Antimatter is similar to ordinary matter except they have the opposite charge, i like to know why this difference in their spin would affect their motion in the curvature of our 4-dimensional spacetime? It can't be due to Earth's magnetic field or the air so what good reason to suspect antimatter would fall up since no test to date had suggest quantum particle falls differently compared to their big counterpart?

Confinement of antihydrogen might help provide a future answer.


I am currently learning Number Theory and one of the appendices of the book I am currently using introduces algebraic numbers and algebraic integers. One of the exercices is to prove the statement in the title: Prove that if $\alpha$ is an algebraic number and a root of $f(x) \in \mathbb{Z}[x]$ where $f$ has leading coefficient $a$, then $a\alpha$ is an algebraic integer. However, that statement does not make sense to me when looking at the definition of these objects. If $\alpha$ is a root of $f(x)$ then $\alpha$ is an algebraic number, but since $f(x)$ has leading coefficient $a$ then $f(x)$ is not monic sur $\alpha$ is not an algebraic integer. Now, I thought about taking the function $g(x) = \frac{1}{a}f(x)$ so that $g(x)$ is monic, but then $g(x)$ might not be in $\mathbb{Z}[x]$ but we would have $\alpha$ an algebraic integer. However this does not solve the issue of $a\alpha$ being an algebraic integer. I have tried coming up with an example but even with simple ones it does not make sense to me. Take $$f(x) = 2x^2 - 4$$ then $\alpha = \sqrt{2}$ is a solution and $f(x)$ has leading coefficient $a = 2$ so we can apply the statement I am trying to prove and get that $2\sqrt{2}$ is an algebraic number but, even if we forget about the monic part of the definition: $$f(2\sqrt{2}) = 2(2\sqrt{2})^2 - 4 = 16 - 4 = 12 \neq 0$$ So $2\sqrt{2}$ is not a root of $f(x)$ therefore it is not an algebraic number, even less an algebraic integer. What am I doing wrong? Is my understanding of these objects wrong in some way?

If $a$ is an algebraic number, show that there exists a positive   integer $n$ such that $na$ is an algebraic integer.   I'm supposing that $a$ is algebraic over a field $F$, that is, there exists a polynomial $p(x)$ over $F$ such that $p(a) = 0$ . If we think about $F$ being $\mathbb{Q}$, then $a = p/q$. And if we think that $p(x) = x-a$, we have that $p(x) = x-p/q$ is our polynomial. But I don't know if it helps. I don't even know if we can suppose that $x-a$ is our polynomial


How do you combinatorially prove the following? $$r \binom {n}{r} = n \binom  {n-1}{r-1}$$  I find it easy to prove such equalities algebraically, but have a hard time finding the right combinatorial intuition. Any advice for coming up with combinatorial proofs myself?

I am unsatisfied with the answers    . (Half of which used algebraic methods despite being advised not to!)   Help finding a combinatorial proof of $k {n \choose k } = n {n - 1 \choose k -1}$  I have completed the algebraic proof, it was easy. I am unsure how to do a combinatorial proof, or what exactly that pertains to.   Is this the expression needed:  $$\begin{pmatrix} n+1\\r\end{pmatrix}=\begin{pmatrix}n\\r\end{pmatrix}+\begin{pmatrix}n\\r-1\end{pmatrix}$$$$???$$


I picked up a copy of this in my grandmother's house, probably 10-20 years ago. I think my mother said it belonged to my aunt Mary, who probably would have read it around the 1970s (high school / college age). The primary characters were a pair of teenage girls who had an older male professor as their guardian. I'm pretty sure the girls had long blonde hair and blue eyes. I don't remember if the girls were feral children raised by dolphins or if they were part of an experiment by the professor, but they were amazing swimmers who could hold their breath for longer than any normal human. Other than that, I just have a few scenes dancing around it my head. First, the professor kept the girls on a boat, presumably so that they could be closer to water. Second, there was a scene where one of the girls put on makeup to try to be normal, and went off on a date. Her sister observes from a hiding place. The date in question sees the sister watching and assumes that this is a sign that they're both interested and he gets more aggressive. She interprets her date's kiss as an attack and goes off of the side of the boat, leading him to think that he killed her (my vague memory is that said date might have been an assistant to the professor or he might have just been a local townsperson).  The girls might have had a psychic connection with each other, but I'm less sure about that. Unfortunately, I read this over a decade ago, and I don't think I even got to finish the book. The front cover had one of the girls on the boat and I want to say that the title talking about them as "dolphin girls". It might have been part of a series.

In the late 1960's or early 1970's there was a book series about a boy whose parents were research scientists on on an island.  There was an explosion and he was blown into the water and somehow developed gills.  I don't remember the author or the name of the series. Can anyone identify this?


I have to change  <<STORE>>SA_MASTER_YYYMMDDHHMMSS.dat file name to  SA_MASTERYYYMMDDHHMMSS.<<STORE>>. Please tell me the command in unix to achieve this  for example 0001.SAMASTER_YYYYMMDDHHMMSS.DAT should be changed to SAMASTER_YYYYMMDDHHMMSS.1 ie if the store has leading zero(0001) i have to eliminate the zeros(1)

I need to rename files names like this  transform.php?dappName=Test&transformer=YAML&v_id=XXXXX   to just this  XXXXX.txt   How can I do it?  I understand that i need more than one mv command because they are at least 25000 files.


I have tried searching for a statement (a quote) that is made in a comment, with zero results. For example,  if I search for comment "news in 1983",  which is an exact quote for my own comment,  I get zero results in search.  The comment I made is . In chat room,  it was suggested that I could use  to search for a statement (a quote) made in a comment. Also,  in chat, it was suggested that information contained in comments might be transient and perhaps information should not be relied upon (stored) in comments. So, since the information does exist,  is there a simple way to search comments? (I can see my own comments on the acitvity tab of my profile; I want to be able to search other users' comments.)

Sometimes I can best remember a question by its comments. How can I search for a question that way?  Downloading the data dump is not viable because it may be a question posted today.


In CartoDB, how can i add a hyperlink to a field in a pop up box?

By far the most of my data is taken up a column of long strings pointing to the source of the data for each point. I need to keep that. However, it would be neat if CartoDB could use this information (i.e. build the URL) without me providing the full URL, only the relevant ending (and save on the size of the table by not repeating the common part as a long string). Is this doable in their info window?


A friend from Jamaica is visiting me in Nigeria. He has a valid US visa. His return flight is from Lagos to London Heathrow, and then London Gatwick to Kingston, all on British Airways. He will be transiting within six hours.    Does he need a transit visa for this?

Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.


I have been doing some research for a while on dual booting, often when I see pages or documentation on it, they have several partitions, and I have one. The one partition I have is ext4, it has plenty of room. But it's mounted, I spent all my money on buying windows 10 to dual boot with my Ubuntu GNOME, IT would be great if I could resize it without mounting it? If you can do it safely with it mounted then I will be happy to do that, if it would be less of a struggle and risk I am open to somehow removing Ubuntu to put windows on. Thanks in advance!

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


I am trying to understand the mechanism when i use finally inside a while loop.  In the below code. In finally line prints and than the while breaks. I was expecting the code not to reach the finally block. Or if it reaches the finally block, there is no break there so the while should continue.. Can anyone explain how this works ?           while(true){             System.out.println("in while");              try{                 break;             }finally{                 System.out.println("in finally");             }          }         System.out.println("after while");   Output is   in while in finally after while

Considering this code, can I be absolutely sure that the finally block always executes, no matter what something() is?  try {       something();       return success;   }   catch (Exception e) {        return failure;   }   finally {       System.out.println("I don't know if this will get printed out"); }


How many ways are there to arrange n objects into n bins, subject to the n constraints that the ith object can't go in the ith bin for any 1 <= i <= n ?  Each bin has to contain exactly one object.

I understand the whole concept of Rencontres numbers but I can't understand how to prove this equation  $$D_{n,0}=\left[\frac{n!}{e}\right]$$  where $[\cdot]$ denotes the rounding function (i.e., $[x]$ is the integer nearest to $x$). This equation that I wrote comes from solving the following recursion, but I don't understand how exactly the author calculated this recursion.  $$\begin {align*}  D_{n+2,0} & =(n+1)(D_{n+1,0}+D_{n,0}) \\ D_{0,0} & = 1 \\ D_{1,0} & = 0  \end {align*} $$


How to use the below to find the derivative of sin(x) (and cosine, too)?  $$\sin(x)=\sum^{\infty}_{n=0}(-1)^n \frac{x^{2n+1}}{(2n+1)!}\ , \ x\in \mathbb{R}$$  $$\cos(x)=\sum^{\infty}_{n=0}(-1)^n \frac{x^{2n}}{(2n)!}\ , \ x\in \mathbb{R}$$  $$\lim_{h\to\infty}\frac{\sin(x+h)-\sin(x)}{h}$$  Thanks!

We all know that the following (hopefully):  $$\sin(x)=\sum^{\infty}_{n=0}(-1)^n \frac{x^{2n+1}}{(2n+1)!}\ , \ x\in \mathbb{R}$$  $$\cos(x)=\sum^{\infty}_{n=0}(-1)^n \frac{x^{2n}}{(2n)!}\ , \ x\in \mathbb{R}$$  But how do we find the derivates of $\sin(x)$ and $\cos(x)$ by using the definition of a derivative and the those definition above?  Like I should start by doing:  $$\lim_{h\to\infty}\frac{\sin(x+h)-\sin(x)}{h}$$  But after that no clue at all.  Help appreciated!


#include <iostream>  enum types { INTEGER, DOUBLE, BOOL, STRING };  class Descriptor {  public:     Descriptor(types type):         _type{type}     {}     types &type() { return _type; }       virtual ~Descriptor() = default;  private:     types _type; };  class Number: public Descriptor {  public:     Number(types descType):         Descriptor(descType)     {}      virtual ~Number() = default;      int intValue; };   void printValue(Descriptor t) {    auto cast = dynamic_cast<Number *>(&t);   if (cast == nullptr) {     std::cout << "Err" << std::endl;   } else {     std::cout << "Works" << std::endl;   } }   int main() {    Number t =  Number(INTEGER);   t.intValue = 1;    printValue(t); }   The output is always Err. However when I change Number (in main) to be allocated on the heap with new the cast works and is able to access any functions within class Number?  Whats the difference in casting a stack object? When I tried to use static cast and access "intValue" it just gave me a garbage value. Is it possible to cast a stack object?

