a) Let $a$ be an odd integer.  If $2^a \equiv 1\ (\text{mod}\ n)$, then $ \varphi(n)|a$.  b) Let $p$ be an odd prime. There exists $a \in \mathbb{Z} >0$ with $\varphi(a) = 2p$.  I think a is false and b is true, but I'm not sure. I'd appreciate any help, thanks!

I did the following proof and I was wondering if its valid. It feels wrong because I didn't actually test the case when purportedly $n$ is not prime, but please feel free to correct me.  Assume there exists $n$ such that $\phi(n) = 14$. Assume $n$ is prime. Then $\phi(n) = n-1$. Then here, n-1 = 14, so n = 15.  We know since Euler's totient function is multiplicative that $\phi(xy)$ = $\phi(x)\phi(y)$, so $\phi(15) = \phi(3)\phi(5)$, but alas $\phi(3)\phi(5) = 2\cdot4 = 8 \ne 14$. If $n$ is not prime a similar argument follows since we know then that $n$ must be composed of prime numbers by the prime factorization theorem.


package com.example.eiraj.listviewseefrgmentsfiirst;  import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.TextView;  public class MainActivity extends AppCompatActivity {      TextView textView= (TextView) findViewById(R.id.textView);      public void show(View view){         textView.setVisibility(View.VISIBLE);     }      public void hide(View view){        textView.setVisibility(View.INVISIBLE);     }      @Override     protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    } }   here two buttons are being used to show data and hide data but whenever I try to run it emulator shows the message unfortunately uihide stopped also I downloaded the apk to run it on my phone but same message came there

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?


On the main tag page a tag can have a number to the right or not. If there is no number to the right then this means that there are either 1 or 0 questions tagged with this tag or that it is a synonym; this is confusing and sometimes annoying.  Can it be changed to remove those tags that have 0 questions, and which are not synonyms, and place a number by the tags that have one? Like this (poor) mock-up:        This leaves a clear delineation between tags with questions, tags without questions and synonyms.  I'm guessing that the ones with 0 questions attached might still be around because they haven't been "deleted" yet. If it's difficult/unwanted to remove these can we have a x 1 by the tags that do have questions and a method of identifying synonyms so people can differentiate between the three possibilities.

On the  page, the number of questions using the tag is shown for each tag, except those which are used on 0 or 1 questions.  This makes it impossible to tell which bad new tags have already been removed from their questions without duplicating someone else's effort of clicking on the tag and observing that it's unused.  I'd like to see the question count for either the 0s or 1s (or possibly both) to save time when looking through new tags.


I understand why a released object moves as it does once it has started moving, and why all objects fall at the same speed, removing other effects. But I don't see why the curvature of space would make it start to move in the first place, thank you.

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?


What I want to prove is... A conjugacy class in  $S_n$ splits into two distinct conjugacy classes under the action of  $A_n$ if and only if its cycle type consists of distinct odd integers. Otherwise, it remains a single conjugacy class in $A_n$.  To prove this statement I proved...  • A conjugacy class in  $S_n$  consisting solely of even permutations (i.e. that is contained in  $A_n$ ) either is a single conjugacy class or is the disjoint union of two equal-sized conjugacy classes when considered under the action of  $A_n$.  • If  $\sigma \in A_n$, then the elements of the conjugacy class of $\sigma \in S_n$ (which is just all elements of the same cycle type as  $\sigma$ ) are conjugate in $A_n$ if and only if  $\sigma$ commutes with some odd permutation.  • $\sigma \in S_n$ does not commute with an odd permutation if and only if the cycle type of $\sigma$ consists of distinct odd integers.  I proved first two lemma and only if part of the third lemma. But I got problem considering if part of the third lemma.  The cycle type of $(1 2 3)$ in $A_{n}$ is $(3)$. But it commutes with $(4 5)$ since $(1 2 3)$ and $(4 5)$ are disjoint. I'm not sure that I'm confusing something or the author of  is saying something wrong. I hope somebody help me.

In Dummit & Foote, page 131  Let $K$ be a conjugacy class and suppose that $K$ is subset of $A_n$ .  Show that if $\sigma$  belongs to $S_n$ then , $\sigma$ does not commute with any odd permutation if and only if the cycle type of  consists of distinct odd integers.  Deduce that $K$ is a union of two -conjugacy classes in $A_n$ if and only if the cycle type of  an element of $K$ consists of distinct odd integers.   [Hint: Assume first that $\sigma$  belongs to $S_n$ does not commute with any odd permutation. Observe that $\sigma$ commutes with each cycle in its own cycle decomposition, so that each cycle must have odd length. If two cycles have the same odd length , find a product of  transpositions which interchanges them and commutes with $\sigma$ . Conversely, if the cycle type of $\sigma$ consists of distinct integers, prove that $\sigma$ commutes only with the subgroup generated by the cycles in its cycle decomposition.]  the exercise number 21 , i uesed the hints to prove that the cycles of cycle decomposition of $\sigma $ must be of odd length , but i don't know how to prove that the cycle type is distinct . the text said find transposition which interchanges them and commute $\sigma$ , my question is , interchange what ?!!! what does this mean ? can anyone help ?


[True/False] If $S$ is a quotient ring of $R$, then either $char(S)$   divides $char(R)$, or $char(S)=0$   $char(R)$ is notation to denote characteristic of a ring $R$  Efforts,  Let $f : R \to R'$ be a ring homomorphism where $\mathrm{char}(R) > 0$.We can  show that   $$0 < \mathrm{char}(f(R)) \leq \mathrm{char}(R).$$ and it follows from Euclidean Algorithm that $char(f(R))$ divided $char(R)$  Solution:   So the statetement should be True. Right? The book says answer is False. Am I missing something here?  Thanks.

Let $\mathcal R$ and $\mathcal S$ be non zero commutative rings with unity. Then:  char($\mathcal R$) is always a prime number   $\mathbb{Q,R}$ contradicts this. ($char(\mathcal R)=0$)  2.If $\mathcal S$ is a quotient ring of $\mathcal R$ then either $char(\mathcal S)$ divides $char(\mathcal R)$ or $char(\mathcal S)=0$  True. This is the argument I used: If ring homomorphism exits between $\mathcal R$ and $\mathcal S$ then $char(\mathcal S)|char(\mathcal R)$, which is true for a ring and its quotient ring. Are there any other arguments that can be used to justify this answer? Also, if $\mathcal S$ is a quotient ring of $\mathcal R$ am I right in assuming that $char(\mathcal S)=0$ happens only when $char(\mathcal R)=0$?   If $\mathcal S$ is a subring of $\mathcal R$ containing $1_\mathcal R$ then $char(\mathcal R)=char(\mathcal S)$   True. $1_\mathcal R$ can't behave differently in a subring. Edit: Any  examples where subring has a different characteristic from that of the ring?   If $char(\mathcal R)$ is a prime number, then $\mathcal R$ is a field.   Statement is wrong (But true the other way around, Field$\implies char(\mathcal R)=0$ or prime) Are my justifications correct?


I'm trying to prove the inequality highlighted by the red line in the picture, but I do not know how. Please provide detail as much as you can, thank you!  For a minimal family, the sufficient statistic $\mathbf{T}$ is also minimal sufficient. For a proof, see Lehmann: Theory of Point Estimation, Example 5.9, pp. 43-44 If we parametrize the family using $\eta=c(\theta),$ this is called the natural parametrization (or the canonical parametrization). We then write $$ f(\mathbf{x}, \mathbf{\eta})=\exp \left(\mathbf{\eta}^{T} \mathbf{T}(\mathbf{x})-A(\mathbf{\eta})\right) h(\mathbf{x}) $$ where $$ A(\mathbf{\eta})=\log \int_{E} \exp \left(\mathbf{\eta}^{T} \mathbf{T}(\mathbf{x})\right) h(\mathbf{x}) d \mathbf{x} $$ The natural parameter space is $\mathbf{H}=\{\boldsymbol{\eta}: A(\boldsymbol{\eta})<\infty\} .$ Theorem 1 : H is a convex set. Proof: Let $0<\alpha<1$ and take $\eta$ and $\eta_{1}$ in $\mathbf{H}$. Write $$ A\left(\alpha \eta+(1-\alpha) \eta_{1}\right)=\log \int_{E}\left(\exp \left(\eta^{T} \mathbf{T}(\mathbf{x})\right) h((\mathbf{x}))\right)^{\alpha}\left(\exp \left(\mathbf{\eta}_{1}^{T} \mathbf{T}(\mathbf{x})\right) h((\mathbf{x}))\right)^{1-\alpha} d \mathbf{x}$$ But $\underline{u^{\alpha} v^{1-\alpha} \leq \alpha u+(1-\alpha) v}$ (take logarithms of both sides and use the fact that the logarithm is a concave function), whence $$A\left(\alpha \eta+(1-\alpha) \eta_{1}\right) \leq \alpha A(\eta)+(1-\alpha) A\left(\eta_{1}\right)<\infty$$

I have no idea how to do this. Any help would be appreciated. The chapter I'm on is about differentiation and the mean value theorem.  Prove $a^\alpha b^{1-\alpha} \le \alpha a + (1 - \alpha)b, \; a,b > 0,\; 0 < \alpha < 1$


I have lenovo laptop, with windows 8.1 installed. I have installed Virtual box on it, try to install ubuntu 14.04 on virtual box, it install successfully. But it work in 800 X 600 resolution, how can I make it full screen.  Thank you in advance.

I've recently installed Ubuntu on Oracle's Virtualbox.  Now I want to install the guest additions.  I started up my Ubuntu guest OS, clicked "Devices" and chose "Install Guest Additions". Nothing happened, and I don't see the CD icon on my desktop.  How can I make this work?


