier curve. When I do this, it works, but is in the wrong direction. I need the molding to be facing outwards, away from the wall, rather than inwards.

I've googled and also searched the answers here but couldn't find my problem so here goes:  I know how to bevel a curve using another object and when I try it with a normal circle it's fine. But I'm trying to use this flat oval shape to bevel a larger curve of the same shape and it's not following the curve at the correct rotation. I've tried everything, rotating the bevel object, clicking random options in the object data menu.. I can't seem to budge it from looking how it is in the screenshot. In the screenshot you can see the curve I've failed to bevel correctly and also the bevel object in the bottom right.  Basically, I want the flat part of the oval to be above and below the curve, not on the sides as it is. I hope that makes sense. Anyone know what I need to do?


I'm trying to set up a LAN server for my family to use at home, where anyone can hop on and play anytime. Because of this, I don't want to use the "Open to LAN" feature on the pause menu since the server would close as soon as I exit that world. I'd like to use the server.jar found  so that I can always have it running in the background without having to be on the server myself. How can I run the server in a way that makes it accessible to any players on my local network?

I would like to create a minecraft server for me and and my boyfriend to play on.  How do I set it up? Do I need any additional software? Do you have some links to walkthroughs or tutorials?  I have tried to set this up a few times but have failed every time.


I wasn't sure whether this was more suitable for here or SuperUser, so feel free to migrate it if necessary.  I am using a dell optiplex 7050 running Ubuntu 19.10, of which I am super user. The desktop was previously connected to my University network via an ethernet cable. I've brought my desktop home and plugged the ethernet cable into my home internet using the same ethernet cable. I have run the google speed test, and the connection speed is fine, around 70mbps.  The default Google search works fine and loads the initial search page, but all other webpages, including SE / Wikipedia / my university website do not load. I have tried Firefox (my normal browser), but it says 'unable to connect - can't establish a connection to ucl.ac.uk. I switched to google chrome, but the same thing happened: ERR_ADDRESS_UNREACHABLE.  I appreciate this is a very broad question, but I have no idea where to start fixing it. Can someone point me in the right direction to try figure out what's going on.  Please me let me know of any commands I can run and post here to help diagnose the issue.

I suspect that the name server provided by my ADSL modem/router is buggy. Whenever I browse to a website for the first time in ubuntu, resolving the domain name takes at least 15 seconds.  To work around that problem, I changed the nameserver configuration in /etc/resolv.conf from 192.168.1.1 (my ADSL modem) to 8.8.8.8 (google's primary DNS). This seems to fix the problem, but unfortunately my changes to /etc/resolv.conf are overwritten by "NetworkManager" at each startup.  What is the proper way to configure the name server IP in ubuntu 10.4?


Throughout the stack exchange sites, often times it happens with me that I find a particularly engaging discussion on a topic, but can't read it immediately due to lack of time or whatever.  When I later try to find that discussion, I cannot at times. It's frustrating.   I'm aware of the star symbol under questions which lets me bookmark it. But if I have to find a particular comment, I still have to scroll down a lot to find it. It's a real pain in the a**.   I'm not looking to permalink a discussion to share it somewhere else. I just want to be able to bookmark it for my own reading...later.   How can I do this? Is there a browser plugin or such that'll let me do this?

I've seen a similar thread for  and a question concerning the very feature I mean in  but no actual suggestion. I decided to post one in order to see if other users agree that such a feature would be of use and also to find out if it would be technically feasible (requiring a sane amount of code modification).  Among the comments on Stack Overflow (and other SE sites), there are some genuine gems. Be it a piece of advice, a suggestion or just a hilarious remark, a comment is sometimes worth returning to.  While I know how to bookmark the comments in my browser, I find this pretty annoying while switching computers (it's hard to keep sync between different browsers). I'd like to keep them in one place, preferably in my SO profile.  Personally, I'd love and use a feature like this. What do you think about it?


Not trying to do anything malicious or violate copyrights. Just out of pure curiosity. If dd creates a full clone of a disk, will it work if I use dd to make a full copy of windows 10 with a license key to another drive and boot it on another computer and have it still worked?