Someone mentioned it in the IRC as the slicing problem.


I am unable to download Ubuntu SDK . Whenever I try the command given on the .  I get an error saying unable to lock the administration directory.

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


Here's some background: I have multiple chapters in the dissertation I am writing. I have LaTeX-labelled the figures, the table and the equations.  Whenever I add a chapter, I create a .pdf of the entire manuscript written till that point, and then I use it as a source of references (talking material) for the subsequent chapters.  The problem: Say if in Chapter 6 I need to talk about a figure in Chapter 2, I have to open the code document and then hunt for the particular figure label. This task would be immensely simplified if there were some way (perhaps a package) which would add sticky-notes (which seem to be quite common in most PDF readers) to all the labelled elements. The sticky-notes then can be scripted to contain the labels. Of course, for the final documents I will need to disable this feature to reduce the clutter of the sticky-notes.   If you can think of some other workaround to achieve the same end, please let me know as well.

Working with documents with huge amount of equations it becomes cumbersome to go back and remind yourself what you labeled a certain equation to (I try to name them in a smart way, but there are too many).  Is there a convenient way to have equations print the label along with the tag/number, so that I can easily check the label in the compiled document?  Something like this would be perfect:  x = y               (14.1) eq:my_label


I've installed Ubuntu 14.04 a few days ago on dual boot with Windows 7 (not using Wubi) and now I see that I am almost running out of space.  I used GParted on a live CD. Now, I have on my drive an unallocated partition which was an empty partition but I can't add it to the Ubuntu's partition. When I right-click the Ubuntu's partition all I can do is Manage flags, Information.  Heres is the output of df -h:  Filesystem  Size Used Avail Use% Mounted on  /cow       1001M  66M  935M   7% /  udev        990M  12K  990M   1% /dev  tmpfs       201M 1.2M  200M   1% /run  /dev/sr0    996M 996M     0 100% /cdrom  /dev/loop0  953M 953M     0 100% /rofs  none        4.0K    0  4.0K   0% /sys/fs/cgroup  tmpfs      1001M 1.3M 1000M   1% /tmp  none        5.0M 4.0K  5.0M   1% /run/lock  none       1001M  76K 1001M   1% /run/shm  none        100M  72K  100M   1% /run/user   Output of sudo parted -l:  Model: ATA Hitachi HDS72103 (scsi) Disk /dev/sda: 320GB Sector size (logical/physical): 512B/512B Partition Table: msdos  Number  Start   End    Size    Type      File system     Flags  1      1049kB  106MB  105MB   primary   ntfs            boot  2      106MB   298GB  298GB   primary   ntfs  3      298GB   320GB  22.2GB  extended                  lba  5      298GB   312GB  14.0GB  logical   ntfs  6      312GB   318GB  5961MB  logical   ext4  7      318GB   320GB  2144MB  logical   linux-swap(v1)

I have two partitions, one of them has a file system and the other is unallocated.  How to merge two partitions?


Does there exist a closed form expression for this sum?  $$ \sum\limits_{i=1}^n \frac {1}{i} $$

One of the joys of high-school mathematics is summing a complicated series to get a “closed-form” expression. And of course many of us have tried summing the harmonic series $H_n =\sum \limits_{k \leq n} \frac{1}{k}$, and failed. But should we necessarily fail?      More precisely, is it known that $H_n$ cannot be written in terms of the elementary functions, say, the rational functions, $\exp(x)$ and $\ln x$? If so, how is such a theorem proved?    Note. When I started writing the question, I was going to ask if it is known that the harmonic function cannot be represented simply as a rational function? But this is easy to see, since $H_n$ grows like $\ln n+O(1)$, whereas no rational function grows logarithmically.  Added note: This  asks a similar question for “elementary integration”. I guess I am asking if there is an analogous theory of “elementary summation”.


I like creating slides in Beamer.  My supervisor doesn't.  He wants me to "generate or convert [the set I did for a conference] to PowerPoint."  I've tried different online and offline products like `Okto all to PowerPoint', TotalPDFConverter, and free-pdf-to-ppt-converter, but none of them quite cut it.    Most will screw up the text and/or the graphics, or simply convert the whole thing into a number of (low-resolution) bitmaps which are included in a PPT.  The best results I get with pdf2picture, which can convert PDFs into WMF or EWMF files which can be inserted into PPT slides.  When converting text to curves, most of the graphics look ok, however transparency doesn't seem to be handled correctly and it's still a lot of work inserting one WMF after another.  It says  that going through Keynote seems to work, but I'm already using PPT in a VM inside Linux---bringing in another OS would really be overkill.  Does anyone have any other hints?  The result should look like the original PDF and it should be editable, but it's alright if for example text is converted to curves or so.

I usually prepare my talks using powerpoint/openoffice-impress/keynote, where I explaing programs, pseudocodes, etc. Recently I was thinking about creating text-only, code-only and pseudocode-only slides with beamer and then exporting them somehow to powerpoint where I modify them to add figures or some minor details for polishing the presentation, which are usually hard to do with beamer. I googled a bit around and found that beamer can export to PDF or PS but not to powerpoint. I wonder anyway if you know some possibility of conversion from beamer to on-screen editable powerpoint/openoffice-impress/keynote.


I am using Angular JS 1 as my view for my project. With each deployment i have to clear cache to make my js changes visible. I cannot ask my client to do the same. I am caching this request for the first time when a new user access the applications because css/images are not going to change that frequently as respect to js files. please let me know if there is any way that we can load only the changed cc/image/js files in user browser and use rest of them from cache.

I have noticed that some browsers (in particular, Firefox and ) are very zealous in using cached copies of .css and .js files, even between browser sessions. This leads to a problem when you update one of these files, but the user's browser keeps on using the cached copy. What is the most elegant way of forcing the user's browser to reload the file when it has changed? Ideally, the solution would not force the browser to reload the file on every visit to the page.  I have found  and  suggestion to be useful. It turns out there is a term for this: auto-versioning. I have posted a new answer below which is a combination of my original solution and John's suggestion. Another idea that was suggested by SCdF would be to append a bogus query string to the file. (Some Python code, to automatically use the timestamp as a bogus query string, was .) However, there is some discussion as to whether or not the browser would cache a file with a query string. (Remember, we want the browser to cache the file and use it on future visits. We only want it to fetch the file again when it has changed.)


I get a string from input ,I want to give it a index like the following:  For example:  string Name = "Jack"   There are 5 possibilities :  Jack   = 1,  Alice  = 2, Stiven = 3, Alex   = 4, Katrin = 5   when I get Name from input I want to go through this enum class and get the index of it

What's the best way to convert a string to an enumeration value in C#? I have an HTML select tag containing the values of an enumeration. When the page is posted, I want to pick up the value (which will be in the form of a string) and convert it to the corresponding enumeration value. In an ideal world, I could do something like this: StatusEnum MyStatus = StatusEnum.Parse("Active");  but that isn't a valid code.


I know $\sqrt2$ and $\sqrt3$ are irrational numbers. However, how can I prove that $\sqrt2$ + $\sqrt3$ is an irrational number? Thank you.

I have proved in earlier exercises of this book that $\sqrt 2$ and $\sqrt 3$ are irrational. Then, the sum of two irrational numbers is an irrational number. Thus, $\sqrt 2 + \sqrt 3$ is irrational. My first question is, is this reasoning correct?  Secondly, the book wants me to use the fact that if $n$ is an integer that is not a perfect square, then $\sqrt n$ is irrational. This means that $\sqrt 6$ is irrational. How are we to use this fact? Can we reason as follows:  $\sqrt 6$ is irrational  $\Rightarrow \sqrt{2 \cdot 3}$ is irrational.  $\Rightarrow \sqrt 2 \cdot \sqrt 3$ is irrational  $\Rightarrow \sqrt 2$ or $\sqrt 3$ or both are irrational.  $\Rightarrow \sqrt 2 + \sqrt 3$ is irrational.  Is this way of reasoning correct?


By mistake my SD card was formatted. When I copy images out of the app lock vault I'm getting an error message that says my SD card is full.  How can I recover my images?

I just deleted a file on my Nexus S that I really need back. (It was actually part of an app using a sqlite database that did a drop table when upgrading to a new version.)  Presumably I need to root the phone first (which I hear is easy on Nexus phones) but am I in a catch-22 here? Namely, does rooting the phone mean wiping/overwriting the partition where the data lives?  If not, what do you recommend for data recovery tools? Presumably the file was just unlinked and not actively overwritten (per usual when "deleting" a file) so technically the data must be there...


It seems that a function of bounded variation is bounded. But how do we prove it?  Maybe to show this, we should prove that if a function is not bounded, then it is not of bounded variation.  So let a function $f$ be unbounded. Now how can I show that $\sup$$t_f$ is not finite?  where $t_f$ =$\sum_{j=1}^n\lvert f(x_j)-f(x_{j-1})\rvert$ where {$a=x_0 \lt x_1 \lt...\lt x_n=b$} is any partition of [$a,b$].

Using the standard definition  $$||f||_{TV} := \sup_{x_0<\cdots<x_n}\sum_{i=1}^{n} |f(x_i) - f(x_{i-1})|.$$   1.When the domain is a bounded interval $[a,b]$, the statement holds.   2.When the domain is $\mathbb{R}$ and the function is monotone, the statement holds both ways (if and only if).  But what about in general? My guess is true, and here is my arguement:  If $||f||_{TV} < \infty$, then $f$ only has jump discontinuities, so we can bound $|f|\leq g$ where $g$ is monotone. By this construction, $||g||_{TV}\leq ||f||_{TV}<\infty$. By (2), we know $g$ is bounded, thus $f$ is bounded.  Edit: I forgot, I probably need to impose a limit behavior at $\pm \infty$ for the function $g$. would $\limsup_{x\rightarrow \infty} g(x) - |f(x)| = 0$ be enough?  is this correct and thank you for your help!