I went through several posts, but nothing has helped me to see wifi networks on Ubuntu 14.04 LTS.   The wifi LED is on, I have installed B43 driver as well as installer and nothing. I have the same problem with Wifi as    So I tried:  sudo apt-get purge --remove bcmwl-kernel-source sudo apt-get install linux-firmware-nonfree   These were ok, and I tried   sudo modprobe b43   Then terminal stopped. What should I do?  $ lspci  00:00.0 Host bridge: Advanced Micro Devices, Inc. [AMD/ATI] RC410 Host Bridge (rev 01) 00:01.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RC4xx/RS4xx PCI Bridge [int gfx] 00:04.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RC4xx/RS4xx PCI Express Port 1 00:05.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RC4xx/RS4xx PCI Express Port 2 00:06.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RC4xx/RS4xx PCI Express Port 3 00:07.0 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] RC4xx/RS4xx PCI Express Port 4 00:12.0 SATA controller: Advanced Micro Devices, Inc. [AMD/ATI] SB600 Non-Raid-5 SATA 00:13.0 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB600 USB (OHCI0) 00:13.1 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB600 USB (OHCI1) 00:13.2 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB600 USB (OHCI2) 00:13.3 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB600 USB (OHCI3) 00:13.4 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB600 USB (OHCI4) 00:13.5 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB600 USB Controller (EHCI) 00:14.0 SMBus: Advanced Micro Devices, Inc. [AMD/ATI] SBx00 SMBus Controller (rev 13) 00:14.1 IDE interface: Advanced Micro Devices, Inc. [AMD/ATI] SB600 IDE 00:14.2 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] SBx00 Azalia (Intel HDA) 00:14.3 ISA bridge: Advanced Micro Devices, Inc. [AMD/ATI] SB600 PCI to LPC Bridge 00:14.4 PCI bridge: Advanced Micro Devices, Inc. [AMD/ATI] SBx00 PCI to PCI Bridge 01:05.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RC410M [Mobility Radeon Xpress 200M] 02:00.0 Network controller: Broadcom Corporation BCM4311 802.11b/g WLAN (rev 01) 06:00.0 Ethernet controller: Qualcomm Atheros Attansic L2 Fast Ethernet (rev a0)     $ sudo lshw -c network *-network                       description: Network controller        product: BCM4311 802.11b/g WLAN        vendor: Broadcom Corporation        physical id: 0        bus info: pci@0000:02:00.0        version: 01        width: 32 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list        configuration: driver=wl latency=0        resources: irq:16 memory:fa9fc000-fa9fffff   *-network        description: Ethernet interface        product: Attansic L2 Fast Ethernet        vendor: Qualcomm Atheros        physical id: 0        bus info: pci@0000:06:00.0        logical name: eth0        version: a0        serial: 00:1e:8c:51:f0:ec        capacity: 100Mbit/s        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress vpd bus_master cap_list rom ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd autonegotiation        configuration: autonegotiation=on broadcast=yes driver=atl2 driverversion=2.2.3 firmware=L2 latency=0 link=no multicast=yes port=twisted pair        resources: irq:40 memory:feac0000-feafffff memory:feaa0000-feabffff   *-network        description: Ethernet interface        physical id: 1        logical name: usb0        serial: 02:f9:06:66:bc:00        capabilities: ethernet physical        configuration: broadcast=yes driver=rndis_host driverversion=22-Aug-2005 firmware=RNDIS device ip=192.168.42.29 link=yes multicast=yes

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.


Is there any tool for data migration without using data loader.Data migration shoud takes place once in 15 minutes from any source to salesforce object.I have tried import2 but it dosnt work..

I am switching from old CRM and looking for easy to use tools to import my data


If you know the Diagonal and Area of a Rectangle, can you find the sides of the rectangle?   I was doing strange math yesterday, and I can across the realization that two different rectangles can’t have the same area and same diagonal. But I haven’t been able to solve a equation that shows this. I also haven’t be able to prove myself wrong? So maybe higher math gods will help? $$\text{Diagonal}=\sqrt{x^2+y^2}$$ $$\text{Area}=xy$$

I need to write concise formulas of these two:$\space \space \space$ $(1)$ finding the dimensions of a rectangle given the Area and the diagonal $\space \space \space$$(2)$ finding the dimensions of a rectangle given the Perimeter and the diagonal  Searching on google I can only find examples using number (eg. “Let’s assume the diagonal is $5$ and the area is $25$”etc) but I’m having trouble writing down formulas that use variables (so that I can use them in my code).  Would appreciate if someone could show me how to formulate the formulas (no pun intended) for these two. Thank you!


My server has rebooted a few times in the past week due to electricity cuts. I would like to know when was the server running.  Uptime only gives me information about the last time it's been on.  Last only gives me information about user login but nobody has logged into the server during this time.  Is there a way to check this with the packages installed by default in Ubuntu server 12.04?

I'm a Rails developer working on a web application on Ubuntu Server 10.04. Due to internal requirements, I was asked to find the last 10 system boot and shutdown times... I have no clue where to find these details. Could someone help me out?


I ran into a problem I have no idea how to begin, maybe you guys can help me out. I think maybe it has something to do with parametric equations? But this is just a guess.  Find equations of both the tangent lines to the ellipse $x^2 + 4y^2 = 36$ that pass through the point $(12, 3)$. I can easily find the derivative using implicit differentiation, but what is meant by two tangent lines?

I was solving a few problems from a textbook and I came across this one:     Find the tangent lines to the graph of $x^2+4y^2 = 36$ that go through   the point $P=(12,3)$   I could find the tangency points $$ but my solution was completely messy (I had four equations that I had to go back-and-forth with.  Is there an elegant/simple solution to that?  Tangency points:  $$P_1 = (0,3)$$ $$P_2 = \left( \frac{24}{5} , 3-\frac{24}{5} \right)$$


Iv installed Ubuntu-GNOME and immediately after that as an old habit I tried to add "Open in terminal" Option in my right click menu. By using   sudo apt-get install nautilus-open-terminal   and  nautilus -q     But then I realized that I already have this option in my right click menu, And now I dont know how can I disable nautilus-open-terminal. I searched nautilus in my softwares but I found nothing.   also tried to use   apt-get --purge remove nautilus-open-terminal    But I faced this error:  E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   How can I fix my Right-Click menu?

I get this error whenever I try to install programs using the terminal:  home@ubuntu:~$ apt-get install myunity E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   Also I'm unable to install updates using the terminal.


I'm creating a simple sortedLL, right now I'm struggling using templates in C++. I am getting an error when compiling, which I'm attaching at the end of this post. Am I missing/coding something wrong when using templates?    sortedLL.h  template <class T> class sortedLL { private:     struct Node     {         T data;         int count;         Node * next;         Node (T data)         {             this->data = data;             count = 1;             next = NULL;         }     };     Node* head;     int lengthLL;     Node* search(T value);     void sortLL(); public:     sortedLL();      void insert(T value);     void printLL();   };   sortedLL.cpp  #include "sortedLL.h"  template <class T> sortedLL<T>::sortedLL() {     head = NULL;     lengthLL = 0; }  template <class T> void sortedLL<T>::insert(T value) {     if (head == NULL)         head = new Node (value);     else     {         Node* searchNode = search(value);         if (searchNode != NULL)         {             searchNode->count++;             sortLL();         }         else         {             Node* newHead = new Node(value);             newHead->next = head;             head = newHead;         }     }  }  template <class T> typename sortedLL<T>::Node * sortedLL<T>::search(T value) {     Node* currentNode = head;     while (currentNode != NULL)     {         if (currentNode->data == value)             return currentNode;         else             currentNode = currentNode->next;     }     return NULL; } template <class T> void sortedLL<T>::printLL() {     if (head == NULL)         std::cout << std::endl;     else     {         Node* currentNode = head;         while (currentNode != NULL)         {             std::cout << currentNode->data << ": " << currentNode->count << std::endl;             currentNode = currentNode->next;         }     } }  template<class T> void sortedLL<T>::sortLL() {     //Perform sort here  }   main.cpp  #include <iostream> #include "sortedLL.h" int main() {      sortedLL <int> LL;     LL.insert(1);     LL.insert(2);     LL.insert(4);     LL.printLL();     std::cout << std::endl;     LL.insert(1);     LL.printLL();      return 0; }   Error    Here is the error in text:  Scanning dependencies of target sortedLL [ 66%] Building CXX object CMakeFiles/sortedLL.dir/main.cpp.o [ 66%] Building CXX object CMakeFiles/sortedLL.dir/sortedLL.cpp.o [100%] Linking CXX executable sortedLL Undefined symbols for architecture x86_64:   "sortedLL<int>::insert(int)", referenced from:       _main in main.cpp.o   "sortedLL<int>::printLL()", referenced from:       _main in main.cpp.o   "sortedLL<int>::sortedLL()", referenced from:       _main in main.cpp.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) make[3]: *** [sortedLL] Error 1 make[2]: *** [CMakeFiles/sortedLL.dir/all] Error 2 make[1]: *** [CMakeFiles/sortedLL.dir/rule] Error 2 make: *** [sortedLL] Error 2

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


Why is $\mathbb Q(\sqrt 2+\sqrt 3)=\mathbb Q(\sqrt2,\sqrt 3)$ ?  I am Having problems understanding why this is true.  Any input would be greatly appreciated!

Is $\mathbf{Q}(\sqrt{2}, \sqrt{3}) = \mathbf{Q}(\sqrt{2}+\sqrt{3})$ ?    $$\mathbf{Q}(\sqrt{2},\sqrt{3})=\{a+b\sqrt{2}+c\sqrt{3}+d\sqrt{6} \mid a,b,c,d\in\mathbf{Q}\}$$   $$\mathbf{Q}(\sqrt{2}+\sqrt{3}) = \lbrace a+b(\sqrt{2}+\sqrt{3}) \mid a,b \in \mathbf{Q} \rbrace  $$  So if an element is in $\mathbf Q(\sqrt{2},\sqrt{3})$, then it is in $\mathbf{Q}(\sqrt{2}+\sqrt{3})$, because $\sqrt{6} = \sqrt{2}\sqrt{3}$.  How to conclude from there?


In my current implementation, I was trying to create custom class inherited by IDictionary<string, Object> interface.  While implementation, I have to implement the below property  IsReadOnly { get; } part of  ICollection<KeyValuePair<TKey, TValue>> interface.   So while doing this I came across below scenario,  I am not seeing that IsReadOnly Property in  Dictionary<TKey, TValue> (.NET built in class) class, then how property implementation of ReadOnly in not exists in Dictionary class as this class is also inherited through ICollection<KeyValuePair<TKey, TValue>> interface.  I have same query regarding CopyTo method also.  This is just my conceptual question.