This is a  about Licensing.    Questions on licensing are off-topic on Server Fault.  If your question has been closed as a duplicate of this question, then this is because we want to help you understand why licence questions are off topic rather than just telling you "it just is". In all likelihood, this question will not address your question directly, it was not meant to.    I have a question regarding software licensing. Can the Server Fault community please help with the following:   How many licenses do I need? Is this licensing configuration valid? What CALs do I need to be properly licensed? Can I run this product in a virtual environment? Can I downgrade this product to an earlier version? Am I entitled to feature X with license Y?


We repeatedly make an experiment where we count the number $n$ of Bernoulli trials of known probability $p$, until some number of successes $s$ is reached. I'm willing to restrict to $p<0.01$ and $s>100$.  I want the distribution of $n$; or just its variance, for I'm confident the distribution is close enough to a Gaussian of mean $s/p$.  Up to the last moment before hitting post I hoped the answer would emerge from memory, reasoning, web search, or a reference, but..    I get that the distribution of the number of success after some fixed number $m$ of trials (not directly what I want) follows a Binomial distribution of parameters $m$ and $p$, which can be approximated by a Poisson distribution with $\lambda=m\cdot p$; and because $\lambda$ is large (about $s$), another valid approximation in the region of practical interest is a Gaussian distribution of mean $m\cdot p$ and standard deviation $m\cdot p(1-p)$. But I fail to progress from there.

Suppose you have a series of n trials, where the probability of success  in each trial is p.  The distribution of the number of successful trials follows a Binomial distribution with parameters (n, p).  The mean is given by np whereas the variance is np(1-p).  So far so good: this is pretty mundane Stats 101 stuff.  But suppose now that I only knew about the successful trials, and had no knowledge of the total number n of trials, which is the variable I am interested in estimating.  For example, I knew I had 100 successful trials, where each trial had a 0.1 chance of success.  Is there a known probability distribution that describes the probable outcomes for n, the total number of trials?  Estimating the mean is easy: if m is the number of successes, then it's just m/p.  But what about variance and other measures?  What if each success had a different (but known) chance of success?  Suppose I had the following records:   success1 (with p=0.1) success2 (with p=0.1) success3 (with p=0.2)   Again, a good estimation of the total number of trials can be obtained by simply summing 1/p for each successful trial.  In this case that number  is 10+10+5=25.  But what about variance and other measures?


In the time between submitting the first draft of a paper to a journal and submitting the third and final version (now), my institutional affiliation has changed.  Should I indicate my original affiliation on my (latest) submission, or my current affiliation?  All the work for the paper was done while I was at the previous institution.

I am moving from one job to another (postdoc to tenure track) this summer and I have papers in several stages of being written, these go from handwritten notes with all the necessary arguments to under revision at a journal. All the papers will have my new contact information put on them but where is the line for changing affiliation? It seems obvious to me that the one that is still in the handwritten notes stage will get the new affiliation and that the ones under revision won't. So somewhere in between is a line.   Where is it?  There are some similar questions so far (see  and  but they do not seem to be quite the same situation since I am not changing fields and the appointments are not concurrent.


Okay. This is similar to a question I asked a few days ago. I am trying to show that $Aut~ Z_p$ is isomorphic to $Z_{p-1}$, where $Z_p$ denotes the congruence class of integers $\mod p$ and $p$ a prime. I have shown $Aut~ Z_p$ consists of $p-1$ elements, using the fact that a homomorphism is uniquely determined by how it maps $[1]_p$, the generator of $Z_p$; the only element it cannot be mapped to is $[0]_p$, otherwise $[1]_p \rightarrow [k]_p \neq [0]_p$ extends to an automorphism.  Now I am trying to show that $Aut~ Z_p$ is a cyclic, and show that mapping the generator of $Aut~ Z_p$ to $Z_{p-1}$ defines an isomorphism. However, I am having trouble showing this. I could use some hints.  Note: At this point, I don't know anything about fields (let alone rings), the order of an element, and related concepts.   Edit: I noticed that the question was asked , but from my cursory reading I didn't see any ideas I could use yet.

