If $f$ is differentiable on $(a,\infty)$, Show that if $f'(x)\rightarrow L$ as $ x \rightarrow \infty$, $-\infty \leq L \leq \infty $  then  $ f(x)/x \rightarrow L $ as $x \rightarrow \infty$.   Deduce further that if $f(x) \rightarrow M$ as $ x\rightarrow \infty$ , and $ f'(x)\rightarrow L $ as $ x \rightarrow\infty $ then $ L = 0$   For the first part I tried converting $f(x)$ to $F(\frac{1}{x})$ and $x \rightarrow 0$ and then using L'Hospital's rule but I am getting stuck. How do I proceed with this problem ?


Why is thymine rather than uracil used in DNA?

What is the advantage gained by the substitution of thymine for uracil in DNA?  I have read previously that it is due to thymine being "better protected" and therefore more suited to the storage role of DNA, which seems fine in theory, but why does the addition of a simple methyl group make the base more well protected?


How can I install Ubuntu without CD and USB?

I want to install Ubuntu on my laptop that doesn't have a CD-ROM drive and I have no spare USB disk. I've tried Wubi, but that doesn't seem to work (since it prompts me to have the CD in the drive, which I don't have).  How can I install Ubuntu, easily and in a fast way?  P.s: I want to dual boot it with Windows 7 (which was preinstalled).  Edit:   When extracting the ISO to a folder and running Wubi it does install, but when I reboot the computer, it doesn't show GRUB, nor can I choose if I want to boot Ubuntu or Windows 7. After trying for the third time today, wubi gives me an error: Permission denied   I'm the administrator on the PC.


Subpanel run to secondary floor apartment from basement

What size wire would I need to run a 100 amp subpanel 28 feet away? I have 6/3 wire would  that do it?


How to emulate a version of OpenGL higher than the one your gpu supports?

Ok so there is a certain game i want to play. when it comes to the requirements, the game is pretty light, the only thing that is preventing me from running the game is my old gpu that doesn't support OpenGL 3, after searching for a while i came across someone talking about the possibility of emulating OpenGL 3, but i didn't get an explanation of how to do it. Does anyone know how to solve this problem? For more specific information, I need OpenGL 3.3 to run the game and the game is called 5d chess with multiverse time travel. Also I'm new to stack exchange so if I'm asking this question in the wrong place, please redirect me to the correct one.


Proving that the set of limit points of a set is closed

From Rudin's Principles of Mathematical Analysis (Chapter 2, Exercise 6)  Let $E'$ be the set of all limit points of a set $E$. Prove that $E'$ is closed.  I think I got it but my argument is a bit hand wavy:  If $x$ is a limit point of $E'$, then every neighborhood of $x$ contains some $y\in E'$, and every neighborhood of $y$ contains some $z\in E$. Therefore every neighborhood of $x$ contains some $z\in E$, and so $x$ is a limit point of $E$. Then $x\in E'$, so $E'$ is closed.  The thing that's bugging me is the leap from one neighborhood to another. Is this formally correct?


Which characters shouldn't be used in a filename?

I wrote a program which creates a file with the name derived from a users txtarea. But it got me thinking ,what if the user uses whitespaces in his name or any other special symbols, which in turn than becomes a file with this name.  Can stuff go wrong?  Ifso,which signs/symbols should I allow to be used in a file's name?  Thank you for your time


If $\sum a_{n}$ is convergent then what about $\sum a_{n}^{2k+1}.$

If $\sum a_{n}$ is a real  convergent series then what can we say about the convergence of the series  $\sum  a_{n}^{2k+1}$ i.e. odd power? It is convergent for positive term series. But what about any infinite series  $\sum a_{n}.$ I tried to find counterexample but did't got. Please help me. Thanks in advance.


What's the name of this bug from Toronto, Canada?

It's about 3 millimetres in length. Found on September 10, 2015.


I inserted a background image in blender by checking the background images box and opening an image, but it isn't working. Not in ortho and not in perspective view, i tried all perfect views. The first time when i inserted an background image it did work, but now it doesn't work anymore. Here is a screenshot:


How to redirect output to a file and stdout

In bash, calling foo would display any output from that command on the stdout.  Calling foo > output would redirect any output from that command to the file specified (in this case 'output').  Is there a way to redirect output to a file and have it display on stdout?


I usually only want to ask questions.  I want to get the best results on my questions, is there anything I can do to ensure this?  Would I get better results from asking questions if I had more reputation?  Does responsiveness help?  I seem to get better/more responses when I am more responsive.


Undefined reference to explicitly instantiated template function

I have a class with a template method that is declared in a header and defined in a cpp file, so  // A.h - declaration struct A {     template<typename T = int> void fun(); };   and then  // A.cpp - definition #include <iostream> #include "A.h"  template<typename T> void A::fun() {     std::cout << "Hello world template" << std::endl; }  // Explicit instantiation template void A::fun<int>();   Now, somewhere else, in a test, I have  #include "A.h"  int main () {     A a;     a.fun(); }   and since I explicitly instantiated the function for int template parameter, all is well. Or should be!  My code links fine with GCC 7.3.0 but fails to link with clang 6, which reports an undefined reference to function fun.  What's going on here? Is there anything else that I should take care of? Perhaps something that GCC takes for granted while clang doesn't?  Thanks!  Edit  @WhozCraig, @Neil Butterworth here are the linking commands for the two toolchains.  GCC:  /usr/bin/g++  -g   CMakeFiles/test_generator.dir/generator/generator.cpp.o CMakeFiles/test_generator.dir/test_utils.cpp.o  -o test_generator -Wl,-rpath,/home/mleoni/PhD/ABI/libcellml/build/src:/home/mleoni/PhD/ABI/libcellml/build/tests/gtest ../src/libcellmld.so.0.1.0 gtest/libgtest_main.so /usr/lib/x86_64-linux-gnu/libxml2.so gtest/libgtest.so -lpthread   clang:   /usr/bin/clang++  -g   CMakeFiles/test_generator.dir/generator/generator.cpp.o CMakeFiles/test_generator.dir/test_utils.cpp.o  -o test_generator -Wl,-rpath,/home/mleoni/PhD/ABI/libcellml/build/src:/home/mleoni/PhD/ABI/libcellml/build/tests/gtest ../src/libcellmld.so.0.1.0 gtest/libgtest_main.so /usr/lib/x86_64-linux-gnu/libxml2.so gtest/libgtest.so -lpthread   @IdeaHat: that didn't resolve the issue unfortunately, I am still getting the same error  Edit 2 Since the code I am actually trying to compile is [obviously] not that one, I tried to compile this MWE and both GCC and clang link it fine with just cc A.cpp main.cpp.  I am now trying to understand what's the difference between this minimal case and the code that I actually have.


What makes cross-correlation (R, ccf) different from "sliding" one of the curves by different lags and correlating?

I have two sigmoid functions, sig1 and sig2, made with this function sigmoid = function(x, A =1, mu=0, ss = 1)  A*1 / (1 + exp(-(x-mu) * ss)). Since they have a true offset of 10 (mu1=50 and mu2=60) I expected their cross-correlation function to peak at a lag of 10. My non-mathematical intuition is that cross-correlation "slides" one of the curves over by a given lag, correlates, and repeats for multiple lags. When I do this by myself in code (my.ccf in the code below) I do directly recover the lags I designed into the curves. However, ccf, the real R cross-correlation function, returns max lag of 4 (see below). What's going on?    To replicate, I did the same thing for two sines. They have a designed "lag" of 10 (see below). Here, the max lag returned by ccf (9) is closer to the designed-in value, but isn't exactly equal. My intuitive function returns 10, the "correct" answer.    Why doesn't the max of the two cross-correlation functions (4 and 9) exactly equal the lag I coded into the curves (10 and 10, respectively)? What's wrong with my intuition? Edit: As pointed out by Whuber, why isn't the max of ccf 1, since these are identical and perfectly aligned vectors.  (code)  # sigmoid function sigmoid = function(x, A =1, mu=0, ss = 1)  A*1 / (1 + exp(-(x-mu) * ss))  # my intuition my.ccf = function(x,y, lag=20) {   lags = -lag : lag    # add padding to y   y.padded = c(rep(NA,lag), y, rep(NA,lag))    # correlate   rr = numeric(length(lags))   for (ii in 1:length(lags)) {     # apply lag to y.padded     I = (1:length(x)) + (ii-1)     y.lagged = y.padded[I]      rr[ii] = cor.test(x, y.lagged)$estimate   }   return(rr) }  # make sigmoids and cross-correlate sig1 = sigmoid(1:100, mu=50, ss=1/3) sig2 = sigmoid(1:100, mu=60, ss=1/3) ccf.sig=ccf(sig1, sig2, plot=F) rr.sig = my.ccf(sig2,sig1,lag=16)  # do the same with sines sin1 = sin((1:100) * 4*pi/100) sin2 = sin(((1:100) - 10) * 4*pi/100) ccf.sine=ccf(sin1, sin2,plot=F) rr.sine = my.ccf(sin2,sin1,lag=16)  # plot sigmoids + ccf.sig p1 = ggplot() + geom_line( aes(x=1:100,y=sig1)) +    geom_line(aes(x=1:100,y=sig2)) + ggtitle("sigmoids 1 and 2") p2 = ggplot(data.frame(lag=ccf.sig$lag, corr=ccf.sig$acf), aes(x=lag, y=corr)) +    geom_line() + ggtitle("ccf function") p3 = ggplot() + geom_line(aes(x=-16:16, y=rr.sine)) + ggtitle("my intuition") p1 + p2 + p3  # plot sines + ccf.sig p1 = ggplot() + geom_line( aes(x=1:100,y=sin1)) +    geom_line(aes(x=1:100,y=sin2)) + ggtitle("sines 1 and 2") p2 = ggplot(data.frame(lag=ccf.sine$lag, corr=ccf.sine$acf), aes(x=lag, y=corr)) +    geom_line() + ggtitle("ccf function") p3 = ggplot() + geom_line(aes(x=-16:16, y=rr.sig)) + ggtitle("my intuition") p1 + p2 + p3


Sounds simple but I seem to fail every time, that is it turns into scrambled eggs instead. How do you make it so that you can flip it over both without it breaking and before it burns?


How to get internal stylesheet using jQuery?

Anyone can please tell me How can I get an internal stylesheet using jQuery. I know how to get the style of hello class but I want to take the style of world class.    <!DOCTYPE html>
Hello world!


can i connect my usb powered speakers to my phone charger?

I have got a 2.0 USB powered speakers which are supposed to be connected to the PC USB port. But that port creates noise in the speakers and is not very convenient. I have a phone charger of output dc 5v and 1A. Can I connect the speakers to the phone charger for power supply? Would it affect my speakers?


If $a,b,q=\frac{a^2+b^2}{ab+1}$ are positive integers then $q$ is a perfect square.