What are the differences in implementing interfaces implicitly and explicitly in C#?  When should you use implicit and when should you use explicit?  Are there any pros and/or cons to one or the other?    Microsoft's official guidelines (from first edition ) states that using explicit implementations are not recommended, since it gives the code unexpected behaviour.  I think this guideline is very valid in a pre-IoC-time, when you don't pass things around as interfaces.  Could anyone touch on that aspect as well?


I want to loop over the value of an input argument, something like that  for i in {0..$1} do   echo $i done   If i call my script: ./my.sh 2  I want  0 1   But i get   {0..2}   How can i do it ?

How do I iterate over a range of numbers in Bash when the range is given by a variable?  I know I can do this (called "sequence expression" in the Bash ):   for i in {1..5}; do echo $i; done   Which gives:     1    2    3    4    5   Yet, how can I replace either of the range endpoints with a variable? This doesn't work:  END=5 for i in {1..$END}; do echo $i; done   Which prints:     {1..5}


I guess the website got this wrong. It says that the Earth is a common noun. In my view it should be a proper noun. Please see the .          The earth moves round the sun.           • Earth is a common noun   • Earth is an abstract noun   • Earth is a proper noun

At the beginning of a sentence is obvious.  I'm referring to the following examples:        A handful of earth.   The earth under this house.   The earth beneath my feet.   What on earth?   The heavens above and the earth below.   The earth moved.   We returned quickly to earth.      Lower: 1,2,3,4 Upper: 7 Not sure: 5,6


We have a large and fairly well tuned SQL Server 2016 Enterprise Edition. Given the number of cores we have, our tempdb is currently comprised of 16 2,950 MB files running on a ram disk with a 16 GB transaction log file. All of the files are set to not autogrow and, as a general rule, this has run fine.  We have recently started to get some random "transaction log for tempdb database is full" errors. There's no set time when this is occurring so it is probably some user interaction. Since all interaction is through stored procedures, it's most likely some strange set of parameters or data that's causing the problem but we are unable to track down exactly what might be causing it. Any suggestions that might help us identify the culprit are appreciated.  I have been using the information in  to track this down. And that gives valuable information but it doesn't give me a way to actually determine what the spurious circumstances are that is causing the transaction log to fill up.   Is there some way to trigger a snapshot or log what is actually causing the issue. Worst case I can write a monitoring program that pings the server every half second and uses variations on those queries to capture anything that is huge and has an open transaction but that still doesn't guarantee that I will actually catch whatever is causing the issue.

I would like to know how to identify the exact query or stored proc which is actually filling up the transactional log of TEMPDB database.


Let's say you ready an action, that when you are on the ethereal plane you will drop your weapon. Does this work, would you return to the material plane without a weapon? Could you blink again and pick it back up later?     : ...you vanish from your current plane   of existence and appear in the Etheral Plane...   At the start of you next turn, and when the spell ends if you are on   the Etheral Plane, you return to an unoccupied space of your choice   that you can see within 10 feet of the space you vanished from.   A scenario where this could be very useful, imagine you are holding a ticking time bomb, you blink into the ethereal plane drop the bomb and blink back just in time, saving your party from the explosion.

After entering the ethereal plane through some means, is it possible to leave objects you brought with you behind, or do they always come back with you?  Does the answer depend on the means you used to enter the ethereal plane, or on the specific object you're trying to leave behind?  Note: You only need to consider content published in official material when answering this question, but if the official material is completely silent on this matter interpretations are also fine.


b = [[1,1],[1,0]] a = [[0]*2]*2 for i in range(2):     for j in range(2):         a[i][j] = b[i][j] print(a) print(b)   and the outputs are:  [[1,1],[1,0]] [[1,0],[1,0]]   I don't know where going wrong. Isn't the a should be the exact same as the b?

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


My employer's payroll company did not withdraw the correct percentage of state taxes from my year's worth of paychecks.  I'm now liable for $2,000 in state taxes.  Can the payroll company be held fully or partially liable for this amount?

I am a basic 30 year old filing Single, W2, healthy working individual. No dependents, no additional schedules, capital gains or losses other than Student Loan interest expense.   I started a new job in January 2019 and somehow during my new hire enrollment, "I or someone" marked in my file as Exempt... I am pretty familiar with filing my own 1040 (as its pretty basic)and I know for a fact that I would never for under any reason think that I am Exempt from absolutely anything tax related. Nobody in my new job's HR department reached out to confirm whether this Exemption was correct or not with me personally. My CPA said that anytime they receive an Exempt W-4 form, that they automatically return the form to the employer to confirm.   I unknowingly went 11 full months in 2019 without any taxes being withheld. Of course my paycheck was more than before, but I also got a better/higher salary job, so I never thought about the difference being from not paying taxes. And, no I do not print out my paystubs. It’s all through Paycom and it clearly shows you your gross pay & a "$XXX" amount in deductions/withholdings - kicker is, you have to click the drop down menu to actually see the entire breakdown. At which point, I never saw the big $0 in taxes being withheld... I know the taxes have to be paid one way or another, but I don't feel like I should be entirely responsible for a $5k-$6k tax liability for a HR clerical error. Even if I did actually input it incorrectly the first time.   Is there a way to check with the IRS to see if they indeed receive my file as Exempt and if they did actually return it to my Employer? I’m just wondering if either HR forgot to follow up with me or even IF the IRS does actually cull these exempt requests in the first place? I don't have the liquidity to simply pay the IRS all at once.   What would be my best option going forward?


I need to make this head smoother. I am already using subdivion surface 3 on whole object.  I found here and try select head and use shade smooth.  Head stil had that visible lines and just not look smooth.    Here is file, I hope I upload it right.

When I create a UV sphere and add the subdivision surface modifier, the following wrinkle appears.    How can I avoid it?  I've read the article  but there seems to be no clear solution.  UPDATE 1  I've used the word 'apply' in the first sentence of the initial version of this question. It's misleading since I want to preserve the modifier without 'applying' it. Rather, what I meant is 'adding' the modifier.  UPDATE 2  I followed josh sanfelici's solution, but still there is an artifact at the pole.  Here is the screen: (A rendered view with a sun lamp)    Maybe it's the limitation of the general-purpose subdivision modifier.  BTW, when the cast modifier is added after the subdivision modifier, the sphere becomes perfect (even for my original wrinkled sphere).  But since I want to edit the resulting sphere (for example, scaling X, Y, etc) while modifier is added but not applied, it's not usable.


I want to have zero margin in my document, but there is no way I can't move it. Right now I can see that Document Margins have left: 0 in  However, I can see that there is some weird margin applied, but I don't know where it is set. I can not move the blue tip (see image)  Where am I supposed to move that tip to the left? Right now is 'blocked'.    Here is another picture to show what is going on...

I'm trying to adjust a simple template in Pages version 5.2 but can't for the life of my figure out how to change the existing layout such that the text spans the full width of the page.  I've turned on Show Layout and tried adjusting the left Document Margin to 0 but it's still indented by about 4.5cm and that throws the footer and header too far to the left.  The Ruler won't allow me to drag the slider any further left than the edge of the layout.  Changing the Column settings doesn't do it either. My Indents settings are all set to 0. I'm completely at a loss as to how to do this.  I've had no issue changing the top, bottom and right margins, but the left margin seems to have this welded in inset.  The following screen snap of the standard Business Letterhead template (with markup in red) indicates what I am trying to achieve.    My thinking is there is some weird margin applied, but I don't know where it is set. I can not move the blue tip (see image below)    How can the tip to the left be moved? Right now it is 'blocked'.


Consider case of Jon Snow. Let's assume if it turns out that      Jon Snow is the last living male of House Targaryen - bastard or no,   Could he petition to be released from his vows? If Daenerys finds out (In the eventuality that she makes it to Westeros) could she make the same request      to have her nephew released from the vows barring him from holding any lands or crowns?   We know that Robb Stark seemed to think he could make the Watch agree to releasing Jon Snow by giving them more men in return. But let's say if the member at hand did not have any bargaining chip except the fact that he didn't know (and he had joined the watch voluntarily rather than forcibly for some crime):   He was heir to some lands.  He was heir to some booming business.  His uncle in Summer Islands left him a small fortune which he could claim if he paid a small processing fees.   Could he ask to be released in those cases, asserting that when he made the decision to take the Black, he wasn't in an informed position to make an educated decision?

So, Jon joined the Night's Watch under the assumption he was the bastard of Ned Stark. This makes sense, since bastards aren't entitled to land or any of the like. But, lets for a second assume that Jon is a Targaryen,  the true born son of Rhaegar and Lyanna. Is there a precedent that would allow him to leave the Watch and take up his true name?


I'm trying to change the numbering for some chapters from numbers to letters, using:  \documentclass{report} \setlength\parindent{0pt} \usepackage{hyperref} \begin{document}  Reference to chapter 1: \ref{chapter_1}  Reference to chapter A: \ref{chapter_a}  \chapter{A chapter} \label{chapter_1}  \setcounter{chapter}{0} \renewcommand{\thechapter}{\Alph{chapter}}% \chapter{Another one} \label{chapter_a}  \end{document}    Of course, using \setcounter{chapter}{0}, I end up with two chapters "1", one denoted as a number, the other as a letter, which messes up the clickable references from hyperref (in the example above, both clickable references lead to the first chapter).   Is there a way to solve that -- change one chapter to use a letter instead of a number, without messing up the references by resetting the chapter number?

The following MWE produces a PDF whose TOC has two entries: “Foo” and “Bar” with correct page numbers. So far, so good. However, upon clicking on the link to “Bar”, I am taken to the page for “Foo” instead.  \documentclass{report} \usepackage{hyperref} \newcommand*\backmatter{\setcounter{chapter}{0}}  \begin{document} \tableofcontents \chapter{Foo} \backmatter \chapter{Bar} \end{document}   (Produced with pdflatex, run twice.)  This MWE is whittled down from a (much!) more complex document but the above does seem to reproduce the error reliably.  Re-setting the chapter count seems to confuse hyperref, even though the page references are still accurate. Notice that in my real document, \backmatter does other things, including setting the numbering style to alphabetical so there’s no chance of confusion even though both chapters are ostensibly labelled as “Chapter 1”.  How do I fix this? Is this a bug? Are there workarounds?