I am writing another exam in Algebra this week and this time the main topic is automorphism. I was again going through the example exercises and exams from previous years and this problem is giving me a hard time to understand:  Prove that for group of automorphisms $\def\Aut{\operatorname{Aut}}\Aut(\mathbf{Z_{n}})$ holds  $\Aut(\mathbf{Z_{n}})\simeq \mathbf{Z_{n}^{*}}$ where $\mathbf{Z_{n}^{*}}=\{1 \leq k \leq q | \gcd(k,n)=1\} $.  My main issue with this problem is that it seems very "general" and I don't really know how to address it with any of the techniques we have used.  Could you please show me some ways this could be approached? I appreciate your help.


I would like to know how to slice my Python string every nth character/letter (in my case the 5th character/letter).   So I have this string "ilikestackoverflow" and I would like for the output to be "ilike stack overf low".

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


I have two txt files :    file1.txt:  user1@domain.fr   user2@domain.fr   user3@domain.fr   user4@domain.fr   ...   file2.txt:  user2@domain.fr   user4@domain.fr     fileIwouldhave.txt:  user1@domain.fr   user3@domain.fr   ...   I'd like to delete addresses in file2.txt to file1.txt.  How can I do it?

I have two lists, a complete list and a partial list. I want a bash script that will search the complete list for any lines that are in the partial, if there are, they will be removed from the complete list. Can anyone help?


I was wondering about the microscopic reason why for example when I open the window in the winter the colder air from outside is more likely to be distributed on the floor (of course only in the first time when the air in the room have not yet thermally equilibrated everywhere). On a macroscopic scale I know that the difference in the density together with Archimedes principle leads to the right reasoning.

The usual explanation for warm fluids rising past cooler ones is that the warmer fluid has a lower density.  I'm trying to understand what this looks like at a molecular scale.  The density seems to be a large-scale phenomenon, and I don't understand how it can affect whether a particular molecule rises or falls.  Consider a cylinder of fluid that is being heated at the bottom.  The molecules at the bottom have a higher average energy.  How does this result in the tendency of the warmer molecules at the bottom to move upwards past the cooler ones?


Suppose $X$ has a continuous, strictly increasing cdf $F$. Let $Y = F(X)$. What is the density of $Y$? Then let $U \sim unif(0,1)$ and let $X = F^{-1}(U)$. Show that $X\sim F$.   The first part seems like the density of $Y$ is just the pdf $f(X)$. The wording of the problem is confusing me though.

Let $X$ be a random variable with a continuous and strictly increasing c.d.f. function $F$ (so that the quantile function $F^{−1}$ is well-deﬁned). Deﬁne a new random variable $Y$ by $Y = F(X)$. Show that $Y$ has a uniform distribution on the interval $[0, 1]$.  My initial thought is that $Y$ is distributed on the interval $[0,1]$ because this is the range of $F$.  But how do you show that it is uniform?


Looking the size of each file in your system manually in order to find the bottlenecks is, obviously, too inefficient. What is the correct way to have a good overview of which files are consuming most of the resources of your disk, in order to decide which ones to discard?

I need an app that tells about file & folder sizes, like what is the biggest file and/or folder on my hard disk, sort this detail from biggest file and/or folder to the smallest & vice versa, also able to tell me about this detail based on the folder that I have chosen.


Sometimes a Google search will show a Quora page and when you visit it, you are forced to sign up or log in. I do have a Quora account but I don't want to sign in on every computer I work on.  How can the login popup be bypassed so that I don't have to spend several minutes in signing in or signing up when I only need to see that Quora question for something very quick?

Quora only shows its first answer on a question's page, the rest gets blurred out.  It then asks the user to register to read all the answers. I really do not like such bullying tactics and I hence will never register.  Yet before I blacklist Quora entirely from my Google searches, I wonder if there was a way to read all the answers without having to register.