Hi everyone I'm attempting to install spotify, I've been running linux for less than 24 hours so please cut me some slack if this seems trivial. Here is a link to the webpage  and the example script.         Add this line to your list of repositories by editing your /etc/apt/sources.list    deb http://repository.spotify.com stable non-free    If you want to verify the downloaded packages, you will need to add our public key  sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 94558F59    Run apt-get update  sudo apt-get update    Install spotify!      sudo apt-get install spotify-client      would someone be nice enough to walk me through this? I'm not even sure where to start.

A while ago Spotify (the streaming music service) came out with a preview for Linux of their client.  So what should I do?


$H$ is a subgroup of $G$ with $\phi(H) = H$  $\forall \phi \in Aut(G) \Rightarrow $ $H$ is normal in $G$    I'm not sure where to begin.  Perhaps we can use this corollary of the First Isomorphism Theorem   $N_G(H)/C_G(H) \cong Aut(H)$   But I'm not sure if this is helpful.

If $N$ is a normal subgroup of $G$ and $H$ a characteristic subgroup of $N$ (i.e., $\sigma(H)=H$ for all $\sigma \in \operatorname{Aut}(N)$). Show that $H$ is normal in $G$.     Does one needs to show that $\sigma(gHg^{-1})=gHg^{-1}$ for every g in G. Would that imply H is normal? is there a alternative way?


When I use the lens to run the calculator (which if often), I can't type just 'calc[enter]' (which is what my muscle memory does), I have to type 'calcu[enter]' otherwise LibreOffice Calc starts.  How can I suppress LibreOffice Calc from showing in the list. Or better still, how can I ensure the calculator program has precedence?

I want to open "LibreOffice Calc" and type in "Cal" in the search bar. I can see Calculator and LibreOffice Calc. Now I could use cursor keys or mouse to select LibreOffice Calc. But this is not what I want! What I want is to reorder the result! I want to have LibreOffice Calc BEFORE Calc, because this would be my preferred result (I just have to press enter if LibreOffice would be the first match).  Is that possible? Can I teach Unity to show result a certain way? Launchy (for Windows) e.g., a keystroke launcher, can do that! (Gnome-Do also works!)  Do you have some tips for me?


I'm curious if, given an integer $n$, there is a general method for finding the orders of the reduced residue classes modulo $n$, as well as how many reduced residue classes correspond to each order. I take $n=663=3\times13\times17$ as an example. There are $\phi(663)=\phi(3)\phi(13)\phi(17)=384$ reduced residue classes $\pmod{663}$. Further, $\lambda(663)=\text{lcm}(\phi(3),\phi(13),\phi(17))=48$, which means any any reduced residue has order at most $48$. However, I'm wondering if I can get more information; namely,  All the possible orders of reduced residue classes $\pmod{663}$; How many reduced residue classes there are for each order.   For what it's worth, a computer script gives that the possible orders are {1, 2, 3, 4, 6, 8, 12, 16, 24, 48} and 1 reduced residue classes of order 1 7 reduced residue classes of order 2 2 reduced residue classes of order 3 24 reduced residue classes of order 4 14 reduced residue classes of order 6 32 reduced residue classes of order 8 48 reduced residue classes of order 12 64 reduced residue classes of order 16 64 reduced residue classes of order 24 128 reduced residue classes of order 48   I chose $663$ as an example but my primary question is about how to determine these facts in general. Thank you in advance!

If I take the $k \in \mathbb{N}$ power of 10 and mod it by a large prime, I notice that the remainders repeat at some point.  For instance $10^k mod~7$ seems to repeat every $8$th value of $k$.  Given $k$ (the power of ten), and a large prime number $p$, how can I compute the size of the cycle?  I tried writing a python script that computes the first instance of a repeat. However, I don't know if this works since a single instance of a repeat may not necessarily mean a full cycle.


Since updating from 13.04 to 13.10 my monitor when on login screen (Lightdm) is always on and the blank screensaver never works.  Gnome Screensaver is activated and is working find when logged in.   This is bad for electricity consumption

I want lightdm to enter power save after a specific period of time.  If I'm logged in then my screen will time out as per the user settings, however when no one is logged in the screen will stay on forever.  I've looked at some posts that make some suggestions on what to do, but none of them seem to work or it's down to my limited knowledge of Linux.  updated 6/2/2014: The settings shown by sudo -H -u lightdm dbus-launch --exit-with-session gsettings list-recursively org.gnome.settings-daemon.plugins.power are as follows:  org.gnome.settings-daemon.plugins.power active true org.gnome.settings-daemon.plugins.power button-hibernate 'hibernate' org.gnome.settings-daemon.plugins.power button-power 'interactive' org.gnome.settings-daemon.plugins.power button-sleep 'suspend' org.gnome.settings-daemon.plugins.power button-suspend 'suspend' org.gnome.settings-daemon.plugins.power critical-battery-action 'suspend' org.gnome.settings-daemon.plugins.power idle-brightness 30     org.gnome.settings-daemon.plugins.power idle-dim true     org.gnome.settings-daemon.plugins.power lid-close-ac-action 'suspend' org.gnome.settings-daemon.plugins.power lid-close-battery-action 'suspend'  org.gnome.settings-daemon.plugins.power lid-close-suspend-with-external-monitor false     org.gnome.settings-daemon.plugins.power notify-perhaps-recall true     org.gnome.settings-daemon.plugins.power percentage-action 2     org.gnome.settings-daemon.plugins.power percentage-critical 3     org.gnome.settings-daemon.plugins.power percentage-low 10     org.gnome.settings-daemon.plugins.power priority 0     org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 120     org.gnome.settings-daemon.plugins.power sleep-inactive-ac-type 'suspend'  org.gnome.settings-daemon.plugins.power sleep-inactive-battery-timeout 0     org.gnome.settings-daemon.plugins.power sleep-inactive-battery-type 'suspend'  org.gnome.settings-daemon.plugins.power time-action 120     org.gnome.settings-daemon.plugins.power time-critical 300     org.gnome.settings-daemon.plugins.power time-low 1200     org.gnome.settings-daemon.plugins.power use-time-for-policy true   I would have assumed the sleep-inactive-ac-timeout 120 would have been the correct entry, but it doesn't time-out unless I'm actually logged in as a user.


 Owner Information

$User.FirstName

$User.LastName

How I would go about getting the current users username or first and last name?  I have been looking at this for the last couple of hours - I was just wondering how I would go about getting their name and then displaying it on the page.  For example the current user is 'John Smith' and in the lightning component I want to output John Smith's name like:     Welcome to our community John Smith!


Currently very new to C++, studying it as part of my programming class.  From what i'm aware, the difference between structs and classes in C++ is that by default, class members are private, and struct members are public.  I wanted to try this out for myself, and wrote a small program in CodeBlocks:  Main.cpp  #include <iostream> #include "TestStruct.h"  using namespace std;  int main() {     TestStruct ts();     ts.print();     return 0; }   StructTest.h  #ifndef TESTSTRUCT_H #define TESTSTRUCT_H  #include <iostream>  struct TestStruct {     TestStruct(){}     virtual ~TestStruct(){}     void print(); };  #endif // TESTSTRUCT_H   And implementation file:  #include "TestStruct.h"  TestStruct::TestStruct() {     //ctor }  TestStruct::~TestStruct() {     //dtor }  void TestStruct::print() {     std::cout << "Testing" << std::endl; }   However, I'm getting a compile time error: error - request for member 'print' in 'ts', which is of non-class type 'TestStruct()'  Am I missing something completely obvious here? I thought it was possible to use a struct exactly like a class.

Is there any good reason that an empty set of round brackets (parentheses) isn't valid for calling the default constructor in C++?  MyObject  object;  // ok - default ctor MyObject  object(blah); // ok  MyObject  object();  // error   I seem to type "()" automatically everytime. Is there a good reason this isn't allowed?


$\int_{0}^\infty \frac{\cos(ax)-\cos(bx)}{x}dx$ I represented the integrand by an integral of $\sin(xy)$ to get an double integral $\int_{0}^{\infty}\int_{b}^{a} \sin(xy)dydx$ Then I want to change the order of this double integral, but I how can I solve $\int_{0}^{\infty}\sin(xy)dx$ first?

Suppose $ \alpha, \beta>0 $. Compute:   $$ \int_{0}^{\infty}\frac{\cos (\alpha x)-\cos (\beta x)}{x}dx $$   Here is what I do: $$\begin{align} \int_{0}^{\infty}\frac{\cos (\alpha x)-\cos (\beta x)}{x}dx &= \int_{0}^{\infty}dx\int_{\alpha}^{\beta}\sin (yx)dy\\ &=\int_{\alpha}^{\beta}dy\int_{0}^{\infty}\sin(yx)dx\\ & \\ &   \qquad\text{let $ yx=u $}\\ & \\ &=\int_{\alpha}^{\beta}\frac{1}{y}dy\int_0^{\infty}\sin u du\\ &=\int_{\alpha}^{\beta}\frac{1}{y}dy\left( -\cos u|_{\infty}+\cos u|_0 \right)\\ &=\log\frac{\beta}{\alpha}(-\cos(\infty)+1)\\ &=\log\frac{\beta}{\alpha}-\cos(\infty)\log\frac{\beta}{\alpha} \end{align}$$  But $ \cos(\infty) $ does not exist right? Does it mean the integral actually diverse?  Edit: The question comes from   Who can point out my mistake in the above deduction?


A 2nd half of 20th century story about a society with no adults except one individual. The punch line is something like “..we killed them [the adults] all”.

I'm trying to find a short story from the 60's(?) about a future society dominated by mutant(?) children who've killed off all the adults except, for sentimental reasons, one. The adult was a man. They kept him out of some kind of respect or gratefulness. It’s told from the children’s perspective. The punchline is something like “...we killed them [the adults] all”. And that’s the last line, nothing after it. It’s not Children of the Corn.


As a marker, there are always some students who will email requesting to meet  as they disagree with the marking. According to the professor, the marker should solve students' marking issues but I am uncomfortable with those students who insist that marks should be given in their way. Some of them are disrespectful. If I refuse to meet them, they will complain to the professor about me not engaging with students and the professor will criticize me. Should I engage with these students?

