Why using [a] and not [an] in "a user interface is like a joke. If you have to explain it, it's not that good"

I've found this phrase across the internet and  they use "A user interface" instead of "An user interface".  Is it an error that has been propagated or is it correct? If it's correct, why?


No such file or directory? But the file exists!

I've downloaded a game (Shank) but the bin file doesn't run. The error that is shown when I try to launch the executable is:  bash: ./shank-linux-120720110-1-bin: No such file or directory


does this work in Ubuntu correctly - or is there missing something?

This (gawky) question is concerning command dd:     dd if=/dev/DVD of=whatever.iso   seems not to work ... and then output follows like:     could not open /dev/DVD - file or directory not found   Is here usage of dd incomplete or not exactly enough - or path simply not correct ?  I wonder about that (this usb-dvd-burner) is not written in /etc/fstab - but     wodim -v -eject whatever.iso   has no trouble to burn iso-images contrary to command dd ?


ALERT! /dev/mapper/edbunto--g-root does not exist Error. Dropping to a Shell!

So I am stupidly new to Linux, like I wasn't even the one who installed it unto my computer.   I'm am using Ubuntu as the Linux software and I was tinkering around when I found something called Disk creator or something I cant remember what it was and I found a thing I believe it was called Hard Drive.   It had 80 gigabytes of memory, and I double clicked it then I clicked on its settings and went to advanced settings.   It had a layout of devices from 01-05 and I clicked on device 01 and changed its partition from Linux to a MAC OS X partition.   Now mind you I don't have a clue at all what a partition is at the time when I did this, after that I rebooted my computer and gave me the following error and a gave me a very limited BusyBox and that's all I can go to after I choose a Ubuntu thing to load which is the GNU GRUB version 2 and I've done so many things searched through thousands of links and can't find one solution that fits my problem.   I cant ever get past the BusyBox no matter what I've tried.   I've seen a lot of peoples problems are the same as mine but there solutions don't ever resolve the kind of problem here someone please help me! Id appreciate it thanks.


A finite group with exactly $2$ conjugacy classes isomorphic to $\mathbb{Z}_2$

Prove or contradict: A finite group with exactly $2$ conjugacy classes always  isomorphic to $\mathbb{Z}_2$.   At first I was trying to work with familiar groups to contradict it(permutations, cyclic, dihedral and general linear) but I could not find any counter example.  So I was trying to prove it.Let $G$ be a group that has exactly $2$ conjugacy classes, obviously one of those classes is $e$, and the other class is the rest of the elements.  So I'll define $f:G \rightarrow \mathbb{Z}_2$ as follows - $f(e) = 0$, and $f(g) = 1$ for every other $g \in G$. It is easy to see that $f$ is homomorphism, and also that $\ker (f) = e$, and by the first isomorphism theorem, we get that $G \cong \mathbb{Z}_2$.  Is it correct?


How to install Ubuntu 18.04.3 over older Ubuntu system

I have downloaded 18.04.3 to a USB drive and cannot get it to install. What do I do after downloading? I am running an older version of Ubuntu


Show equivalence of statement $\left(P\rightarrow Q\right) \wedge \left(Q\rightarrow R\right)$ to ...

Show that $\left(P\rightarrow Q\right) \wedge \left(Q\rightarrow R\right)$ is equivalent to $\left(P\rightarrow R\right) \wedge \left[\left(P\leftrightarrow Q\right) \vee \left(R\leftrightarrow Q\right)\right]$  After one page of expanding and collapsing the right hand side, I get as a result  $$ \left(P\rightarrow Q\right) \wedge \left(Q\rightarrow P\right) \wedge \left(P\rightarrow R\right) $$  Can anybody help? Although this question has been marked as a duplicate, the linked page only provides a partial answer (one direction) and the other answer is in Polish notation which I am not familiar with.


How to use FileNameMap interface in Java?

This interface provides one method, namely getContentTypeFor(String fileName). However, I have no idea how to use it. I implemented interface in Eclipse and ended with:  import java.net.FileNameMap;  public class Fnam implements FileNameMap {  public static void main(String[] args) {  }  @Override public String getContentTypeFor(String fileName) {     return null; } }   The method returns null. How should I change it to get the MIME type ?


I have a small problem with footnote. My code:  \documentclass[12pt, a4paper]{mwart} \usepackage[demo]{graphicx} \usepackage{caption}  \begin{document} Some text... \begin{center} \includegraphics[scale=0.4]{image1.jpg} \captionof{figure}{Some text\footnote{Source: http://link.com/example-link/}} \end{center}  Some text \begin{center} \includegraphics{image2.jpg} \captionof{figure}{Some text\footnote{Source: http://link.com/example-link2/}} \end{center} \end{document}   I have superscript with number at "Some text", but footnote doesn't appear at the bottom of page. Where can be a problem?


Any advice on communities or forums where I can find play testers for a new tabletop role play game?  It's designed for casual players to game together virtually. So imagine pen & pen style RPG played over WhatsApp or Slack. Games usually take about an hour or two and there's a whole element designed for off the cuff role play between games.  A large part of the game is story creation mechanics that make games really quick to setup. This is the bit we're working on the most at the moment.  Rather than hand this over to someone else to run, like in , I'd like to have an involved discovery session with the players. Ideally looking to understand how the feel about the game as much as watch them play.  Any suggestions on where to look would be greatly appreciated!


Can spells with a verbal component be cast underwater if the caster can't breathe water?

My party recently tipped over a boat of enemies into what was essentially rapids and trapped the enemies in a cube of force underwater. The warriors inevitably drowned as they had no way out. However, trapped in the cube of force was a wizard with access to a teleportation spell (Misty Step) with a verbal component. Could the wizard use his spell with a verbal component underwater and escape a watery death? If the rules don't specify anything about verbal components underwater specifically, have any of the designers mentioned anything about this?  Note: as a 5e DM I made a ruling on the spot (decided to allow it on the condition that the caster goes directly from "holding breath" to "suffocating") so I am aware that it's within my power to decide how it works in my world. I'd just like to know if the rules or someone wiser than me has addressed this yet.


I'm trying to set up SPF for our domain to prevent or reduce spoofing. The difficulty I'm having is with how to look at any particular email and determine if it would pass SPF.  We of course know which internal mail servers we have that are sending mail for our domain. The problem is finding the external ones, like constant-contact, etc, that have been used by the marketing folks to send mail as users in our domain that should be included in our SPF record.  I understand it analyzes the "MAIL FROM" data and references it with the IP address of the connecting server. Often times I see "MAIL FROM" something like "user@ac.example.com" but the mail is actually "From:" user@example.com" yet it passes SPF.  When checking to see if a particular email would pass an SPF test, how is the "From:" field considered, when "MAIL FROM" is the real return-path sender?


I have an error in this code  void f(list<CClass*> mylist,CP* Database,string namePoi){ //some code list <CClass*>::reverse_iterator ite;             for (ite=mylist.rbegin(); ite!= mylist.rend(); ite++) {                     mylist.insert(++ite,Database->getPointer(namePoi));//compiler error                 } }   The error is  : no matching function for call to 'std::list::insert(std::list::reverse_iterator&, CPOI*)' the lineDatabase->getPointer(namePoi)  is giving the right output but I think I m not using the right insert command because when I use a normal iterator(not reverse_iterator), it works perfect. Thanks


On today's news, it says that Fermilab have done measurements on the spin of muons and that they are measured to wobble faster than expected according to current physics theories. Apparently this may turn physics 'on it's head' and suggests that there might be a fifth force. What measurements have been made? and Why do the measurements suggest the need for a fifth force? Here is an extract from the BBC article   "The Muon g-2 experiment involves sending the particles around a 14-metre ring and then applying a magnetic field. Under the current laws of physics, encoded in a theory known as the Standard Model, this should make the muons wobble at a certain rate. Instead, the scientists found that muons wobbled at a faster rate than expected. They say this might be caused by a force of nature that's completely new to science.  Fermilab is America's premier particle physics lab. No one yet knows what this potential new force does, other than influence muon particles. Theoretical physicists believe that it might also be associated with an as-yet undiscovered sub-atomic particle. There is more than one concept for what this hypothetical particle might be. One is called a leptoquark, another is the Z' boson (Z-prime boson)."  Does anyone know any more details?


When I add a "hat" to a character, I cannot get a gap before the superscript

I like how there is a gap between the subscript and the superscript when I write ${w_i}^T$. However, if I try to put a hat on the vector, like $\hat{w}_i^T$, this space goes away. Any ideas?  I tried putting in an extra set of braces, as suggested for a similar question , but it didn't work.


What is meant by ^1 as array index (e.g. arr[^1]) in C#?

int []arr = new int[4]; arr[^1];   // returns the last element  I'm trying to figure out the syntax above. It's returning the last element, but why?


How do I Get WiFi working on my Dell Inspiron 1501 with BCM4311 [14e4:4311]?

My wireless doesn't work with Ubuntu 12.04.(it worked with 10.04 LTS) I have a Dell Inspiron 1501. I followed the steps posted below:  Run these:  sudo apt-get install --reinstall bcmwl-kernel-source broadcom-sta-common broadcom-sta-source  echo "blacklist brcmsmac" | sudo tee -a /etc/modprobe.d/blacklist.conf  echo "blacklist bcma" | sudo tee -a /etc/modprobe.d/blacklist.conf  The first makes sure that the sta driver is in place, the second and third blacklists the two drivers brcmsmac and bcma which clash with the correct sta driver. Copy/paste or make sure your typing is correct! The last step is to go to 'Additional drivers' and enable the driver.**  ....and now i have no Network device on my PC(wired or wireless)


APEX Dataloader fail INVALID_FIELD_FOR_INSERT_UPDATE, cannot specify Id in an insert call