I am a new developer in java, and i am making a small app i am getting error about null object reference Here Is My Logcat File: E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.torque, PID: 24687 java.lang.IllegalStateException: Could not execute method for android:onClick at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:414) at android.view.View.performClick(View.java:5610) at android.view.View$PerformClick.run(View.java:22265) at android.os.Handler.handleCallback(Handler.java:751) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6077) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) Caused by: java.lang.reflect.InvocationTargetException at java.lang.reflect.Method.invoke(Native Method) at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409) at android.view.View.performClick(View.java:5610)  at android.view.View$PerformClick.run(View.java:22265)  at android.os.Handler.handleCallback(Handler.java:751)  at android.os.Handler.dispatchMessage(Handler.java:95)  at android.os.Looper.loop(Looper.java:154)  at android.app.ActivityThread.main(ActivityThread.java:6077)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.drawerlayout.widget.DrawerLayout.openDrawer(int)' on a null object reference at com.example.torque.NavDrawermenu.openDrawers(NavDrawermenu.java:48) at com.example.torque.ProfileActivity.ClickMenu(ProfileActivity.java:19) its showing errors in my two files Profileactivity and nav drawer activity Here is Navdrawer.java Code I Think the error is in the openDrawer function: public void ClickMenu(View view) {     openDrawer(drawerLayout); }  public static void openDrawer( DrawerLayout drawerLayout) { drawerLayout.openDrawer(GravityCompat.START); }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Let $\frak{g}$ be a simple Lie algebra over $\mathbb{C}$. We will call a representation of $\frak{g}$ tautological if it is a fundamental representation of smallest dimension.   For $V$ a tautological representation, can all representations of $\frak{g}$ be realised as a sub-representation of some tensor power of $V$?  My intuiton here comes from the A-series . . .

Under what conditions can you determine all representations of a Lie algebra from the fundamental and antifundamental ones using just the tensor product, direct sum and Clebsch-Gordan decomposition? I think this is true for $\mathfrak{su}(2)$ and $\mathfrak{sl}(2,\mathbb{C})$, or at least that's what physics books lead me to believe!   Is it true in general for semisimple Lie algebras?


I would like to know which form of this question is “more correct” than the other:   What would you have preferred (that) he do? What would you have preferred him to do?

Why is this sentence correct?     She suggested that he go to the cinema.   I would definitely use goes instead of go.


What is the largest possible frequency of AC that could be produced inside of an electric circuit (if there is such a limit). And what effects would such a high frequency have?

As a start I assumed  which is the reciprocal of  as the frequency upper limit, but not so sure. On the other hand, is there a lower limit? Can we consider the reciprocal of our universe as a theoretical limit which is not yet limited, or just assume 0? I am just curious to know if you have any ideas with thanks.


I have the following sentence and am struggling to work out where the comma goes. Should it be:  She said, 'I understand', and walked away.  or   She said, 'I understand,' and walked away.  Many thanks. Jo

What is the rule for comma placement before a quotation mark? When should the comma go before and when should it go after the quotation mark?


I'd like to know if there's a way of having multiple equations in one block of equation. Here's my first equation:  \begin{equation}    \binom{n}{2} + 3 = \frac{1}{2} n^2 - 2 \end{equation}   Now I'd like to write every step of this problem. Is this possible without creating more equation blocks?

What is the "best LaTeX practices" for writing equations with multiple steps?  Feel free to recommend packages that might help.  Do these methods work just as well within an enumeration?  Here is what I currently do:  \documentclass{article}  \begin{document}  \begin{enumerate}  \item Using the previous property, $|\mathbf{x} + \mathbf{y}|^2$  \( = (\mathbf{x} \cdot \mathbf{y}) \cdot (\mathbf{x} \cdot \mathbf{y}) \)  \( = \sum_{i=1}^k (x_i + y_i)(x_i + y_i) \) (by the definition of inner product  \( = \sum_{i=1}^k (x_i^2 + 2 x_i^{} y_i^{} + y_i^2) \)  \( = \mathbf{x} \cdot \mathbf{x} + 2 \mathbf{x} \cdot \mathbf{y} + \mathbf{y} \cdot \mathbf{y} \)  \( \leq |\mathbf{x} \cdot \mathbf{x}| + 2 |\mathbf{x} \mathbf{y}| + |\mathbf{y} \cdot \mathbf{y}| \)  \( \leq |\mathbf{x}| |\mathbf{x}| + 2 |\mathbf{x}| |\mathbf{y}| + |\mathbf{y}| |\mathbf{y}| \) (by Property 4)  \( = (|\mathbf{x}| + |\mathbf{y}|)^2, \)  and since both sides are $\geq 0$, we can take the square root.  \end{enumerate}  \end{document}   The main problem is that, because of the enumerate environment, I can't indent each step of the equality, so that first term looks sort of separate...