An annoying aspect of working with a "strict" grading system (e.g., 90%+ = A, 85% = A-, 80% = B+, etc.) is what I call the "grade grubbing" phenomenon: the people who feel compelled to raise complaints about the grading because they didn't get the final score they want—but have no real argument in support of a higher grade. This is not about legitimate requests to reconsider because of a mistake but instead students searching for any reason why they deserve the X points they need to get a better grade. It’s exemplified by the kind of argument that begins “I know it’s wrong but . . . .”  I do not have the power to change the grading structure—that is imposed from higher up.   Are there any satisfactory methods of discouraging such behavior? I don't want to stop people with legitimate issues from asking for regrades (mistakes happen!), but I would like to avoid having to deal with the student who tries every which way to get the few points they need to move up a level.


How do I set spawn point using command block with coordinates 8,462 4,00000 8,591?I have been trying, but haven't been able to do it right.

What command do I use to make everyone spawn at one place? because I am making a map and I don't know how to make everyone spawn at one place, the rule place.


I need to draw a nonuniform text bubble and fitting the text inside of it.

I am designing a poster, which has some geometrical shapes (TikZ paths) surrounded by some text. I would like the text to flow neatly around these shapes. I bet there's some clever TikZ magic that could do this.  EDIT: This is the sort of effect I want, sorry to not be clear:    \documentclass[a4paper]{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \draw (0,0) to (2,-2) to (2,-4) to (4,-4) to [out=up, in=down] (6.5,0); \node [text width=6cm, anchor=north west] at (0,0) { \hspace{5pt}  This is the sort of effect I want to \\ \hspace{23pt} achieve, with text automatically \\ \hspace{36pt} constrained by some \\ \hspace{46pt} geometrical form. Here \\ \hspace{55pt} it's just a curve, \\ \hspace{57pt} but this could \\ \hspace{57pt} also be the \\ \hspace{57pt} text label \\ \hspace{57pt} of a node.}; \end{tikzpicture} \end{document}


I'm just working through some information theory and entropy, and I've come into a bit of a problem.  In many texts, it's easy to find the "chain rule" for entropy in two variables, and the "conditional chain rule" for three variables, respectively; $$H(Y|X) = H(X,Y) - H(X)$$ $$H(X,Y|Z) = H(Y|Z) + H(X|Y,Z) = H(X|Z) + H(Y|X,Z)$$  However, I'm trying to determine the entropy of three random variables: $H(X,Y,Z)$. I haven't done a lot of probability/statistics before, and googling hasn't really turned up anything too fruitful.  Can anyone help me derive this result??

I have been reading a bit about conditional entropy, joint entropy, etc but I found this: $H(X|Y,Z)$ which seems to imply the entropy associated to $X$ given $Y$ and $Z$ (although I'm not sure how to describe it). Is it the amount of uncertainty of $X$  given that I know $Y$ and $Z$? Anyway, I'd like to know how to calculate it. I thought this expression means the following:  $$H(X|Y,Z) = -\sum p(x,y,z)log_{2}p(x|y,z)$$  and assuming that $p(x|y,z)$ means $\displaystyle \frac{p(x,y,z)}{p(y)p(z)}$, then  \begin{align} p(x|y,z)&=\displaystyle \frac{p(x,y,z)}{p(x,y)p(z)}\frac{p(x,y)}{p(y)}\\&=\displaystyle \frac{p(x,y,z)}{p(x,y)p(z)}p(x|y) \\&=\displaystyle \frac{p(x,y,z)}{p(x,y)p(x,z)}\frac{p(x,z)}{p(z)}p(x|y)\\&=\displaystyle \frac{p(x,y,z)}{p(x,y)p(x,z)}p(x|z)p(x|y) \end{align} but that doesn't really help.  Basically I wanted to get a nice identity such as $H(X|Y)=H(X,Y)-H(Y)$ for the case of two random variables.  Any help?  Thanks


I'm looking for some intuition behind how a cNOT gate works.  I think I understand the mathematics; but, I'm having trouble imagining how two electrons would interact to produce the predicted result.  If I understand correctly, the input to a cNOT gate is two unentangled electrons. I picture these as two Bloch spheres with vectors pointing in arbitrary directions.   To implement a cNOT gate, we would (1) bring these two electrons close enough to become entangled, (2) prevent electron x from rotating in the z direction (thereby preserving its state in that direction), and (3) allow electron y to rotate (which changes the probably of measuring it in the up state with respect to the z axis).   My understanding is that entanglement is a result of electrons rotating to align their spin axes into a lower energy state.  If that's the case, why is electron y affected more when electron x's axis is pointed up than when it's pointed down?   It would make sense if the effect was symmetric (large when the angle is close to either 0 or $\pi$, and small when it is close to $\frac{\pi}{2}$), but given that y can be oriented either up or down, I don't see how the effect of x can be small with oriented up and large when oriented down.  This post addresses the implementation of cNOT, but from a perspective that seems more mathematical than intuitive.   This video gives the type of answer I was looking for:  (I would have added this as the answer; but, I can't while the post is marked as a duplicate.)

I think I understood very well how operations on one qubit are done - if qubit is electron, we just apply magnetic field in direction we want to make spin precess (unitary operations on single qubit).  I sort of understand how entanglement happens - you let 2 electrons interact and the lowest possible energy state is entanglement, so nature just puts them there. (?) But why all of a sudden we can make unitary operations on 2 qubit hilbert space? What physically lets us do so?   Rephrasing questions - How is CNOT operation realized physically?


Please prove that $$e^x - x$$ is always bigger than or equal to 1

How to prove $$1+x \leq e^x~\forall x \in \mathbb{R}$$  I'm stuck, I tried taking logs but didn't know how to proceed.


Is multiplication comutitive  in numbers I.e   Is  N×M equal    M×N?? Where N and M any numbers   And why??

Why is it that $$ab=ba$$ for positive integers $a,b$? Is there an intuitive explanation or we just need to accept it as a given fact?


I want to ask, because this cycle throws me false ?, not know why that is the result. I think it has to do with floating point  Thank you for your help.  double a = 2d; System.out.println(a);  double b = 2.6d ; System.out.println(b);  for (int i = 0; i < 6 ; i ++) {     a+= 0.1; }  System.out.println ( a==b ) ;   RUN  2.0 2.6 false

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


Can somebody first please tell me what is the row rank and column rank of a matrix ? What is the relation of each with the rank of a matrix ? Any kind of explanatory proof would be very helpful , thanks ! Also , I am not looking for an intuitive proof , I need the mathematical proof and its explanantion , for I did not uderstand much when I looked at the proof on the internet .

I am looking for an intuitive explanation as to why/how row rank of a matrix = column rank. I've read the proof at  and I understand the proof, but I don't "get it". Can someone help me out with this ?   I find it hard to wrap my head around the idea of how the column space and the row space is related at a fundamental level.


I accidentally left 1tb of unallocated space, and decided to expand my /home partition(sda6) but somehow I cannot, tried all different "answers" here but none of them worked, so I have to ask directly..  I have Windows 10 + Ubuntu 17.10 dual-boot solution, with Ubuntu booting first at boot(selecting OS in GRUB), and using Gparted from Ubuntu ISO(set up via Unetbootin in Win 10).  Here I post also image if partitions - sorry for phone picture..  EDIT: I installed it using one big guide out there, if i recall correctly - sda1 is default partition which PC shipped with, should do something with Windows i believe, sda2 is Windows C: drive, sda3 is well..swap, sda5 is / (root fs), sda6 is /home, sda7/8/9 is /boot, /var and /tmp in this order. Hope that helps, Also updated screenshot now with mount points. PS: Sorry for language

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


I am trying to install Eclipse IDE using a file eclipse-rcp-kepler-SR1-linux-gtk-x86_64.tar.gz I have followed all the steps mentioned in  But I am still not able to launch Eclipse: error : cannot execute binary file  I have already installed jdk 1.7. uname -i i686

When I download Eclipse and extract it and write at terminal ./eclipse I see this error bash: ./eclipse: cannot execute binary file    What can I do?


I have a bar plot drawn with pgfplot and reading values from a CSV file. Is there a way to add a number above each bar where the number comes from another column in my CSV file ?

I am using LaTeX, TikZ and PGFplot in order to automatically generate several series of diagrams, one of which is comprised of bar charts. Each bar in each bar chart may have a unique label and height -- I have used PGFplot before and I know that I can read in coordinates from files, but would it be possible for me to create labels for each bar using textual data stored in a tab-separated file? If so, how would I do this? A simplified example of a file I might use is shown below.  # foo.dat # Label | X-Position | Height  A    1    15 B    2    20 C    3    12 D    4    24   Thanks for your help!


import java.util.Scanner;  public class Basic {     public static void main(String[] args) {         Scanner CalcType = new Scanner(System.in);         double fnum, snum;         String math;          System.out.println("--------------------------------------------------");         System.out.println("Welcome to the basic calculator made by codermadi!");         System.out.println("--------------------------------------------------");         System.out.println("Enter first number!");         System.out.println("--------------------------------------------------");          fnum = CalcType.nextDouble();          System.out.println("--------------------------------------------------");         System.out.println("Enter second number!");         System.out.println("--------------------------------------------------");          snum = CalcType.nextDouble();          System.out.println("--------------------------------------------------");         System.out.println("+ | - | / | x | %");         System.out.println("--------------------------------------------------");          math = CalcType.next();          if (math == "+") {             System.out.println(fnum + snum);         }         if (math == "-") {             System.out.println(fnum - snum);         }         if (math == "/") {             System.out.println(fnum / snum);         }         if (math == "*") {             System.out.println(fnum * snum);         }         if (math == "x") {             System.out.println(fnum * snum);         }         if (math == "%") {             System.out.println(fnum % snum);         }          System.out.println("-------------------------------------------");         System.out.println("Thank you for using codermadi's calculator!");         System.out.println("-------------------------------------------");     }  }   I have a problem, when I type the type of math I want my calculator to do it doesn't output the if statements.. My problem is at the bold text.  -  -  -  -  Had to add these because StackOverFlow wants me to add more details.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I had recently submitted my paper to this journal on the advise of my guide and quite fortunately, I received an email a few days back saying that the paper had been accepted for publication. So before I pay the requisite fee of $165 (what is your opinion? is this too much?) I just wanted to know how good the journal was (the website says it has an impact factor of 2.13) and how much value such a publication will have. Would be really nice if someone could guide me on this. (This would be my first publication and I'm an undergraduate student) This is the journal's website link:

What are the best strategies for assessing if a journal is a "vanity" or "predatory" journal that should be avoided (both for publishing in and reviewing for)? For example, how would one go about determining if a journal/publisher belongs on ?