I have a trigger and a class that seem to be causing an insert fail in Dataloader.  I am trying to insert 200 records to see if an error is generated before moving these to production. I'm just inserting the mandatory fields such as Name, Owner, Market, Customer_Success_Manager__c, and Business Unit.   Each time I get an error:     UpdateCSMTeam:execution of AfterInsertcaused by: System.DmlException:   Insert failed. First exception on row 0 with id01MJ0000009gXthMAE;   first error: INVALID_FIELD_FOR_INSERT_UPDATE, cannot specify Id in an   insert call: [Id]Class.UpdateCSM.updateTeamMem . I've listed the class   and trigger below.   APEX CLASS  public class UpdateCSM {             public static void updateTeamMember(List<Account> accounts) {                     List<AccountShare> ashareLIST = new List<AccountShare>();                     List<AccountTeamMember> ATM = new List<AccountTeamMember>();                    Set<String> rmMember = new Set<String>();                     Map<ID, ID> acctToBRepMap = new Map<ID, ID>();                      for(Account a:accounts){                              AccountShare caSharingRule = new AccountShare();                                caSharingRule.AccountId = a.Id;                                caSharingRule.OpportunityAccessLevel = 'Edit';                                caSharingRule.CaseAccessLevel = 'Edit';                                caSharingRule.AccountAccessLevel = 'Edit';                                caSharingRule.UserOrGroupId = a.Customer_Success_Manager__c;                                ashareLIST.add(caSharingRule);                                    if(a.Customer_Success_Manager__c!= null){                                   AccountTeamMember Teammemberad=new AccountTeamMember();                 Teammemberad.AccountId=a.id;                 Teammemberad.UserId=a.Customer_Success_Manager__c;                 Teammemberad.TeamMemberRole = 'Customer Success Manager';                                   ATM.add(Teammemberad);                             if(!ATM.isEmpty()){                                    insert ATM;                                              insert ashareLIST;                                                         if(a.Customer_Success_Manager__c==null){                                            list<AccountTeamMember> ratm = [SELECT UserId                                                                             FROM AccountTeamMember                                                                             WHERE (TeamMemberRole = 'Customer Success Manager')                                                          AND AccountId =:a.id];                                             if(ratm.size()>0)                                                 delete ratm;                                        }                                    }                                 }                            }                         }                    } ...   APEX TRIGGER  trigger UpdateCSMTeam on Account (After update, After insert){         UpdateCSM.updateTeamMember(trigger.new); }


I have created a CNAME for www.example.com  to   example.org  I would like to create a CNAME for   example.com  to  example.org  Or, do I not need to do that?  Our former email domain rather than pointing to an IP address now needs to point to a cloud domain.


How to edit a file that has a space in its name?

I'm on Ubuntu 18.04. If I go into my home directory and right-click and select "new document" and then "empty document", a new file appears called "Untitled Document". Now I want to edit what's in this file, and so in the terminal I type:     gedit ~/Untitled Document   And what happens is that gedit opens two temporary documents, both non-existent yet, one called "Untitled", and the other called "Document". How am I supposed edit the file called "Untitled Document"? Also, to edit the contents of a document like this I must use the terminal? I didn't see any option for editing when I right-clicked.


Lipschitz Continuity of $\sqrt{1 + \|x\|^2_2}$

Let $f: \mathbb{R}^n \rightarrow \mathbb{R}$ be a vector-valued function given by $f(x) = \sqrt{1 + \|x\|^2_2}$. Show that the gradient of $f$ is Lipschitz continuous, in particular with Lipschitz constant $L = 1$.  I want to show this directly from $\|\nabla f(x) - \nabla f(y)\|_2 \leq \|x - y\|_2 \; \forall x, y \in \mathbb{R}^n$. However, the gradient of $f$ is not exactly very clean, and I get lost in the algebra. Is there a simpler way to do this that I'm missing?


A few months ago my iPhone was stolen... a few days ago I recieved a facetime call from a weird email at 4am so I didnt pick up then a message that says add +57(318)xxx-yyyy for iMessage and Facetime then it says This phone number was associated with the Apple ID (my email address) on Iphone (my Name)... What this means? Is the person who stole my iPhone?


PHP File upload not working, noting output to browser

Im trying to build an image upload for my site, I have the following only nothing is output at all, yet my page renders okay? Can anybody see where I may be going wrong?\      //if they DID upload a file... if($_FILES['profile_image']['name']) {     //if no errors...     if(!$_FILES['profile_image']['error'])     {         //now is the time to modify the future file name and validate the file         $new_file_name = strtolower($_FILES['profile_image']['tmp_name']); //rename file         if($_FILES['profile_image']['size'] > (1024000)) //can't be larger than 1 MB         {             $valid_file = false;             $message = 'Oops!  Your file\'s size is to large.';         }          //if the file has passed the test         if($valid_file)         {             //move it to where we want it to be             move_uploaded_file($_FILES['profile_image']['tmp_name'], 'uploads/'.$new_file_name);             $message = 'Congratulations!  Your file was accepted.';         }     }     //if there is an error...     else     {         //set that to be the returned message         $message = 'Ooops!  Your upload triggered the following error:  '.$_FILES['profile_image']['error'];     } }  else { echo    'success';     }     <form method="post" action="./process-signup.php" enctype="multipart/form-data" >       <input type="file" class="profile_image text-input" name="profile_image" placeholder="Upload a picture"/><br />     <input type="submit" id="signup-com-btn" value="Complete Signup" />  </form>


source .bash_profile is not working in shell script. How can i do?

I am trying to use 'source ~/.bash_profile' command from a shell script. But this doesn't work. My script is like this:  test.sh  #!/bin/bash source ~/.bash_profile   I use many ways to run the script ./test.sh, bash test.sh and sh test.sh. if run with . /test.sh it is work. This is the running the script? This is the right way to run the installation script?  btw I also test by changing script with . ~/.bash_profile, bash ~/.bash_profile, sh ~/.bash_profile, bash -c '~/.bash_profile'. What is the 'source' problem in shell script. Please explain me what is the right way? How can i source .bash_profile in the script. Thank to everyone!!


Remove link preview in discussion dashboard

It can be sometimes bothersome when, in the Discussion (Comments) dashboard, where the admin can see a list of comments, moving the mouse over a link will cause a preview of that link. Sometimes the preview gets in the way of looking at the comment. This is especially true with spam comments.  And I am also concerned that a link to a page/site that had some 'bad' code would cause a compromise of my site.   Is there a way to disable this 'feature'? Not sure where it is coming from.


I want to achieve that I override one method in JSONObject. So it always return a list even if it has one element:  import java.util.ArrayList; import java.util.List;  import org.json.JSONArray; import org.json.JSONObject;  public class JSONObjectDecorator extends JSONObject {      public JSONObjectDecorator(JSONObject jsonObject) {         super(jsonObject, JSONObject.getNames(jsonObject));     }      @Override     public List<String> get(String field){         List<String> result = new ArrayList<String>();         if (!isNull(field)) {             Object data = get(field);             if (data instanceof JSONArray) {                 JSONArray array = (JSONArray) data;                 for (int i=0; i< array.length(); i++){                     result.add(array.getString(i));                 }             } else {                 result.add(data.toString());             }         }         return result;     }      }   Right now this code gives a StackOverflowError because of this line:  Object data = get(field);   How should I achieve this?  UPDATE: I know why it is a StackOverflowError, and as @Andy Turner highlighted super.get solves the constructor issue, but then when I call for example getString() on an instance of the JSONObjectDecorator it throws an exception that the field is not String. (because it is the List, probably "getString" calls "get")   I will check where "get(String field)" called in JSONObject and I think solution will be to override those methods too.


What square do attacks of opportunity occur in -- the square being moved out of or the one being entered

On Pathfinder core rulebook page 180, in regard to Provoking an Attack of Opportunity:     Two kinds of action can provoke attack of opportunity: moving out of a   threatened square and …   Two situations,   1:  If there is a threatened creature flanked by two others (T - threatened creature, F - flanking creature, X - square that threatened creature is moving to for the first 5' of a full move action)  F T F   X   2:  Or, if there is a non-flanked creature moving into a flanking square:  F X F   T   Do the attacks of opportunity happen in the square T occupies before the first 5 feet of movement or after they have left the threatened square as part of that movement?    NOTE:  T is moving a full 30 ft, I've only shown the first 5ft of movement.  Combat reflexes aren't involved here as neither flanker has them.  Flanking bonuses and sneak attack damage are affected by whichever happens.   By RAW it isn't obvious because the phrase 'moving out' doesn't really state whether the attack is happening before moving out or is 'activated' by the movement.    Can the attackers choose?  The first situation came up on a game this past week when our opponent turned tail and ran, and one of the flankers was a rogue.  We weren't sure if the rogue's sneak attack damage came into play or not.


How does Wish work with spells that interact with material components?

How does  work with spells that interact with material components?  For example, how does wish work with a spell like ? Do an exquisite chest and small chest just appear with the wish? Or do you need them?   Wish says it doesn't need any expensive components to cast, but things are a bit unclear here.


When should I use double or single quotes in JavaScript?

console.log("double"); vs. console.log('single'); I see more and more JavaScript libraries out there using single quotes when handling strings. What are the reasons to use one over the other? I thought they're pretty much interchangeable.


How can I remove Windows XP from harddrive

I installed Ubuntu for the first time. I am very happy with it.  My question is How can I erase Windows XP from my Hard drive and just keep Ubuntu?  I Finally had success with the direct download to my hard drive after several failures on DVD and Cd's I would like to totally get rid of XP.!


has 1568 reputation yet is still a new contributor:    It's probably that .


I just click tab to go to edit mode and the object disappears.  There aren't any armatures or anything else of that kind on the mesh. I'm using Blender 2.74 (latest one).


I am part of a “study team” that authored a paper. How do I list in in my CV?

I was a member of a study team that produced a couple of research papers. The authors of the paper are, for example:      Michael Jordan, Tiger Woods, John Smith and The ABC Study Investigators   In the acknowledgements, it reads:     The ABC Study team consists of members from Harvard University (James Bond, Thomas Harper, David Price, and Jason Jolly)   (Suppose that my name is David Price.)  Can I list such papers in the publication list of my CV? If not, how can I show that I participated in these research papers?  In PubMed, my name was listed as one of 'collaborators.'


Eject second internal hard drive in Ubuntu

I have SSD and HDD hard drives in my laptop and I have Ubuntu on SSD and windows 10 in HDD and (sometimes) I want to eject HDD when I am working on Ubuntu (because of power saving and...), how to do that?


In Minecraft, do clocks still work while in item frames?

Do clocks still work when in item frames?


Perl regexes from a file -- how to use $1?

I have a list of regexes that I run on a string to convert it from one style of formatting to another.  For now, all of these regexes are stored in a file.  Usually, this works fine.  If it reads "Frog" into $from, and "Toad" into $to, then "$string =~ s/$from/$to/" changes all frogs into toads, as desired.  Now I want to do something trickier: given a date "2015-04-15", I want to to change it to "04/2015", again reading from a file.  If I load "(\d\d\d\d)-(\d\d)-(\d\d)" into $from and "$2/$1" into $to, this doesn't work: it replaces the dates with the literal string "$2/$1", with actual dollar signs in the output.  What's do I need to do?  This is a script for home use only.  I am happy to use eval{} or any other strange thing if it will make my life simpler.


How can I sign out other sessions via remote desktop?