Let $u \equiv w \bmod \Phi(m)$. if $\operatorname{gcd}(a, m)=1$ then how to elementary prove that $a^{u} \equiv a^{w} \bmod m$ ?

I've read about Fermat's little theorem and generally how congruence works. But I can't figure out how to work out these two:   $13^{100} \bmod 7$ $7^{100} \bmod 13$   I've also heard of this formula:  $$a \equiv b\pmod n \Rightarrow a^k \equiv b^k \pmod n $$  But I don't see how exactly to use that here, because from $13^1 \bmod 7$ I get 6, and $13^2 \bmod 7$ is 1. I'm unclear as to which one to raise to the kth power here (I'm assuming k = 100?)  Any hints or pointers in the right direction would be great.


I have ubuntu 12.04 and I want to update to 13.04, but without downloading it from the website. How can I do it ?

What are the different ways I can use to upgrade Ubuntu from one release to another?


What actually happens inside a loop when placed in a changing magnetic field that EMF gets induced across it? And also if it is connected and the direction of the magnetic field is changed then subsequently the  direction of flow of current changes. To sum up I would like to ask the scientific reason behind the Faraday's law.

I want to know if there is any way to prove the Faraday's law or is it just an experimental observed phenomena?  More specifically, is there any reason why the proportionality constant is 1? How did Faraday discover it? I also heard that we can prove Faraday's law using the principle of least action, but is that true?


I am trying to create a LaTeX document that will automatically number paragraphs without the need to use \paragraph - the reason for this is that I am processing text that will be written by others who do not use LaTeX.  Edit: this is why the solution at  does not address my particular problem as it requires that \paragraph is replaced by \item.  This gives me the same problem as far as I can tell.  I have searched for several solutions which have helped me make progress and also warned that the use of \everypar can be problematic...  The current situation is that I almost have a solution but a new \section or \subsection causes the subsequent paragraph to drop the numbering as shown in the attached image.  Further paragraphs are numbered correctly.  Alternative numbering solutions would be acceptable to me - I have no real preference for whether the paragraph numbers flow consecutively through all sections or follow a within-section pattern.  My minimal working example is as follows (note I have a need to use the \titlesec package to make the document look pretty).  I am really scratching my head about this one - any help or pointers will be gratefully received!  \documentclass[11pt]{article} \usepackage{lipsum} \usepackage{titlesec}     \setcounter{secnumdepth}{3}  \newcounter{para} \newcommand*{\numberedparagraph}{% \refstepcounter{para} \textbf{\thepara.\space} }  \let\oldep\everypar\newtoks\everypar   \oldep{\the\everypar\everypar{\numberedparagraph}}  \begin{document}  \everypar{\numberedparagraph}  \section{Section 1}  \lipsum[1-2]  \section{Section 2}  \lipsum[4-5]  \subsection{A Subsection}  \lipsum[6-7]  \end{document}

I am using the paragraph section head, i.e.,   \paragraph{This is a cool paragraph}    I would like it to compile with numbering. If I change the secnumdepth (i.e., \setcounter{secnumdepth}{4}) this will work, but produce the "wrong" type of numbering, i.e.,      1.1.1.1 This is a cool paragraph      1.1.1.2 This is another cool paragraph etc.   What I would like is      1 This is a cool paragraph      2 This is another cool paragraph   or, if not,      1.1 This is a cool paragraph      1.2 This is another cool paragraph   where the first 1 indicates the section number and suppresses the subsection and subsubsection numbers. Can this be done?


I think I understand how the equivalence principle shows how light can bend and therefore space must be curved. What I do not understand is how curved space makes an object move directly toward the center of the earth.  I think what I am missing is how time is bent in the presence of mass as well.  If some could please explain how time is bent in the presence of mass, and how curved space results in an object moving straight down when I drop it. GR is driving me crazy.