When I adjust the focus of my camera, in general, does this affect the focal length? I have heard that it does.

When I change the focus distance on my Pentax 55-300mm lens, the focal length appears to change.  More specifically, the lens appears to zoom in as I focus towards the minimum focusing distance.  This is most noticeable at the 55mm end of the lens.  Is this normal?


I just picked up my passport today at the Chinese Consulate, and realized my visa was stamped on one of the three observation pages on my passport after I came home. I'm not sure whether I need to get a new passport and ask them to reissue the visa. Has anyone experienced this situation before?

just wanted to inquire that can Visas be stamped on the Observation Pages of the Passport? I called my Embassy for renewal of Passport, however, the Passport Officer commented that you still have Observation Pages left. This was pretty strange to me as i never heard that Visas can be stamped on the Observation Pages. Does anyone has this experience?


I have to show whether the groups $(\mathbb{C}, +, 0)$ and $(\mathbb{C} − \{0\}, \times, 1)$ are isomorphic. I know that two groups are isomorphic if there exists an isomorphism from one to the other. An isomorphism from $G_1$ to $G_2$ is a bijective homomorphism. We call $G_1$ and $G_2$ isomorphic, and write $G_1 \cong G_2$ if an isomorphism from $G_1$ to $G_2$ exists. I tried the following by using the lecture notes: $\varphi:\mathbb{C}− \{0\} \mapsto \mathbb{C}$, then $x\in \mathbb{C}−\{0\}$, and $\varphi(x)\in \mathbb{C}$, then $|x|=|\varphi(x)|$. Now note that the element $i\in \mathbb{C}−\{0\}$ has order $4$. However, no element in $\mathbb{C}$ has order $4$, I think???. Hence, no isomorphism can exist. Hence, the groups $\mathbb{C}−\{0\}$ and $\mathbb{C}$ are not isomorphic. Any tips or help would be grateful!

Let $(F,+,\cdot)$ be a field.   Then to prove that $(F,+)$ and $(F-\{0\},\cdot)$ are not isomorphic as groups.  I am facing difficulty in finding the map to bring a contradiction!!


I have a simple LaTeX tabular table:  \begin{tabular}{|l|l|l|}   \hline   A  & B  & C \\   \hline   A1 & B1 & C1 \\   \hline   A2 & B2 & C2 \\   \hline \end{tabular}     Now the padding at the top of the cells is much smaller than the padding at the bottom, I guess because space for descenders is reserved. It makes the text look unaligned. How do I add some padding at the top of the table cells? I tried \arraystretch but it also adds padding at the bottom.

How do you guys go about controlling column padding in tables?   Update  To clarify, I'm looking for a way to control both vertical and horizontal padding. So, if I had a simple table like in the following code snippet, I could pad the columns and make them look a bit less... ugly. :P   \begin{tabular}{|l|l|}     \hline     column 1 & column 2 \\      \hline     I really would like this less & crammed\\     \hline \end{tabular}   I tried this by using the command \vspace but it leaves gaps in the vertical lines.


Is there any graph that all its vertices are cut vertices? I couldn't find a graph with this property? and if there is no such graph  how can i prove that it does not exist.

I'm trying to prove that any simple connected graph with at least $3$ vertices ($|V| \ge 3$) has at least $2$ vertices whose removal will not lead to the increment of number of components. In other words, there are at least $2$ vertices that are non-cut vertices.  Attempt at solution:   I tried to prove it using induction by the number of vertices: $n - t \ge 2$, where $n$ is the number of vertices our graph has, and $t$ is a number of cut vertices.   Base  Let $n =3$, then the graph will look like this:  $О-О-О$  Clearly, it has one cut vertex (the middle one). So, $3-1 \ge 2$ holds.  Or it can be a full graph, then $3 - 0 \ge 2$ also holds. Assumption  Let $n = k$, and the formula holds, $k - t >= 2$ Step  Prove for $n = k + 1$ If we add one vertex to the graph, it could either be a cut vertex or non-cut vertex. In case it is a cut vertex, we have $$\begin{align*}&(k+1) - (t+1) \ge 2\\ &k + 1 - t - t\ge 2\\ &k\ge 2\end{align*}$$   In case it is not a cut vertex...and I'm stuck here, because anything can happen. The number of cut vertices might increase, might decrease, or stay the same.  I'm sure there is better and shorter proof to this, and I really hope someone could help me.


I Tried  DELETE FROM installments WHERE EXISTS (SELECT * FROM `installments`               JOIN student               ON installments.s_id=student.s_id               WHERE installments.curr_sem=3                    AND student.bat_id=10 AND student.p_id=170 AND student.DeleteStatus=0);   but show error     #1093 - You can't specify target table 'installments' for update in FROM clause   Please help me

I have a table story_category in my database with corrupt entries. The next query returns the corrupt entries:  SELECT *  FROM  story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category INNER JOIN         story_category ON category_id=category.id);   I tried to delete them executing:  DELETE FROM story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category        INNER JOIN story_category ON category_id=category.id);   But I get the next error:      #1093 - You can't specify target table 'story_category' for update in FROM clause    How can I overcome this?


What commands look up the hostname of a LAN device at a given IP address? For example:  dig -x ip.address nslookup ip.address   are not giving LAN device names, only registered domain names on the WAN.

My network includes machines running Linux and others running Windows. And my machine is running Linux.


I am working on a game where I want to allow users to mix multiple colors (similar to shown in this video): . I have the following questions:  I am expecting that this is done using shaders. What kind of shader I have to use for such implementation? What will be the logic to create this type of shader?  Are there any other ways using which this feature can be implemented?  Are there any open source tutorials or examples?   I would appreciate any suggestions and thoughts on this topic. Thank you.


I haven found a answer to the question from 2013 but is this answer still valid with SNI.    Is it possible to have a certificate or SAN with www.*.domain.com which works with current Browsers?  example:  plain www.subdomain1.domain.com/ => secure www.subdomain1.domain.com/ plain www.subdomain2.domain.com/ => secure www.subdomain2.domain.com/  I know how to configure nginx to accept the domain but I'm not sure if the browser accept the certificates.  Many thanks for answers.

I'm using TinyDNS, and have successfully used wildcard records of the form:  +*.<domain>:<ip>   (+ for A records.)  Can I also use:  +development.*.<domain>:<ip>   ?  My intention is for all subdomains to have their development website point to our dev machine in one rule.


I'm currently peer-reviewing a paper (for a computer science conference; review is double-blind). While reading it, I came up with a method for the problem they're solving, somewhat inspired by their approach but fairly separate. I haven't implemented and tested it yet, but I expect it to be better than their approach, and it is definitely (in my mind) simpler. The idea came from slightly reframing their approach based on papers that they've cited in their submission, so they had the tools to do so, but they may not be as familiar with as I am (it happens to be right in my wheelhouse).  I see two options here:   Suggest the reframing and the new method to them in the review. They may or may not do anything about it, but if they do, all I get is thanks to an anonymous reviewer in their acknowledgements, assuming the paper gets in. (In my opinion, their paper is probably borderline for this conference.) If they don't use the idea, then it just goes away. Don't say anything about it in the review; develop the method independently. think, at this early stage, that it's reasonably likely a whole new paper can be written based on this method and related improvements I have in mind. If their paper gets in to this conference, or is put online / gets in somewhere else before I'm done with my paper, cite them. If it doesn't, I could either ignore their paper and write my own – which feels somewhat dishonest, though I wouldn't really be using their results in my new paper – or ask the PC to get me in touch with the authors for possibly collaborating on a single joint paper with both methods. I don't know if that kind of thing is ever done.   Option 1 is clearly ethical, but if option 2 is also ethical, it's both better for my career and possibly better for scientific progress as a whole (if they don't end up using the idea). So my question is: is option 2 okay? What do I do in the case where their paper doesn't get in?

I received a journal paper for a review. The paper suggests a solution to an important problem, but the solution is very complicated and has mediocre performance. While reading the paper, I thought of a different solution, which is much simpler and has better performance (to give some scale: their solution is 1 page to write and 5 pages to prove; my solution is 5 lines to write and half a page to prove).  What should I do now?  A. Write my solution in the review, hoping the authors will remember to "thank the anonymous reviewer"?  B. Recommend that the paper published as is, then write a paper of my own with my improved solution?  C. Something else?  EDIT: Before I found the superior solution, I thought of recommending "resubmit with major revision", with the reasons that I mentioned above: your solution is too complicated and its performance is too weak.  However, now I am not sure it is the good course of action. A major revision may take a long time. The authors might even decide to delay or stop working on the paper without telling the editor (or me). Meanwhile, I will have to postpone the publishing of the superior solution for an indefinite amount of time. What do you think?


I'm pretty sure this isn't the right place to ask this. I'm not aware of a stack site out there where this question would fit. If someone could point me to the right place it would be awesome.     The question I was going to ask is:       I am incorporating a blogging feature into my car enthusiast site. I want each user to be able to have their own blog and be able to browse other people's blogs. What blog engine would be best for this scenario?      I am using ASP MVC 4 and found  to look promising; however, I am a bit confused at the setup. This seems to be a blog set up for a personal site and not a "Nest of blogs" type of system. I've never done a blog before so I'm fresh meat here.

Stuff like polls, recommendations based on subjective constraints, puzzles, webcomics etc. do not belong on the serious main SE sites, where professionals should be considered at work and having just a few spare minutes ("code's compiling") to answer questions, so they should not be distracted by such things. However, I'd also like to have a home for these things still using the SE engine. For the reason I mentioned before, this needs to be a separate place though. Let's call it four.[sitename-here].com.


Could we define proper $\mathbb Q$ module structure on ring of integer $\mathbb Z$? Any comments are welcome.

This is an exercise from Chapter 3 of Golan's linear algebra book.  Problem: Show $\mathbb{Z}$ is not a vector space over a field.  Solution attempt:  Suppose there is a such a field and proceed by contradiction. I will write multiplication $FV$, where $F$ is in the field and $V$ is an element of $\mathbb{Z}$.   First we rule out the case where the field has characteristic 2. We would have   $$0=(1_F+1_F)1=1_F1+1_F1=2$$  a contradiction.  Now, consider the case where the field does not have characteristic 2. Then there is an element $2^{-1}_F$ in the field, and   $1=2_F(2^{-1}_F1)=2^{-1}_F1+2^{-1}_F1$  Now $2^{-1}_F1\in\mathbb{Z}$ as it is an element of the vector space, but there is no element $a\in\mathbb{Z}$ with $2a=1$, so we have a contradiction.  Is this correct?


I ask because I have what I think is a solution, but it doesn't fit the spirit of the joke, which is to say, it doesn't produce anything like a pin.  The solution I get is the equation below:  $$-\frac{135\sqrt2\ln(3-2\sqrt2)+404}{16\sqrt2}$$  However, this solves to a transcendental number, beginning:  $$-2.98126694400553644032103778411344302709190188721887186739\cdots$$  So, I'm appealing for better or more informed solutions if I have made a mistake.  Does the equation solve to something nice and friendly, or is the whole thing just a wheeze?

This question is inspired by my own answer to a  which I tried to answer and got stuck at one point.     The question was:     HI DARLING.      USE MY ATM CARD, TAKE ANY AMOUNT OUT, GO SHOPPING AND TAKE YOUR FRIENDS FOR LUNCH.      PIN CODE: $\displaystyle \int_{0}^{1} \frac{3x^3 - x^2 + 2x - 4}{\sqrt{x^2 - 3x + 2}} \, dx $      I LOVE YOU HONEY.      Anyone knows? Are we gonna get an integer number?     My attempt:  Does this help?     $$\frac{3x^3-x^2+2x-4}{x-1}=3x^2+2x+4$$   (long division)   \begin{align*} I&=\int\frac{3x^3-x^2+2x-4}{[(x-1)(x-2)]^{1/2}} dx = \\ &=\int\frac{(3x^2+2x+4)(x-1)^{1/2}}{(x-2)^{1/2}} dx = \\ &=\int 3(u^4-4u^2-4)(u^2+1)^{1/2}du \times 2 \end{align*}   after the substitution   \begin{gather*} (x-2)^{1/2}=u\\ du=\frac1{2(x-2)^{1/2}}dx\\ u^2=x-2\\ (x-1)^{1/2}=(u^2+1)^{1/2} \end{gather*}   Update:  may help us proceed.    I tried to proceed:     $$6\int (u^4-4u^2-4)(u^2+1)^{1/2} du = 6\int ((t-3)^2-8)t \frac{dt}{2u}$$   after $u^2+1=t$ and $dt=2udu$   \begin{align*} u^4-4u^2-4 &= (u^2+1)^2-(6u^2+5) \\ &= (u^2+1)^2-6(u^2+1)+1 \\ &= ((u^2+1)-3)^2-8 \end{align*}   I wonder whether this question can be solved from here?    Update:   This has been getting a lot of views, and I think most people came for the sort of problem mentioned in the title (where I got stuck) rather than the original problem itself.  Keepin this in mind, I'm reopening the question and here's the kind of answers I expect — Solutions to the original problem are good, but I'd prefer solutions that continue from the part where I got stuck — the polynomial in $u$ — that's the sort of problem mentioned in the title.


Show that if any continuous real-valued function on a metric space $X$ attains its maximum value, then $X$ is totally bounded.  So, want to show that for every $\epsilon > 0$ there exists a finite subset $\{x_1,...,x_n\}$ of $X$ s.t. $X\subset\cup_{k=1}^nB(x_k,\epsilon)$. I'm thinking to prove it using contrapositive, that if $X$ is not totally bounded then there exists a continuous real valued function on $X$ that is unbounded above, but I'm stuck!! Any help would be appreciated.

Suppose $(M,d)$ a metric space. I want to show that      If every continuous real-valued function on $M$ attains a maximum, then $(M, d)$ is compact.   I was trying to do this by assuming $M$ non-compact and showing explicitly a function which does not attain a maximum. If $M$ is not bounded it's enough to take the distance from a fixed point as we can always find a sequence which "exits" every compact and pushes the distance at infinity. But what if $M$ is bounded?


I have been suspended on , and that includes a suspension on the meta and presumably the chat. However, surely I should be able to chat on others sites such as Area 51 or Stack Overflow? Yet when I went onto the Area 51 chat earlier, it told me that I wasn't allowed to chat because     your account is suspended on the parent site and cannot chat for 14 days.   My chat account is  and you may notice that it says the same message. What should I do? Surely I should be allowed to chat in non-PPCG rooms?

Chat has many problems.   (Wut? I'm not suspended here!)  I think chat should be redone. The URL is weird, sometimes its chat.stackexchange.com sometimes its chat.SITE.stackexchange.com. Then here its chat.meta.stackexchange.com and the chat profile on other sites is not linked here.  I think we should use one site, and its chat.stackexchange.com. That way, there's no funny suspension issues.  Instead, it should be like chat.stackexchange.com/?site=SITE. Sites like stackoverflow will be just as the name is for SITE, not chat.stackoverflow.com.  Then for the suspension detection thing, it should not check the referrer, otherwise that ^ happens. Instead, it should look at the site for the room and check if the user is trying to chat.  and say "Hey! You're not suspended here! Chat!" or "Sorry, you're suspended. No chatting for you :(". Also, the caching issue with SE 1.0 sites needs to be fixed.  Also, this makes all chat profiles one, not have multiple. Also, based on the site part of the URL, the CSS changes according the the site.  Here's how to get it.   Get a test account suspended. Go to a room like chat.SE.com/rooms/35/the-bridge Click "all rooms" Go to a random room on a different site. You're still suspended and can't chat.   This needs to be so that its not suspended on "chat.SE.com" but it checks on the site for the room. Example: I can't chat in Arqade rooms but I can chat in the charcoal chatbot sandbox room. Otherwise I can only chat on chat.SO.com and chat.meta.SE.com.    Ok if you don't like "redo" then lets go with "change some stuff"


num = 0 def regex(m):     num = num + 1     return '' % (m.group(1), '/number/', num)   re.sub('', regex, source)   source is
hogehogehello
aaaa

aa

aaaaaa
   result  UnboundLocalError: local variable 'num' referenced before assignment   ideal         source ideal is
hogehogehello
aaaa

aa

aaaaaa
    I do not want to use finditer if possible. I would like to complete with as short a code as possible.  I tried use global num. but Error SyntaxError: name 'bum' is assigned to before global declaration.

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


I have the following array environment:  \begin{array}{ccc} 0 & = & \text{some equation} \\ 0 & = & \text{some other equation} \\   & \vdots \\ 0 & = & \text{last equation} \end{array}   However, I get lots of spacing around the equal signs here, not unlike when using the eqnarray environment.  I want to use the array environment because \vdots is of smaller width than =, and gets centered under it.  Any help on conforming the padding/spacing to other equations would be greatly appreciated.

I have a system of equations with an arbitrary number of equations (k). I'd like to use \vdots to compactly describe the system, like so:  \begin{align*}   R(-1) &= \sum_{i=1}^m A(i)R(i-1) \\   R(-2) &= \sum_{i=1}^m A(i)R(i-2) \\         &\vdots                    \\   R(-k) &= \sum_{i=1}^m A(i)R(i-k) \end{align*}     I'd like the dots, however, to be centered with = or the entire equation. Is there an elegant way of centering a column or row with AMSMath? I'm currently using an unholy combination of whitespace operators (\; \, etc.) to get the job done.


Given a playlist in Windows Media Player 12, is there a plugin I can use that can copy those files to a folder with the location and name I specify?

Over a period of time I have assembled mulitple playlists. I would like to export the songs of these playlists into corresponding folders. I have tried looking into windows media player but couldn't find any such option.


I am simply trying to have two figures in one section on one page with text in between. In the below example the PDF result is text1, picture1, text2, text3 which is not what I intended. Text1  \begin{figure}[h!]   \includegraphics[width=0.4\linewidth]{picture1.jpg}   \caption{A boat.}   \label{fig:boat1} \end{figure}  Text2  \begin{figure}[h!]   \includegraphics[width=0.4\linewidth]{picture2.jpg}   \caption{A boat.}   \label{fig:boat1} \end{figure}  Text3  Any help would be greatly appreciated!

How to insert text between two figures or images in LaTeX? I have this code  \begin{figure}[htbp]   \centering     \includegraphics[width=0.5\textwidth]{1.jpg}     \caption{Resala's Donation Page.} \end{figure}  and for the volunteering activities, they do record all their activities...  \begin{figure}[htbp]   \centering     \includegraphics[width=1\textwidth]{2.jpg}     \caption{Resala's Project Page.} \end{figure}   but what happens is the text is placed before the first image and all images are placed at the end of the page.


Looking for a book where the good guy lives backwards through time and the bad guy lives forward. The good guy was an alien and keeps getting killed by the bad guy. The bad guy was a Neanderthal(?) who keeps killing the good guy through time until the beginning of time which is at the end of the book.

I am trying to find a book I read about ~10 years ago. I really want to read it again, but all my google searches, goodreads.com lists have come up empty.  What I remember is:   The Protagonist is from the future and is being reincarnated(not sure of the method) throughout time periods on Earth.   He is fighting humans that look at themselves as deities or gods At one time he was Prometheus, bringer of fire to the human race Towards the end, he and a spaceship crew are the first Homo Sapiens on Earth and all humanity are their descendants involves traveling back in time    I just remember it as a great read but, for my life, can't remember the name or author  Any help is much appreciated..  Oli


I have polygon layer with multiple types of area (forest, grass, and many more), and I´d like to divide this layer into many layers by the area type.  I´ve tried Split function but I receive an error 000354 - because the type of areas are in Czech and contain national characters.  Please does anybody know how to do this??  For example how to automatically rename the types of areas to valid form, or how to write an python script which creates this layer for each of the area type in with definition query  for layer?  I'm using ArcGIS 10.1 for Desktop.

I have a feature class with over 2,000 features, and I need to make them all individual feature classes based on a field.   Is there a way to do this?


I'm familiar with Einstein's formulae $V=\frac{u+v}{1+ \frac{uv}{c^2}}$ and $\Delta t'=\frac{\Delta t}{\sqrt{1-\frac{v^2}{c^2}}}$, the former being velocity addition and the latter being time dilation. Each of these equations imply that you can't go faster than light; the former cannot exceed $c$, and the latter will give an imaginary number in the denominator if you try.  But why are these formulae true? I understand it numerically, but how would you explain this conceptually?

Please will someone explain what time dilation really is and how it occurs? There are lots of questions and answers going into how to calculate time dilation, but none that give an intuitive feel for how it happens.


Hi I want add some attribut to python object. But its name I don't know and it is a varieble.  In js it will be like this:  obj[somename] = 'str'

Suppose I have a python object x and a string s, how do I set the attribute s on x? So:  >>> x = SomeObject() >>> attr = 'myAttr' >>> # magic goes here >>> x.myAttr 'magic'   What's the magic? The goal of this, incidentally, is to cache calls to x.__getattr__().


“in the bus” or “on the bus”  I know that, when we travel by bus we say, “I am on the bus”, but how about for objects, for example   There must be a cell-phone charger in the bus.  Or   There must be a cell-phone charger on the bus.

Examples:   In a car, van, etc. On a bus, boat, motorcycle, etc.   How can one decide which preposition to use? Is memorization the only way or is there a better way?  Note: People generally explain this by either distinguishing between open and closed vehicles or between large and small vehicles. However, the examples I've given defeat both explanations.


I would like to texture a window frame that is part of a wall. Whenever I try texturing the window frame the wall gets textured with it. I want to texture the window frame without texturing the wall. I tried:   Selecting the window frame. Clicking the + icon at the right side of the material properties. Here is where I get stuck: I cannot give the new material a color. I would have to click the New button to do that but that is not mentioned in the solution.   I am using Blender version 2.82a. Any help would be appreciated. Thanks.

How do you add more than one material to a mesh?   I have tried adding two materials to the object, and then assigning one of the materials to a vertex-group, but I could not find a place to assign it.  I am making a striped bouncy ball that I want to deform, so adding a different material by separating the mesh into different objects would not be ideal.


How can I get my Macbook Pro Retina to not make that annoying 'bong' chime sound when booting up?   You can always hold "mute" during boot up, but that gets annoying fast if you always want the sound muted. Older systems (OS X 10.6 and below) can use StartupSound.prefPane, but that no longer works on modern  claims to do this, and it does, but it suffers from a bug where it will always unmute the system volume on login, even if the volume was muted when you last logged out.  Is there a way to accomplish this?

Anyone know how to disable that cheesy startup sound when I power on my Mac?  If it makes a difference, I'm running Mac OS X 10.6.


While the fellowship is trying to make for the pass of the Redhorn Gate, during Book 2 Chapter 3, why is it that Legolas seems so much lighter than his companions of other race?  Are elves actually physically lighter than others or is it just one of the many graces given to the Eldar by Eru?     With that he sprang forth nimbly, and then Frodo noticed as if for the first   time, though he had long known it, that the Elf had no boots, but wore only   light shoes, as he always did, and his feet made little imprint in the snow.   As a side note, my brothers and I used to always joke that the reason Legolas was so light on his feet was because elves are hollow-boned, but I seriously doubt that that's the actual reason.

In The Lord of the Rings: The Fellowship of the Ring when the Fellowship is climbing the mountains and are pretty much overcome by the snow; Legolas is quite able to walk on the snow, when the rest have to wade through the snow:     Slowly they moved off, and were soon toiling heavily. In places the snow was breast-high, and often Boromir seemed to be swimming or burrowing with his great arms rather than walking.      Legolas watched them for a while with a smile upon his lips, and then he turned to the others.      `The strongest must seek a way, say you? But I say: let a ploughman plough, but choose an otter for swimming, and for running light over grass and leaf or over snow-an Elf.'      With that he sprang forth nimbly, and then Frodo noticed as if for the first time, though he had long known it, that the Elf had no boots, but wore only light shoes, as he always did, and his feet made little imprint in the snow.      'Farewell!' he said to Gandalf. `I go to find the Sun!' Then swift as a runner over firm sand he shot away, and quickly overtaking the toiling men, with a wave of his hand he passed them, and sped into the distance, and vanished round the rocky turn.      -The Fellowship of the Ring (The Ring Goes South).   [Emphasis added is mine]  How is this so? Is there any canon explanation of this (or any similar) ability?


I am working on an addon which I am close to finish and I'll share it totally free with a game community. But... As in outer life, this game community has some "weird" guys. These "weird" guys takes your work, whatever it is, they change some things so to make it looks a bit different, they put a price on it, they move your hard work into an other server, where you are unknown as person and they earn a lot of money of it!!! So what I need is your advice and your knowledge so to encrypt my addon code or protect it in some way from all this situation.

Can I hide the source code in an add-on for Blender?  I want to sell add-ons for a fee. And I want to hide the code.


Prove or disprove.       Let $f_n(x)=x^{n-1}+x^{n-2}+\cdots +x+1$. Then $f_p(x^{p^{e-1}})$ is irreducible in $\mathbb Q[x]$ for all prime $p$.   I know if $p$ is a prime $f_p(x)$ is $p$-th cyclotomic polynomial and is irreducible.

I'm trying to show that $f(x)=1+x^p+x^{2p}+\dots +x^{p(p-1)}$ is irreducible over $\mathbb{Q}[X]$. I'm well aware that cyclotomic polynomials are irreducible, however the (many) proofs of this statement are quite involved. Since this exercise appears in a textbook that only covers basic algebra, there should be a more direct approach to this exercise.  I tried all criterions that I know to solve this (Eisenstein, linear substitutions, reducing to $\mathbb{Z}_p[X],\dots$). Only one remains. We know that $f(x)=\frac{1-x^{p^2}}{1-x^p}$, or equivalently $1-x^{p^2}=(1-x^p)f(x)$. We know that the roots of $1-x^{p^2}$ are given by $$e^{\frac{2\pi i k}{p^2}}, \mbox{ for $0\leq k\leq p^2-1$ }. $$ Similarly, the roots of $1-x^{p}$ are given by $$e^{\frac{2\pi i kp}{p^2}}, \mbox{ for $0\leq k \leq p-1$}.$$  Hence the roots of $f(x)$ are given by $e^{\frac{2\pi i k}{p^2}}$ where $p\not|  \;k$ and $0\leq k\leq p^2-1$. One way to show that $f(x)$ is irreducible over $\mathbb{Q}$ is to show that any product of linear factors of $f(x)$ is not a polynomial over $\mathbb{Q}$. I tried to show this, but it is too difficult.  Does anyone know a elementary way of solving this exercise?


When I'm trying to open my PHP file in gedit command through terminal it's showing this error statement.    but it's working when nano command is typed.    I want to open my php file in sublime or some other editor. How is it possible? Is there any command or any installation required?

How to run X11 GUI applications from a remote server using SSH?  For example:    my first desktop 192.168.1.1 my second desktop IP 192.168.1.12   I 'm sshing from my first desktop to the second and i want to run the GUI applications from the second and redirect X11 to the first.


I am trying to create a picturebox of large size. I am able to create and draw Bitmap of size upto 8500x8500. But when I clear it and load another Bitmap of same size, it shows OutofMemoryException.  Following is the code snippet:  pictureBox_MouseMove() {     //Draw some lines... }  buttonClear_Click() {      Bitmap new_image = new Bitmap(8500,8500); // OutofMemoryException }   I would also like to know how to allocate memory to these objects.  Thanks in advance.

I'm trying to write a light-weight image viewing application. However, there are system memory limitations with .NET.  When trying to load large bitmaps (9000 x 9000 px or larger, 24-bit), I get a System.OutOfMemoryException. This is on a Windows 2000 PC with 2GB of RAM (of which 1.3GB is used up). It also takes a lot of time to attempt loading the files.  The following code generates this error:  Image image = new Bitmap(filename); using (Graphics gfx = this.CreateGraphics()) {     gfx.DrawImage(image, new Point(0, 0)); }   As does this code:  Stream stream = (Stream)File.OpenRead(filename); Image image = Image.FromStream(stream, false, false); using (Graphics gfx = this.CreateGraphics()) {     gfx.DrawImage(image, new Rectangle(0, 0, 100, 100), 4000, 4000, 100, 100, GraphicsUnit.Pixel); }   Also, it is enough to do just this:  Bitmap bitmap = new Bitmap(filename); IntPtr handle = bitmap.GetHbitmap();   The latter code was intended for use with GDI. While researching this, I found out that this is in fact a memory issue where .NET tries to allocate twice as much as is needed in a single contigous block of memory.    I know from other applications (Internet Explorer, MS Paint etc.) that it IS possible to open large images, and rather quickly. My question is, how do I use large bitmaps with .NET?  Is there anyway to stream them, or non-memory load them?


Quick question. I am currently making a synthetic division calculator and as a part of that I need to test whether or not a P/Q (a double) will work as a factor in an equation (given to the method as a list of integers).  Here is my code in the main class:  public static void main(String[] args) {     List<Integer> coeffs = new ArrayList<>();     coeffs.add(1);     coeffs.add(-6);     coeffs.add(11);     coeffs.add(-6);     System.out.println(coeffs); // Returns [1, -6, 11, -6]     System.out.println(doesPqWork(coeffs, 1)); // Returns 'true' as intended     System.out.println(coeffs); // Returns [-6, 11, -6]     System.out.println(doesPqWork(coeffs, -2)); // Returns 'false' not as intended     System.out.println(coeffs); // Returns [11, -6]     System.out.println(doesPqWork(coeffs, 3)); // Returns 'false' not as intended     System.out.println(coeffs); // Returns [-6] }   and here is the P/Q method itself:  private static boolean doesPqWork(List<Integer> coefficients, double PQ) {     List<Double> results = new ArrayList<>();     double lastResult = coefficients.get(0);     coefficients.remove(0);     for(int coeff : coefficients) // 2, 1     {         double multiplied = PQ * lastResult;         lastResult = coeff + multiplied;         results.add(lastResult);     }     return results.get(results.size() - 1) == 0; }   Please ignore how this method works to calculate it, I am only wondering why on earth the "coeffs" ArrayList is shrinking every time. I have been coding in Java for two years now and I have never come across this issue.  I thought that it was because when I call "coefficients.remove(0)" it is for some reason linking back to the "coeffs" list in the "main" method, yet when I create a new variable which would not possibly link back it still does weird thing.  I know a way I could fix this by creating some choppy code and repeating variables, but that seems really wasteful and I really want to know the source of this unintended behavior so I can fix it.  I am probably making a stupid mistake here, but if I am not then could someone please explain to me just what the heck is going on? Haha.

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


I want to create a granite tile design in blender. But I dont know how to get the white dot like pattern on my mesh ( like in the picture attached). Someone please tell me how to acheive this.

I have made a polished granite material with a node setup. Using this photograph as reference, how can I improve this further?


I am currently working in c# application forms. I have created a .mdf database called Student_CB.mdf. Its located with in the solution for the project.  What i am trying to do is create a connection string to it. The string needs to stay localised to the solution as i will be opening the project on other PC's and not just my own PC.  The connection string in the properties states its the following string:  Data Source=(LocalDB)\v11.0;AttachDbFilename="C:\Users\Donald\Documents\Visual Studio 2013\Projects\DesktopApplication\DesktopApplication\Student_CB.mdf";Integrated Security=True    I have tried putting this into an SqlConnection in my c# but its not liking it.  Any help or ideas with where i am going wrong?

Specifically, in VS 2008, I want to connect to a data source that you can have by right-clicking on the automatically-generated App_Data folder (an .mdf "database"). Seems easy, and it is once you know how.


So my brother recently bought Rust and lets me use his Steam account to play it. Would there be a way for him to play CS:GO while I play Rust. Is there a way to do that with Steam Family Sharing?

I own a lot of games on Steam, and I'm overall a big fan of the service.  However, one thing about it really bothers me, and I'm wondering if anything can be done about it.  Let's say I have two different online, multiplayer games, both of which I legally own.   If I bought these games normally, I could be playing one of them online, while my fiance could play the other one online on another computer.     However, with Steam, I can only be signed in on one computer at a time.  So, despite the fact that I have bought about 40 games, if I'm playing one of them, someone else in my house is not able to play any of the others.  Is there a way to get around this?  I don't think this is illegal or immoral as I own both of the games in question, and only one person is playing the game at a given time (same IP address and the same household, so it should be easy for Steam to verify that I am not sharing my games unfairly).    If I had bought simple boxed copies, this wouldn't be an issue, but since I became such a fan of Steam, I can't play any of those games at the same time as my fiance.    Is there anything that can be done?


Let's say you have a density plot of data in 2D (or even 1D). Surely there are algorithms which infer the number of clusters which exist in the data without users having to explicitly set this number (e.g. like with traditional k-means).  How does one use unsupervised learning to solve this?

We find the cluster centers and assign points to k different cluster bins in  which is a very well known algorithm and is found almost in every machine learning package on the net. But the missing and most important part in my opinion is the choice of a correct k. What is the best value for it? And, what is meant by best?  I use MATLAB for scientific computing where looking at silhouette plots is given as a way to decide on k . However, I would be more interested in Bayesian approaches. Any suggestions are appreciated.


I want to install Ubuntu 12.04 on my Toshiba Qosmio laptop, that is preinstalled with Windows 8. I would like to install it side-by-side with Windows, not erase Windows 8. However, the installer does not detect any operating system. How can I fix this?  *NOTE: My laptop has two hard drives, could this be the problem? I am booting Ubuntu from a DVD with Ubuntu correctly written to it. I am booting it with secure boot disabled and with the BIOS set to CSM Boot, not UEFI mode. The boot mode is set to boot from DVD drive, but that isn't the problem here. I am sure about all the stuff I just listed above. There is no chance it is wrong.  This is not a duplicate of another question this question  because none of the answers given works for me.  Thanks

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?


I've read over the information I can find on 17.04 Zesty Zapus    The only information I can go off of for official support:  "Ubuntu 17.04 will be supported for 9 months until January 2018. If you need Long Term Support, it is recommended you use Ubuntu 16.04 LTS instead."  Does this indicate that 17.x will not at any point have long term support?  Edit: This was specifically related to if 17.04 Zesty Zapus was going to be receiving LTS. Not about defining the difference between Non-LTS and LTS. This is meant to be informational to this specifically, not a duplicate of a more broad question.

What are the differences between an Ubuntu Long Term Support release (LTS) and a normal release?


This issue happened for my 32 kingstone flash drive. I tried to make bootable USB by using dd command:  sudo dd if=file.iso of=/dev/sdb   After that I can't do anything with my USB stick.    When trying new partition table with GParted:

I have a 8 GB pendrive. I used to write raw data into the pendrive (without creating filesystem) using the dd command.    Today, when I inserted the pen drive, the I am unable to write anything on to it.  When I open gparted it is showing the total space on the pen drive as 500 MB. I am unable to create a new partition table or a partition on the pen drive now.   Here is the fdisk -l output.   Disk /dev/sdb: 0 MB, 512000 bytes 255 heads, 63 sectors/track, 0 cylinders, total 1000 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00095df6   What's wrong with the pen drive? How can I recover the lost space?   Device Boot      Start         End      Blocks   Id  System   When I open gnome-disks, it shows the total space as 8 GB but when I try to create a new partition using it, it shows the following error:  Error creating partition on /dev/sdb: Command-line parted --align optimal --script "/dev/sdb" "mkpart primary ext2 1MiB 7969177599b"' exited with non-zero exit status 1: Error: The location 7969177599b is outside of the device /dev/sdb.  (udisks-error-quark, 0)


I have used Mendeley to manage references in a paper and create a bibliography. I would like to place all the cited references into one folder in Mendeley - is there a way of doing this automatically?   The reason is to be able to share the selected references in a group.

This is a related question to my previous one about .   Given the relatively large number of papers that are out there, it's inadvisable to force every student to start from ground zero in building up a reference library. To me, this suggests that there should be some centralized ways of keeping track of bibliography references.   The low-cost but high-maintenance route to me would be to have an SVN repository to which people can update their own personal bibliography files. Are there other more time-efficient routes to manage this process when:   people have different computing platforms and workflows (Windows with Office, OS X with iWork, Linux with TeX, etc.)? working with collaborators at other institutes?  it's important (according to university/workplace regulations) not to have data stored "in the cloud"?


I have just been notified of spam emails coming from my server, luckily i limit the amount of emails sent per account to 50 per hour, I have taken a screenshot on my mail reports, all of these email addresses are non existent how has this happened and how can I prevent it?    I have changed the Cpanel password.

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


I have recently updated my Ubuntu before updated the open terminal option is appearing after update it is not appearing. I have seen many thing but yet cant find anything. Please help me how my open terminal appeared in all folders.

This option seems to have gone away after upgrading from Ubuntu 16.04. I tried installing nautilus-open-terminal but it is unable to locate the package for 18.04. Also trying to install nautilus-actions gives:  Package nautilus-actions is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source     How to fix this?


Im trying to adapt list view to an alertDialog, the program crashes on dialog.setAdapter with NullPointerException.   The alertDialog should pop when user is clicking on item in listview.  ArrayAdapter<String> dialogAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, userFunc);     lv.setAdapter(dialogAdapter);      listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {         @Override         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {               if (position == 0) {                   AlertDialog.Builder alertDialog = new AlertDialog.Builder(ManagerFunctions.this);                 LayoutInflater inflater = getLayoutInflater();                 View convertView = (View) inflater.inflate(R.layout.user_op_list, null);                 alertDialog.setView(convertView);                 alertDialog.setTitle("Choose option");                 lv = (ListView) convertView.findViewById(R.id.lv);                  alertDialog.show();   This line is the one I'm getting error on:          lv.setAdapter(dialogAdapter);

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?


Is there a good way by specifying it in the preamble, to underline my section titles (not chapter titles), instead of having to do \chapter{\underline{Section Title}} for all chapter titles in the body?  I would like it as something like in this picture below:    Thanks!

Forgive the stupid simplicity of this question, and please feel free to refer me to an older answer. I'm not quite familiar enough with LaTeX terminology to have found it.  All I want to do is set a different default format for my section titles. Instead of just being bolded and slightly larger than the main text, I'd like them to be of normal weight, the same size as the main text, and all caps.   I'm using the article class.


I'm using ubuntu 14.04.1. I installed lxde for lubuntu desktop environment. But it's creating a lot of problems for me, so I want to completely remove it now. I read the instructions online and followed them. I've removed all the files by all the ways explained on askubuntu and ubuntuforums. But it's not gone yet. But as explained in question  hasn't work for me. Please suggest, I don't want to re-install my ubuntu.

I installed few environments that I wanted to try out on Ubuntu 12.04, but none of them worked at all. It could be that I installed them all at the same time, meaning the OS didn't get a chance to work everything out, but either way, they didn't work. I would now like to remove them.   The one's that I installed are Xubuntu/Xfce, Lubuntu/LXDE, Kubuntu/KDE, Fluxbox, OpenBox, cinnamon, and MATE. I installed them. Everything seemed to have been working properly until I actually tried to use the shells and nothing loaded at all. Except for Fluxbox, I think that one worked. I want to know of any way to repair or perhaps just remove the packages entirely. I might have already removed them because I did the apt-get remove command on all of them, but they were still in the list on the login screen.


currently I'm actually having a security concern regarding acquiring root privilege on my server.   Current situation: I login using SSH to my server and I use my user account for this, this user account can also get root privilege with the same password.   Required situation: Login with the user, require a DIFFERENT password for root privilege.

How can I give a user one password for normal usage when logging in, and another password for system administration and sudo access? I want one user to have two passwords.


Consider the following equation:   $$ 1 + \sqrt 2 + \sqrt 3 + \sqrt 6 = \sqrt{a+\sqrt{b+\sqrt{c+\sqrt{d}}}}$$   where $a$, $b$, $c$, $d$ are integers. Find $ a+b+c+d$

is it possible for someone to run a computer search for me to turn up integers $a,b,c,d$ such that $$1+\sqrt{2}+\sqrt{3}+\sqrt{6}=\sqrt{a+\sqrt{b+\sqrt{c+\sqrt{d}}}}$$? Note: I know they exist, I just can't find them.