When I sign in via remote desktop sometimes the guest user is active and I need to wait for their permission to disconnect them before I can log in via remote desktop. However I do not want any user to be able to prevent me from signing in. How can I make it so when I sign in via remote desktop other sessions are automatically ended?  I am using windows 8


Kodak esp 5020 new cartridge not printing

Just installed new cartridges neither will print anything tried cleaning the print heads multiple times with no results and copying a b+w/color page multiple times then stuck my finger on them they are not dried out finally resorted to manually cleaning the print head with isopropyl alcohol which got me a couple of black spots and streaks along one edge.  Anyone with more printer experience have any other ideas?


How to ask for code from authors who have proposed algorithms in computer science?

I am developing an algorithm, and I want to compare its performance with various existing state-of-the art methods. I would like to contact the authors of these methods and ask if they can send me the code for their methods.  What should I tell them? Should I say that I am developing a method that is in some way an alternative to their method? Or is enough to ask to say that I want to do generic comparisons?


Aren't Low Quality Posts review audits too easy to spot?

I just met this review audit:     Wow, that's difficult to miss. You can see the high score of the answer, as well as the author's rep which is higher than 100k.  However, I remember that the review audits in the Close Votes review queue will "anonymize" the vote count and the author so that it can catch robo-reviewers more easily. More specifically, the vote count is replaced with a 0 instead of the original high score, and the user's name and reputation count is replaced so it is more obscure.  Why isn't this the case for the Low Quality Posts review audits? Shouldn't this be applied as well?


I use TeX Live. See my example:  \documentclass{article} \usepackage[utf8x]{inputenc} \usepackage[english]{babel} \begin{document} Check ligatures: ﬁrst % here I have ligature for "fi" \end{document}   I have Unicode symbol here: ﬁ. When I compile the above LaTeX file I get:  ! Package ucs Error: Unknown Unicode character 64257 = U+FB01  Then I apply the LaTeX system recommendation and compile the following file:  \documentclass{article} \usepackage[utf8x]{inputenc} \usepackage[english]{babel} \DeclareUnicodeCharacter{FB01}{ﬁ}% Here I defined a Unicode ligature \begin{document} Check ligatures: ﬁrst \end{document}   But when I compile this LaTeX file I get:  ! Missing number, treated as zero. <to be read again>                    F l.4 \DeclareUnicodeCharacter{FB01}{ﬁ}  So my question is: How can I input ligatures in a LaTeX file using just the ligature's Unicode symbol?


Required Suggestion for filling German student Visa Application

I'm from India, got my acceptance in German university. In all my study documents and passport my father name is :RAMA, but while filling out Visa application there is column for Father's surname. Is it necessary to fill out the application with my father's surname or should I leave it blank.


Intuitive analysis of gradient, divergence, curl

I have read the most basic and important parts of vector calculus are gradient, divergence and curl. These three things are too important to analyse a vector field and I have gone through the physical meaning of gradient, divergence, and curl.  Gradient indicates the direction of maximum rate of change of a function, and it is defined as $\nabla u(\mathbf{x})\equiv\mathrm{grad} \, u(\mathbf{x})$ where $u(\mathbf{x})$ is a scalar function of the position vector $\mathbf{x}$.   Whereas divergence represents the volume density of the outward flux from an infinitesimal volume around a point and is defined as $\boldsymbol{\nabla} \boldsymbol{\cdot} \mathbf{A}(\mathbf{x})\equiv\mathrm{div} \, \mathbf{A}(\mathbf{x})$  And the curl signifies the infinitesimal rotation around a point and is defined as $\boldsymbol{\nabla} \boldsymbol{\times} \mathbf{A}(\mathbf{x})\equiv \mathrm{curl} \, \mathbf{A}(\mathbf{x})$  And now I have study and also mathematically formulate that $\boldsymbol{\nabla} \boldsymbol{\cdot} \left[\boldsymbol{\nabla} \boldsymbol{\times} \mathbf{A}(\mathbf{x})\right]=\mathrm{div} \left[\mathrm{curl} \mathbf{A}(\mathbf{x})\right]=0$.  And $\boldsymbol{\nabla} \boldsymbol{\times}\left[\nabla u(\mathbf{x})\right] =\mathrm{curl}\left[ \mathrm{grad} \, u(\mathbf{x})\right]= \boldsymbol{0}$ where u is a scalar function  Now my question is how can I interpret those two expressions? I mean, I want the physical significance of these two expressions in the sense of definition of gradient, divergence, curl, and also using graphical representation.


I have a very old laptop Toshiba Satellite M305-S4848, from 2010. I used to run Ubuntu 14.04 on it until a few years ago. Now, I’m trying to use it again. Everything is fine, except for the fact it can’t update its Ubuntu 14.04 (nor the Firefox). It tells me to check the internet connection, but everything else is fine. I’m even typing this from it right now. Please, how should I proceed to solve this? Thanks in advance.


TikZ external Library and pgfplots reading data from external txt file

I'm using the external library of TikZ for speeding up the compilation of my LaTeX document.  In another thread, Christian Feuersänger reported that from December 2012, the external library uses MD5 checksums to find out whether a source file changed or not and whether the corresponding figure must be re-built in order to be up-to-date. This works fine for my figures that have been made using plain TikZ.  However, I also use pgfplots to plot the run of variables whose data is stored in an external txt file. This is a MWE of what I do and how I do it:  %%% this is the main.tex file %%% \documentclass{article} \usepackage{tikz} \usetikzlibrary{external} \usepackage{pgfplots} \tikzexternalize \tikzsetexternalprefix{./PDF/} \begin{document} \begin{figure}   \tikzsetfigurename{fluk-p}   \tikzpicturedependsonfile{data.txt}   \input{fluk-p.tex} \end{figure} \end{document}  %%% This is the fluk-p.tex file %%% \begin{tikzpicture}   \begin{axis}[xlabel={Zeit\,[s]}]      ] \addplot [color=red] table [x index=0,y index=1] {data.txt}; \addplot [color=blue] table [x index=0,y index=2] {data.txt};   \end{axis} \end{tikzpicture}  %%% This is the data.txt file %%% 0  1  2 1  2  1 2  1  2   If I change something in the fluk-p.tex file -- say the xlabel -- TikZ finds out correctly and re-builds the figure. But if I change something in the corresponding data.txt file TikZ does not notice this. I thought I could fix this issue with the \tikzpicturedependsonfile{data.txt} command but I was wrong obviously.  Can anybody help how I can make TikZ to notice changes not only in the fluk-p.tex but also in the data.txt?  Thanks in advance! Sven


If $f$ is nonnegative and integrable then $F(x) = \int_{-\infty}^x f$ is continuous.

I'm learning about measure theory, specifically the Lebesgue integral of nonnegative functions, and need help with the following problem.       Let $f:\mathbb{R}\to[0,\infty)$ be measurable and $f\in L^1$. Show that $F(x)=\int_{-\infty}^x f$ is continuous.   I know is isn't much but the only thing a could think of is that given $x, y \in \mathbb{R}$ with $x < y$ we note that $F(x) \leq F(y)$, i.e. $F$ is increasing. So maybe we can apply one of the convergence theorems of Lebesgue integration theory.    I was also wondering if this problem can be solved using only Riemann integration theory.


Does male circumcision really damage sexual sensitivity for men?

In my point of view, nowadays the male circumcision procedure is becoming unpopular. There may be substantial grounds for that.  There may be numerous subjective opinions about noticeable sensitivity reduction, but are there any objective medical studies that confirm the negative effect is really presented and sexual sensitivity is in fact damaged after male circumcision? For the moment, I am not interested in advantages of this procedure. Sensitivity reduction (provided that it really damages sexual health of men) is the one disadvantage that outweighs all the advantages of this controversial procedure.        Update:  Some information about the matter can also be found on Quora:


$A$ and $B$ are bounded linear operators from the normed linear space $X$ to itself. If $AB$ is invertible are $A$ and $B$ invertible?

I think I understand the proof for square matrices, such that $(AB)^{-1}=B^{-1}A^{-1}$, but I'm not sure if I can just say the same for the bounded linear operators A and B.  Does the existence of $(AB)^{-1}:X\rightarrow X$ imply the existence of $B^{-1}$ and $A^{-1}$?


Java: Accessing original class of an item inside an array list

Let's assume I have the following classes:  public class AnSuperClass { ... }   and  public class AnBetterClass extends AnSuperClass { ... }   Also I have the following ArrayList:  private final ArrayList<AnSuperClass> theList;   and I put some object of type AnBetterClass and AnSuperClass in it like so:  theList.add(new AnBetterClass()); theList.add(new AnSuperClass());   If I iterate over the list: how do I know which one of the two classes I have? The following query will always return false:  boolean foundOther = false; for(AnSuperClass asc: theList)     if(!(asc instanceof AnSuperClass))         foundOther = true; return foundOther;   Help desirable  P.S. Annotation do not work either.


Sandbox session gets confused across browser tabs

I have noticed that if I login to a test.salesforce.com sandbox in one Safari tab, and a different test.salesforce.com sandbox in a second tab, that the login sessions can become confused. One tab will switch over to use the other org's session. I understand that it is normal for tabs to share the same session information but this presents a difficulty when trying to work reliably with two sandboxes at once. What is the best solution?


Can I sync minecraft for PlayStation 4, with minecraft PC?

I started playing on Playstation 4. I created my home and many other things. I do not want to do it again.


Javascript dynamic regex, match string between brackets that have prefix

I have regex that will return value between square brackets, even if there is another set of brackets inside.      const string = 'test[number[20]] test1[20]'     const regex = /[^[\]]+\[[^[\]]+\]/g     const data = test.match(regex);     // [ "number[20]", "test1[20]] //idc about second value   And this works just fine, but I want to add that it should match only brackets that have prefix test. I am really bad with regex, could somebody explain how to achieve this, and how to make it dynamically generated, so string 'test' can be changed in regex.  Thank you for your time and patience.  Edit: Whole idea is that string might be something like this:  'number[20].isnull(12)'   Basically I will be making multiple regex, which will return multiple data, Example for upper string  RegexType returns number; RegexValue returns 20, RegexIsNull returns 12   But string might be just 'number' and we would be getting,  RegexType returns number, RegexValue returns null, RegexIsNull returns null   But it might be array as well , which can contain more declarations  'array[number[5]]'  RegexType returns array, RegexValue returns number[5], RegexIsNull returns null;


Including the interaction but not the main effects in a model

Is it ever valid to include a two-way interaction in a model without including the main effects?  What if your hypothesis is only about the interaction, do you still need to include the main effects?