They say that gravity is technically not a real force and that it's caused by objects traveling a straight path through curved space, and that space becomes curved by mass, giving the illusion of a force of gravity.  That makes perfect sense for planetary orbits, but a lot less sense for the expression of gravity that we are the most familiar with in our day-to-day lives: "what goes up must come down."  Imagine that I hold a ball in my hand, several feet off the ground, with my fingers curled around it, and my hand is above the ball.  Then I open my fingers, releasing my grip on it, being very careful to not impart any momentum to the ball from my hand as I do so.  An object at rest remains at rest unless acted upon by an outside force.  If the ball is not moving (relative to my inertial reference frame), it has no path to travel that's any different from the Earth's path through space.  It should remain at rest, hanging there in the air.  And yet it falls, demonstrating that an outside force (gravity) did indeed act upon it.  How does curved space explain this?


I am creating an adventure map and I need the player to be able to place levers on gold blocks. How can I do this via command block?

I want people to only be able to place TNT on only Quartz Blocks and I've see this done before where you can only place blocks on certain other blocks but I'm not sure of the command used to do that.  Does anyone know?


The task says: Find generating function for a series $a_n$ ($ n \geq 0$) where $a_n$ is subsets of some $n$-memeber set  I tried to solve it but couldn't so I looked in solutions, this is a solution  $$a_n=2^n \qquad f(x)=\sum_{n \geq 0} 2^nx^n=\frac{1}{1-2x}.$$  What I don't understand is, why is $ a_n = 2^n $?  Thanks for help!

What is the proof that given a set of $n$ elements there are $2^n$ possible subsets (including the empty-set and the original set).


I am no stranger to booles, but this one won't work and it is driving me crazy. What am I missing here?

When using a Boolean modifier on an object, the "Operation" choices (Difference, Union, Intersect) are all not working normally. Choosing "Union" makes it do the effect of "Intersect" and "Difference" makes it do what "Intersect" is supposed to do. What's the deal here?   This is happening with following a simple tutorial. It's a simple primitive cube and primitive cylinder. No normals or doubles problems.   My specs are:  Macbook Pro 13" Retina early 2015 512GB i7 with 16gb RAM upgrade OS-X version 10.11.4


I want to change the background image URL from a JS controller using jQuery. How can I change background in the :after pseudo class?  document.querySelector('.className').style.background = `url('${profilePicture}')`;   SASS file:  .className {     width: 0%;       &:after {          background: url("../../../images/user.svg") center no-repeat;               }        }

I have an image URL in a imageUrl variable and I am trying to set it as CSS style, using jQuery:  $('myObject').css('background-image', imageUrl);   This seems to be not working, as:  console.log($('myObject').css('background-image'));   returns none.  Any idea, what I am doing wrong?


I'm not sure how else to write the title, but here goes!  I'm currently designing a new logo for an organization. I have designed various mockups sketches, but my client has rejected them all, and I have to go back to square one. I initially gave the client a design brief for her to fill out, but should I file another, revised one or should I just design more with the design brief I already have?  Sorry if this question might sound awkward; I'm not sure how else to phrase it.  Thank you! :-)

I'm in a process of creating Graphic Design contract. I've decided to provide each client with 3 logo concepts and 3 rounds of revision. Ideally, I would create 3 concepts and client will chose one, but it happend to me before that client didn't like and concept and I end up with doing 10+ more (yes, I've worked without contract).  How can I prevent this situation? Should I charge hourly for each new concept separately? How can I express my thoughts clearly in a contract (without sounding like 'if you don't like any, you'd have to pay more)? I don't want to scare client and put thoughts into their minds saying that there is a possibility that they won't like me ideas.


I have a several systems running Ubuntu 16.04.  I use git to manage my . files so I can maintain the same settings across systems, but the gnome-terminal settings are not in these files and instead in gconf.  I'm now adding an Ubuntu 18.04 system and I'd like to export my settings from 16.04 and import them on my 18.04 system.  How can I accomplish this for gnome-terminal settings from 16.04 to 18.04?

I made some custom GNOME-Terminal settings and profiles, and I want to preserve those after reinstalling Ubuntu.  What do I have to save to backup my settings, and how do I reapply them afterwards?  This is not a duplicate of , because   Configuration systems changed since the old question, from gconf to dconf. The other question does not explain how to properly backup, and then reapply the settings.


I have an  ASUS X55A-SPD0204O laptop. The rest of the FN+Fx (where x = number) like sound + - mute, screen turn off, wireless etc. work perfectly.  The problem is with the 2 brightness keys. They just won't work. Any suggestions?