They are 15-year-old girls  They are 15-year-olds  Are both of them the same and correct? if so, could anybody possibly kindly tell me when would you rather use which one?

Thank you so much all for supporting and wrote back to my previous question?  They are 15-year-old girls  They are 15-year-olds


I'm trying to create a dynamic content box. When I click one button, the box's content changes with .html(). When I click another, the content changes again.  This is fine, but anything created within this box doesn't seem to be selectable.  So for example:  $(document).ready(function(){      boxContent1 = "

";      $("#caseStudy").on('click',function(){         $("#botBox").hide().html(caseStudy).fadeIn(1000);     });  });   in this case, the content of #botBox changes just fine. However, when I try to interact with it  $(".studySelector").on('click',function(){     alert("testing!"); });   nothing happens. Why is this happening?

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Is spectral norm (i.e. the maximum singular value of a matrix) submultiplicative? I am absolutely confused. How to express the singular value of the product of matrices in terms of that of the original matrices? Please help.

We had in our lecture on numerical analysis the following: Let $\mathrm{Lin}(X,Y)$ be the set of all linear maps $X\rightarrow Y$. Let $A\in\mathrm{Lin}(\mathbb R^l,\mathbb R^n)$ and $B\in\mathrm{Lin}(\mathbb R^n,\mathbb R^m)$ and $\|C\|_{op}:=\max_{\|x\|\leq1}\|C(x)\|$. Then our lecturer followed $\|A\circ B\|_{op}\leq\|A\|_{op}\cdot\|B\|_{op}$. So he didn't prove it and so I've tried it by my own. My attempt: $$\begin{aligned} \|A\circ B\|_{\mathrm{op}} &= \max_{\|x\| < 1}\|(A \circ B)(x)\| \\ & \leq \max_{\|x\| < 1} \|A\|_{\mathrm{op}} \|B(x)\| \\ &= \|A\|_{\mathrm{op}} \max_{\|x\|\leq1}\|B(x)\|\\ &= \|A\|_{\mathrm{op}}\|B\|_{\mathrm{op}} \end{aligned}$$ But this seems too easy. I am really interested in a nice proof so anybody could help? Thanks a lot!


Unable to install openJDK 7 in Ubuntu machine. getting error like below : $ sudo apt-get install openjdk-7-jre   Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies: openjdk-7-jre : Depends: libatk-wrapper-java-jni (>= 0.30.4-0ubuntu2) but it is not installable E: Unable to correct problems, you have held broken packages.

After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


I would like to know what are the causes for a chiffon cake to have a caved in centre.  After baking, the cake turns out with a nice dome. The cake is overturned immediately to cool. But after about 15 minutes of cooling, the centre of the cake which was previously a dome became caved in (not too deeply caved in, maybe just about 2cm from the level of the cake height.)  So the result after the cake is cooled, the top of the cake (which was previously the bottom) is light and fluffy and the bottom of the cake (which was previously the top) is dense.   The sides and bottom of the cake are evenly browned. The sides do not shrink as much as the centre.   The cake is baked at 160C-Fan for 45min for a 5-egg recipe. I use cake flour and a very small amount of baking powder.

Beating of the whites is perfected.  When folding in the cake mixture and the egg whites is there a specific technique?  I place in about 1/3, fold, 1/3, fold, and the rest using a spatula, and turn the bowl to get it folded evenly.  Do I leave the cake to cool in the oven with the door open ajar? And for how long?  Or is there a specific way to cook it, e.g. high temp then low temp?


I'm changing php versions, successfully, but only for a while, then it rolls back.   I have several php versions installed:  leonid@DevSSD:~$ sudo a2enmod php php5.6  php7.0  php7.1  php7.2     So, I do   sudo a2dismod php7.2 sudo a2enmod php5.6 sudo systemctl restart apache2   Php page with php_info() changed, versions changed correctly. I don't care about cli, don't need it yet.    After a while php changed back to 7.2; I don't known why or who changed it. I don't know what log file to check.  I really multiple php versions, at least 5 and 7 latest release.  Holding the package does not help, because I have them all the different php versions and modules I need installed. Nothing is being changed or updated by APT between the version changes.  No, this is not a duplicate of the suggested question, because I have followed a guide, and can make any php version default, but for a little while, I have had a problem somewhere in configs.

I am trying to update to install PHP 5.5, 5.6 or 7.0 in Ubuntu 12.04/14.04/16.04 LTS, and I can only get PHP 5.3.10 for Ubuntu 12.04, PHP 5.5.9 for Ubuntu 14.04 or PHP 7.0.4 for Ubuntu 16.04 using official repositories (using apt-get).  I'm not really sure how to do a manual update – as I need:   to play around with the new(est) PHP features to install older PHP version due support in the software


How did the convention of 'multiplying' using  the cross symbol $4\times 3$ become $4\cdot 3$, using a dot in the middle?

Why does the "$\times$" used in arithmetic change to a "$\cdot$" as we progress through education? The symbol seems to only be ambiguous because of the variable $x$; however, we wouldn't have chosen the variable $x$ unless we were already removing $\times$ as the symbol for multiplication. So why do we? I am very curious. It seems like $\times$ is already quite sufficient as a descriptive symbol.


What's the easiest way in F# (in a functional/recursive style) to, given a number in words, convert it to it's numeric equivalent?  I'm looking at only English for now. E.g:  let parseNumber (s : string) =     match s with     | "One" -> 1     | _ - failwith "Cannot parse"  let result = parseNumber "One Thousand Two Hundred" // result should be 12000   Is there any way of doing this that doesn't involve a massive look-up table?

Is there an efficient method of converting an integer into the written numbers, for example:  string Written = IntegerToWritten(21);   would return "Twenty One".  Is there any way of doing this that doesn't involve a massive look-up table?


I have to add a bubble notification in WordPress wp_nav_menu like the following code.

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   Here I have to add this part in it.   2   I have seen this one and tried it.   add_action( 'walker_nav_menu_start_el', 'wpse_10042_nav_menu_post_count', 10, 4 );   function wpse_10042_nav_menu_post_count( $output, $item, $depth, $args ) {      $output .= ''.my_function_here().'';      return $output; }   And get it from here   But the problem is its adding to every menu link. I want to add it to only one menu item. Not everyone in the list.

I have re-worded this to make more sense.  Ok, I have a plugin that uses a remote service that check for updates, much like default WordPress plugins, in this case it just checks an XML file.  I want to show a menu bubble like this  when an update is available.  It can show just a "1" or text like "alert", it doesn't matter.  Since my plugin uses an options page (using add_options_page) the plugin settings show up under the default "Settings" submenu.  I think I need to add the following CSS to get the bubble to show up,   1   and tie into the global $submenu. The problem is I cannot use a hard-coded array value for the menu since each site will have different values.  So I cannot use $submenu[80][10] .= 1  How can I find my plugins submenu value, do I have to loop through the array and match the string values?  Also even when I hard-coded the values I could not get the bubble to show up.  //adding plugin to menu add_action('admin_menu', 'sec_plugin_checker');  function sec_plugin_checker() {   add_options_page(' Plugin Checker', 'Plugin Check', 'activate_plugins',    'sec_plugin_check', 'sec_checker');   // the conditional where I want the bubble to appear  if (!empty($matches)){      echo "Match found !
";      global $submenu;     foreach( $submenu as $item ) {      $item[41][20] = sprintf( __( 'Updates %s', 'sec_plugin_checker' ),                   "                  1");           }   }   and here is what a var_dump($submenu); looks like,   ["options-general.php"]=> array(9){ ...  [41]=>     array(4) {       [0]=>       string(20) "Plugin Check"       [1]=>       string(16) "activate_plugins"       [2]=>       string(21) "sec_plugin_check"       [3]=>       string(23) " Plugin Checker"       ...        }


I would like to confirm a proof I made:  For every $a,x,y \in\mathbb{R}$ such that $x≤a≤y$, we have $|a|≤\max\{|x|,|y|\}$.  I assumed that $|x|≤|y|$, so: $-|y|≤a≤|y|$, and that means: $a≤|y|$. Then, I assumed: $|y|≤|x|$, so $-|x|≤a≤|x|$, and that means: $a≤|x|$ From here, I let $b\in\mathbb R$, such that $b=\max\{|x|,|y|\}$ and that means $a≤b$. From here I don't really know what to do or if all I did is true or not. Thank you for your help!

Prove that $|a| \leq \max\{|b|,|c|\}$ if $b\leq a \leq c$.  I showed that $a\leq c$ and therefore $-c\leq a \leq c$ so that $|a|\leq c$ but then I got stuck. Is this the right approach?


How do I launch a cmd window and input the commands i specify into the cmd for windows using a python script?   For example , the script will launch the cmd and input the following : runas /username:Admin control  Then cmd will then prompt the user for their passwords and open the control panel. Any idea? Thanks

How do you call an external command (as if I'd typed it at the Unix shell or Windows command prompt) from within a Python script?


("Multivariate" regression in this post means a multidimensional response variable.)  I have been playing with multivariate regression for the past two days, and I have noticed something that did not make such an impression on me the first time I studied multivariate regression: it seems to be exactly the same as doing one regression per response variable.  If I do the multivariate regression, I get a matrix of parameters. If I do one regression per response variable, I get several vectors of parameters that can be concatenated to form the matrix of parameters, so doing the multivariate regression does not affect the parameter estimates.  Okay, the parameter estimates are the same either way. The next place where there could be differences is in standard errors on the parameters. The Rencher and Christensen book I'm consulting does not give a way to calculate standard errors for any individual value in the parameter matrix, but it gives a way to determine if a row of the parameter matrix is significant, which is pretty close and at least analogous to an F-test on one parameter in a vanilla OLS regression. However...  ...nothing in that calculation seems to use the dependence of the response variable!  What's going on? What does multivariate regression get us that one regression per response variable lacks?  (For context, a lot of what I do is two-sample ANCOVA where I want to extend a two-sample t-test to account for sources of variability: the covariates in the regression. I now want to try this with multivariate response variables and test the indicator variable, I suppose a two-sample MANCOVA. But it seems that I do not get any advantage by doing one MANCOVA instead of one ANCOVA per response variable.)  Reference  Rencher, Alvin C., and William E. Christensen. Methods of Multivariate Analysis. 3rd ed., Wiley, 2012.