Adiabatic theorem - quantum mechanics and thermodynamics

A  is defined as follows:  Rapidly changing conditions prevent the system from adapting its configuration during the process, hence the spatial probability density remains unchanged. Typically there is no eigenstate of the final Hamiltonian with the same functional form as the initial state. The system ends in a linear combination of states that sum to reproduce the initial probability density.    An  is defined as follows:  Gradually changing conditions allow the system to adapt its configuration, hence the probability density is modified by the process. If the system starts in an eigenstate of the initial Hamiltonian, it will end in the corresponding eigenstate of the final Hamiltonian.    A diabatic process involves a sudden change of the Hamiltonian, while an adiabatic process involves a gradual change of the Hamiltonian.  The word adiabatic, in thermodynamics, is usually reserved for processes that do not involve the exchange of heat between the system and surroundings. Does this use of the word adiabatic have any relation to the use of the word adiabatic in quantum mechanics? How about the word diabatic?


Controlling for baseline in pre-post between design: using $\Delta(T_2-T_1)$ or controlling for T1 in the regression model (or both)?

I have a mixed between-within design, with three groups and Pre (T1) and Post (T2) measurements. I'm hesitating on the right statistical analyses to do, but I would like to compare each group to the other two separately while taking into account the baseline measurement. I would like to run multiple regressions with planned contrasts. I came up with 4 options:  Note: this question is not about omnibus tests such as ANOVA, ANCOVA, etc.  (a) Planned contrasts between groups at Post (but does not take T1 into account, so just as a reference) # Model in R: lm(T2 ~ Group)  (b) Planned contrasts between groups on change score (Post - Pre) # Model in R: delta <- T2-T1 lm(delta ~ Group)  (c) Planned contrasts between groups at Post, while controlling for Pre (in the regression model) # Model in R: lm(T2 ~ Group + T1)  (d) Planned contrasts between groups on change score (Post - Pre), while controlling for Pre (in the regression model) # Model in R: delta <- T2-T1 lm(delta ~ Group + T1)  Furthermore, , it is also important to include interactions with covariates in the model to prevent Type 1 errors, so the models (c) and (d) would actually look like this: lm(T2 ~ Group + T1 + Group:T1) # Or lm(delta ~ Group + T1 + Group:T1)  Related questions: , , . Question Which option is best? Is option (d) redundant given that it controls for time 1 in the model AND also uses delta (T2-T1) as a dependent variable? On the contrary, are there any additional benefits to doing both?


How do I manage double-faced cards in Innistrad (MTG) tournament play?

I read about the new mechanic in Innistrad, the upcoming MTG edition, called . These cards have two faces, and no standard Magic back. They have actual creatures on both sides. In the linked article they describe two options for handling those cards:     To put a double-faced card into your deck, you have two options: You   can put your entire deck in opaque card sleeves, as many players   already do, or you can use the checklist card provided in many   Innistrad packs. If you're using checklist cards to represent any of   the double-faced cards in your deck, you must use checklist cards to   represent all of them.   I am not happy with either of these options. As a card collector I want my cards nice and clean and I will definitely not remove them from their sleeve during actual play, which is required for the first option. Those cards would take damage really fast. So this option does not work for me.  The alternative is using those checklist cards, but as far as I understand it, this requires me to keep the real cards on a separate pile. Every time I play a checklist card, I will search this pile and put the right card into play. Shouldn't be a problem if you are playing for fun at home or with people who know your deck well. But in a tournament situation, this will leak important information to my opponent. How many double-faced cards am I playing? How many of those are left? It is also very likely that my oppponent my get a glimpse at some of them while I search for a card in the pile, because double-faced cards are hard to hide.  I am considering additional cards to act as decoys. Lets say I only have 4 checklist cards in my deck but I bring 20 different double-faced cards for the exchange-pile. Would this be allowed in a tournament? Or are there better ways to handle that?


what is reason behind android update application

What things responsible for android update. . Means if i have a android phone which will not upgrade my os version . In this scenario , why it is not upgradable ?.. what factor make it .?  Any hardware problem or  any other ?


Are there experiments that are banned from being done at the LHC?

Are there experiments that are banned from being done at the LHC because they are too dangerous?


Prove that $\lim_{x \to \frac{2}{\pi}}\lfloor \sin \frac{1}{x} \rfloor=0$ in the $\epsilon$-$\delta$ way

Given: $$\lim_{x \to \frac{2}{\pi}}\lfloor \sin \frac{1}{x} \rfloor=0$$  How to prove this limit using the $\epsilon$-$\delta$ way? (the biggest problem is to find $\delta$)


Udev: running a shellscript that accesses an X display

After getting my 3g-modem to work in Arch Linux I wanted to eliminate some manual labour required in the process.  Hence I needed to create an udev rule.  After some trial and error I came up with the following rule named 11-my-rule.rules which I placed at /etc/udev/rules.d/:  # start at sdb to ignore the system hard drive KERNEL!="sd[b-z]*", GOTO="my_media_automount_end"  # run the script and create a testdir to verify the rule works ACTION=="add", RUN+="/myscript.sh", RUN+="/bin/mkdir -p '/media/pendrive'"  #remove the testfolder on removal of usb ACTION=="remove", RUN+="/bin/rm -R '/media/pendrive'"  # exit LABEL="my_media_automount_end"   My testscript which is meant to be ran is as follows:  #!/bin/bash  DISPLAY=:0 xterm   Which displays xterminal.  I have tested the script itself and it works.  Also the second RUN+ that creates the test-directory works as well.  Hence I am at a loss just what am I doing wrong.


How to to resize an ext4 partition from the command line?

What's the easiest way to resize an ext4 partition (or any type partition depending on the method) from the command line (potentially with the fewest commands, but also the easiest to understand)?  Using a tool like Gparted is obviously easy in a GUI, but what about in the command line? I guess text-based GUIs can count for the answer too since it's technically still in the command line. It just needs to be easy.  By partition I mean a simple partition on a single disk of a personal computer (e.g. on a laptop). For example, I want to resize /dev/sda4. There's no RAIDs, there's not more than one disk drive, there's not anything complicated here. Just a simple partition on a single disk (/dev/sdaX on /dev/sda).


Why are blocks respawning in my Minecraft 1.3 SMP server?

The Minecraft forums seem to be filled with threads regarding a "block respawn" bug. I set up a 1.3 SMP server on my LAN, and notice this as well. All blocks respawn a couple of seconds after being destroyed, and non-local players lag tremendously.  It makes the game unplayable. Has Notch commented this issue? Is there a solution that makes the game worth buying?


I have a list of items displayed one below the other. I have been trying to make the images next to the text display parallel to the text but it seems like the images almost hover over the text. The image shows what is being displayed:            <title>Page</title>

                                                                                User ID

                                                                                Password

                                                                                Confirm Password

      I want the check mark and 'X' images to displayed right next to the text rather than slightly above the text. This is how I want the images to be displayed:


Does every prime ideal of a ring contain a minimal prime?

Let $R$ be a ring and $\mathfrak p \subset R$ a prime ideal. I think that it is easy to show that $\mathfrak p$ contains a minimal prime ideal of $R$, by the following argument: pass to the localization $\varphi : R \to R_\mathfrak p$, fetch a minimal prime $\mathfrak q \subset R_\mathfrak p$ and contract it back to $R$ to get a minimal prime $\varphi^{-1}(\mathfrak q) \subset \mathfrak p$. However, the commutative algebra wiki  that only in a Noetherian ring do prime ideals always contain a minimal prime. Is there anything wrong with my reasoning, and, if so, what is it?


Is it a good practice to refer to countries, ships etc using the feminine form?

While talking about ships and countries, is it a good practice to use the feminine form?  For example:  "Her economy" - while referring to a country's economy "Her flag (or deck etc)" - while referring to a ship  Is this practice common? Is it used today?


short story about astronauts who enter a black hole and witness the death of the universe

I was listening to a podcast called Exploration, which is hosted by Professor Michio Kaku. He mentioned a short story about astronauts who fall into a black hole and live long enough to witness the death of the universe due to the time dilation. But he did not give the name of the story.  The link to the podcast:


Another User Accessed my account and added a texture pack

It appears my minecraft account (as well as a list of other accounts), got infiltrated last night. I was able to get everything situated. However, in regards to Minecraft. When I logged into my account I noticed there is a new texture pack installed. I've never used texture packs, and everything I've researched on how to remove the texture pack requires me to go into my own .minecraft folder. The problem is, the texture pack isn't in my folders. How do I get rid of this?  Update: Unless they've changed their textures in the last week and it was just coincidence that it happened in the same time. Resource pack says I have default texture pack selected.  Update: The universe pulled the ultimate april fools day prank


All right, say I have this:  <select id='list'>     <option value='1'>Option A</option>     <option value='2'>Option B</option>     <option value='3'>Option C</option> </select>   What would the selector look like if I wanted to get "Option B" when I have the value '2'?  Please note that this is not asking how to get the selected text value, but just any one of them, whether selected or not, depending on the value attribute. I tried:  $("#list[value='2']").text();   But it is not working.


Is it necessary that if we concider a system then always work done by internal forces would be equal to zero?

I am getting confused in between these two cases: Case 1: When we solve pulley-block problems using work-energy theorem then the work done by tension force gets cancelled out because in one block tension and displacement is in same direction while the other end these two will be in opposite direction so work done by tension +TS and -TS gets cancelled out. Case 2: Concider 2 electrons in space. These two have a repulsive electrostatic force in between them and both have work done positive (qe) (S) where S is displacement. So in case 1 when we considered a system the internal forces turned out to be zero and when we considered case 2 when the internal forces didn't get cancelled out but got added up.. So isn't it wrong to say that work done by internal forces is always 0 if we concider a system.


If$(ab)^n=a^nb^n$ & $(|G|, n(n-1))=1$ then $G$ is abelian

Let $G$ be a group. If $(ab)^n=a^nb^n$ $\forall a,b \in G$ and $(|G|, n(n-1))=1$ then prove that $G$ is abelian.  What I have proven is that:  If $G$ is a group such that $(ab)^i = a^ib^i$ for three consecutive integers $i$ for all $a, b\in G$, then $G$ is abelian.  A proof of this can be found in the answers to  old question.


Well known Kepler laws state that earth revolve around sun in an elliptical path with sun at one of the focii.  My question is rather simple. Why so?   I mean for an equilibrium of earth that is it is not accelerated towards or away from sun its gravitational force must be balanced by centrifugal force (pseudo force as frame corresponding to earth)   But following an elliptical path it distance from sun won't be same and hence the gravitational force and hence how is this?   I suspect may be it is due to presence of other celestial bodies but that seems too vague and escaping from the truth   Also maximum of derivations in gravitation are done by assuming circular path of earth around sun. (atleast at my level)   Please give me the real physics behind it?


Domain Name has hyphens and exact match, should I change it?

The blog is currently a blogspot blog. Used part of the name of the real website that I got the idea to start a blog for. Time to get a registered domain for it, instead of the( name.blogspot.com )it is now I got itchy and bought a domain name that has 4 words and hyphens. Also, I believe it is an exact match domain. I see now that hyphens are possibly bad and so maybe are exact match domains. I am not sure if it is wise to use this new domain name or get a different one. Or, if I use this domain name should i just get it with no hyphens, just a run on of 4 words. A different alternative is to use the name of the site i originally started the blog for and add a couple words which I think would be exact matched domain. If I do that should I use hyphens or no hyphens.  Summary, Use hyphens or not in domain with 4 words but the 3 word is actually the letter n such as cookies-n-creme for example. Or, use the real websites name plus the two word exact match meaning NAMEwordword.com If I go this route do i use hyphens or not. I hope you can understand this question. Hard for me to put it into typing. The reason it is exact match name is that it is actually descriptive of the blog and I haven't been able to come up with anything descriptive that isn't.


Do Fortnite V-Bucks Purchases Save on All Platforms?

So I'm thinking of buying some V-Bucks on Fortnite, Battle Royale mobile. Do the purchases save cross platform?


"Yesterday" time specification shown when it was actually the day before yesterday

Looking at , I see "asked yesterday" (which I really hate; I'd like to see an exact time specification rather than this vague one, especially in the list of questions). But it was not asked yesterday! When I hover over it to show the exact time, it shows it was actually the day before yesterday!  This snapshot was taken at 2012-03-31 15:00 UTC (plus or minus a few minutes):    Whatever different opinions you may have on the implementation, yesterday is a word with a certain meaning. Redefining it is not a good idea. At least rephrase this as "1 day ago" or something.


how to get complete value after multiplying 2 digits?

I am having trouble with multiplying my numbers and getting not correct value.  I have numbers 1,2,3,6,12 and 2.95,3.95,6.95,15,95  but when I multiply my number 3 with 2.95 using 2.95 * parseInt('3') it returns 8.850000000000001  and when I multiply 12 with 15.95 it returns 179.3999999999998.  I dont want this too long zeros and this kind of value .8500000000001  its also returns some of those numbers when they multiply.  how to get rid of this? how can I get complete value like 12 * 15.95 should give 179.40


SQL group by day, show orders for each day

I have an SQL 2005 table, let's call it Orders, in the format:  OrderID, OrderDate,  OrderAmount 1,       25/11/2008, 10 2,       25/11/2008, 2 3,       30/1002008, 5   Then I need to produce a report table showing the ordered amount on each day in the last 7 days:  Day,        OrderCount, OrderAmount 25/11/2008, 2,          12 26/11/2008, 0,          0  27/11/2008, 0,          0  28/11/2008, 0,          0 29/11/2008, 0,          0 30/11/2008, 1,          5   The SQL query that would normally produce this:  select count(*), sum(OrderAmount)     from Orders     where OrderDate>getdate()-7     group by datepart(day,OrderDate)   Has a problem in that it will skip the days where there are no orders:  Day,        OrderCount, OrderAmount 25/11/2008, 2,          12 30/11/2008, 1,          5   Normally I would fix this using a tally table and outer join against rows there, but I'm really looking for a simpler or more efficient solution for this. It seems like such a common requirement for a report query that some elegant solution should be available for this already.   So: 1. Can this result be obtain from a simple query without using tally tables?  and 2. If no, can we create this tally table (reliably) on the fly (I can create a tally table using CTE but recursion stack limits me to 100 rows)?


Is it possible to have back references after each chapter with a single main.bib file?

I'm using LaTeX + BibTeX to write my dissertation. I have one separate .tex file for each chapter. And I'll generate one bibliography for each chapter. But all the references are from the same file (main.bib).   So, there are many situations in which different chapters will cite the same reference. Thus, one reference can appear more than once in the bibliographies of the whole dissertation (but in different chapters). I'd like to use back references from the . I'm just wondering whether it would be possible to do so?  % chapter 1 Bibliography [1]. A and B, Nature, 1991. 15, 20. ...  % chapter 2 Bibliography ... [3]. A and B, Nature, 1991. 55, 67. ...


Migrate from Local to Domain login - Win7Pro

I have a desktop computer that I just upgraded from Win7 HomePrem to Win7 Pro.  I have added a Win2008 server to the environment, and I would like to start logging in to my desktop with a domain credential.  Is there a clean way to do this without losing my profile & settings?


Fill with @row_number based on group field in QGIS 3

Is there a way to fill the table with a row number so that count will restart as new group (identified by a separate column) starts? As a result, "row number" column will restart the count when the new attribute value for a group is found, and will produce row number (1,2,3 etc.) record within this group.  seems to answer my question, but SQL in QGIS does not allow such statements (DENSE_RANK) (or it does but I don't know how?).


Time travel short story told entirely as a monologue

I was recently reminded of sci-fi short story which I read quite some time ago (several decades, possibly) which was entirely a monologue.  The narrator is talking to two professors and it's revealed that they stole something technical from him.  Either the secret to time travel directly or something that could be extended into time travel.  During the story it becomes clear that the narrator has learned to manipulate time travel to such an extent that he was able to alter events so that he could not only win over his rivals, but in such a way that they'd be psychologically identical, so he could gloat over their downfall.  The resolution, according to my memory, was the narrator had taken over the religious order the rivals had created, and done so in such a way that the rivals were now seen as heretics and the story ends with the populace showing up with torches and pitchforks to take down the rivals.


How do I read / convert an InputStream into a String in Java?

If you have a java.io.InputStream object, how should you process that object and produce a String?    Suppose I have an InputStream that contains text data, and I want to convert it to a String, so for example I can write that to a log file.  What is the easiest way to take the InputStream and convert it to a String?  public String convertStreamToString(InputStream is) {     // ??? }


Do the destination tickets in Ticket To Ride require that the player completes the routes, or only that the tickets are completed?

In other words, if the two cities are connected, is that sufficient for gaining the points on the destination ticket, or does the holder of the destination ticket have to connect the two cities using his own trains?  I have read over the official rules but it does not seem to be explicit about it.  I would appreciate a citation for answers if possible.


Mock a service while running a BrowserTest?

I am trying to test the output of a controller that returns some information in a given page. This controller has a custom http client injected into it.  I want to create a BrowserTest that can navigate to a fake node, and then test for certain text or values. I also want to change the mock to return different values, so I can further test the output to account for those cases.  I tried:      $client = $this->getMockBuilder('\Drupal\mymodule\Client\AuthorizeClient')       ->disableOriginalConstructor()       ->getMock();     $client->expects($this->any())       ->method('request')       ->with('w12345', FALSE)       ->willReturn([]);      $this->container->set('mymodule.auth_client', $client);   But I get errors in the test that refer to the original class, and not the one I am trying to replace. I looked around in the core but wasn't really able to find what I was looking for. Does it make sense to do this? Is there a way to do a Kernel test to test responses from the route in question?


How can I use expect to send a password to an ssh connection.  say the password was p@ssword and the ssh command was ssh me@127.0.0.1  What would I do with expect to a make it input the password when it says  me@127.0.0.1's password: ?  The proper action of using an SSH key pair isn't an option because I would have to use ssh (scp) to put the key on the server, which would ask for a password.


Relationship between R2 and correlation coefficient

in simple linear regression  R-squared is equal to the squared correlation coefficient between the actual y and the predicted y (i.e. 𝑦 hat )  how to prove this relationship?  Thanks!


Is chi-squared necessary if comparing entire populations?

I'm using 2010 Census data on race, which contains (to the best of their ability), the complete population of the U.S. rather than just a sample.  I've divided the U.S. up into four geographic areas based on fire risk, and then calculated the ratio between the population of each race within an area and the entire U.S. population of that race (e.g. 20% of the U.S. White population and 7% of the Asian population lives in Area A).  Initially, I wanted to compare these ratios in each area and see if there were significant differences between them and their expected values. This would help test my hypothesis that certain racial groups live disproportionately in areas with higher fire risk.  An example: if 15% of the U.S. population lives in Area A, we would expect 15% of Race A and 15% of Race B to live there. If 25% of Race B lives there, and that is significantly greater than the expected 15%, that might mean Race B lives disproportionately in Area A.   The problem is that because these are proportions of populations in the whole U.S., not just in the area of interest, the predicted %'s don't add to 1. So chi-square wouldn't work.  My question: is chi-square even necessary? These are counts of the entire population, not a sample, so there isn't any random sampling variation that could account for the differences. The differences are true.


Let's take take a look at the oath of the Night's Watch from Game of Thrones:  "Night gathers, and now my watch begins. It shall not end until my death. I shall take no wife, hold no lands, father no children. I shall wear no crowns and win no glory. I shall live and die at my post. I am the sword in the darkness. I am the watcher on the walls. I am the shield that guards the realms of men. I pledge my life and honor to the Night's Watch, for this night and all the nights to come." ―The Night's Watch oath  But as of S06E02   Now that Jon Snow has died, his watch has ended.  But apparently he's breathing again.  So how much of this makes sense to still be binding? Is he technically free from his oath now? Does the "until my death" part contradict the "and all the nights to come" part?


How general is the Lagrangian quantization approach to field theory?

It is an usual practice that any quantum field theory starts with a suitable Lagrangian density. It has been proved enormously successful. I understand, it automatically ensures valuable symmetries of physics to be preserved. But nevertheless the question about the generality of this approach keeps coming to my mind. My question is how one can be sure that this approach has to be always right and fruitful. Isn't it possible, at least from the mathematical point of view that a future theory of physics does not subscribe to this approach?


How would I smooth a 90 degree pipe angle?

I would like to smooth out this pipe. I know that I should have made it out of a curve. Is there any way to smooth the pipe?


I've reached the reputation cap 1 hour ago (200), but a minute ago I received an upvote for an answer which is not an accepted one and now I have 210. Is this a bug or the rep cap was changed recently?


Prevent GNU screen from terminating session once executed script ends

I'm trying to force GNU screen to create a "virtual" terminal, without attaching to it, execute script inside and NOT terminate session once script ends.  I tried many combinations, including:  screen -dmS udplistener /share/Sys/autorun/start_udp_listeners.sh   or  screen -S udplistener -X /share/Sys/autorun/start_udp_listeners.sh   and none of them worked. I either get session without executed script, script executes, but session is terminated once it finishes or I'm getting "No screen session found" error.  What I'm basically trying to do is to run UDP listener, written in PHP and make it work in infinte loop (don't break listening). Yes -- I could run PHP script with & at the end, forcing PHP CLI to run as daemon. The problem is, that I'm using a piece of junk called server (QNAP -- never, ever buy this junk!) which does seems to be ignoring this. As soon as I logoff SSH session, scripts stops.  So screen seems to be the only option. But I can't understand, why it terminates session once executed command or script ends?  EDIT: I've also tried example found in the Internet:  screen -dmS name screen -S name -p windowname -X stuff 'mc '   No lack! After attaching to it (screen -R name) I see that Midnight Commander HASN'T been executed. Though example author said, it will be.


I wanted to add a list and some code:    the list sometimes becomes bold on editing, but I wrote it correctly. I don't know what to do with code at all because its parser doesn't work properly


As made clear in update 3 on , this notation: var hash = {}; hash[X]  does not actually hash the object X; it actually just converts X to a string (via .toString() if it's an object, or some other built-in conversions for various primitive types) and then looks that string up, without hashing it, in "hash". Object equality is also not checked - if two different objects have the same string conversion, they will just overwrite each other. Given this - are there any efficient implementations of hashmaps in JavaScript? (For example, the second Google result of  yields an implementation which is O(n) for any operation. Various other results ignore the fact that different objects with equivalent string representations overwrite each other.


Are there Race/Alignment restrictions for classes in the PHB?

I'm looking through the PHB and I notice that none of the Classes explicitly state an Alignment or Race limitation.  There is flavor text, but there is nothing that looks like a rule. I see some stuff scattered around, e.g., Alignments lists Paladins under Lawful Good. This seems like an actual rule since it doesn't say "Many Paladins" or "Most Paladins" but very definitively "Paladins". I know that Paladins are Lawful Good in older revisions, but assuming I knew nothing about D&D, is there a definitive (RAW) grid somewhere in the PHB or supplemental documentation?  Or is a Neutral Good Tiefling Rogue perfectly acceptable?


Images don't show after eclipse project export as jar

Help please, I am new to programming and have built a little tennis app. The game works when i run it through eclipse, however, when I export it as a jar the images don't show. I have a class just for the images with a static method.  public static Image getImage(String fileName){     Image img = null;     File file = new File(fileName);     try {         img = ImageIO.read(file);     } catch (IOException e) {         e.printStackTrace();     }      return img;      }   My folder structure is like this.    The get image is called from various classes. Below is an example of how its called.  public Ball(double x, double y){     super(x,y,BALL_DIAMETER, BALL_DIAMETER);     this.x = x;     this.y = y;     //Get the image.     imgBall = Images.getImage("src/resources/ball.png"); }//End of constructor   Thanks for any help much appreciated   I have tried this in the image class but it didn't work.  public static Image getImage(String fileName){     Image img = null;     URL url = Images.class.getResource(fileName);     try {         img = ImageIO.read(url);     } catch (IOException e) {         e.printStackTrace();     }      return img;      }


how can I download Ubuntu and also keep all my files saved to my laptop at the same time? I have a bunch of apps that I don't want to get deleted and I've already downloaded the iOS on my USB and before I do anything I need to know how I can download it without anything getting removed.


A Regular Tetrahedron is a cool Polyhedron.

A regular tetrahedron has this property:  For any two of its vertices exists a third vertex, which forms a regular triangle with these 2 vertices.(It doesn't necessarily have to be a face of it).  Are there any other polyhedrons that have the same property?  I think there isn't such a polyhedron. But not sure how to prove it. I've tried proving that there isn't an irregular tetrahedron with this property, assuming that there is a pair of unequal sides.   Current answers are a little confused with the conditions of the problem.


How do I get on a Minecraft PE server when it says 'invalid name'?

I am having trouble getting onto a server in Minecraft PE on iOS. When I tap on the person's server it just says invalid name:    I have tried turning off and restarting the iPad, going to home screen and logging back into the server but I have had no luck and no change. Is there a reason why this is so?


Sorting the list of dictionaries in descending order of a particular key

I have a list of dictionaries in python, for example  [{'a':3, 'b':4, 'c':5, 'd':'6'}, {'a':1, 'b':2, 'c':7, 'd':'9'}]   I want to sort it based on the value of 'c' in descending order. I tried using sorted() method using key = lambda but no help.  Any ideas??


Command works on terminal but doesn't work in cron

I have the following command that I can run from any folder and it will start my (Angularjs) webapp by using the grunt task runner tool -  cd /root/dev/myapp && grunt serve   However when I put it in cron it doesn't work -  */1 * * * * cd /root/dev/myapp && grunt serve   Any ideas on why it is not working?


Prove about eigenvectors and eigenvalues

Prove that if $\lambda$ and $\mu$ are different eigenvalues of $f$ and $v$ and $w$ are eigenvectors asociated with them respectively, then $v + w$ is not an eigenvector of $f$.  What could be the statement to prove it?  Thanks in advance.


Is there a POSIX shell alternative to read -e?

How can I achieve the effects of read -e (which turns on line editing via readline and is available in bash) from a general (POSIX) shell? I don’t want to lose POSIX compatibility just because of this one command.


What does accepting an answer actually convey (2015 edition)?

From time immemorial, prominent placement for accepted answers has been baked into Stack Exchange.  The reason is that, by accepting an answer, the OP is saying "I did that and it worked for me; I don't need any more help".  That signal is valuable.  So we pin that answer to the top of the list, so viewers will see it first.  (Except for self-answers, because of concerns over gaming the system.) There have been lots of meta posts about whether this pinning is actually a good idea when there are other, higher-voted answers.  No really, lots.  For example:     (see links there to several more)         This cluster of problems has been  and probably others on the team.  Discussions of moving the accepted answer are controversial, even if we provide . All of this raises what, to me, seems a more basic question that we ought to answer first: what does it actually mean, today, and in practice rather than in theory, when somebody accepts an answer?  'Cause that's the signal that we'd be disrupting if we change how pinning works. I'm dubious about the theory, in two ways:  On many sites that weren't even a glimmer in Joel's eye when he launched Stack Overflow, answers aren't actually testable or verifiable.  I think that sometimes people pick answers that worked for them in some fuzzy way, and other times they pick answers that they like for their own reasons.  Subjective-leaning sites can be especially prone to this (as ).  On the parts of the network I frequent, people still answer questions that already have accepted answers.  (I had been under the impression that this doesn't much happen on SO, but I was wrong.  More on that in a bit.)  So the fact that the original asker has been helped might not mean much to the community, which is supposed to address the question for future readers too.   I don't know how to systematically investigate my first point, but we can science the second one.  I used  (h/t msh210) to answer the question: how often do questions with accepted answers get new answers?  (The query reports separately on positively-scored new answers, but this isn't a big difference on most of the sites I tested.)  Deleted answers don't count in this query. I ran the query on the top five sites by number of questions and a smattering of other non-tiny sites.  I was surprised by what I found:  Approximately half of the questions with accepted answers got newer answers on: Stack Overflow, Mathematics, Ask Ubuntu, English Language & Usage, Emacs, and Chemistry.  Approximately one-third of the questions with accepted answers got newer answers on: Super User, Server Fault, Programmers, Mi Yodeya, and Skeptics.  I didn't find any in my sample with drastically higher or lower proportions.   That's a lot of answering for questions that the OP said he's done with. So, to restate the question: What signal do we intend acceptance to deliver?  What are people who see the pinned answer with the green check mark expected to do with that information?  How should it modify behavior?  Here's the data I collected: Site            Qs w/accept     w/newer A       A upvoted SO              5891756         2860654         2277478 Super User      131019          47618           36618 Server Fault    107697          34887           27483 Mathematics     279096          169396          150686 Ask Ubuntu      70594           35399           27346 English         34726           17995           15557 Programmers     27608           9788            8740 Mi Yodeya       6342            2532            2362 Chemistry       5197            2529            2331 Skeptics        3116            945             871 Emacs           2787            1586            1450


i am using ubuntu12.04,unable to install tools and packages showing error

Reading package lists... Done Building dependency tree        Reading state information... Done Package ninja is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  deepak@ubuntu:~$ sudo apt-get install cscope Reading package lists... Done Building dependency tree        Reading state information... Done Package cscope is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source


All my system text on Ubuntu 18.04 has disappeared!

I have run into a weird problem on ubuntu 18.04 on kernel 4.15 (generic). Today, I rebooted my perfectly working system and found that all the text had been replaced by these tiny placeholder rectangles everywhere!  I can't even fiddle with settings because I can't see them. The weird part is that all text in chrome works normally. I have searched a bit and apparently this bug existed for 16.04 and was due to a kernel problem. The solution was to upgrade to a new kernel. I am on the latest ubuntu kernel so I don't really know what to do. Could somebody here help? Update I solved the problem by referring to  somewhere else on this site.  This can be the result of some invalid permissions settings on Font files. You need to set correct permissions for fonts. To fix the permissions of all fonts ending with .ttf or .otf extension use these two commands. find /usr/share/fonts -iname '*.ttf' -type f -exec sudo chmod -v 644 {} \; find /usr/share/fonts -iname '*.otf' -type f -exec sudo chmod -v 644 {} \; Then use this command to re-build font cache sudo fc-cache -r -v This should fix the problem.


Apparently, I shouldn't have spent sleepless night trying to debug an application. I wanted to restart my nginx and discovered that its config file is empty. I don't remember truncating it, but fat fingers and reduced attention probably played their part.  I don't have backup of that config file. I know I should have made it.  Good for me, current nginx daemon is still running. Is there a way to dump its configuration to a config file that it'll understand later?


Meaning of 'sick' in 'Kylie Jenner is showing off the new sick ride in her driveway'

Kylie Jenner is showing off the new sick ride in her driveway, but the new whip is so expensive it has some fans calling for her to give that money to people in need.        Yahoo: Kylie Jenner Shows Off New $3 Million Luxury Car, Fans Upset Pointing Out People Are Starving   I saw this from . I feel the word 'sick' means something good here. I found a definition in :     very informal very impressive, attractive, enjoyable, etc. This word is used mainly by young people.      The hair, make up and outfit is sick! She looks amazing!   (Macmillan Dictionary)   I'm not sure if I understand it correctly. 'Sick' can also mean unpleasant. How can we determine if the speaker means good or unpleasant?


In a Drupal 8 site, I want to add menu items with "no link", I was thinking that nolink is allowed but when I entered this, I got error      Manually entered paths should start with /, ? or #.   Is there a way for adding menu items not clickable without adding "#" because "#" add attribute [data-drupal-link-system-path=""] and [class="is-active"]


Why do two minus signs make a plus sign and is there a corresponding rule for division and multiplication signs?


Prefix figure number for a given section only

My document consists of several chapters. At the end of each chapter there is a section for appendices. What would be the correct way to number figures and tables in the appendices as. For example, Figure 1 in the appendix of chapter three should be numbered as: 3.A1  I have found some  of how to prefix figure numbers for appendices, but not for my special case.


Force exception to be treated by debugger as unhandled exception

I've got a situation where I have a callback from unmanaged code to managed C# code.  The C# code is throwing an exception and if I let it propagate back through the unmanaged code it gets silently ignored. In the callback I'd like to catch the exception and then force it to be treated like an unhandled exception - either breaking in the debugger, or aborting the process if not running under the debugger. What's the best way to handle this?  Or, are there any references to discussions about this issue? (I don't have control over the unmanaged code - it's a Win32 WndProc callback).


How come Ron knew nothing about the Sorting Hat?

In Harry Potter and Philosopher Stone Ron is oblivious about the sorting ceremony same as everyone else.      "How exactly do they sort us into Houses?" he asked Ron.    "Some sort of test I think. Fred said it hurts a lot, but I think he was joking."   While it is understandable that Fred and George would lie to make a good laugh, Ron got the whole bunch of other family members who would have passed the sorting ceremony before - including three elder brothers and his parents. Ron definitely knew about different houses in the school and that he'd probably end up in Griffindor as the rest of his family. Have they never ever discussed the sorting in their family? Have he never bothered to ask (anyone except Fred) of such an important part of being accepted to the school? It's just unbelievable. Especially after we see Ron was actually interested in the matter as he was scared by Fred's interpretation:     "So we've just got to try on the hat!"- Ron whispered to Harry.   "I'll kill Fred, he was going on about wrestling a troll."     Hermione seems not to know either:     No one was talking much except Hermione Granger, who was whispering very fast about all the spells she'd learned and wondering which one she'd need.   That implies that information about the Sorting Hat is not in the Hogwarts, A History - and it's also a very strange omission for such a book.   We could assume it's some sort of a secret and those who were accepted to Hogwarts bound not to tell others, but in Harry Potter and Deathly Hallows Albus seems to know about the Hat already:     ..."But if it matters to you, you'll be able to choose Griffindoe over Slytherin. The Sorting Hat takes your choice into account." - "Really?" - "It did for me," - said Harry.


I can not boot ubuntu installation CD nor installation USB-drive with HP Envy DV6 notebook

Hello two weeks ago I uninstalled windows 10 and installed fedora 23 using a USB drive created by win32diskimager.   My notebook : HP Envy dv6 current OS : fedora 23  Fedora 23 have some bugs with my computer so I decided to give ubuntu a chance.  However I cannot boot from usb or CD/DVD for the installation. I have make some research and changed the boot order I have activated the legacy mode and deactivated the secure boot option but it still does not work.  I have not the option to boot from CD/DVD not from an USB drive in the F9-bootmenu  I have:  HDD EFI BOOT FROM EFI FILES (In this menu my CD or USB is visible)   But I have already installed an OS (fedora 23) with a bootable usb drive on this pc but it doesn't work anymore.  Could you please help me? :)  ps : i'm french, sorry for the mistakes :).


Start a command based application from the GNOME search box

I just installed Firefox 57 on my Ubuntu 17.10 box. Firefox came as an tar.bz2 file, so I extracted it and are able to start Firefox by issuing this command: /path/to/firefox.  Is it possible to start Firefox from the GNOME search box, as I could when I installed older Firefox instances by the use of .deb files?


Lagrangian and Hamiltonian EOM with dissipative force

I am trying to write the Lagrangian and Hamiltonian for the forced Harmonic oscillator before quantizing it to get to the quantum picture. For EOM $$m\ddot{q}+\beta\dot{q}+kq=f(t),$$ I write the Lagrangian  $$ L=\frac{1}{2}m\dot{q}^{2}-\frac{1}{2}kq^{2}+f(t)q$$ with Rayleigh dissipation function as   $$ D=\frac{1}{2}\beta\dot{q}^{2}$$ to put in Lagrangian EOM $$0 = \frac{\mathrm{d}}{\mathrm{d}t} \left ( \frac {\partial L}{\partial \dot{q}_j} \right ) - \frac {\partial L}{\partial q_j} + \frac {\partial D}{\partial \dot{q}_j}. $$  On Legendre transform of $L$, I get $$H=\frac{1}{2m}{p}^{2}+\frac{1}{2}kq^{2}-f(t)q.$$  How do I include the dissipative term to get the correct EOM from the Hamiltonian's EOM?


How to report a possible bug in gij (GNU libgcj) version 5.4.0?

I found some possible bugs in gij (GNU libgcj) version 5.4.0, but I did not know where can I report them to the developer?  My OS: Ubuntu 16.04.6 LTS  gij version:  $ gij -version java version "1.5.0" gij (GNU libgcj) version 5.4.0 20160609  Copyright (C) 2007 Free Software Foundation, Inc. This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


What's wrong with my argument of choice function from infinite family of nonempty sets?

Let $(A_i \mid i \in I)$ be a family of non-empty set. Then $A_i \neq \emptyset$ for all $i \in I$, thus $\exists a_i \in A_i$ for all $i \in I$. We define $f:I \to \bigcup A_i$ by $f(i)=a_i$.   From reading other posts in MSE, I'm sure that my argument is wrong without Axiom of Choice, but I can not understand why it's wrong. The usual answer is that you can not appeal to Existential Instantiation infinite many times. However, I'm unable to understand this explanation under set theory. Maybe the problem is related to underlying logic, with which I'm not familiar.  Please explain me why you can not appeal to Existential Instantiation infinite many times?


Greetings all,  I have a server with two tomcat services (one being run on port 80, the other 8080).   What I'm wanting to achieve is to have two different DNS records for these two ports, so they'll be accessible via:  http://example1/ http://example2/   Instead of  http://example1/ http://example1:8080/   I know this isn't possible using DNS A records, but does anyone know of another solution I could look into?  Thanks,  Andrew


I have ZERO experience at this. The laptop is 10 years old, running Windows 10 Home, and it is slowwwwwwww. I've done all the hdd cleanupa and defrag, but nothing changes.   My question is, if my Grandkids (ages 9 and less) still want to run it for games, am I doomed? Or is there a version of Linux I can install on USb stick that they can play Minecraft and Roblox from?  I'm just barely pc savvy, and know nothing about tech acronyms, so please don't assume I get everything you type unless its somewhat explained.   Thank you


passing and setting variables in a heredoc

I have a script that has to do many different things on many different remote machines.  I thought that a heredoc would work for this, but I am not able to use a variable defined elsewhere in the script and one defined in the heredoc. Here is some code: #!/bin/sh  FOO="foo" ssh some.remote.host << EOF   BAR="bar"   echo "FOO=$FOO"   echo "BAR=$BAR" EOF  This only prints the following:  FOO= BAR=bar  If, however, I quote the EOF line like this: ssh some.remote.host << "EOF" then it only prints the following:  FOO=foo BAR=  Any hints on how I can use both variables inside the heredoc? Thanks.


I'd love to see the approximate number of matches found for a search from the "Search" box. This would be useful to determine the effect of your search terms - did they, or did they not, narrow down the search?  This would be especially useful now that we have the new search operators.


If someone asks how to do XYZ, and you think doing XYZ at all is a Bad Idea™, is it valid to post an answer saying so? You aren't answering the question, but instead, arguing the question's validity.  You could do this in a comment, but I don't think comments carry enough weight on occasion.  For example, I came across this today ; for those not wanting to link away:     I would like to build a wiki based website about professors, so that students can share information and check the reputation of the professor before working for him.   and I really wanted to post an answer that said, "I think this is a very bad idea". (In fact I did anyway, despite awareness that it could get myself flamed.)  Was I wrong? What should I have done instead?


Why do all heavier gases in the atmosphere not settle down to the surface?

Some pollutants heavier than air that are released into the atmosphere include $\text{CO}_2,\text{SO}_2,\text{SO}_3,\text{NO}_2$ etc. Since these gases are heavier than air, Why do they not settle down closer to the surface? By that, I mean why is the concentration of these gases not maximum at sea level?    article has been used as a reference: it is evident that the $\text{CO}_2$ concentration around the 200 HPa band is more than the 800 HPa band in the month of July. Note that this article also does not provide clarity on surface $\text{CO}_2$ levels, it gives data for the 5 km-25 km altitude range.


Proving that closed (and open) balls are convex

Let $X$ be a normed linear space, $x\in X$ and $r>0$. Define the open and closed ball centered at $x$ as  $$ B(x, r) = \{y \in X : \Vert x − y\Vert < r\} $$  $$ \overline{B}(x, r) = \{y \in X : \Vert x − y\Vert \leq r\}. $$ Then $B(x, r)$ and $\overline{B}(x, r)$ are convex.  I tried to prove this, but either my calculation is incorrect, or I am on the wrong path:  I aim to show for the closed ball $\overline{B}(x,r)$ (for open ball I assume the proof is similar). Suppose $y,z \in \overline{B}(x, r)$. Then $\Vert x − y\Vert \leq r$ and $\Vert x − z\Vert \leq r$. We must show that $t \in [0,1]$ implies $ty + (1-t)z \in \overline{B}(x,r)$. But $t \in [0,1]$ implies $$ \Vert ty + (1-t)z - x\Vert = \Vert t(y-z) + z - x\Vert \leq |t| \Vert y-z\Vert + \Vert z-x\Vert \leq |t|(\Vert y-x\Vert + \Vert x-z\Vert) + \Vert z-x\Vert < |t|(2r) + r = r(2|t| + 1), $$ which is not necessarily $\leq r$. We probably wanted to end up with $< |t|r$ or $\leq |t|r$ as our final inequality.  Thanks in advance.


What is the correct word order in this sentence?

I was looking at the title of :     To whom does the Islamic State sell their oil?   and it sounds strange to me. Shouldn't the word order be the following?     Whom does the Islamic State sell their oil to?   Or are both correct? And what is the rule that dictates the correctness?


Prove $A = \{x ∈ X : f(x) ≥ a\}$ has finite measure

Let $(X, \mathcal{A}, \mu)$ be a measurable space. I want to prove that is $f: X \longrightarrow \mathbb{R}$ is measurable, non-negative and its integral on $X$ is finite, then $\forall a>0$ the set $$A = \{x ∈ X : f(x) ≥ a\}$$ is $\mu-$finite (that is, $\mu (A) < \infty$). I think I could use  lemma to prove this statement but I don't really know how to do it. Could someone help me?


I am new to android programming and am trying to draw a circle on the screen. Eventually I'd like to have the circle move around. But for now I have been having trouble getting the circle to draw. When I run the code, it gives me an error:      "Attempt to invoke virtual method 'long   android.graphics.Paint.getNativeInstance()' on a null"   My Code:   package com...  import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View;  public class MainActivity extends AppCompatActivity {      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(new MyView(this));     }      class MyView extends View {        private Bitmap b;         public Paint p;          public MyView(Context context) {             super(context);             Paint p = new Paint();             p.setColor(Color.GREEN);             b = Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888);         }          @Override         protected void onDraw(Canvas canvas) {             canvas.drawCircle(50, 50, 10, p);         }     } }


How do I prove the statement below by the method of mathematical induction?

If $n ∈ N$ and $n \ge 4$ , how do I prove by the method of induction that $n! > n^2$?


How do I force a DIV block to extend to the bottom of a page even if it has no content?

In the markup shown below, I'm trying to get the content div to stretch all the way to the bottom of the page but it's only stretching if there's content to display. The reason I want to do this is so the vertical border still appears down the page even if there isn't any content to display. Here is my DEMO:   body {     font-family: Trebuchet MS, Verdana, MS Sans Serif;     font-size:0.9em;     margin:0;     padding:0; } div#header {     width: 100%;     height: 100px; } #header a {     background-position: 100px 30px;     background: transparent url(site-style-images/sitelogo.jpg) no-repeat fixed 100px 30px;     height: 80px;     display: block; } #header, #menuwrapper {     background-repeat: repeat;     background-image: url(site-style-images/darkblue_background_color.jpg); } #menu #menuwrapper {     height:25px; } div#menuwrapper {     width:100% } #menu, #content {     width:1024px;     margin: 0 auto; } div#menu {     height: 25px;     background-color:#50657a; } <form id="form1">

 </form>


Currently, Stackexchange claims 53 Q&A sites. I count 55, including MSO. I'll grant that MSO ought not to be counted, given that we don't count the other metas. But that still leaves me at 54, not 53. Count for yourself:  (I counted the occurrences of the word 'ago' on the page, I didn't do it manually.)


Centering \section* and adding them to the ToC

I'm using LaTeX and the book class and have one problem:  I want that my starred sections (only starred sections) appear in the center of the pages instead of the left side of the pages and also these sections to be added to the table of contents automatically.


Can I play my PSOne games (previously bought for PS3) on PS Vita ?

I know that exists a retrocompatiblity, but those PSOne games I've own, were bought before PS Vita being released.


What is it all about this usage? would of+verb

We short men are in big trouble because if we want a shoe that feels decent we feel short and you can’t put in lifts, if you get a shoe with lifts it doesn’t feel comfortable I feel really trapped, that why I cannot believe that there is a god because if there was he wouldn’t of don’t this to me and made me only 5.4″ he or it would of made me to be at lease the regular American height which is 5.8” or taller , its a disaster to be short for a male.   The text is written by a native English speaker. It is the first time I face a usage in which would of + verb is used. Is it grammatically correct? What is the meaning of the parts I have shown in bold?


I'm totally new to Ubuntu. I've installed version 16.04 and I'm having trouble finding my way around. I've tried just about all possible ways to make Ubuntu look like windows 7. Every way I tried was missing something, Is there a way to make version 16.04 be like win7?


Experiments used to observe particle spin properties (such as ) rely on a varied magnetic field and a dipole-like reaction in the particle, deflecting it in one direction or another.  In the case of a point-particle such as an electron, how is it explained that a dipole with spatially separated poles exists in a single point?


SFF and Mi Yodeya (and other sites without CSS update) are experiencing odd link colors & Broken User Profile pages

Odd CSS link colors have appeared again on at least some of the sites without the CSS update, specifically including Science Fiction & Fantasy and Mi Yodeya, and likely others.  User profile pages also have broken layouts.  I believe it's related to this previous bug report:    This time, Seasoned Advice is not affected as they've had the CSS redone.


In a follow up to one of the business problem i have discussed here, for one of the logistic regression model, i have 19 predictor variables of     which around 8 are categorical with multiple categories.     Instead of including all in the model where one could correlate to another, i am thinking of using a chi square test of independence at a given p value. With this i would come to realization if there is any correlation among the     categorical predictors.    If so i would include the correlated variables one by one in the model and would used the significant one. I have researched on this on SE where they have suggested to use chi- square but unsure if my approach to drop these correlated var is justified.


Is $ 2^n + n < 2^{(n+1)}$ when $ n > 2 $  How can I prove this? I need it in order to prove a language is context free


Can the set of all functions from $\mathbb{R}$ to $\mathbb{R}$ be defined?

I remember seeing something a long time ago about the inability to define a set of all functions from $\mathbb{R}$ to $\mathbb{R}$. However, I haven't seen a page about there being no restrictions on $f$. I see that the cardinality of the set of all CONTINUOUS functions is $\mid \mathbb{R} \mid$, but what is the paradox I'm thinking about as far as sets of functions goes? Does this problem perhaps arise when we consider the set of all functions from ALL sets $A$ to ALL sets $B$? Can someone give some context on all of these, and what I may be thinking of? It's been quite a while since I've studied this.


When I try the following in racket:   (* 1.1 1.1)   why does it return   1.2100000000000002   instead of  1.21   while   (* 1.2 1.2) ; is 1.44, as expected   Edit  and the following returns false:  (= (* 1.1 1.1) 1.21); #f


How does the compiler/program deduces the size of memory to be deleted(released) in case of delete[] arr;

When using operator new  we explicitly provide the size of memory to be allocated:      int* arr = new int[100];   But when deleting, we just type delete []arr; How does the compiler/program calculates the size of arr, as we provide no information about it to operator delete?


How do I block installing new apps and internet browing on my Android phone?

I'd like to be able to block internet access from my Android Pixel 4 cell phone. The ideal solution would prevent me from installing new apps onto my phone. I'd like to have a set of apps, so that I cannot add new apps, such as web browsers. I tried to set this up with Google Family Link, but it will still let you install apps that are rated E for everyone. I also tried this with AppBlock by blocking the app store, but I can download apps from play.google.com from my computer. I would appreciate any assistance in reaching towards a solution. A potential solution could be one that requires an administrator to have a password to install apps would be acceptable, because I can give that password to someone who isn't me. I'll note that one possible solution would be to stop internet access with my phone plan. But I'd still like to use the internet for apps like Uber, so that wouldn't work. Thanks!


MariaDB fail to start (NO_NEW_PRIVILEGES)

I have a similar problem that here :    But I can't upgrade the kernel (this is a vps).  Does someone have an idea ?


How to solve differential equations of the form $f'(x) = f(x + a)$

What could one do to find analytic solutions for $f'(x) = f(x + a)$ for various values of $a$?  I know that $c_1\sin(x + c_2)$ is solution when $a = \frac{1}{2}\pi$, and of course $c_1e^x$ when $a = 0$.  For instance, is there a function satisfying $f'(x) = f(x + 1)$?  What about negative or imaginary $a$?  Is there possibly a generalization?


Detecting headphone connection/disconnection in Linux

I am trying to detect a signal when a headphone is connected or disconnected from the system.  What is the best way to do this?  If there is a special board with drivers, that will be my preferred way.


In an exercise in Atiyah-Macdonald it asks to prove that the prime spectrum $\operatorname{Spec}(A)$ of a commutative ring $A$ as a topological space $X$ (with the Zariski Topology) is compact.   Now because the basic open sets $X_f = \{\mathfrak{p} \in \operatorname{Spec} (A) : \{f\} \not\subseteq \mathfrak{p} \}$ form a basis for the Zariski Topology it suffices to consider the case when   $$X = \bigcup_{i \in I} X_{f_i}$$   where $I$ is some index set. Then taking the complement on both sides we get that   $$\emptyset = \bigcap_{i \in I} X_{f_i}^c$$  so there is no prime ideal $\mathfrak{p}$ of $A$ such that all the $f_i$'s are in $\mathfrak{p}$. Now from here I am able to show that the ideal generated by the $f_i$'s is the whole ring as follows. Since there is no prime ideal $\mathfrak{p}$ such that all the $f_i \in \mathfrak{p}$, it is clear that there is no $\mathfrak{p}$ such that $(f_i) \subseteq \mathfrak{p}$ for all $i \in I.$ Taking a sum over all the $i$ then gives $$\sum_{i \in I} (f_i) = (1).$$  Now here's the problem:          How do I show from here that there is an equation of the form $1 = \sum_{i \in J} f_ig_i,$ where $g_i \in A$ and $J$ some finite subset of $I$?       This part has been giving me a headache. I am not sure if the finiteness bit has to do with algebra, topology or the fact that we are dealing with prime ideals.  This is not a homework problem but rather for self-study.  $\textbf{Edit:}$ I have posted my answer below after the discussion with Dylan and Pierre.


Find all x for which $\sum_{n=1}^n x^{n^2} n!$ is convergent  So I tried using the ratio test and got $\lim_{n\to \infty} x^{2n+1}(n+1)$ but I don't know how to proceed from that.   I also tried using the root test which gave me $\lim_{n\to \infty} x^{n}(n!)^{1/n}$ which wasn't really helpful either...


I am running Ubuntu 16.04 LTS on an Intel Quad Q9450@ 2.66GHzx4, 64 bit. I am trying to install Ubuntu 16.04.3. Afte downloading the iso file and clickimg it, a series of folders is saved, and there is no executable file or the like. I have also tried burning a dvd within ubuntu of the new os files by right clicking on the iso and burning ot to dvd, however, the dvd contains the same series of files and no executable, and no expanation text. I am new to ubuntu and the cumputer was given to me. How do inStall/upgrade? Thanks


A cashier wants to work five days a week, but he wants to have at least one of Saturday and Sunday off.  How many ways can he choose the days he will work?


In Firefox or Chromium I usectrl+tab (or ctrl+shift+tab) for this function.


Ok so... My friend and i used to walked to school sometimes but we haven't done that recently. I messaged him " we haven't walked in a while " He replied " for a while* " And now we're arguing over it. Which is correct?  Thanks


SQL Qry required to get a comma separated string from a table

In my database there is a table with values below  image attached  In need a qry to get the result like this