The brightness shortcuts via fn key don't work.  I tried each solution from . After editing /etc/default/grub file I rebooted.  GRUB_CMDLINE_LINUX="acpi_osi=Linux" GRUB_CMDLINE_LINUX="acpi_backlight=vendor" GRUB_CMDLINE_LINUX="acpi_osi=linux acpi_backlight=vendor" GRUB_CMDLINE_LINUX="acpi_osi_Linux"   What other workarounds/solutions are there?  Relevant output:  $ sudo lshw -C display   *-display UNCLAIMED             description: 3D controller        product: GK107M [GeForce GT 750M]        vendor: NVIDIA Corporation        physical id: 0        bus info: pci@0000:01:00.0        version: a1        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list        configuration: latency=0        resources: memory:f6000000-f6ffffff memory:e0000000-efffffff memory:f0000000-f1ffffff ioport:e000(size=128) memory:f7000000-f707ffff   *-display        description: VGA compatible controller        product: 4th Gen Core Processor Integrated Graphics Controller        vendor: Intel Corporation        physical id: 2        bus info: pci@0000:00:02.0        version: 06        width: 64 bits        clock: 33MHz        capabilities: msi pm vga_controller bus_master cap_list rom        configuration: driver=i915 latency=0        resources: irq:50 memory:f7400000-f77fffff memory:d0000000-dfffffff ioport:f000(size=64)


For an example I have 100 tables (table1,table2,table3,table4 and table5.....) in my DB, table1 with the coloumns col1, col2...col7 like wise every table has some columns. The column col7 have the value 'BOLD'. Here I want to retrieve the tables which holds the value 'BOLD'.

I would like to search an entire MS SQL 2000 database for one value. This would be to aid development only. Keep that in mind when considering this question.   This will get all the table names and the column of the data type I'm looking for:  SELECT Columns.COLUMN_NAME, tables.TABLE_NAME FROM INFORMATION_SCHEMA.Columns as Columns  JOIN INFORMATION_SCHEMA.TABLES as tables  On Columns.TABLE_NAME = tables.TABLE_NAME WHERE Columns.DATA_TYPE = 'INT'     I was thinking something like this:  -- Vars DECLARE @COUNTER INT DECLARE @TOTAL INT DECLARE @TABLE CHAR(128) DECLARE @COLUMN CHAR(128) DECLARE @COLUMNTYPE CHAR(128) DECLARE @COLUMNVALUE INT  -- What we are looking for SET @COLUMNTYPE = 'INT' SET @COLUMNVALUE = 3 SET @COUNTER = 0  -- Find out how many possible columns exist SELECT @TOTAL = COUNT(*)   FROM INFORMATION_SCHEMA.Columns as Columns  JOIN INFORMATION_SCHEMA.TABLES as tables  On Columns.TABLE_NAME = tables.TABLE_NAME WHERE Columns.DATA_TYPE = @COLUMNTYPE PRINT CAST(@TOTAL AS CHAR) + 'possible columns' WHILE @COUNTER < @TOTAL BEGIN     SET @COUNTER = @COUNTER +1     -- ADD MAGIC HERE END   Any ideas?  UPDATE I recently found this  that works quite well.


Everytime I type..  sudo apt-add-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ bionic main'    I get...  E: Malformed entry 53 in list file /etc/apt/sources.list (Component) E: The list of sources could not be read.   Same thing if I try to purge wine.