Need a copy of value. No need referenced value

I just need to copy the value of data.notes. I have used below code. But still detailsOfCurrentNotes value changes according to the value of data.notes. So could you tell me how to do this?  notes :Note[]   const detailsOfCurrentNotes = Object.assign({}, data.notes);  //here data.notes changes  // detailsOfCurrentNotes also get that value


i have a bit of an issue. I live in a 2 story house and I'd like to run 2 ethernet cables down to the first floor from my room. The issue is that when I drilled the hole, i drilled it diagonally through the joist and it eventually punctured my family room wall. Would it be alright to drill a hole in the joist from the bottom hole that would eventually meet the puncture hole halfway and create an opening for the cables?  Or would that destroy the structural integrity of the joist?  The drawing depicts a side view of the joist and drywall. The red is the wood joist. The purple is the diagonal puncture I foolishly made. And the blue is the hole I'm thinking about making. But I need advice on if it's the best option. I don't want my room crumbling..


When I describe my hobbies, should I write      I play piano   or      I play the piano   Are both forms acceptable? And how would you handle the phrase     I am an amateur musician, playing the saxophone, guitar and piano.   Should there be three "the" or only one? or none?


Sorry to disturb you but i have been making a quiz app that counts the score.But when  it displays my score it shows 0.  Is there something wrong with my variables?.  Is there a way to fix it?  Here is the code:  package quiz;  import java.util.Scanner;   public class quiz {  public static void main(String[] args) {     //–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––     //User input      Scanner in = new Scanner(System.in);     //User input     //––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– //SCORE int score = 0; //SCORE //––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– //Yes or No String yn;       //Yes or No      //––––––––––––––––––––––––––––––––––––––––––––––––––––      String q1 = "Is the hottest chili on earth called the Carolina      Reaper(y/n)?"; String q2 = "Was beethoven the father of mosart(y/n)?"; String q3 = "Is the worlds best sellng album the Thriller(y/n)?"; String q4 = "Was Steve Jobs the maker of microsoft(y/n)?"; String q5 = "Did Steve jobs Die(y/n)?"; String q6 = "Was the first Iphone the Iphone 2(y/n)?"; String q7 = "Was  Rich Miner the only developer of android (y/n)?"; String q8 = "Is the Goliath  tarantula the  biggest spider on earth(y/n)?"; String q9 = "Is Octopus wolfi the biggest octopus on earth(y/n)?"; String q10 = "Adolph Blaine Charles David Earl Frederick Gerald Hubert Irvin John Kenneth Lloyd Martin Nero Oliver Paul Quincy Randolph Sherman Thomas Uncas Victor William Xerxes Yancy Wolfeschlegelsteinhausenbergerdorff Broke the record for the most confusing name(y/n)?";    //QUESTIONS   System.out.println(q1); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q2); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q3); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q4); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q5); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q6); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q7); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q8); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q9); yn = in.nextLine(); if (yn == "y"){     score++; } System.out.println(q10); yn = in.nextLine(); if (yn == "y"){     score++; }  System.out.println("Awesome, you scored "+ score +"/10");      }    }   Thanks!  Sorry if my code is sloppy i am a beginner.


Can I install Mojave on boot drive and still keep Catalina running

I’ve tried a few times now but I get a message ‘you need to update to a later os’ when I try to boot up from the external.  It would seem that Catalina doesn’t like it. I still want Catalina installed but I need Mojave as an external boot drive.  Any ideas anyone?


how to get all possible solutions to delete duplicate items from a list (python)

If I have a list like this [C, B, A, B] and I want to get all possible solutions to remove duplicates: [C, B, A], [C, A, B] How can I get this result in pure python?


What's wrong with this demonstration? (1 = -1)


How to make xrandr customization permanent in Ubuntu 15.10?

/etc/X11/xorg.conf is not present on Ubuntu 15.10 what should I have to edit?   Video Card: Advanced Micro Devices, Inc. [AMD/ATI]: Wrestler [Radeon HD 6320]  Driver: X.Org X server - AMD/ATI display driver wrapper by xserver- xorg-video-ati Monitor: Samsung s19b150n   The command(s) I run:  cvt 1360 768 xrandr --newmode "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync xrandr --addmode DVI-0 1360x768_60.00


Start Screen session when background programs running

I have Matlab running in a Linux session for almost 2 days, and afraid to lose the computations if my network connection fails. Will moving Matlab to the background and starting 'screen' be the answer for that?


Is data recovery possible in encrypted phone?

I need a suggestion! Tomorrow I am giving my phone to service centre for repairing my broken camera. I am feared that whether they can access my files or not? My phone is on android 10 out of the box and it is encrypted by default. I am going to reset my phone before giving it to the service centre. Is it possible to recover data on a encrypted phone?


No post content on review result page for Low Quality Posts queue if review resolution set to close

On the  there is a column with review resolution:    When you click on a link with "Close" resolution there is no post content on the result page, :    Any other resolution, i.e. Looks OK, Recommend Deletion, Delete refers to the page where post content is present, :


I am having trouble collecting my first troll mutagen in Witcher 3. I have found several trolls in the game, but none of them have dropped a single troll mutagen. I have received advise from others to re-kill the trolls by saving the game and reloading it. I have tried this several times, and none of my trolls re-spawned. In fact, when I revisit locations where trolls were slain, they never reappear. I am unsure if this is a bug in the pc version or something else.  What must I do to force troll respawn in Witcher 3?


I'm trying to understand each part of this completed proof that my professor did, here is my interpretation in parentheses, please advise as necessary.  Proof: Assume that $2^{1/2}$ is rational, then $2^{1/2}$ = $p/q$ for some integer $p$ and $q$ with $q \neq 0$ and $\gcd(p,q) = 1$  $$(p/q)^2 = 2 = p^2 / q^2 $$ $$\text{ (What was the purpose of squaring √2 and p/q?)}$$  $$p^2 = 2q^2$$ $$ \text{ (Is this basically just canceling out the q^2 on left side, and multiplying the right side?)}$$  2 | p^2 => (2 divides p^2 since it is a factor)  2 | p => (thus 2 divides p)  p = 2k for some integer k => (definition of even)  (2k)^2 = 4k^2 = 2q^2 => (Why are we squaring 2k, and how does 4k^2 = 2q^2?)   q^2 = 2k^2 => (Canceled out 2 on one side, and dividing on other)  2 | q^2 => (2 divides q^2)  2 | q => (thus 2 divides q)  2 | gcd(p,q) => (2 divides gcd of p and q)  2 | 1 Which is a Contradiction (no clue how I got here)


I am using Ansible to install the Nginx packages on my Slave1 server from Master server (Note- both Master & Slave server's are having Ubuntu 18.04 and i am running these inside Docker containers), but everytime i am running the Ansible command to do this, getting below error. I am stuck here, what is the solution for this. Please heklp me in debugging this issue.  root@afb19093484e:/# ansible Slave1 -m apt -a "name=nginx state=present"   172.17.0.3 | FAILED! => {     "changed": false,      "cmd": "apt-get update",      "msg": "E: Release file for http://security.ubuntu.com/ubuntu/dists/bionic-security/InRelease is not valid yet (invalid for another 3d 21h 33min 13s). Updates for this repository will not be applied.\nE: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease is not valid yet (invalid for another 3d 23h 23min 36s). Updates for this repository will not be applied.",      "rc": 100,      "stderr": "E: Release file for http://security.ubuntu.com/ubuntu/dists/bionic-security/InRelease is not valid yet (invalid for another 3d 21h 33min 13s). Updates for this repository will not be applied.\nE: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease is not valid yet (invalid for another 3d 23h 23min 36s). Updates for this repository will not be applied.\n",      "stderr_lines": [         "E: Release file for http://security.ubuntu.com/ubuntu/dists/bionic-security/InRelease is not valid yet (invalid for another 3d 21h 33min 13s). Updates for this repository will not be applied.",      ],


Permutations with repetition and size constraint

Suppose you are given the digits 1, 1, 2, 2, 3, 3, 4, 4. How would you find the number of 3-digit permutations you can create from those?  For 8-digit permutations the answer should be $\frac{8!}{2!2!2!2!}$ I believe.  However, I cannot think of a way to do this when asked for permutations where not all of the set is used. I have tried $\frac{8P3}{2!2!2!2!}$ but that does not match the amount when I try manually listing all permutations which seems to be 60.  If the problem were to be generalized what would a solution look like?  Thanks in advance.


Inflation, in the ordinary sense, increase in the prices of goods and services. Some economists say inflation up to 5% is even desirable. Why is this so? When governments struggle to control inflation, why is desirable?


I am having an array like :  array (   ['fruit1'] => banana,   ['fruit2'] => apple,   ['fruit3'] => grapes,   ['fruit4'] => orange  )   And I want the array Like :  array(banana,apple,grapes,orange);   Please suggest how can I convert it.


What is the best way to unit test a method that doesn't return anything? Specifically in c#.  What I am really trying to test is a method that takes a log file and parses it for specific strings. The strings are then inserted into a database. Nothing that hasn't been done before but being VERY new to TDD I am wondering if it is possible to test this or is it something that doesn't really get tested.


"Ain't no ",Is this not a double negation

I have heard this song ,"Ain't no party like a chipmunk party" ,there is a negation in the word Ain't itself, why we need to use no after that .Aren't those two negations cancelling out ?


What is the use of type casting 'null' to any reference type in JAVA?

Is there anything which can be achieved by type casting null to say String ref type?  String s = null; String t = (String) null;   Both does the same thing.  sysout(s) displays null  sysout((String)null) displays null


What is the cost of living in Brazil - Rio

I'll be travelling to Rio (actually Volta Redonda, 100km north of Rio) for three months for research. I live in Canada.   I am looking for an approximate cost of living per week in Brazil so I may do my finances. Using some sources online mainly Numbeo, I used the estimate of $200 BRL per week with a total of 2400 BRL over 12 weeks. I plan on eating out more and cooking less. Is this too high, too low, or just right?


"Bone Heat Weighting: failed to find solution for one or more bones" error

I am a noob at blender and I am just starting out... I am attempting to create a Halo Spartan Model for animation. I am at the stage where I am attempting to pair the model with a rig, but I keep getting the error "Bone Heat Weighting: failed to find solution for one or more bones". I've tried everything but i have no idea whats wrong.... Here is the File that im working on. thanks FILE HERE:


I'm using QGIS 2.18.9 on Windows 10. I've created an atlas in composer and when exporting images, the first few will export fine and then the map image becomes corrupt or fills as completely blank. Here is an example of a corrupted image (colored right-side of main map)    I'm using the OpenLayers Statmen plugin for the basemap. I've tried a few others and they either fail as well or do not allow the map tile to be printed at the scale. If it clear cache and reboot it will work for about 7-10 images and then fail again.


A twice differentiable function $f$ satisfies $f′′(x)+f(x)=−xg(x)f′(x)$, $\forall x\ge 0$.

Consider $f\in C^2$ so that $$f''(x)+f(x)=-x\,g(x)f'(x), \ \forall x\ge0 $$ where $g(x)\ge 0$. Then ($\forall x\ge 0$)         (A) $f(x)^2+f'(x)^2$ is non-increasing,   (B) $f(x)^2<3f(0)^2+(2f'(0))^2$,   (C) $|f(x)|\le\alpha$, where $\alpha$ is a fixed real constant.   (D) $\lim_{x\to\infty} f(x)\sin\left(\dfrac{1}{x}\right)$ exists.        Answer Given: (A),(B),(C),(D)  What I have tried : I differentiated option (A) and then with the help of the given equation in the question I was able to show that  it is less than zero . Hence I was able to infer that option (A) is correct .   Now coming to option (B).  I assumed the function in option (A) to be $h(x)$.   $$ h(x) = f(x)^2 + f'(x)^2 $$  Since $h'(x)<0$ ,therefore $h(x)$ is a decreasing function   hence for all $x\ge 0$  $h(x)< h(0)$  which implies $(f(x))^2 + (f'(x))^2<(f(0))^2 + (f'(0))^2$  From the above expression we can get the second option .   Is my method correct ?. If not , please show the right method .  I am unable to get the the 3rd and 4th option .


In a conference on elliptic curves (an introduction to the subject), the speaker said that an elliptic curve (I.e. an equation of the form $y^2=x^3+ax+b $ where the RHS has distinct roots) is, in the complex space, a torus/Riemann surface of genus 1.  What is meant by that? Are we talking about a 2-dimensional manifold the 4D space?


how do I open a custom module form in colorbox popup?

I am creating a form in custom module, and I need to show this form in a view. How do I show this form in a color-box popup?  I have created a custom block to render this form, but I don't understand how to show this form in a view page, inside a popup.


Why does the new review page sometimes shows questions to vote to close without anybody having voted to close it?

I was reviewing  for , and noticed that nobody voted to close it, even though the page reports a duplicate.      Why does this happen?


A is a proposition formula that contains only iff. A is a tautology iff each atomic proposition in A appears an even number of times.

I just started to study Mathematical Logic and I am having trouble finding a simple proof of the following exercise.    Let A be a propositional formula that contains only the $\equiv$ connective. For those who are not familiar with it $f_\equiv(T,T)=f_\equiv(F,F)=T$ and $f_\equiv(F,T)=f_\equiv(T,F)=F$. Show that A is a tautology if and only if each atomic proposition that appears in A appears an even number of times. I have managed to find a complicated proof using inductions and the fact that $\equiv$ is both commutative and associative but I don't believe this was the point of the exercise. Any help would be appreciated.


MacOS - sending sound over bluetooth and video over HDMI at the same time?

I've been using my 13" 2015 MacBook Pro with BenQ projector. I'm connecting these with simple HDMI and watching Netflix, that's all, no Apple TV, no fancy stuff.  Right now my projector is connected to 5.1 home theater but I need something more mobile and I've been thinking about a bluetooth soundbar, .  My question is, will watching movies using HDMI cable and streaming audio using bluetooth at the same time work? It will look something like this:  Macbook <===== HDMI CABLE (VIDEO ONLY) =====> Projector Macbook <===== BLUETOOTH (AUDIO ONLY) =====> Soundbar   Has anyone tried it?


I want to add an event manager but, it won't work?   Console shows me   "ReferenceError: event is not defined"     document.getElementsByTagName('div')[0].addEventListener("mousemove", myFunction(event));  function myFunction(event) {     var x = event.pageX;     var y = event.pageY;     var coor = "Coordinates: (" + x + "," + y + ")";     document.getElementByTagName('p')[0].textContent = coor; }


Show that any prime ideal from such a ring is maximal.

Let R be a commutative ring with an identity such that for all $r\in$ R, there exists some $n>1$ such that $r^n = r$. Show that any prime ideal is  maximal. (Atiyah and MacDonald, Introduction to Commutative Algebra, Chapter 1, Exercise 7.)    Any hints?


Splitting an equation with a long square root

I want to split up a very long equation. Here is my code:  \documentclass[11pt,a4paper,oneside,onecolumn,article]{memoir} \usepackage[latin1]{inputenc} \usepackage{mathtools} \usepackage{amsmath} \usepackage{amsfonts} \begin{document} \begin{equation} \text{RBE}(LET_d,D,(\alpha /\beta)_{phot}) = \frac{1}{2D}\cdot \left(\sqrt{\left(\frac{\alpha}{\beta}\right)_{phot}^2+4D\left(\frac{\alpha} {\beta}\right)_{phot}\left(p_0+\frac{p_1}{(\alpha/\beta)_{phot}}\cdot LET_D\right)+4D^2\left(p_2+p_3\sqrt{\left(frac{\alpha}{\beta}\right)_{phot}} \cdot LET_d\right)^2} -\left(\frac{\alpha}{\beta}\right)_{phot}\right) \end{equation} \end{document}   And it looks like this:   Thank you in advance!


jQuery Validate Plugin - How to create a simple custom rule?

How do you create a simple, custom rule using the jQuery Validate plugin (using ) that doesn't use a regex?  For example, what function would create a rule that validates only if at least one of a group of checkboxes is checked?


Why was Hulk so intent on killing Natasha (Black Widow) while on the Helicarrier?

She had never attacked him or offered any violence towards him in any way. Yet he stalked her throughout the bowels of the ship intent on killing her as she did her best to avoid him and play hamster in the ducting. This has always bugged me as it seems to go against Hulk's established rage nature. What was it about her that pissed him off?


Java -version reporting wrong version on Mac OSX Mountain Lion

I just installed Oracle's Java version 7u7 on my Mac (running OSX Mountain Lion). However, when I run java -version it still displays the old version (6u29).    How do I fix this? Do I even need to fix this? What version will browsers (Firefox) use in this case? And what version will be used when I run Java applications directly?  I've seen  but this doesn't work in my situation (probably because this question is about the JRE and the other question about the JDK). In my case the Java Preferences app only displays Java 6 versions (32 bit and 64 bit).    Update:   which java points to /usr/bin/java /usr/bin/java is a symlink to /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java /System/Library/Frameworks/JavaVM.framework/Versions/ only contains the folder A (awesome version name) - which Current points to.


Percentile calculation for the combined group

I was struggling to find some solution of my problem which is as below:  Let say, I have 20 groups and for each group I have say 10the percentile value. Then is it anyway possible to calculate the 10th percentile for the combined group using those 20 individual 10th percentile?  If there is not any exact solution then any approximation will also be helpful.


What's happening at $a=-1$ in $\int x^a dx$?

If we take the right limit   $$\lim_{a\to-1}\int x^a dx=\lim_{a\to-1}\frac{x^{a+1}}{a+1}=+\infty$$  but on the other hand  $$\int\lim_{a\to-1} x^a dx=\ln x$$  I'm aware you can't just commute the limit and the integral, but I'd still like an explanation here. To me this is analogous to someone saying "The right limit of $1/x$ is $+\infty$ and the left one is $-\infty$ but $1/0$ is $7$ (or something)"  Is there an intuitive explanation to this break in continuity?


Compress and uncompress windows junctions

I want to compress a folder with windows junctions inside and be able to restore it with the junctions as a junctions, 7z and RAR, they don't. Any idea? Thanks.


I get a Local variable 'first' referenced before assignment error when I run my code.  def start():      global a     a = [" "," "," "," "," "," "," "," "," "]     global first     first = randrange(2)      def reverse():          if first == 1:             first = 0         else:             first = 1          if first == 1:             turn = "X"         else:             turn = "O"   That is just a part of my code where the error occurs. However when I paste the code into IDLE it works no problem so I don't know why this is happening.  Anyways, my full code (unfinished Tic Tac Toe):  from os import name from os import system from random import randrange from time import sleep     def cls():     system(['clear','cls'][name == 'nt'])   def start():      global a     a = [" "," "," "," "," "," "," "," "," "]     global first     first = randrange(2)      def reverse():          if first == 1:             first = 0         else:             first = 1          if first == 1:             turn = "X"         else:             turn = "O"            while True:          reverse()         cls()         printBoard()         print ""         print "Its %s's turn." % (turn)         print ""         move = raw_input("Enter your move (1-9): ")          if move.isdigit() == True:             move = int(move)              if move in range(9):                 move = move - 1                 if a[move] == " ":                     a[move] = turn                  else:                     print "Incorrect move: Place taken"                     reverse()                     sleep(2)                  else:                 print "Incorrect move: Number out of range"                 sleep(2)              else:             print "Incorrect move: Move not a number"             sleep(2)        def printBoard():     cls()     print a[0],"|",a[1],"|",a[2]     print       "---------"     print a[3],"|",a[4],"|",a[5]     print       "---------"     print a[6],"|",a[7],"|",a[8] start()


In XCOM: Enemy Unknown, which types of scenery are destructible?

Inspired by , I thought it would be helpful to have a list of the scenery types that can and cannot be destroyed by weapons fire, grenades, etc.


Why is speed/position relative but acceleration not?

I think i understand it now, if found this:   I know that position and speed are relative. There is no such thing as universal coordinates. Then why is acceleration absolute? Is the 3th and 4th derivative of position to time also absolute? Where/how can i see this in the math/laws of motion?  For example: you are in a rocket and you have an accelerometer with you, and someone else is standing on an astroid that is not attracted by gravity towards something else, so it has no net force on it. If the engines of the rocket are turned on, then you will see that on the accelerometer, and you will know that it is you that is accelerating, not the astroid.   Also if the universe were completely empty, except for a bucket of water. If the water would be pushed towards the edges of the bucket, then we would know that the bucket is rotating around its axis. But what would happen if you could rotate space itself around the bucket?  It probably is because $F=ma$ and not something else like $F=m^2a^3+2a+...$, is that correct? Can $F=ma$ be deduces from deeper principles, or is it an experimental law?


I am spending the summer in Dresden. When I came here, I was carrying my iPhone 5s. Now I bought a new iPhone 6s here in Dresden and I am using it, as well as my older one, which was broken (the front camera doesn't work.) Will there be any trouble at Indira Ghandi International Airport, Delhi, if I carry the phones together in my hand bag?  Please let me know about the details, the procedures, and the problems that might occur and how to avoid them.


If I'm sampling from N items, how many samples are needed to get all N items at least once?

I have a situation where I have N items in the population (e.g. these are item IDs in some inventory). Suppose I can sample and get back 1 item at a time, where each item has an independent and uniform distribution of being sampled; for example, I would call some function sample() and it would return one of the N items with probability $\frac{1}{N}$.  On average, how many samples would I need to observe all N items at least once? In other words, how many samples would I need to get the entire population? Obviously, I would need at least N samples as a lower bound, but is there a tighter bound?  Thank you for any help. I'm a software engineer, so please be gentle with any math.


What's the word for a person who possesses extensive vocabulary?

Verbose or wordy do not serve the purpose as intended, as both are used negatively.  Articulate or well-spoken, in my opinion, do not do justice also, as somebody could have smaller lexicon pool, yet still be fluent in their expression.  Thence, I cannot consider my query as a duplicate of the other.  Please help, & thank you!


This lock notice about collaborative effort is partly misleading

is locked  with the following notice:     This question and answer are a collaborative effort: if you see something that can be improved, edit it!    Except that while the answer can be edited because it's a Community Wiki question, the question itself  can't be, because it's locked. I don't know the reason why it was locked, but maybe the notice's text should be changed or omitted? (I have no opinion on whether the question should stay locked or not.)


I am planning to travel to Amsterdam on the 22nd of December.   Before that, I plan to head to my home country to get my visa stamped (21st November - 12th December). As I would just have a week after I return to the USA before I leave for Amsterdam. I wanted to apply for my Schengen Visa now. I emailed the Consulate and they didn't give me a straight forward answer. What do you think are my chances to get the visa now.


Continuity of two variable function $\tan^{-1}(y/x)$

For $(x,y)\in \mathbb{R^{2}}$ with $(x,y)\neq (0,0)$. Let $\theta=\theta (x,y)$ be unique real number such that $-\pi<\theta\leq\pi$ and $(x,y)=(r \cos\theta , r \sin\theta)$ with $r=\sqrt{x^{2}+y^{2}}$, then function $\theta :\mathbb{R^{2}}\setminus\{(0,0)\}\to\mathbb{R}$ is   continuous bounded but not continuous.   Clearly, function $\theta$ is defined as $\theta (x,y)=\tan^{-1}\frac{y}{x}$ which is bounded. I am not able to prove that function is not continuous.


Add an existing WebPart Using the Sharepoint client object Model

My knowledge of the Client Object model is fairly limited, although I have been able to remove and move existing web-parts on a particular page. But I'm now struggling to find and then add a custom web part programmatically using the SharePoint Client Object Model.  The web-part I'm trying to find resides in the Miscellaneous category. I know this by clicking "Page"-->"Edit Page"-->then clicking "Add a Web Part" in one of the zones. Two list boxes appear on the page: one with a heading Categories and another with a heading Web Parts.  So I'm trying to get a web-part in a category named "Miscellaneous" and then I would like to add it to the right hand side of the default.aspx of my sharepoint site.


She is very arrogant because she comes of/from a rich family.  of is the correct preposition here. But how does using from here makes it grammatically wrong?


Run a process on another network PC as the logged in user

In a controlled network environment, we plan to put automated testing applications on some workstations - they interact with our GUI-based software running on those PCs.  I want to be able to launch these processes from another PC on the network, as simply as possible (i.e. not mucking about with COM!) Is this possible somehow, to remotely run an .EXE? Since the process involves GUI, I think it has to run as the logged-on user?  If it matters, workstations are on Windows 7.


Every subgroup of the integers has finite index

I think that this statement is false, but only in the trivial case. $\{ 0 \}$ is obviously a subgroup of $(\mathbb{Z},+)$ with infinite index.  In the case of a nontrivial subgroup of $(\mathbb{Z},+)$, intuition tells me that these subgroups will have finite index. How should I begin to prove this?  What I know:  Nontrivial subgroups of $\mathbb{Z}$ are of the for $n\mathbb{Z}$ for some $n\in\mathbb{N}$. These subgroups are infinite cyclic groups.  I read in another  posted here that I should try use the smallest positive element of $n\mathbb{Z}$ and Euclidean division to explicity describe all of $\mathbb{Z}$, but I'm not sure what that means, precisely.


In the 80's TV cartoon  there was a Golden Condor:    I remember it was somehow solar-powered, but I don't remember how it flew. For instance, it did not flap its wings to take off.  By what principle was it able to fly?


If a relation is both symmetric and anti-symmetric, isn't it always reflexive? I am supposed to consider a set, S, where some Relation A is both symmetric and anti-symmetric. I thought that anti-symmetric means that if (x, y) is in the relation, then (y, x) cannot be in it unless x = y. So, wouldn't it hold that it is reflexive?


Inequality : $\sum_{k=1}^n x_k\cdot \sum_{k=1}^n \frac{1}{x_k} \geq n^2$

I have to show the inequality of $$\left(\sum_{i=1}^n x_i\right)*\left(\sum_{i=1}^n \frac{1}{x_i}\right) \geq n^2.$$For $x_1, ... x_n \in \mathbb{R_{>0}}$ and $ n \geq 1$. I wanted to show this inequality by induction. The basis is clear, but I am not sure how to do the inductive step. Can someone help me with that?


Hi!  Is this card working with Ubuntu. Is there any driver? When I installed Ubuntu 12.04 there was a black screen.  Thx, Akitoru


Why do object assignments refer to memory locations when primitive types don't?

I have a bit of an odd question regarding how primitive types work in Java. When using Objects when you assign an ObjectA to be ObjectB be like such  Rectangle ObjectB = new Rectangle(); ObjectA = ObjectB;   Any calls to ObjectA refer now to ObjectB's memory location. However when using integers or other primitive types this is not the case. For example  int x = 3; int y = x; int x = 5; return y;   y will return 3, the value of x when y was initialized.  The question I have is why does assignment for objects create references in memory, whereas primitives make a copy of the values of each other? Other than the fact that this is useful, how is this implemented in Java?  I'd appreciate anyone who can provide me a greater understanding of how assignment works between primitive types and objects.


Retail boxed Steam activated games: can they be resold?

I recently purchased retail boxed versions of   Dead Island (which is awesome) Warhammer 40k: Space Marine (not so much)   I finished both games and I was thinking of reselling them or giving them to a friend to play. However, these are both Steam activated games that had a required Steam registration code I had to enter -- and validate on Steam -- as part of the installation.  If I give these games to a friend or resell them, will they even work? Is the registration code single use and tied to a single person / computer / Steam account?


I seem to be having issues when I try and save the output file as a .png, or .jpeg for that matter. I've set up my user preferences, File, Render Output to my desktop as well as render output in the editor window. What am I missing here? I'm obviously very new to this program and your help would be appreciated. Thanks for your time


Why is the cross product of vectors in the given image like this?

I know the question seems kind of unclear but why (in the attached image) the cross product like this, I hope someone can clear my doubt.


I am an Indian Citizen, I am travelling from Venezuela to India, I am transiting via Paris(CDG). Do I need to take Airport transit Visa for France or I don't require one.  My friends said these answer,  "None as long as you have the single ticket You will be in transit thru out the journey and you will not do immigration in Paris"  "Actually you don't really need transit Visa in Paris and Amsterdam"  But many people say I need transit Visa, I don´t know what to do. Any information will be highly helpful, thank you!


Locking a MySQL database so only one person at once can run a query?

I am having a few issues when people are trying to access a MySQL database and they are trying to update tables with the same information.  I have a webpage written using PHP. In this webpage is a query to check if certain data has been entered into the database. If the data hasn't, then i proceed to insert it. The trouble is that if two people try at the same time, the check might say the data has not been entered yet but when the insert takes place it has been by the other person.  What is the best way to handle this scenario? Can i lock the database to only process my queries first then anothers?


Why does one variable change but the other does not?

While some people are saying that this question has been answered before, its only the answer that has been given before to a different question with much more specifics (ie. asking specifically about call-by-reference / call-by-value, whereas this question does not presuppose knowledge of eiither)  The following code appears to be very confusing.  We can logically deduce that the reason why z.id updates after the function is because it is an object.  But why? What particular trait or characteristic of javascript is doing this?    function changea(a) {   a = 100; // does not change a }  // no return  function changez(z) {   z.id = 100;  // does change z } // no return  var a = 0;  // a is zero  changea(a)  // a variable  alert('variable a is equal to ' + a); // why does this stay at zero?  var z = {id: 0}; changez(z); alert('variable z.id is equal to ' + z.id); // why does this change to 100   see the demo here:


How to get a German Umweltzone sticker while on the road?

I'm driving a Czech rental car into Germany and would like to have an Umweltzone sticker so that I can drive into cities. Where can I get one while on the road and what documents are needed?  The car itself is a brand new Skoda that certainly meets the environmental requirements. It just needs the sticker to certify this.


Is there any way I can see if a questions has been bumped by Community?

Some old questions are usually "edited" by Community profiles on the network sites, in order to get more attention if they meet certain criteria.  Is there a way to know that an old question has already been bumped by Community, or does the warning on the yellow board disappear after some time?


What are the assumptions of linear regression

Can anyone explain the assumptions of linear regressions?    If possible with an example?  Is this really important to check these assumptions before proceeding?


What is the difference between continuous derivative and derivative? According to my teachers solution to the assignment,it seems there exits difference between continuous derivative and derivative. However, aunt Google does not tell me what I want.  Edit: Here is a example. $$f(x) = \begin{cases} \frac{1-cos2x}{x} & \text{otherwise}  \\ k & \text{if x=0}  \end{cases}$$  Does k is continuous but not continuous derivative at $0$?  Thanks:)


What is the exact shape of the main component of the Mandelbrot set? I’m referring to the heart-shaped area centered at at the origin. Is there a simple way to express this shape in Cartesian or polar coordinates?


When I create a list of list in Python, why do all my inner lists get the same values?

So, I was working on Python for making List of arrays for my project work.   Sample code:  var0 = 0 var1 = 0 car = [0,0] listitem = [car[:] for i in range(10)] for i in range(10):     car[0] = var0 + i + 1     car[1] = var1 + i     listitem[i] = car print listitem   As the logic would suggest we would be expecting an output like:  [[1,0],[2,1],[3,2],[4,3],[5,4],[6,5],[7,6],[8,7],[9,8],[10,9]]   But the output comes as:  [[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9]]   I have come with a theory where the car array uses some pointers to the variable space.  Does anyone has a probable explanation for the same? Thank you


After a fresh ubuntu installation from the terminal, I mean what are the commands line I should enter to enable softwares sources such as universe/multiverse/main?


How to recover boot options after deleting them with EasyBCD?

I have a dual-boot Asus notebook and I almost-accidentally deleted every boot option with EasyBCD.  Now I can only load Ubuntu, because there are no more boot options on the Windows partition.  Is there a way to boot on Windows again?  I also have a recovery partition (factory reset from Asus), but I can only access it when the first boot screen from windows appears (pressing F9). I can create a new boot option at BIOS, but I don't know what to put on the EFI file patch there. There's some .EFI files on the recovery partition...


$x^a - 1$ divides $x^b - 1$ if and only if $a$ divides $b$

Let $x > 1$ and $a$, $b$ be positive integers. I know that $a$ divides $b$ implies that $x^a - 1$ divides $x^b - 1$. If $b = qa$, then  $$x^b - 1 = (x^a)^q - 1^q = (x^a - 1)((x^a)^{q-1} + \ldots + x^a + 1).$$  I'm interested in the converse of the statement. If $x^a - 1$ divides $x^b - 1$, does this imply that $a$ divides $b$?


My Mac doesn’t help an admin user?! Help!

I have two Mac Book Pro's laptop with me.  In one of the laptop, I am getting the following popup prompting when I try to change the login options.  It is prompting me like this:    In my another Mac Book Pro, it's simply showing the prompt like this. So I guess, it should show the same prompt message in first Mac Book Pro too.    How to get administrator name to login into the first laptop?  I tried with possible usernames & password (I have never changed my password) that I am aware of but they are not working.     How to find/get the administrator name back so that I can log in with my password.


Find all nonisomorphic $3$-regular graphs on $8$ vertices.  I know one possible graph is two tetrahedrons, since tetrahedrons are 3-regular graphs on 4 vertices. It also seems that this graph is the only disconnected graph, though I'm not sure how to prove this. But how can one systematically find these graphs? I know that we can label the vertices $v_1,\cdots, v_8$ and assume WLOG that $v_1$ is adjacent to $v_2, v_3, v_4.$ However, the remaining $4$ vertices all need to be connected to $3$ other vertices and there seems to be way too many cases to consider.


Is 'off of' ever a valid substitution for 'from'? For example,      'It's that guy off of Friends.'   Would it ever be acceptable to use this construction in formal written English?  I live in the West Country (UK) and I hear this construction frequently.


Prove $T$ has at most two distinct eigenvalues

The question is from Axler's Linear Algebra text. The $\mathcal{L}(V)$ stands for the space of linear operators on the vector space $V$.          Suppose that V is a complex vector space with dim $V=n$ and $T \in \mathcal{L}(V)$ is such that     $$\text{null} \ T^{n-2} \neq \text{null} \ T^{n-1}  $$     Prove that $T$ has at most two distinct eigenvalues.      I fist thought of solving this by contradiction. That is, I thought, suppose there were three distinct eigenvalues. Then, there would be an equation like  $$(x-\lambda_1I)^{d_1}(x-\lambda_2I)^{d_2}(x-\lambda_3I)^{d_3} $$ where the $d_i$'s are positive integers that sum to dim $V$. Call this polynomial $q(x)$ the characteristic poly. Thus, by Cayley's theorem, $$q(T)=(T-\lambda_1I)^{d_1}(T-\lambda_2I)^{d_2}(T-\lambda_3I)^{d_3}=0 $$ Then multiplying out and setting dim $V = d_1+d_2+d_3 = n$, I could then get a poly with the various powers of $T$ (this is a little tricky to write down). In particular, I wanted to see the powers $n-2$ and $n-1$. I thought, ok, so now, rewrite the poly in terms of each of these and using the fact that $\text{null} \ T^{n-2} \neq \text{null} \ T^{n-1}$ you get some vector $v \in V$ such that, $$T^{n-1}v = (\text{poly}_1)v = 0 $$  but  $$T^{n-2}v = (\text{poly}_2)v = k \neq 0 $$ I can think of some interesting things about $(\text{poly})_1$ and $(\text{poly})_2$, in particular, each has the monic term $T^n$. At this point, I'm not sure any of this helped.  Well, anyways, I'm sure someone has a much better approach! Thanks in advance to anyone who read this.


\documentclass{beamer} \usetheme{CambridgeUS} \useoutertheme{infolines} \usepackage{tikz} \usepackage{tabularx} \usepackage{ragged2e}    \begin{document} \begin{frame} \frametitle{Introduction}  \begin{itemize}         \item Text:         \break         \begin{itemize}            \item \justify \textbf{What is lorem ipsum}: Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum. \break             \item \justify \textbf{why do you use it}:It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content here, content here', making it look like readable English. Many desktop publishing packages and web page editors now use Lorem Ipsum as their default model text, and a search for 'lorem ipsum' will uncover many web sites still in their infancy. Various versions have evolved over the years, sometimes by accident, sometimes on purpose (injected humour and the like).          \end{itemize}         \break         \end{itemize}   \end{frame} \end{document}   I use the package ragged2e to align text. However when I use \justify every item in the list lose the bullet in front of it


How to change the function: woocommerce_myaccount_page_id code below:  <a href="<?php echo get_permalink( get_option('woocommerce_myaccount_page_id') ); ?> ">   To redirect it to WordPress login screen instead of "My account" page.  <a href="<?php echo get_permalink( get_option( 'WHAT CODE ENTER HERE TO REDIRECT TO PAGE WP-LOGIN.PHP?') ); ?> ">


How to show that $|D_{2n}| = 2n$ via the presentation?

Consider the dihedral group  $$D_{2n}= \langle a,b \mid a^n = 1 = b^2, b^{-1}ab = a^{-1}\rangle$$  How can I show that $|D_{2n}| = 2n$?   I'm trying to show that we can write every element in the form  $$x = a^i b^j$$ where $i= 0, 1, \dots, n-1$; $b = 0,1$.   I managed to show existence, and it is clear that there are $2n$ such elements, so if I can show that every choice of $i,j$ gives a distinct element, I'll be done.  Any ideas?


Let $X$ be an arbitrary random variable  takes values in $\{0,1,2,...,10\}$. What are the minimum and  maximum values of variance of random variable $X$?


New install 12.4 LTS no network conncections

I installed 12.4 LTS on a Dell D520 with Broadcom 1390.  No network connection, wired or wireless is recognized.  No network is displayed for wired or wireless in network connection box.  Both wired and wireless network connections worked under Windows XP before Ubuntu install.  I verified ethernet cable connection with another computer. Did not do dual install - replaced XP.  I found solution for wireless card, but that requires wired connection.  How can I make it recognize a network?


I try to plot quadratic fonction.  \documentclass{article} \usepackage{tikz}  \begin{document} bad, negative square equal...negative!   \begin{tikzpicture} \draw plot (\x,\x^2/4/1.0); \end{tikzpicture}  good \begin{tikzpicture} \draw plot (\x,\x*\x/4/1.0); \end{tikzpicture} \end{document}   I found a solution, but why this surprising result? Is there a way to use the square function?


How come my shaded smooth model looks sharp?

My model is shaded smooth, and autosmoothed. But some edges/faces look sharp. How come? And how do I fix it?


Does Enlarge increase your normal reach?

If my character, a medium-sized creature, were to drink a potion of growth, would his reach with a weapon increase?


How to find a file in the filesystem from the command line?

I'd like to find where a file (with a partially-known filename) is in the file system.  I'd like to know how to do this from the command line, rather than using a GUI utility.  In Windows, I'd run the following:  cd /d C:\ dir *filename* /s   What's the Linux equivalent?


Find files which are created a certain time after or before a particular file was created

I need a shell script which finds files which are created 1 hour before or 1 hour after a particular file (test.txt) was created.   If I go with find -newer, that means I'd have to create a temporary file, use touch to change the time on that 1 hour before the creation time of the test.txt file, and then use -newer tempFile to find the files which are newer than the tempFile, ultimately finding the files which are created 1 hour before the test.txt file. Then I have to go back through that process to find those an hour or more older than the file I'm interested in. That seems like a lot of extra work to go through to answer a simple question.  I also see find -mmin, but I worry that it's an extension to POSIX find.  Any other suggestions?


Set default/restrict text formats based on node type

In Drupal 8 (not D7) as noted  How do you limit a text input to only specific content types/fields.  For example, I create a new input type here: admin/config/content/formats and call it "blog_body" and I want it to be the only (or at least default) option for the body field on blog post node type. Preferably it is not available on other nodes too.


warning: hostname no-reverse-dns-configured.com does not resolve to address

This is what comes up in /var/log/mail.log.1. I have absolutely no idea the domain no-reverse-dns-configured.com is being read. Also the said IP has nothing to do with my server. I don't event imagine where to start looking.


Can you say more than four 'and' words in a row?

If I was describing to a shop sign image creator a Fish and Chip shop sign by its individual symbols, I might say to the shop sign image creator:  Please can I have the symbols for: fish, 'fish' and and, '&' and chips, 'chips'?  That conversational sentence contains four 'and' words in a row albeit by using the word 'and' instead of 'ampersand' to say the symbol '&'. Can more than four 'and' words in a row exist in a conversational sentence?


Transferring contacts from iCloud to Android

I have a Samsung Android phone and need to transfer my iCloud contacts to that phone. How do I accomplish this?


How can I identify hardware components in a laptop?

I just reinstalled my Windows and now I don't have all the hardware components recognized. I have an  laptop and  website seems to have all the necessary drivers for my model. The problem is that I don't know exactly which components I have. For example, in my laptop video card case the site has available drivers for ATI and Intel chips.   How do I know what are the right drivers for my machine?


Is there a workaround to delete cookies in Edge 44.17134?

Currently,  which prevents deleting cookies - causing an exception: OpenQA.Selenium.WebDriverException: 'Unknown error’  Microsoft’s response was to mark it as Won’t Fix and advise updating the version of Edge.  Unfortunately, telling clients to update their browser version isn’t ideal. Is there a workaround which will allow me to remove a cookie, without this exception?


Greatest Common Divisor with Fibonacci Numbers

Prove that for all integers $n\geq 0$:  $$\gcd(F_{n+1},F_n)=1$$  I am extremely lost. Please can some provide some hint or direction? Thank you so very much


Need help to pivot one column into rows in SQL Server 2012 - no aggregates and no label column exists

I'm trying to get this  PatID   FacID   RxNo        RejectCd 121403  463     57074566    R9  121403  463     57074566    76 121403  463     57074566    88 121403  463     57074566    8C    To look like this             PatID   FacID   RxNo        RejectCd 121403  463     57074566    R9,76,88,8c   Tried using a pivot or doing it in stages but I'm stuck. Can't pivot because I don't have a field for the column names. Also don't know how many Reject Codes will actually exist till it runs but we can ignore that part for now. I think this will be really challenging for any SQL nerds out there. Thank u!


Fatal error occurred, no output PDF file produced

we are executing following code from .php file.  $result1 = shell_exec("R CMD Sweave /var/www/html/r/r_latex_sweave.Rnw");  $result2 = shell_exec("pdflatex /var/www/html/r/r_latex_sweave.tex");  But, we are getting this errors :  $result1 = shell_exec("R CMD Sweave /var/www/html/r/r_latex_sweave.Rnw"); [11:53:55]  $result2 = shell_exec("pdflatex /var/www/html/r/r_latex_sweave.tex");  can you please help us on this?  thanks.


What is the difference between Clamav and Clamtk? I know that both of them are antivirus.


While going through apex pdf i got line      Static variables defined in a trigger don’t retain their values   between different trigger contexts".   Can anyone please explain me with some code sample. I am confused as to what is the meaning of defining a static variable inside a trigger. Static variables are are used in Class context. So what a static variable does in trigger context.


NullPointerException When retrieving JSON data

I have been playing around with some JSON, trying to get and display the strings to show in a custom ListView with Textviews in my app. But I'm getting an NullPointerException when running. Can somebody tell me where I'm making a mistake and point me to a right direction maybe.    This is the JSON:  [{"id":"1","client_id":"1","client_name":"Company A"},{"id":"2","client_id":"2","client_name":"Company B"}]   this is the Model class:  public class Model {     private String client_name;     public String getClient_name() {         return client_name;     }     public void setClient_name(String client_name) {         this.client_name = client_name;     } }   Wrap class:  public class Wrap {    private ArrayList<Model> models;      public ArrayList<Model> getModels() {         return models;     }      public void setModels(ArrayList<Model> models) {         this.models = models;     } }   this is my Adapter:  public class Adapter extends ArrayAdapter<Model> {     public Adapter(Context context, int resource) {         super(context, resource);     }      @Override     public View getView(int position, View convertView, ViewGroup parent) {         ViewHolder viewHolder;          if (convertView == null) {             convertView = LayoutInflater.from(getContext()).inflate(R.layout.listview_item, null);             viewHolder = new ViewHolder(convertView);             convertView.setTag(viewHolder);         } else {             viewHolder = (ViewHolder) convertView.getTag();         }         final Model p = getItem(position);         viewHolder.textone.setText(p.getClient_name());          return convertView;     } }   The ViewHolder :  public class ViewHolder {     public TextView textone;     public ViewHolder(View convertView)     {        textone = (TextView)convertView.findViewById(R.id.txt_field);     } }   The url:  private static final String SO_URL = "http://www.example.com/webservice/?value"; private static final String PARAMS = "[{\"table\":\"locations\",\"operation\":\"select\"}]";   This is the AsyncTask's doInBackground method :  protected String doInBackground(Void... params) {             try {                 //Create an HTTP client                String  URL = URLEncoder.encode(PARAMS, "UTF-8");                 HttpClient client = new DefaultHttpClient();                 HttpPost httpPost = new HttpPost(SO_URL + URL);                  //Perform the request and check the status code                 HttpResponse response = client.execute(httpPost);                 StatusLine statusLine = response.getStatusLine();                 if(statusLine.getStatusCode() == 200) {                     HttpEntity entity = response.getEntity();                     InputStream content = entity.getContent();                      try {                         //Read the server response and attempt to parse it as JSON                         Reader reader = new InputStreamReader(content);                          Wrap wrap =  new Gson().fromJson(reader,Wrap.class);                         for (Model model : wrap.getModels()) {                             adapter.add(model);                         }                         adapter.notifyDataSetChanged();                         content.close();                     } catch (Exception ex) {                         Log.e(TAG, "Failed to parse JSON due to: " + ex);                         failedLoadingPosts();                     }                 } else {                     Log.e(TAG, "Server responded with status code: " + statusLine.getStatusCode());                     failedLoadingPosts();                 }             } catch(Exception ex) {                 Log.e(TAG, "Failed to send HTTP POST request due to: " + ex);                 failedLoadingPosts();             }             return null;   I'm getting this exception msg :  Failed to parse JSON due to: java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.ArrayList com.bloomcore.dbnewapp.Wrap.getModels()' on a null object reference


How to create a non-trivial "private" class in Python?

so I am developing a library for dealing with trees (as graph structures). I already have a class Tree that implements many things.  I now want to create two new classes, let's say Tree2D and Tree3D, that will inherit from Tree, and for which I will add 2D and 3D geometry.  As I plan to have several methods that can be applied to both 2D and 3D geometry, I would like to create a class TreeGeometry, in which I will implement those methods, and then make Tree2D and Tree3D inherit from it.  However, I do not want that someone can instance TreeGeometry objects directly. In a sense, I want this class to be "private". I've read about abstract class, so I think it might be the appropriate thing, but I'm not sure that I can make such an abstract class inherit from Tree.   Any advice on how I should proceed ?


Can Framing Frame Day 1 still be completed in stealth if the extra restroom guard spawns?

Occasionally, in Framing Frame Day 1, an additional guard will spawn in the restroom.  This brings the total number of guards on the map to seven:   One at the front desk. One in the security room. One in the restroom. Four on patrol.   Even with Smooth Talker, you can  and . That leaves two guards that you need to deal with.  Is it possible to complete Framing Frame in stealth when this extra guard spawns?


I don't truly understand some basic things in C like dynamically allocating array of arrays. I know you can do:  int **m;   in order to declare a 2 dimensional array (which subsequently would be allocated using some *alloc function). Also it can be "easily" accessed by doing *(*(m + line) + column). But how should I assign a value to an element from that array? Using gcc the following statement m[line][column] = 12; fails with a segmentation fault.  Any article/docs will be appreciated. :-)


Linear regression - Can I log transform dependent variable and one of the independent ones and keep the rest not transformed?

I have model where my dependent variable is Total money spend and then I have independent variable Income and some other variables. Is it okay to use log transformation on the dependent variable and one of the independent ones and keep the rest unchanged?


Let $A$ and $B$ be real $n\times n$. Is it true that if $ABA=A$ is true $B=BAB$ ?  My reasoning: $$ABA=(ABA)BA=A  \; \Leftrightarrow A(B-BAB)A=0.$$  But as it follows from the latter, that $B-BAB=0$, if in the general case the matrix $A$ is not invertible?


Finding the limit $\lim \limits_{n \to \infty}\ (\cos \frac x 2 \cdot\cos \frac x 4\cdot \cos \frac x 8\cdots \cos \frac x {2^n}) $

This limit seemed quite unusual to me as there aren't any intermediate forms or series expansions which are generally used in limits. Stuck on this for a while now .Here's how it goes :    $$ \lim \limits_{n \to \infty} \left[\cos\left(x \over 2\right)\cos\left(x \over 4\right)       \cos\left(x \over 8\right)\ \cdots\ \cos\left(x \over 2^{n}\right)\right] $$


Can't get out of a loop that's supposed to check wHether the value typed in is correct or not

This is part of a small project we're doing and I get stuck in this part when executing the original program. Changing the values to be integers seems to solve it but I need them as rational numbers. I really don't understand what I'm doing wrong.    void main() {         float potencia;         printf("\nInsira a potencia contratada (em kVA):");         scanf_s("%f", &(potencia));         while (potencia != 3.45 || potencia != 4.6 || potencia != 5.75 || potencia != 6.9 || potencia != 10.35 || potencia != 13.8 || potencia != 17.25 || potencia != 20.7);         {         printf("\nPotencia inserida nao disponivel, insira uma das seguintes: 3.45, 4.6, 5.75, 10.35, 13.8, 17.25, 20.7 ");         scanf_s("%f", &(potencia));         }  }


Html file became a rtf file then a txt file

I have been working on a html file on my mac os 10.10 via Texedit for about a week. When I started my computer today the file appeared on my machine as an rtf, and when I opened it I saw my page as rich text with no javascript of html tags. I then tried to restore it but all the versions were rtf. I then choose to view the page a plain text and restore again and now all the versions were plain text. Again no javascript or html tags. How can I restore my file as a html file?


remove accents or tilde from a string in python

I have the following example string to make a function which will remove accents  is an email header and I store it in the bd but since I get the header I get it that way   ('Cotización pruebá ácentos')     string = m['subject']  self.remove_accents(string.decode('utf-8'))   the function that I have is the following  def remove_accents(self, s):     return ''.join(c for c in unicodedata.normalize('NFD', s) if               unicodedata.category(c) != 'Mn')   it removes the accents but it returns something like this  =?utf-8?b?q290axphy2nds24=?= =?utf-8?b?ihbydwviw6e   how do I decode the chain


PROBLEM  Prove that a power series $\sum_{n=0}^{\infty}{{a_n}{z^n}}$ which converges for any $z \in \mathbb{N}$, converges for any $z \in \mathbb{C}$.  MY ATTEMPT  Since the power series $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ converges for any $z \in \mathbb{N}$, then $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ can be considered (?) to be a polynomial in $\mathbb{C}$.  Hence, $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ is entire, and therefore continuous in $\mathbb{C}$ (since differentiability implies continuity).  It follows that $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ converges for any $z \in \mathbb{C}$.  QUESTION     I am aware that, while I may have (some) ideas for a (general) proof, admittedly there are several grey areas (i.e., gaps) that need to be filled.  Would you be kind enough as to fill in these gaps, by providing useful hints?


Direction of Friction of a cup on a table cloth

I'm having a bit of trouble figuring out which direction kinetic friction is supposed to act in.    A glass of water is placed on a cloth at distance d from the table edge, and the cloth is spread out across the table until length l from the same table edge. The cloth is pulled at constant velocity v towards the edge of the table, and is pulled at a speed such that the l-d length of cloth slides under glass and the glass remains under the table.   Would the friction between the glass and the cloth act in the direction the cloth is being pulled or in the other direction?


How to create a polygon (fixed width buffer) around a polygon in QGIS?

I have created a polygon in QGIS (in this case it describes a country's maritime baseline).  I need to create a second polygon whose boundary is a fixed distance from the original polygon. (in this case I need to create the territorial sea boundary, which lies 12 nautical miles outside the baseline).  I think geoprocessing tools>buffer is correct tool for this job? But I can't figure out what units QGIS uses for the buffer distance.  What should I enter in buffer distance to generate a 12nm buffer?


Continuous Functions from $\mathbb{R}$ to $\mathbb{Q}$

The following is not a homework problem. I am doing it for self study.      Prove that any continuous function from $\mathbb{R}$ to $\mathbb{Q}$ is constant.    Here is my proof:     Let $f:\mathbb{R}\rightarrow \mathbb{Q}$ be such a function.    ? We first show that $\mathbb{Q}$ is disconnected. Let $p$ be an irrational number. Then we can write $\mathbb{Q}$ as  $$ \big( \mathbb{Q} \cap (-\infty,p) \big) \cup \big( \mathbb{Q} \cap (p,\infty) \big),  $$  which is a disconnection of $\mathbb{Q}$.      Moreover, $\mathbb{Q}$ is also totally disconnected, as any open subset $U$ of $\mathbb{Q}$ must contain two rational numbers and there is always an irrational number between the two, and we can use that rational number to create a disconnection. Therefore the only connected subsets of $\mathbb{Q}$ are the singleton sets $\{q\}$, where $q \in \mathbb{Q}$, which are closed.       We will show that $f(\mathbb{R})$ must be connected. Assume not, then    $$ f(\mathbb{R})= U\cup V, $$   where $U$ and $V$ are nonempty open subsets of $\mathbb{Q}$ such that    $$ U \cap V= \emptyset .$$    This implies   $$ \mathbb{R} = f^{-1} \big( U \cup V \big) = f^{-1}(U)\cup f^{-1}(V),  $$   where $f^{-1}(U),f^{-1}(V)$ are nonempty, nonintersecting subsets of $\mathbb{R}$. This, however, is a contradiction, as $\mathbb{R}$ is connected. Therefore no such set $U$ and $V$ can exist.       As we have already shown, the only connected subsets of $\mathbb{Q}$ are the singleton sets $\{q\}$, so $f(\mathbb{R})$ must be such a set.   Something about this does not seem quite satisfactory, as if I am missing something. Could anyone tell me a flaw in my logic? Also, is there a more satisfactory way to prove this theorem?


How do I spawn Enderdragons in Minecraft?

What is the quickest way to spawn  in Minecraft?   Is there an easy single-player mod? Would it be easier to do it somehow with Bukkit?


i own a Xiaomi Redmi 4A smartphone and i have access to fairly dark site to observe the night sky.I would like to know if it is possible to get a good photo of the milky way.  (f/2.2 , I can choose iso between 100-3200 and whatever shutter speed i want)


CTRL and ALT keys mapped to Shift for some reason

I installed Ubuntu 14.04, and I'm loving it. However, when playing a game called Garry's Mod I noticed that my CTRL and ALT keys on my wired keyboard were both being detected as Shift. I looked at the keyboard layout chart and confirmed this. I also noticed that my Windows, or Super Key, Right CTRL and Right ALT are all being mapped to Left Shift.  They're all working perfect, they're just being detected wrong. I have selected the United States layout which is what my keyboard is supposed to be and is in Windows. Can anyone help? My keyboard is being detected as a SONiX USB Keyboard (the actual keyboard brand is Avazz).   my xev -event keyboard output is this for every single one:   KeyRelease event, serial 28, synthetic NO, window 0x4a00001,     root 0xdc, subw 0x0, time 2446369, (730,547), root:(795,599),     state 0x1, keycode 50 (keysym 0xffe1, Shift_L), same_screen YES,     XLookupString gives 0 bytes:      XFilterEvent returns: False   The only thing that changes is the time. The sudo evtest command shows all the modifier keys as   type 4 (EV_MSC), code 4 (MSC_SCAN), value 700e1v type 1 (EV_KEY), code 42 (KEY_LEFTSHIFT), value 0  for lsusb, the driver it's using is the usbhid driver.  lsusb shows something confusing; the same port as my keyboard is being shown in other commands is showing up in lsusb as my wireless mouse's driver, Logitech, Inc. Unifying Receiver. This may be the problem, but I'm probably simply mistaken in what port it is on. Due to this, I'm not sure what driver is what. I'm going to post all of them, although this might be annoying. I have a separate keyboard plugged in along side my main one to use the CTRL, Super, or ALT by the way, so don't be confused by the Logitech Classic Keyboard Driver.  Bus 001 Device 009: ID 0bda:8172 Realtek Semiconductor Corp. RTL8191SU 802.11n WLAN Adapter Bus 001 Device 008: ID 046d:c315 Logitech, Inc. Classic Keyboard 200 Bus 001 Device 007: ID 1a40:0101 Terminus Technology Inc. 4-Port HUB Bus 001 Device 006: ID 0480:0200 Toshiba America Info. Systems, Inc.  Bus 001 Device 004: ID 0c45:6340 Microdia  Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 004: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller Bus 002 Device 003: ID 046d:c52b Logitech, Inc. Unifying Receiver Bus 002 Device 002: ID 0c45:7603 Microdia  Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub   For lsusb -t, the driver being used is usbhid. for i in $(ls /sys/module/usbhid/parameters/); do echo -ne "$i\t"; more /sys/module/usbhid/parameters/$i; done is:  ignoreled   0 mousepoll   0 quirks  (null),(null),(null),(null)  I don't think you need this since I said it's usbhid, but here's it anyways.  for i in $(ls /sys/module/hid/parameters/); do echo -ne "$i\t"; more /sys/module/hid/parameters/$i; done's output.  debug   0 ignore_special_drivers  0 modinfo usbhid's output is:  filename:       /lib/modules/3.18.3-031803-generic/kernel/drivers/hid/usbhid/usbhid.ko license:        GPL description:    USB HID core driver author:         Jiri Kosina author:         Vojtech Pavlik author:         Andreas Gal srcversion:     A395FA22EA2729BAC1557C9 alias:          usb:v*p*d*dc*dsc*dp*ic03isc*ip*in* depends:        hid intree:         Y vermagic:       3.18.3-031803-generic SMP mod_unload modversions  signer:         Magrathea: Glacier signing key sig_key:        29:DB:FD:FC:5A:CC:82:3C:C5:2C:39:4C:C1:C7:4C:01:C3:BE:BF:78 sig_hashalgo:   sha512 parm:           mousepoll:Polling interval of mice (uint) parm:           ignoreled:Autosuspend with active leds (uint) parm:           quirks:Add/modify USB HID quirks by specifying  quirks=vendorID:productID:quirks where vendorID, productID, and quirks are all in 0x-prefixed hex (array of charp)  cat /sys/kernel/debug/usb/usbmon/2u > /tmp/usb.mon.out is telling me not found even though I changed 2 to my bus ID. What am I doing wrong here? Clarify if you can please, kinda confused there. I tried putting 2, 02 and 002. The output of  sudo ls /sys/kernel/debug/usb/usbmon/ is  0s  0u    1s  1t  1u  2s  2t  2u


Given Riemann mapping $f:\Omega\to\mathbb D$, prove $\inf_{z\in\partial\Omega}|z-a|\le\frac1{f'(a)}\le\sup_{z\in\partial\Omega}|z-a|$.

I'm looking at the following problem from some old qualifying exam I found:     Let $\Omega$ be a simply connected proper open subset of $\Bbb C$, let $a\in\Omega$ and suppose we are given an analytic bijection $f:\Omega\to\mathbb D:=\{z:|z|<1\}$ satisfying $f(a)=0$ and $f'(a)>0$. Prove $$\inf_{z\in\partial\Omega}|z-a|\le\frac1{f'(a)}\le\sup_{z\in\partial\Omega}|z-a|.$$   To be honest, I have no idea where to start with this; my first thought was noticing that $1/f'(a)=(f^{-1})'(0)$, and was hoping to use this to try to apply the maximum modulus principle to some function involving $f'$ or $(f^{-1})'$ and $z-a$, but the first issue I come to before even trying to write a function down was realizing that $f'$ and $(f^{-1})'$ might not even be defined on the respective boundaries, so it doesn't seem like I could use maximum modulus to determine anything about the points on the boundary with respect to those functions.  I also assumed when I saw this that this was just something proved and used in the proof of the Riemann mapping theorem, but it doesn't actually seem to show up there.


what sort of a regex pattern should i use to check if an email is in this patter, xxxxxxx@my.hello.co.uk  xxx being letters and numbers  tried this  [a-zA-Z0-9._-]+@[my.hello]+.[ac]+.[uk]  doesn't work though


Stopover of 5 hours at tokyo NRT should I buy transit visa traveling from US to India

I am traveling on American Airline from Los Angles LAX to Bangalore,India on 23 dec 2013 there is layover and change of flight at Tokyo NRT and Malaysia. Layover time at NRT (4.20pm-9.40pm) is 5 hours should I but transit visa?   I have F1 visa and Citizen of India.  I searched there was an old answer (to buy transit visa only if layover of overnight we need to buy) any new updates?


Add Secondary IP Address That Is Seen By A Server

I need to add another IP address and I need the server to be able to know see it.  On the client: curl using the second IP/interface On the server: netstat or tcpdump  I want to be able to see the second IP address in the server.  Tried ip link add, ip address add, ifconfig. Nothing works. On the server there is always the "main" address of the client.  Everything is on the LAN, no need for DNS, etc..


Can I just save files as a PDF from Illustrator?

I use illustrator a lot and I'm always exporting PDFs. Since the PDF is a "save as" rather than an export, I end up editing the PDF and saving out. This causes version conflicts. Could I just work in PDF? What would be lost if I never used the ai format?


How to build a regular expression which prohibits hyphens from appearing at the start and end of a string?

I want to build a regular expression which only matches [A-Za-z0-9\-] with an additional rule that hyphens (-) are not allowed to appear at the start and at the end.  For example:  my-site is matched.  m is matched.  mysite- is not matched.  -mysite is not matched.  Currently, I've come up with ^[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9]+$.   But this doesn't match m.  How can I change my regular expression so that it fits my needs?


how do S1 ∈ S2, when R2 is not a subspace of R3?

if dim(S2) = 3, S1 ⊂ S2, then what are the possible dimensions of S2?   Answer: 1, 2, 3  (this is from our quiz)   is R^2 a subspace of R^3?   Answer: R^2 is not a subspace of R^3 because its elements (2-component vectors) do not even come from R^3 (the set of 3-component vectors)  (this is from )  My question is, S2 is a plane through origin right? Since it is the possible dimension, how R2 is not a subspace of R3?   We been debated about this for days, if you would kindly provide any hint to us, we will be greatly appreciated.  EDIT: I am greatly appreciated for everyone's reply. Sorry this is my first time posting and a few typo is already fixed.


Is there any difference of meaning between "to want to be" and "to want to become" when they express a change of "permanent" state , eg a profession or a personality trait? Is one of them more usual/informal?   Example of profession change:        I want to be an actor.   I want to become an actor.      Example of personality change:        I want to be a good person.   I want to become a good person.


Debian 10 — adjust sleep settings via command line

I have a machine that I access only via SSH that I just updated to Debian 10 a couple of days ago. Since the update it seems to be going to sleep when it is inactive. This has never happened with previous updates like from 7 to 8 or from 8 to 9. It seems like maybe the sleep settings have reverted to a default state. How can I view and edit the power and sleep settings in the command line? Any guidance much appreciated. Thanks!


My old computer broke down a few days ago, so I'm using a laptop until I can get it fixed.  As a side effect, I no longer have my usual browser cookies, so I had to log back into Stack Exchange.  While doing so, I noticed that I kept having to log in to every Stack Exchange site I visited — the usual "Welcome back [username], you've been logged in." auto-login banner seemed to be conspicuously missing.  In fact, a quick look at the "network" tab in the developer tools suggested that no requests to stackauth.com were being made at all.  Eventually, I decided to dive into .  Turns out that the code to make the global auth check and bring up the banner is simply:    gauth.checkStackAuth(StackExchange.options.stackAuthUrl);   And, what do you know, running that command from the developer console does auto-log me in.  However, the reason this code isn't being run automatically is because it's disabled in the site config (apparently for all SE sites).  For example, the page I'm typing this question on has the following config options set:  StackExchange.init( {     "locale": "en",     "stackAuthUrl": "https://stackauth.com",     "serverTime": 1408393334,     "networkMetaHostname": "meta.stackexchange.com",     "styleCode": true,     "enableUserHovercards": true,     "site": {         "name": "Meta Stack Exchange",         "description": "Q&A for meta-discussion of the Stack Exchange family of Q&A websites",         "isNoticesTabEnabled": true,         "recaptchaPublicKey": "6LdsB7sSAAAAAAzjgEF_Hd8vXv-C42sa_KyofaGR",         "recaptchaAudioLang": "en",         "enableNewTagCreationWarning": false,         "globalAuthDisabled": true,                // <--- HERE         "isMetaSite": true,         "enableSocialMediaInSharePopup": true,         "useGoogleOAuth2": true     },     // etc.   So, apparently, global auto-login has been deliberately disabled for some reason.  Why is that, and is there any planned timeline for re-enabling it?


Can an Android phone be used as a Bluetooth headset/speakers?

Is there a way to make an Android phone (HTC Desire HD) act as Bluetooth speakers or headset?  I'd like to use the phone as wireless headphones whilst watching a movie on a computer (running Ubuntu).


Why are some place holders '@' and others '%'?

For example:  watchdog('alerts', 'Message for %user was sent.', array('%user' => $user));   and  drupal_set_message(t('options: @options', array('@options' => $form_state['values'])));   Is there any difference?


Overriding Related list standard button with Lightning Component & prepopulate parent record field in form

Is there any way to override 'New' standard button with lightning component and refer the parent record as prepopulated value in record creation screen?  I saw in some posts to achieve this using visualforce override and pass parent recordid in url but I wanted to achieve using only lightning component.  Please let me know if more details are needed.    As shown in screenshot I have to override this standard 'New' action to open a form and prepoulated opportunity and account information and few fields of Agreement record itself.


Lightning component button in Lightning list view

I have a requirement where in a list view of the Custom object, user can select multiple records and click a custom button.On click of this button, lightning component needs to open and ID of the selected records needs to be obtained in this lightning component. Could anyone please let me know how to achieve this in lightning?


Difference between "for any" and "for all"?

In a textbook (on economics, not "pure" mathematics), one definition requires that some condition holds for any $x,\ x' \in X$, and right afterwards another one requires that some other condition holds for all $x,\ x' \in X$.  My question: is there a difference between the two (for any, for all)?    Though searching for previous questions returns thousands of results for the query "for any" "for all", I couldn't find this specific one. Sorry if I missed it.


Let $g$ be a function from $(0, 1)$ to $\mathbb{R}$ and $\int_0^1 g^2(x)dx$ finite. Does this imply that $\int_0^1 g(x)dx$ is finite?   So I know that $| \int_0^1 g(x)dx | \leq \int_0^1 |g(x)|dx = \int_0^1 \sqrt{g^2(x)}dx$. Not sure how to continue.


Cannot unfollow locked post from Following tab

Initially I was unable to unfollow deleted posts from the Following tab in my profile. That seemed to been fixed recently so I was cleaning out the deleted posts when I encountered one that would not unfollow.  Turns out the deleted post is locked since it was deleted as Spam.


Why would using higher ISO and faster shutter speed yield more noise than using lower ISO and slower shutter speed?

I'm trying to see how  correlates with practice. That answer basically says I need to let enough light into the camera and then use the highest ISO value and I'll get the lowest noise then.  So I make two shots with the same camera. Camera has aperture set to a specific value, fully manual mode, camera is on a tripod and focused onto a specific faraway object. Shooting is done around midnight, so it's rather dark. The scene is a large industrial building standing faraway across a field from the camera. The field has no light sources, all lights are on the industrial building.  I dunno if it's important but images are written as JPEG inside camera - no shooting to raw and external post-processing. Maybe that's why I see my unexpected result.  Camera highest ISO value is 3200 (not using extended ISO values).  So I first shoot with ISO 1600 and shutter speed set to 1/125 second and then I shoot with ISO 3200 and shutter speed set to 1/250 second. The amount of light should be identical and indeed both shots look properly exposed and exposed the same way.  When I open the pictures in an image viewer and zoom in to one hundred percent  I see that ISO 1600 shot is much cleaner than one with ISO 3200. I checked that several times and I'm sure - it's not the other way around.  Why is this? Is this because of post-processing difference?


output is proper but showing runtime error in c

#include<stdio.h> void main() {      int i = -1, j = 1,k,l;     k=!i&&j;     l= !i||j;     printf("\n%d\n%d",i,j); }   shows in output: Runtime error time: 0 memory: 10304 signal:-1  but if i replace void by int and add return 0 in program it works fine without any error why?


Changing the zero product property and defining division by zero

I know that defining division by zero is not possible because it violates the zero product property we define, that is, $0\times a=0$ for every $a$. I wonder whether we can somewhat circumvent and change the definition of the zero product property (or make a new definition about multiplying by zero), then safely deducing a definition for dividing by zero and then possibly building a system when this definition exists and proving useful theorems?


Absolute convergence implies convergence in absolute value squared

I am trying to show that for each sequence of real numbers $\{a_k\}_{k = 1}^\infty$, with $\sum_{k=1}^\infty |a_k| < \infty$, we also have that $\sum_{k=1}^\infty |a_k|^2 < \infty$.  In my "proof", so far I have deduced that for each positive integer $n$, we have \begin{align} \sum_{k=1}^n |a_k|^2 \leq \left(\sum_{k=1}^\infty |a_k|\right) \left( \sum_{k=1}^n |a_k|\right). \end{align} I am tempted to say that taking the limit as $n \to \infty$, we have \begin{align} \sum_{k=1}^\infty |a_k|^2 \leq \left(\sum_{k=1}^\infty |a_k|\right)^2, \end{align} but I am not completely convinced of this step. The reason is that all we seem to know is that the partial sums $\sum_{k=1}^n |a_k|^2$ are bounded, but  this  this alone is not sufficient to deduce convergence.  Is it possible to extend the inequality regarding the partial sums to deduce the convergence of $\sum_{k=1}^\infty |a_k|^2$?


Unphysical degrees of freedom in the Yang Mills Lagrangian

Im taking my first course in QFT and has stumbled upon something that I do not understand.  Given the Yang Mills lagrangian  $$\mathcal{L} = -\frac{1}{4}F^{a}_{\mu \nu}F^{a\mu \nu}$$  with $F^{\mu \nu} =F^{a\mu \nu} \frac{\sigma^{a}}{2}$ (the pauli matrices). How can I determine the number of unphysical and physical degrees of freedom of this theory?  I know this Lagrangian describes massless spin(1) gauge bosons $A^{\mu}$, which means (I think) that the gauge boson has 2 physical degrees of freedom. However, I do not understand how to count all the remaining degrees of freedom. I suspect it is related to that there are 3 generators for SU(2), although I do not know how to make the connection.  I hope that my question is clear (=


How many three digits numbers are there such that there is no $1$ adjacent to $2$ on the right side?

I made three case that $2$ is at extreme right then we have $9\times 10 = 90$ numbers, $2$ in middle has $81$ numbers,and with $2$ in beginning has $90$ numbers. This makes $90+90+81=261$ numbers and we add the numbers with no $2$ in them, that is $8\times 9 \times 9= 648$. Thus total will be $909$. What will be the common numbers counted multiple times and how to eliminate them?


Is there any connection between special relativity and general relativity?

Is there any connection between  and ? We know that gravity causes relativistic effects according to general relativity which car similar to special-relativity. so is there any connection between general relativity and special relativity?  Or any thing in the scientific literature which has attempted to unify the special and general relativity?


What would the collision of two photons look like?

Could someone explain to me what the collision of two photons would look like? Will they behave like,   Electromagnetic waves: they will interfere with each other and keep their wave nature Particles: they will bounce like classical balls   I assume that energy of that system is too small to make creation of pairs possible.


How to select the most recent set of dated records from a mysql table

I am storing the response to various rpc calls in a mysql table with the following fields:  Table: rpc_responses  timestamp   (date) method      (varchar) id          (varchar) response    (mediumtext)  PRIMARY KEY(timestamp,method,id)   What is the best method of selecting the most recent responses for all existing combinations of method and id?   For each date there can only be one response for a given method/id. Not all call combinations are necessarily present for a given date. There are dozens of methods, thousands of ids and at least 365 different dates    Sample data:  timestamp  method  id response 2009-01-10 getThud 16 "....." 2009-01-10 getFoo  12 "....." 2009-01-10 getBar  12 "....." 2009-01-11 getFoo  12 "....." 2009-01-11 getBar  16 "....."   Desired result:  2009-01-10 getThud 16 "....." 2009-01-10 getBar 12 "....." 2009-01-11 getFoo 12 "....." 2009-01-11 getBar 16 "....."   (I don't think  is the same question - it won't give me the most recent response)


I am looking forward to mastering linux. I have been repeatedly told to refer to man pages when you are in doubt.   Though I am very comfortable with the commandline, I find it very difficult to quickly and efficiently use man to find help with commands. Hence I end up googling up how to get things done. It is even more painful when the system I am using does not have internet access and I have to walk back to my office to get help from the internet.  How does one master man pages? What are the most common tricks that can be used to quickly get whatever you want from the man page? What are the most commonly used keyboard shortcuts?


I need help proving "For each $x,y,z$ in $\mathbb{N}$, if $x<y$, then $xz<yz$."  This must be done using Peano's axioms and the definitions of addition, multiplication, and ordering.   I have tried induction on z, and the base case works out but I run into an issue when it comes to the inductive part seeing as I am no longer dealing with equality.   Maybe induction is not the correct approach to this proof, and maybe a direct $P\implies Q$ proof would be more logical, however once I assume $x<y$, I don't have much to work with to deduce $xz<yz$, besides the definition of order.


Meta Description says "Your browser does not currently recognize video format"

My site is indexed on google search but the description is "Your browser does not currently recognize any of the video formats available. Click here to visit our frequently asked questions about HTML5 video."    Is there a way to get rid of this? I just want my other content to showup.


How can I remesh a curve that has been converted to mesh?

Is it possible to somehow remesh plane? I have a logo that needs to be curved along an object. So I import the SVG logo and convert it to the mesh. But the plane has a bad distribution of polygons and vertices so when I use the shrink wrap modifier it breaks in some of the parts. The remesh modifier looks to work only on models with some thickness. I ended up manualy cleaning the mesh, but wanted to find a faster way. Beautify faces helped in one of four cases.


I want to find the version of a .class file

Is there any way to find the java version from a compiled java .class file ?


Uk visit visa refusal under 4.2 a+c and 4.10

My visit aim to meet my sister and nephews, as they had not travel to my home last 10 years. Because my little nephew is ill and that disease  called autism spectrum disorder (ASD). He needs his mom special care at all time. I have also my mom in my home country she  is ill and is suffering asthma, allergy, and arthritis. I have done my engineering degree and start my own business. Iam the first carer of my old mom here in my home country. I have presented that during my trip my sister( married) here in my country   will take care my mom  for some days. My father has been died. I have submitted property detail , my car, house detail etc. Now if i want to reappear then what steps are necessary for explaining ECO that i am a genuine visitr and come back after my trip


In Blender 2.8, I have applied a Background image of a sky-scape to the camera view and have hit render. However, the rendered image shows the cube and gray world background, not the cube and the sky background image. I have fiddled about with the settings but to no avail.  Any thoughts?    Edit 1  I believe this question to be different than the question, "Why won't my 'background' render" (of which this question was closed as a duplicate) because the image I have is a Background image. The question mentioned by Ketchup boy 2002 relates to an image applied to an empty, which apparently is not renderable.


Is $D_{2n}$ isomorphic to $D_n \times \Bbb{Z}_2$ for all $n$? For all odd $n$?   I just want to see if my thinking is sound here. My thought process is this.  $\mathbb{Z}_2 \cong \{e,j\} \subset D_n$   where $e$ is the identity and $j$ is a reflection about some axis.   let $\phi \colon D_n \times \{e,j\} \to D_{2n}$ defined by the map  $(a,b) \mapsto ab$  This is a surjective homomorphism and because the sizes are the same, it is an isomorphism.   Is this right? Have I done enough?


I have just got the "" Hat.Isn't that a bit early as I am in GMT and the time is 1310.  Or do we get then whenever it is Dec 25 anywhere?


Does the interval $[0,1]$ contains more real numbers than $(0,2)$?

It is a common saying that there are more real numbers than integers, since you can not uniquely map integers to real numbers - even after using up all integers, there will still be at least one real number left that you haven't mapped to any integer.  So I applied the same argument to the two intervals in question. One obvious way to map number from $[0,1]$ to $[0,2]$ is $\times 2$ - $0$ is still $0$, $0.25$ becomes $0.5$, and $1$ becomes $2$. Good enough.  However, if we change the second interval to an open interval, namely $(0,2)$, then the number $0$ and $1$ in the original mapping is now the "remaining" number, while all numbers in $(0,2)$ have already been "used". Does that mean that $[0,1]$ have more real numbers than $(0,2)$? (even though $(0,2)$ seems to be bigger than $[0,1]$…)  Does my argument even make sense? I did some Googling but didn't found anything useful.