I understand that multivariate regression models contain more than 1 dependent variable, but what is the difference between running a multivariate regression with dependent a and b to a set of independent variables, rather than running two regression models, one for a and one for b against the same set of independent variables?


Ever since updating all packages on TeX Live Utility (on Mac OS) yesterday, including biblatex-chicago, I have been getting this non-critical error message/warning every time I run xelatex on a file using biblatex-chicago: Runaway argument? { /usr/local/texlive/2020/texmf-dist/tex/latex/biblatex-chicago/chicago-notes.cbx :6629: Paragraph ended before \blx@defformat@i was complete. <to be read again>                     \par  l.6629 \DeclareFieldFormat{annotation}{\par                                            \nobreak \vskip \bibitemsep #1} ?  /usr/local/texlive/2020/texmf-dist/tex/latex/biblatex-chicago/chicago-notes.cbx :6629: You can't use `macro parameter character #' in vertical mode. l.6629 ...ation}{\par\nobreak \vskip \bibitemsep #                                                   1} ?   /usr/local/texlive/2020/texmf-dist/tex/latex/biblatex-chicago/chicago-notes.cbx :6629: LaTeX Error: Missing \begin{document}.  Is this due to a bug? And if so, is there some way to fix it?

After updating my TeXLive 2020 distribution today, biblatex-chicago has stopped working for me. The following MWE: \documentclass{article} \usepackage[authordate]{biblatex-chicago}  \usepackage{filecontents} \begin{filecontents}{\jobname.bib} @book{test2020,   title = {Test title},   author = {Author},   date = {2020},   publisher = {test},   location = {test}, } \end{filecontents} \addbibresource{\jobname.bib}  \begin{document}   \cite{test2020}   \printbibliography \end{document}  produces this error: Runaway argument? { ! Paragraph ended before \blx@defformat@i was complete. <to be read again>                     \par  l.2523 \DeclareFieldFormat{annotation}{\par                                            \nobreak \vskip \bibitemsep #1}  The culprit must be in one of these packages, I think, but I'm unable to detect which one: [ 5/24, 00:31/15:37] update: biber.x86_64-darwin [27659k] (53064 -> 56144) ... done [ 6/24, 02:37/05:09] update: biber [1165k] (53064 -> 56144) ... done [ 7/24, 02:42/05:07] update: biblatex [7408k] (53063 -> 56143) ... done [ 8/24, 02:54/04:26] update: biblatex-ext [617k] (56081 -> 56150) ... done [ 9/24, 02:57/04:26] update: biblatex-jura2 [367k] (53243 -> 56133) ... done  I have this problem (since today's update) on a Mac and a Linux machine. (I haven't updated another Linux machine which still compiles alright this MWE.) Any ideas?


According to Hermione in DH, food is one of the Five Exceptions to Gamp's Law on Transfiguration.  Yet, in CoS, Professor McGonagall is able to give Harry and Ron a plate on which sandwiches appear continously. One can object that some sandwiches cannot be considered as food, but they still are. The same can be said about Molly Weasley making sauce from her wand in GoF while grumbling about how the twins abuse magic.  Is there any canon explanation on how McGonagall and Mrs Weasley created food from nowhere?  By canon, I mean anything coming from the books, Pottermore, or JKR quotes.

In Harry Potter and the Goblet of Fire, when the kids and Arthur get to  The Burrow from Privet Drive and Molly is cooking and raging about Fred and George's shenanigans, the following occurs:     Mrs. Weasley slammed a large copper saucepan down on the kitchen table and began to wave her wand around inside it. A creamy sauce poured from the wand tip as she stirred.   In Deathly Hallows, Hermione says that this is not possible:     “Your mother can’t produce food out of thin air,” said Hermione. “no one can.   Food is the first of the five Principal Exceptions to Gamp’s Law of Elemental   Transfigura—”      “Oh, speak English, can’t you?” Ron said, prising a fish out from between his   teeth.      “It’s impossible to make good food out of nothing! You can Summon it if you   know where it is, you can transform it, you can increase the quantity if you’ve already got some—”   So how was Molly causing sauce to pour from her wand, seemingly out of thin air?


I am trying to update some applications using the command  sudo apt update   But i am getting an error like below  E: Type 'https://packagecloud.io/AtomEditor/atom/any/' is not known on line 1 in source list /etc/apt/sources.list.d/atom.list E: The list of sources could not be read.   Ubuntu version: 16.0.4

Every once in a while I see users having issues to update due to errors like this:  E:Type 'ain' is not known on line 1 in source list /etc/apt/sources.list.d/some-ppa.list'   with varying types/line numbers/source list files (often after removing a PPA).  How can such an error be fixed?


Let $a,b,c$ be the length of sides of a triangle then prove that: $a^2b(a-b)+b^2c(b-c)+c^2a(c-a)\ge0$  Please help me!!!

For any triangle with sides $a$, $b$, $c$, prove the inequality $$a^2b(a-b)+b^2c(b-c)+c^2a(c-a)\ge 0 .$$   This is IMO 1983 problem 6.  I tried substituting $a=x+y$, $b=y+z$, $c=z+x$ but well it doesn't help in any sense except wasting 3 pages that lead to nothing (please don't mind the joke). Using $a=2R\sin A$, $b=2R\sin B$, $c=2R\sin C$ also didn't lead to anything for me. Could you give me a hint for finding the proper substitution?


I have installed Ubuntu 12.04 on my iMac 2011. I want to use the function keys on the keyboard to skip to the next song, but I get this splash when I press the key:    Can you help me?

Just got a new keyboard, the Microsoft comfort curve 2000, and everything seems to work fine except for the 'back' and 'forward' multimedia keys.  I am running Ubuntu 11.10 and have tried going into system settings -> keyboard -> shortcuts, then I try and hold down the keys to set the action I want them to perform, but nothing changes.  Any thoughts on where else to look?   -- UPDATE --  I rebooted and the options to change the keyboard shortcuts seem to be working now. Now I can tweak the whole thing and I managed to assign the media keys correctly.  Thanks to everybody for the suggetions


I'd like to be able to add collapsible #regions within my post.  For example  Blah blah blah I am very smart and I will tell you how its done.  Blah blah blah blah, if you're interested, that's like THIS:  #region explaining how to DO IT BABY    int main() {   puts( "DO IT BABY" ) ; }    #endregion  Blah blah blah, more explanation.  (( the #region and #endregion pairs become invisible, and they basically look how #regions look in visual studio. ))

It would be great to have the option to fold code snippets, entire questions and answer posts on a user basis and allow defining some generic foldable regions within the question/answer editor.  Non generic folding info could be stored in cookies perhaps to move the storage/processing requirement to the client side.  Definable folding can take any free and safe HTML tag or other multi character trick (<>Fold this<>)


Let $R$ be a local ring (commutative with identity) ans $M$ and $N$ be finitely generated $R$-modules.     If $M\otimes_R N=0$, then $M=0$ or $N=0$.   The problem clearly seems to be an application of the Nakayama lemma. If we can show that $M=\mathfrak mM$ or $N=\mathfrak mN$, where $\mathfrak m$ is the unique maximal ideal of $M$, then by Nakayama we would have $M=0$ or $N=0$, for the Jacobson radical of $M$ is nothing but $\mathfrak m$ itself.  I am unable to figure out what to do.

If $R$ is a local ring and $M$ and $N$ are finitely generated $R$-modules such that $M\otimes N=0$ then how does it follow from Nakayama's lemma that either $M=0$ or $N=0$?    This is an exercise in Atiyah and Macdonald. The part I could not show in the hints is $({M{\otimes}_R N)}_{k}=0$ implies $M_{k}{\otimes }_{k} N_{k}=0$, where $k=R/\mathfrak m$ and $\mathfrak m$ is the maximal ideal of $R$.


I design graphics and I have so many they clog my computer, and many too large for downloads in my shop when I use 300 resolution on photo shop.  I design my graphics at 300 resolution.  They are large and easy to work with. I resize my 300 resolution to 100 resolution and have never found any difference in printing, size, or quality.  It saves space and allows me to have them available as downloads. Am I missing something?

I have been designing graphics for years.  I have gone through a dozen printers.  I have not found any difference in the printing of my 300 resolution images, and the 100 resolution, I changed the 300 resolution to.  Changing from 300 resolution to 100 saves space and I find no difference in quality or size of printed image.  Am I missing something?


I am writing a thesis, it is very long now over 300 pages. I am using glossary package a lot, and I am using two computers. When I compile my .tex file over my laptop I get the following error:  ! TeX capacity exceeded, sorry [main memory size=5000000]. \l__morewrites_internal_tl ...lsnumberformat}{257}  while when I compile it over my PC, It compiles without any issue. In both systems I am using TexLive and I also used morewrites package to deal with similar error I had before. Does anyone know why? Please help me.

My document contains many thousands of glossary items. When compiling with XeLaTeX, about 1/8 of the way through the document, it reports:  ! TeX capacity exceeded, sorry [main memory size=3000000]. \@glolist@ ...},{13586},{9406},{4539},{12811},{179                                                   51},{5831},{1047},{14948},    The numbers you see above are ones placed in #1 of \newglossaryentry{#1}{#2}. These unique numbers are assigned to each entry for convenience. I have successfully compiled short tests of the document, which only used 1% of the full content. The resulting .glo file is about 1 MB in size.   Could this be the result of some error on my part or am I giving TeX too much work to do?  Update:  I have followed the instructions below (edited texmf.cnf and running  fmtutil-sys --all. This has allowed me to compile an additional portion of the book, but no matter the settings I add, I can't go beyond 5/8 of the way through.  A compile with extra_mem_top.xelatex = 30000000 and extra_mem_top.xelatex = 50000000 both result in:  TeX capacity exceeded, sorry [pool size=3186676].   Update:  I have done the following:  $ kpsewhich texmf.cnf /usr/local/texlive/2011/texmf.cnf $ nano /usr/local/texlive/2011/texmf.cnf   To the texmf.cnf file, following instructions at , I added:  main_memory = 230000000 extra_mem_top = 10000000 extra_mem_bot = 10000000 save_size = 150000 stack_size = 150000  main_memory.xelatex = 30000000 extra_mem_top.xelatex = 30000000   After this, I tried: - fmtutil-sys --all, then compiling xelatex file.tex. - fmtutil --all, then compiling xelatex file.tex. - fmtutil-sys --byfmt xelatex, then compiling with xelatex file.tex. - texhash, then compiling with xelatex file.tex.  All of these resulted in no changes in results. I still get:  TeX capacity exceeded, sorry [pool size=3186676].


Suppose there is no cycle that goes through edges $e$ and $g$.  The question is to prove that for every path that begins at one of the vertices incident to $e$ and and ends at a vertex incident to $g$, that there exists some vertex $u$ that is always on that path.   My work:  Pick the edge closest to beginning vertex such that $e$ and this edge, call it edge $f_{j-1}$ (connection $v_{j-1}$ and $v_j$) do not form a cycle on the graph $G$.  Then using this cycle and a path joining a vertex on the cycle to one of the vertices $v_{j+1}, \ldots, v_n$, construct some contradiction by creating a cycle with edge $f_j$.   Any thoughts?

There is a proof in my textbook for the following claim, which doesn't make a whole lot of sense to me.  My annotations are in bold.  Could someone perhaps elaborate on what's going on?  Claim.  If there does not exist a cycle containing edges $e$ and $g$ then there exists a vertex $u \in V (G)$ such that every path in $G$ sharing one end with e and another with $g$ contains $u$.  Proof: The claim trivially holds if $e$ or $g$ is a loop OK, so we assume that neither is. Let $P$ with vertex set $v_1, v_2, . . . , v_k,$ in order, be a path with $e$ joining $v_1$ to $v_2$ and $g$ joining $v_{k−1}$ and $v_k$. Let $f_i \in E(P_i)$ be the edge with ends $v_i$ and $v_{i+1}$. Let $j$ be chosen minimum so that no cycle in $G$ contains $e$ and $f_j$ We can do this because we know that at least the edge $g$ will not create a cycle by assumption, right?. We will show that $u = v_j$ satisfies the claim.  Suppose not. Let $C$ be a cycle containing $e$ and $f_{j−1}$ What if $f_j = e$?  then what cycle? a single vertex? and let $P′$ be a path from an end of $e$ to an end of $f$ Not sure what the book meant by $f$ here, any guesses? avoiding $u$. Choose a subpath $Q$ of $P′$ with one end in $V (C)$ and another in ${v_{j+1}, v_{j+2}, . . . , v_k}$ as short as possible. Then $C \cup Q \cup P$ contains a cycle containing both $e$ and $f_j$, a contradiction. (The last statement requires some case checking.) This ending seems a bit abrupt and non-obvious to me  Thanks for the help


$\sqrt{x}=\sqrt{1\cdot x}=\sqrt{(-1)^2\cdot x} = \sqrt{(-1)^2} \cdot \sqrt{x} = (-1) \cdot \sqrt{x}=-\sqrt{x}$  The idea popped into my head while I was evaluating an integral. I have a feeling that I made some obvious mistake because the "proof" is so simple, but I don't see any flaw. Of course, there must be a flaw somewhere. What is it?

We know $$i^2=-1 $$then why does this happen? $$ i^2 = \sqrt{-1}\times\sqrt{-1} $$ $$ =\sqrt{-1\times-1} $$ $$ =\sqrt{1} $$ $$ = 1 $$  EDIT: I see this has been dealt with before but at least with  I'm not making the fundamental mistake of assuming an incorrect definition of $i^2$.


If I have an ostringstream that contains various numbers separated by -  (That's: space - space btw)  Could I extract each number individually?

I'm trying to iterate over the words of a string.  The string can be assumed to be composed of words separated by whitespace.  Note that I'm not interested in C string functions or that kind of character manipulation/access. Also, please give precedence to elegance over efficiency in your answer.  The best solution I have right now is:  #include <iostream> #include <sstream> #include <string>  using namespace std;  int main() {     string s = "Somewhere down the road";     istringstream iss(s);      do     {         string subs;         iss >> subs;         cout << "Substring: " << subs << endl;     } while (iss); }   Is there a more elegant way to do this?


I noticed on Wikipedia there's always a 'The' before 'Ohio State University' but nothing before 'Arizona State University'. My findings were mirrored by search results of a corpus that includes articles of authoritative news outlets such as CNN, The Economist, BBC.  How come the use of the definite article is inconsistent between these two state universities?  Edit: My question is different from the one re [without THE] X University vs THE University of X. My question is: why for the same pattern ie X State University, it's THE Ohio State University and [without THE] Arizona State University? Does it mean the use of 'THE' can be arbitrary and prescriptive?

Possible Duplicate:          I was updating my LinkedIn tagline and thinking about whether I should put the article before the name of the university.     Student at the University of […].   Student at University of […].   I am leaning towards the former but I am not sure.


I am using macOS High Sierra.  I erased my 1 TB disk using disk utility to using Mac OS Extended (Journaled) file system.  I want to perform partition on my disk and want to split into two parts, i.e. 500 GB both.  But I am unable to do it as partition symbol is disabled in disk utility.    Any help would be appreciated. Thank you.

I want to put 2 partitions on my USB stick: first one (so Windows can see it) with FAT32 (so also macOS can write to it) and a second one, bootable with  on it.  I started looking how to partition the stick and I discovered that Disk Utility will not let me create partitions on the USB stick (the button is disabled), let alone configure the partition as bootable in the MBR.  There is plenty of ways to do that on GNU/Linux, other also works on Windows but I didn't find anything for macOS. Is there any free (as a beer) way to do that?


I found out that on Ubuntu 20.04 with GNOME Flashback, the Snap Shop utility from System Tools menu (the tool to install software on the system) window becomes completely transparent with white text when a non-standard theme is activated. Below are two screenshots: the first is from standard Radiance theme, the second is from a custom-made theme which is an exact copy of Radiance theme under another name. There is a Calculator window on the screen to demonstrate that the application looks identical in both themes. However, Snap Shop is different.  This is screenshot from Radiance theme:   This is screenshot from a copy of Radiance theme:   Any hints how to fix this?

I'm using Ubuntu 20.04. Recently I've deleted some default icons from /usr/share/icons folder. I don't know if it's related, but, since then, my Ubuntu Software gets into a transparent background. There's a way to revert this?  Here is a screenshot:  Ubuntu Software


How can I download single file from an SVN repository?  For example:  svn co http://server.com/svn/trunk/test.file test.file svn: URL 'http://server.com/svn/trunk/test.file test.file' refers to a file, not a directory   But I can download directories in this way.

"It is not possible to check out a single file. The finest level of checkouts you can do is at the directory level."  How do I get around this issue when using Subversion?  We have this folder in Subversion where we keep all our images. I just want to check out one file (image) from that. This folder is really big and has ton of other stuff which I don't need now.


Some badges are awarded instantly (like the early badge awards designed to inspire a pavlovian reaction), some seem to be awarded in some kind of late night batch job (the harder to reach ones?) - is there any way of telling which is which?    So that if you are due a badge, there is a visual clue to suggest how long you should wait before yelling "where's my ^&%&%$(& badge!".  Perhaps a little icon with the letter 'i' in it, next to the instantly awarded badges along with a textual note at the bottom of the badges page would be enough.  ADDENDUM As noted below there appears to be a third badge timing, certainly for the 'Tenacious' badge.

Do badges get calculated in real time, or do they get calculated by an external service? How long does it take for a badge to be awarded, once its requirements are met?  Does Stack Overflow use any external services to do things, like maintenance, e-mailing or badge calculation?


I have a generic ListManager class with a method returning an object at a specific index. I am checking that the index is within range to avoid exceptions. What should I do if the index is out of range? I tried to return null but that's not possible. I would like to do this without using try catch. Any suggestions?  public T GetAt<T>(int index) {     if (index <= list.Count() - 1)         return list[index];     else         return null; //This will not compile }

I have a generic method with this (dummy) code (yes I'm aware IList has predicates, but my code is not using IList but some other collection, anyway this is irrelevant for the question...)  static T FindThing<T>(IList collection, int id) where T : IThing, new() {     foreach T thing in collecion     {         if (thing.Id == id)             return thing;     }     return null;  // ERROR: Cannot convert null to type parameter 'T' because it could be a value type. Consider using 'default(T)' instead. }   This gives me a build error      "Cannot convert null to type parameter   'T' because it could be a value type.   Consider using 'default(T)' instead."   Can I avoid this error?


This is always the case and I am so curious to know why. Here are examples (the highest voted questions from various sites):   Stack Overflow:  Super User:  Ask Ubuntu:  Ask Different:  Server Fault:

I noted a fact on Stack Overflow badges.  ● Nice Answer  × 39355 ● Nice Question × 7601   (5.2:1 rate)  ● Good Answer  × 6433 ● Good Question × 1199   (5.3:1 rate)  ● Great Answer  × 712 ● Great Question × 105   (6.8:1 rate)  All in all, since the badges are awarded for the same amount of accumulated votes in each category, it appears that people tend to vote more for the answers than the questions...  Just a thought...


I searched on google and tried the boot repair program that you install on a flashdrive and boot from it to reinstal/fix grub but when I use the program, I get an error that says "The boot of your pc is in legacy mode. Please change it to EFI-mode" and it gives me this link;   Any help is appreciated!

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


When most of us want to see the definition of a SQL Server stored procedure, we fire up SSMS, find the object, right-click and select Modify or one of the other scripting options. This works fine, manually.   Some people also have the good fortune to get licensed for Redgate products that let you search, compare, and analyze the compiled database objects.  But supposing I would like to write desktop utilities that analyze stored procedures or other objects compiled on a SQL Server instance. There seems to be very little in the mainstream that is designed to accommodate that kind of software design.   So my question is: is it even possible, using C# and readily available NuGet packages, to connect to a SQL database and return the same DDL script that would be rendered into a query window using SSMS?  I know that there are lots of utilities already out there to cover almost anything I could want, but this is a programming question, not a request for a product recommendation.

Is there a way to get stored procedures from a SQL Server 2005 Express database using C#? I would like to export all of this data in the same manner that you can script it our using SQL Server Management Studio, without having to install the GUI.  I've seen some references to do thing via the PowerShell but in the end a C# console app is what I really want.  To clarify....  I'd like to script out the stored procedures. The list via the Select * from sys.procedures is helpful, but in the end I need to script out each of these.


I'm currently running into an issue. I'm currently making use of javax.net.ssl.HttpsURLConnection in the code below.  I try to establish a connection but am getting an HTTP 407 proxy authentication required (as expected in this scenario) and as a result, when I try to write the payload to the connection I'm getting an IOException which I am catching. In this catch, I am trying to get the response code (which may I add works for all other HTTP responses that I have tested so far). In this instance though I'm getting a null pointer when it tries to get the response code.  java.lang.RuntimeException: java.lang.NullPointerException     at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1256)     at sun.net.www.protocol.http.HttpURLConnection.getHeaderField(HttpURLConnection.java:2740)     at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:489)     at com.ibm.net.ssl.www2.protocol.https.b.getResponseCode(b.java:43)      conn = (HttpsURLConnection) url.openConnection(proxy);     ......     ......     ......     catch (IOException ioException)         {             try             {                int connRespCode = conn != null ? conn.getResponseCode() : 0;    Does anyone know why this would be occurring?

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?


$$ \sum_{n = 2}^{\infty}\frac{(-1)^{n}}{\sqrt{n} + (-1)^{n}} $$  Wolfram Alpha returns nothing useful, except that the ratio test was inconclusive.

Prove that $\displaystyle\sum_{n=2}^\infty\frac {(-1)^n}{\sqrt{n}+(-1)^n} $ diverges.  It is easy to see that this absolutely diverges, however how can it be proven to diverge in general? The idea as posted in another forum was to group the terms in the sequence as follows:  $$\sum_{n=2}^\infty \frac{(-1)^n}{\sqrt{n}+(-1)^n}=-\sum_{n=1}^\infty \left(\frac{1}{\sqrt{2n+1}-1}-\frac 1 {\sqrt{2n}+1}\right)$$  and then show that this sequence diverges. I did end up getting an answer from that forum (thank you!) however it depended on results from WolframAlpha which seem extremely difficult to solve by hand. This question is from Apostol's Calculus, written in 1969, so I'd like to have a solution which doesn't depend on WolframAlpha.


I would like to remove the page numbers behind my acronyms. Is there a way to do this?     I create my acronyms the following way:  \makenoidxglossaries \setacronymstyle{long-short}  ...  \begin{document}      ...      \printnoidxglossary[type=acronym]

I am using the glossaries package to make a glossary. However I don't want the page numbers where the entry is referenced to be shown after the description in the glossary. How can I do that? Actually I use in preamble:  \usepackage[acronym]{glossaries} \makeglossaries   and inside the document:  \printglossary[type=main,style=long]   I don't want the page numbers to be displayed because there are entries that are added in preamble with the command \glsadd{entry} and it will appear as present on page 1. And sometimes the page numbers list won't be complete, that is, there will be parts of the text which will contain one term and it won't reference directly the glossary.  How to prevent the page number to appear on glossary?


If you have done well in undergrad (i.e one of the top students of the graduating class; physics and mathematics major with highest honors; with exposure to engineering) and have done a masters for 1-2 years with research experience and publications (i.e assisted professor and PhD students and have coauthored 2-3 papers), do you have a good chance of going to a top 10 physics graduate school?

When applying to a PhD program in the US, how does the admissions process work? If an applicant is weak in a particular area, is it possible to offset that by being strong in a different area?  Note that this question originated from this . Please feel free to edit the question to improve it.


Im tired that everytime my dock (i use docky) crash i have to manual reopen it.  There is a way for auto restart docky everytime it crash?  I mean something that can auto reopen the app when it crash...  ps i'm a newby non english on xubuntu

docky crashes from time to time for me. How can I make it restart automatically after it crashed?


I was recently searching for wallpaper managers for Ubuntu 18.04. I remember coming across one that had the option of changing the wallpaper at random time intervals. Problem is, I cannot find what it was called. Does anyone here know of any? Thank you.

I want to have my wallpaper be seasonal (summer, fall, winter, spring), but also update daily with a seasonal themed wallpaper. So essentially, I am thinking of having 4 directories (summer, fall, winter, spring). During summer, my wallpaper background would rotate through the images in the summer directory on a daily basis. Then on Sept. 21, the wallpaper directory would change to fall, and the wallpaper would then cycle through those images on a daily basis, etc. I am comfortable writing a script, but where would I start? How this question is unique Edit: To clarify further about what makes this question unique. While there are many methods to create a slideshow, they all depend on setting the images directory. What I am asking is how to dynamically change the images directory. So slide show today comes out of the /images/winter/ directory, and slide show in spring comes out of the /images/spring/ directory. I could manually do this by just changing the directory in the appearance settings every season, but I don't want to have to that when I can tell the computer to do it for me.


First of all, what are the differences between these two:  and ?   And secondly, do I need to learn both in order to study  and ?

What exactly are  (and )?   I want to self-study QM, and I've heard from most people that Hamiltonian mechanics is a prereq. So I wikipedia'd it and the entry only confused me more. I don't know any differential equations yet, so maybe that's why.    But what's the difference between Hamiltonian (& Lagrangian mechanics) and Newtonian mechanics?  And why is Hamiltonian mechanics used for QM instead of Newtonian?  Also, what would the prereqs for studying Hamiltonian mechanics be?


My fiance picked this poster up today because it looked cute, we aren't sure were this is from and wanted to know if anyone could tell us where this is from.

So I see an image that I believe is from either an anime or a manga. What are some ways that I can go about finding what series it's from? Try these options:   (browser built-in support and plugins)        Note: Please note that as of May 9, 2016, ALL  questions are now . Therefore, you can't ask an identification request question on this site. However, such questions are still welcome  for users with at least  (globally on StackExchange).    Protip: If you are using Google Image Search in a non-English language,  or just use  for better, more accurate results.


My boyfriend is from France and I am from Michigan, he is coming in July to visit with me and my family but we are flying into Toronto and from Toronto we are crossing the U.S border by car. Would there be a problem at the border with him not being  Canadian or a U.S citizen? As in...can he cross the border by car if he is not from either country?

I'm a citizen of an EU member state traveling to a small city in Vermont. Looking at flight data, it seems that it would be quite a bit quicker to fly into Montreal (Canada) and then drive a rental car to my final destination in Vermont (and back), rather than getting a connecting flight into a small local US airport. I am slightly worried about the trouble I might get myself into by crossing a land border twice, though.  Can anyone give me an idea of what I'd be getting into in terms of:   Crossing time Discomfort Additional paperwork required   For both the outbound (Canada/US) and the return leg (US/Canada) of my journey, when compared to crossing the border at an international airport?  Also, do I need to take any special actions when I'm arranging a rental car if I intend to drive it over to the US and back?


I'm new to Ubuntu and liked it a lot! However after testing it on my old crappy laptop I now want to remove it. I've looked at tutorials on how to uninstall and it says to start by deleting the Linux partition of the hard drive.   However after opening Computer management, I cannot locate my Linux partition. Same as when I go to System Configuration and click on the "boot" tab, my computer does not list any operating system other than Windows 7. Any way around this or perhaps a different way to uninstall?

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


Prove $$\int ^{\pi/2}_0 \frac{\sin^m x}{\sin^m x+\cos^m x}dx=\frac{\pi}{4}$$ for all real values of $m$.

Evaluate the integral $$\int^{\frac{\pi}{2}}_0 \frac{\sin^3x}{\sin^3x+\cos^3x}\, \mathrm dx.$$  How can i evaluate this one? Didn't find any clever substitute and integration by parts doesn't lead anywhere (I think).  Any guidelines please?


I found stories related to mine but none answered how I should fill out the Visa Waiver Program ESTA form. I moved to the US with my mother when I was 9 years old and left when I was 12 (with a Brazilian passport). We became illegal on the last month we were there.    Now, 11 years later, I wish to go back to the US for a visit. I recently got my Italian citizenship and passport, so I would go under the Visa Waiver Program. I’ve seen answers here in which most people could go back through the VWP.    Should I answer “yes” or “no” on the ESTA form to the question that asks if I ever overstayed in the US?    Although illegal, I was a minor the whole time I was there.    Could anyone who’s been/has a kid who’s been through a similar situation help me, please?

I can't seem to find a story related to mine so here it is.  I am 25 and a German citizen. In 1998 when I was 7 years old my family moved to the states and we stayed until early 2002 and left voluntarily. Basically we overstayed. I am aware that my parents had the ten year ban and since I was a minor at the time of our overstay I did not receive such ban.  Ever since 2002 I have not attempted to go back to the USA for any reason. However now that I am older I would like to go back for vacation and stay for a short period of time (one month) during my christmas break.  I've lived in Germany since leaving, have a great job, enough money in the bank account. My whole life is here and I have no intention on moving anywhere else.  After reading a bunch of stories online I have decided to apply for a B2 visa to be on the safe side but I was curious about the ESTA approval. For the last question. 8) Have you ever stayed in the United States longer than the admission period granted to you by the U.S. government?   I should put yes but is it a no if I stayed when I was a minor? And what are my chances on getting the B2 Visa?


I would like to know how to prove the following: $2^n \in O(n!)$ I know that I have to show that for a constant C, we have $2^n \leq C*n!$ Right?

I'm having difficulty solving an exercise in my course.  The question is:      Prove that $n!\geq 2^n$.   We have to do this by induction. I started like this:   The lowest natural number where the assumption is correct is $4$ as: $4! \geq 2^4 \iff 24 \ge 16$. The assumption is: $n! \ge 2^n$.   Now proof for $(n+1)$ which brings me to: $(n+1)! \ge 2^{(n+1)}$  I think I can rewrite it somehow like this:  $$ {(n+1)} \times {n!}  \stackrel{\text{(definition of factorial)}}{\ge} 2^n \times 2 $$  $$ (n+1) \times 2^n \ge 2^n \times 2 $$  Then I think I can eliminate the $2^n$ and have something like this: $n+1 \ge 2$, or $n \ge 1$.  But I think I'm wrong here some where and was hoping somebody has some advice on this. How can I prove the above assumption?  Any help would be appreciated, kind regards.


I have read a few times to disable root login and sudo as root using another user.  But is using a public key as good if not better security?

I have recently found an argument against disabling a root user login in Linux at   I assume that, if everybody uses a public key authentication, there's no risk at losing the root password.  Is it always better to disable the root login via ssh?


When I use my data for Pokémon GO, no Pokéstops or Pokémon in the sightings appear just the road and the avatar walking however when I use WiFi or hot-spot, the Pokéstops and Pokémon appears again. I have been facing this problem just 3 days ago and I can't play without WiFi or hot-spot. What should I do? I have tried deleting the game and almost everything.

It connects to Pokemon Go via wi-fi perfectly fine, but when I try and connect to Pokemon Go via 3G it just gets stuck at the first bar on the loading screen with the eventual pop up saying "Failed to get player information from the server." My 3G connection works perfectly fine with every other app I have, and has been easily able to stream HD videos so I can't see connectivity with 3G being an issue.   It makes even less sense as once connected via wi-fi, the game easily continues to operate via mobile data once I leave the house. However once the app crashes (which it usually does after 15-30 minutes) I try to reload it on mobile data and it gets stuck on the loading screen. If I can find a local free wi-fi spot nearby I can re-connect easily, and then move back onto mobile data.  I've tried removing and reinstalling Pokemon Go and that didn't work. I also reset all my app preferences on my phone and that didn't work.  Not sure if this helps, my phone is a Huawei P8, Android version 5.0.1.  I signed up to Pokemon Go using my Google account.


I search a command that give formated time like HH:MM:SS when I give just seconds. As example, if the search command is \formatetime{}, it should give the following result: \formatetime{50}   % should print “50” \formatetime{60}   % should print “1:00” \formatetime{3661} % should print “1:01:01”  Is it possible to do that?

I spent 3 hours trying to write a command to format a time (duration) expressed as a floating number (in seconds) in a nice form as follows:  if the time is < 60 write as a float with 3 decimals (i.e. milliseconds)  else let h,m,s be the hours, minutes and seconds corresponding to the time      if h=0 then write as m:ss (ss always with 2 digits, m can have only 1)      else write h:mm:ss (mm and ss with 2 digits, h can have only 1)   So 1.25678 gives 1.256, 125.35 gives 2:05, 18249 (which equals to 5*3600+4*60+9) gives 5:04:09.  I tried several packages for the comparison/formatting. No success. Can someone help me ? Thanks !


I try to understand a conceptual difference between:  var x = '8aaaaa dddd r     '  function noSpace(x){   return (x.split(" ").join("")); } noSpace(x) //Results in "8aaaaaddddr"   AND  var x = '8aaaaa dddd r     '  function noSpace(x){   x.split(" ").join("");   return x; }  noSpace(x) //Results in "8aaaaa dddd r     "   Why does the second version don't work as the first one?

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


I'm due to fly from the UK with IcelandAir, from Glasgow, via Reykjavik in Iceland (a Schengen country) on 30th March, to Florida. The stop-over in Iceland is approx 2.5 hours.  Does anyone know if this would count as time in a Schengen country (even though I won't leave the airport)?  IcelandAir's website states "You are affected by the travel restrictions if you have been in a Schengen country at any point in the 14 days before your planned entry date to the US."  Do you think the airport connection means I will have been in a Schengen country in the 14 days before"?  I realise the word before is ambiguous because it may not apply to the current day.  Any comments welcome.

Starting Friday the 13th, all non-USA passport holders are not allowed entry into the USA when coming from the Schengen area. Does this include layovers?   I'll be traveling from Africa, laying over in Frankfurt and finally arriving in Dulles. As a US citizen, what will be the impact of my layover?


My question is very simple.  I know every metric space is Hausdorff, but the converse is true? anyone knows some counterexample?  Thanks

Is there an example of a compact Hausdorff space that is not metrizable?  I was thinking maybe the space of continuous functions $f: X \rightarrow Y$ between topological spaces $X, Y$, might work, but I'm sure I'm missing some conditions.


The server code of my Oracle database contains two files (classes) namely: Main.javaand DBManager.java. DBManager.java contains SQLPRocessing and SQLProcess methods (functions) that perform executeUpdate and executeQuery operations with the query statement, respectively. The SQL queries for dumping and fetching the data are written at the Main.java class. My database contains two tables T1and T2. My code has two queries for inserting the data as:  public void SQLProcessing(String ID, String X, String Y, String XE, String YE){     db.SQLProcess("INSERT INTO T1 VALUES("+Double.parseDouble(ID)+ "," +Double.parseDouble(X)+ "," +Double.parseDouble(Y)+")");     db.SQLProcessing("INSERT INTO T2 VALUES("+Double.parseDouble(ID)+ "," +Double.parseDouble(XE)+ "," +Double.parseDouble(YE)+")");                     }   Similarly, for getting the data back from the database, I use single SELECT query as:   public ResultSet SQLProcess(String msg1, String msg2, String msg3, String msg4, String msg5){     ResultSet rs = db.SQLProcess("SELECT * FROM T1, T2 WHERE T1.ID = T2.ID");     return rs; }   While executing the code, I get an error:  Exception in thread "Thread-1" java.lang.NullPointerException at Main.sendTo(Main.java:132) at Main$ServerReceiver.run(Main.java:79)   The line 132 of Main.java contains while(rs.next()) and line 79 contains sendTo(socket.getInetAddress()); . However, when I see the database, data is sent and stored in the database. So, I think the problem is with the SELECT query. I tried many possible SELECT queries from different threads, I could not solve the problem. Is my guess correct? Could anybody provide the real SELECT query for my case? Or is the error is triggered from another source?  The problem is with the cursor. It is null and I added an if statement as:  if(rs!=null) {         while(rs.next()){//code}    Then it does not generate any error. However, the client device does not get any data from the server. How can I fix it?

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?


How would I go about showing that the composition of Galois extensions may not be Galois? I figure I can just provide a counterexample but I'm having a hard time thinking of any.

Let $ K/ L /F $ be fields. If $K / L$ is Galois and $ L / F $ is Galois, then $ K / F$ is Galois. We mentioned this very quickly in today's class without justifying. But I have trouble seeing this. Any help is appreciated.  Our definition for $ K / F$ being Galois is the $F$-automorphism group $G = G( K / F) : = \{ \sigma \in aut (G) : \sigma_F = id_F \}$ fixes only $F$, i.e. $ \{ x \in K : \sigma (x) = x \text { for all } \sigma \in G  \} = F$.  But we also showed that $ K /F$ is Galois if and only if $ K/F$ is normal and separable.


I am trying to write in multiple files using ofstream. The problem is that I'm not able to write to more than 1020 files at the same time.  I don't understand if it's my laptop problem or if it's an internal limit of fstream.  I wrote a simplified version of my program. Obviously in this example it's not necessary to open multiple fstream channels.  #include <fstream> #include <vector>  using namespace std;   int main(){   vector<ofstream> write(2000);   char namefile[50];    for(int i=0; i<2000; i++){     sprintf(namefile,"text_%d.txt",i);     write[i].open(namefile, ofstream::out);      if (write[i].fail())       printf("Error writing to %s\n", namefile);      write[i] << "Hello!";     write[i].flush();   }    for(int i=0; i<2000; i++)     write[i].close();    return 0; }

When running my application I sometimes get an error about too many files open.  Running ulimit -a reports that the limit is 1024.  How do I increase the limit above 1024?    Edit ulimit -n 2048 results in a permission error.


Receiving undefined reference error in program code #ifndef Property_H #define Property_H  #include <iostream> #include <iomanip> using namespace std; #include <string> #include"Record.h" #include<vector>   template<class T> class Property { public:    Property();  ~Property();   Record* operator[](int);   void operator+=(Record*);   T getname();   void setname(T);  private:   T name;   //Record* elements[MAX_ARR] ;   vector<Record*> elements;   int size;     };   #endif  #include "Property.h"  template <class T> Property<T>::Property() {   size = 0; } template <class T> Property<T>::~Property(){}  template <class T> Record* Property<T>::operator[](int s) {   if (s<0 || s >= size) {     cerr<<"Overflow"<<endl;     return NULL;   }   return elements[s]; }  template <class T> void Property<T>::operator+=(Record* element) {   elements.push_back(element); }  template <class T> T Property<T>::getname(){return name;}  template <class T> void Property<T>::setname(T x){ name=x;}  This is the error g++ -o F main.o ReportGenerator.o Record.o  Property.o /usr/bin/ld: main.o: in function `main': main.cc:(.text+0x2c): undefined reference to `Property<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::Property()' /usr/bin/ld: main.cc:(.text+0x68): undefined reference to `Property<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::setname(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)' /usr/bin/ld: main.cc:(.text+0x8f): undefined reference to `Property<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::~Property()' /usr/bin/ld: main.cc:(.text+0xdc): undefined reference to `Property<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::~Property()' collect2: error: ld returned 1 exit status  It occurs when I test out the creation of my object in my main.cc Property<string>foo; foo.setname("j");  From what I've learned in so far and even looking at online examples of template objects my code should be working fine. It seems to be an error at compilation but I'm not sure what this means. I also receive an error when I call foo after initializing with brackets(). Been at it all night kind of want to cry in anger at this point. Property<string>foo; foo.setname("j");

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)