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


I've looked at so many questions and answers but none of what i found has actually worked!  So basically if the title doesn't help much then what I'm trying to do is execute an AsyncTask from a dialog but it's not executing and when it does, it'll show up as an null object and if I'm honest it's bloody annoying!  So if anyone can help then that would be great.  The Class is subbed.  Here's the Async class:   static class UpdatePassword extends AsyncTask<String, String, String> {      Context context;     String oldPassword;     String newPassword;      public UpdatePassword(String setOldPassword, String setNewPassword, Context context) {         this.oldPassword = setOldPassword;         this.newPassword = setNewPassword;         this.context = context;     }      @Override protected String doInBackground(String... params) {         HttpRequestUtils httpRequestUtils = new HttpRequestUtils(context);         if (TextUtils.isEmpty(oldPassword) || TextUtils.isEmpty(newPassword)) {             return null;         } else {             String response = null;             String baseUrl = "rest/ws/user/update/password";             ApiResponse apiResponse = null;             try {                 response = httpRequestUtils.getResponse(baseUrl + "?oldPassword=" + oldPassword + "&newPassword=" + newPassword, "application/json", "application/json");                 if (TextUtils.isEmpty(response)) {                     return null;                 }                 apiResponse = (ApiResponse) GsonUtils.getObjectFromJson(response, ApiResponse.class);                 if (apiResponse != null && apiResponse.isSuccess()) {                     return apiResponse.getStatus();                 }                 Log.i("Update", "password call" + apiResponse);             } catch (Exception e) {                 e.printStackTrace();             }             return newPassword;         }     } }   And here's what I'm doing to execute it:  String oldPassword = changePassOld.getText().toString(); String newPassword = changePassNew.getText().toString(); AsyncTask task = new UpdatePassword(oldPassword, newPassword, ProfileFragment.this.getContext()); task.execute();   Edit: I have noticed that i only have doInBackground but even when i had preExecute, it still wouldn't work

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


[1] "That picture was taken in the park where I used to play."    (Here, 'where' is an relative adverb.      [2] "I remember the day when we first met."    (Here, 'when' is an relative adverb.)   Source :       [3] "Grandma remembers a time when radio shows were popular."    (Here, 'when' is a relative pronoun.)      [4] "I want to visit the island where my grandma was born."   (Here, 'where' is a relative pronoun.)   Source :    It seems to be confusing that "when" and "where" are relative adverbs in sentence [1] & [2] while they're relative pronouns in sentence [3] and [4].   How can we determine whether "when" and "where" are relativel pronouns or relative adverbs?

I am not familiar with the idea that an adverb can function as a conjunction at the same time. Here are a couple of sentences that are confusing me.     This is the reason why she left him.   ...and     He was transferred to New York, where he was promoted to a higher level.   The  why, where, when, and how seem to introduce a clause. Therefore, can they also be called conjunctions? If yes, would I be right in assuming that relative adverbs can function as conjunctions at the same time?


There are similar questions but none seems to hit the mark. I am looking for feedback on developing a desktop application using a JavaScript framework. Here are some details to remove confusion between a desktop-like web application and a true desktop application:   It needs to run entirely standalone. There are lots of discussions about JavaScript frameworks for web development but this is strictly a desktop application (using WebKit probably) which narrows the field of contenders. Needs to run on Windows, Linux and Mac at least. For performance it needs to communicate with threaded native code - C++ probably. The QtWebKit Bridge would be a possibility. This may not influence the framework used. The UI needs to have a rich set of layouts and controls just as in a native desktop app, as well as charting and custom graphics.   Some contenders include Adobe AIR, Ext JS and Dojo/Dijit. Ext JS 4 was recently released with a MVC architecture that looks very attractive and may change previous comparisons of frameworks.  I am looking for feedback from others who have experience developing desktop apps like this and strengths and weaknesses they have encountered with different frameworks.

I know there's JScript.NET, but it isn't the same as the JavaScript we know from the web.  Does anyone know if there are any JavaScript based platforms/compilers for desktop development? Most specifically Windows desktop development.


I'm a 17-year-old girl living in Mexico and dreaming of studying at a university in Romania. I speak Spanish and English and am trying my best to learn Romanian, and I can hardly find anyone to whom I can speak in Romanian. My only Romanian e-friend who's actually willing to help won't Skype with me because he lives with his family and the time difference means he'd wake them if we were to Skype at a decent time for me.   Now that you know this, you can imagine my excitement when I randomly found an active user with a totally Romanian name, Bogdan Alexandru, and even more so when I clicked his profile and found that he is indeed from București. But he has no contact links on his profile. Is there any way I can contact him and offer to trade services (like an I'll-help-you-with-Spanish-if-you-help-me-with-Romanian thing)? Or will I just have to put something on my profile, answer one of his questions and hope he looks at my page?

There has been quite a few times that I wished I could send a message to another user on SO - not ask a question for everyone to see, but just a short message informing them of something or requesting them to do something.  Are there any plans to allow this to happen in the future?  Related: