When I try to add the button created in an object to the linearLayout, it behaves as if the button is null, even though it has been initialized.  I have tested that the button isnt actually null and that the linear layout is declared correctly, which it is.  The linearLayout goes from being not null in onCreate() to null in getLinearLayout();     public Province(Context context, int id, int x, int y){         this.id = id;         this.x = x;         this.y = y;         button = new Button(context); //creates button, context is passed in through the MainActivity         selected = false;         selection(); //selection call     } //selection method     public Button selection(){         linearLayout = getLinearLayout();  //layout from MainActivity         button.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));         linearLayout.addView(button);  //adds button to current view, button is not null despite error         button.setId(id);         button.setX(x);         button.setY(y);         button.setOnClickListener(new View.OnClickListener() {             public void onClick(View v) {                 if(getCurrentPlayer().getStage() == 0) {                     troops++;                     getCurrentPlayer().modTroops(-1);                 }                 else {                     if (selected)                         selected = false;                     else if (!selected && getCurrentPlayer().select(0) > 0)                         selected = true;                 }             }         });         return button;     }   Here is the code where linearLayout is defined;  @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         linearLayout = findViewById(R.id.linear);  //refrences MainActivity xml with id linear         //linearLayout is not null here;         lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);         map = new Map(this, 0);     }   Here is the get method:  public LinearLayout getLinearLayout(){         if(linearLayout == null)             throw new IllegalArgumentException("Linear Layout is null");         //the exeption is thrown here so linearLayout is now null;         return linearLayout;     }   This is the error that appears:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.addView(android.view.View)' on a null object reference         at com.example.hedgemonics.Province.selection(Province.java:56)         at com.example.hedgemonics.Province.<init>(Province.java:28)         at com.example.hedgemonics.Map.<init>(Map.java:10)         at com.example.hedgemonics.MainActivity.onCreate(MainActivity.java:28)

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


I posted , and it turns out that the problem was due to my own carelessness (kind of like discovering a typo in my code, but not exactly as silly of a mistake).  What should I do with my question in this case?  Should I close it, delete it, or answer it and leave it alone?

A while ago I asked , and got an answer which I upvoted and accepted.  Recently the thread about closing 'typo' questions made me realise that's essentially what my question is - no one else is ever likely to have the same problem. Should I vote to close or delete it? If I do, will the guy who answered lose the 25 rep?


I have two documents file1.tex and file2.tex in two different folds fold1 and fold2, which are in the fold father.  In file1, I defined \label{file1:hello}, how do I use it in file2?

I want to cross-reference between different .tex files, just because I want to put every chapters separately.  Let's say in file chapterI.tex I have \label{a} and I want to access this in file chapterII.tex using something like \ref{a}. How to do this exactly in LaTeX, moreover if LEd have an easy feature to cover this, it will be better (I have put those both files in the same project).  I found another question with similar title, but I just didn't really understand. It's here: .


I am runing my code from anonymous window  HttpRequest req=new HttpRequest(); Http http=new Http(); //Header req.setHeader('Content-Type','text/xml'); req.setHeader('SOAPAction',''); //Body String reqbody='<?xml version="1.0" encoding="utf-8" ?>'+'<env:Envelope xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns'+':xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns'+':env="http://schemas.xmlsoap.org/soap/envelope/">' +'<env:Body>' +'<n1:login xmlns:n1="urn:enterprise.soap.sforce.com">' +'<n1:username>[REDACTED]</n1:username>' +'<n1:password>[REDACTED]</n1:password>' +'</n1:login>'+' </env:Body>' +'</env:Envelope>'; system.debug(reqbody); req.setbody(reqbody); //Method req.setMethod('POST'); //Endpoint req.setEndpoint('https://login.salesforce.com/services/Soap/c/44.0'); //Request Sent HttpResponse res=http.send(req);  System.debug(res);

Im trying to get the session ID of another user in the same org by sending the following request by using the data from my enterprise wsdl and its an developer edition.  <?xml version="1.0" encoding="UTF-8"?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:enterprise.soap.sforce.com">    <soapenv:Header>       <urn:organizationId>xxxxxxx</urn:organizationId>    </soapenv:Header>    <soapenv:Body>       <urn:login>          <urn:username>xxxxxxxxx</urn:username>          <urn:password>xxxxxxxxx</urn:password>       </urn:login>    </soapenv:Body> </soapenv:Envelope>   But when i send this request i get      Missing SOAP ACTION header  but in my wsdl i dont have the action ,its blank    how to overcome this problem ?I got totaly struck over here since there is no action though its asking for action header.Following method handles the http request.   public string   processrrequest(string ep,string message,string method) {      HttpRequest req = new HttpRequest();     req.setEndpoint(ep);     req.setMethod(method);     req.setHeader('Content-Type', 'text/xml');     req.setHeader('SOAPAction','');     req.setBody(message);     system.debug('Request::'+req.getbody());     Http http = new Http();     HttpResponse res =http.send(req);     //Dom.Document doc  = res.getbodyDocument();     system.debug('Response::'+res.getbody());     system.debug('Response2::'+res.getStatus());     Dom.Document doc= new Dom.Document();     doc=res.getBodyDocument();     system.debug('doc::'+doc);     return 'hai'; }


The natural way (and I think, the easier) to solve $$\lim_{n\to \infty}\left(\frac{1}{n+1}+\frac{1}{n+2}+\cdots+\frac{1}{n+n}\right)$$  involves Riemann sums. Multiplying and dividing by $n$, we get  $$\lim_{n\to \infty}\left(\frac{1}{n+1}+\frac{1}{n+2}+\cdots+\frac{1}{n+n}\right)=\frac{1}{n}\sum_{i=1}^{n}\frac{n}{n+i}=\frac{1}{n}\sum_{i=1}^nf\left(\frac{i}{n}\right)$$  where $f(x)=\frac{1}{1+x}$. The last expression is a Riemann sum associated to the partition $P_n=\{0, \frac{1}{n},\dots,\frac{n}{n}\}$ of $[0,1]$, so by Darboux Theorem  $$\lim_{n\to \infty}\frac{1}{n}\sum_{i=1}^nf\left(\frac{i}{n}\right)=\int_0^1\frac{1}{1+x}dx=\ln2$$  However, I'm curious if there are other techniques that can be used to find that limit, so my question is      Is it possible to find $$\lim_{n\to \infty}\left(\frac{1}{n+1}+\frac{1}{n+2}+\cdots+\frac{1}{n+n}\right)$$ without using Riemann sums? If so, how?

What is the sum of the 'second half' of the harmonic series?  $$\lim_{k\to\infty}\sum\limits_{n=k+1}^{2k}{\frac{1}{n}} =~ ?$$  More precisely, what is the limit of the above sequence of partial sums?


If W₁ ⊆ W₂ ⊆ W₃......, where Wᵢ are the subspaces of a vector space V, and W = W₁ ∪ W₂ ∪......  Prove that W ≤ V.  So I proved that: If W₁ and W₂ are two subspaces of V and W₁ ∪ W₂ ≤ V then W₁ ⊆ W₂ or W₂ ⊆ W₁. (I let u ∈ W₁ - W₂ and v ∈ W₂ - W₁ and it was trivial)  Now I don't know how to use this to prove the problem. I'm getting confused. Maybe I don't have to use induction?

Let be $ V $ vector space :   a) If we have an infinite chain of subspaces $ {U}_{1}\mathrm{\subseteq}{U}_{2}\mathrm{\subseteq} $  Show that $ {U}\mathrm{{=}}\mathop{\mathrm{\cup}}\limits_{{k}\mathrm{{=}}{1}}\limits^{\mathrm{\infty}}{U}_{K} $  is a subspace .   b) if  $ V $ is finite dimensional show that there is a some subspace ,call it  $ {U}_{P} $ ,such that $ {U}\mathrm{{=}}{U}_{p} $   and hence $ {U}_{P}\mathrm{{=}}{U}_{{P}\mathrm{{+}}{1}}\mathrm{{=}}{\mathrm{....}} $


Im trying to do a first person animation of unsheathing a sword, i have child of constraint on the sheath with the actual sword as the target, and the actual sword has a child of constraint and target set to the hand bone so that it all moves together. The start is fine but as soon as i try to unsheathe the sword in the animation, after i move the timeline, it clips back. Is it possible for me to remove the child of constraint in the middle of the animation meanwhile keeping its position and rotation ( i tried deleting the constraint after doing the beginning animation but it just reset's its position elsewhere) I can provide any other asked information if needed. Thanks!

I had a sword object rigged with a single bone, with a ChildOf constraint making it a child of a sheath (with an influence of 1). Throughout an animation i move the sheath, and the sword bone follows as expected.  However, i cant seem to lower the influence of the sheath to zero and still have the sword retain the position it was just at, and I am wondering how i should go about making this happen.  Thanks for your time.


I have a JSON Array that looks like this  [{'age':1, 'name':'james'}, {'age':3, 'name':'henry'}, {'age':10, 'name':'andrew'}]   is it possible to order this by the age of the people so that it goes like this  [{'age':10, 'name':'andrew'}, {'age':3, 'name':'henry'}, {'age':1, 'name':'james'}]   Thanks for the help

I have a list of dictionaries and want each item to be sorted by a specific value. Take into consideration the list: [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]  When sorted by name, it should become: [{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]


As a kid in 1993-1994, I watched some kind of Sci-Fi TV series about a guy who was turned into a machine. Or at least half of him was entirely a machine and the other was human, split vertically. I remember there was some kind of conflict between machines or a machine-like race and the protagonists of this series, which ended up with him turning into a half machine. Also, I remember the woman that loved that guy when saw him turned into a half robot/half man was shocked but touched his human side on a cheek and cried or something like that. It was a dramatic scene which was memorable. I don't remember anything else beside that and that the whole setting of series was on some kind of starship.   Also, not sure but I think series was produced by Disney, although I might be mistaken. And I think it was a miniseries, as the entire show was 6 episodes, each 45-60 minutes long.

When I was a kid we had a VHS tape of some Disney live action (not animated) sci-fi movie. It may have been a mini-series or a made-for-tv movie, but I'm not sure. I'm also not sure about the year but it would probably have been late 80s or early 90s based on when I would have seen it. I know it was Disney because they had some live action Goofy and Mickey running around the movie's set as an introduction discussing the plot with a host before the movie.  The plot is basically as follows:   A starship is loaded with mostly children and teenagers as a cross-galaxy human settling effort. Accidents (which are not really accidents and later revealed) cause adult crew members to be killed.  They travel to another planet and face all sorts of troubles. It arrives at the new planet after overcoming obstacles.   Other memorable scenes that may help:   Navigating out of earth's asteroid belt made out of space junk. One of the adults was killed via an airlock malfunction. The ship was supposed to be peaceful with no weapons. At one point they bring on board some crazy guy who puts together a rail gun. There's a memorable line like "Do you want no weapons at all or a well aimed rock?"  There's a planet or space station (I can't remember which) that has a fight scene with the evil bad guy. This scene takes place on what looks to be a carnival or fairground. The bad guys are trying to steal the ship the kids are on because it has some kind of really good futuristic space drive.   Hopefully you remember it better than I do! I've tried looking online for it before with no luck.


Obviously closed subspaces turn quotient spaces into normed spaces rather than just merely vector spaces. However the dimension involved in Freholm's index are purely algebraic.  Why do we thus require the range to be closed? Or is a subspace with finite codimension necessarily closed?  Moreover, what could happen if the range wouldn't be closed but would be of finite codimension though?  I'm thinking of some example like: $l^p_0\subsetneq l^p,1\leq p\leq\infty$

$X,Y$ are Banach spaces and $A\in B(X,Y)$ is a Fredholm operator (that is, the dimensions of ker($A$) and coker($A$) are both finite), then are closed linear subspaces ker($A$) and Im($A$) complemented? (A closed linear subspace $H$ in a Banach space $Z$ is called complemented iff there is a closed linear subspace $G$ such that $H+G=Z$ and $H \cap G=0$)


I follow the upgrade guide here   apt-get update apt-get dist-upgrade   to perform the kernel-level patches to Ubuntu 14.04LTS   However, I don't know how to check if the patches are successfully applied or not.  Is there a way to check and certify the patches?

The current Meltdown Intel processor vulnerability is currently remedied by having the page table isolation enabled. There is a question how to turn this off:   My question is opposite: is there a way to check on a running system whether the PTI mechanism is effective on the system and thus the system is protected? I'm specifically looking for cat /proc/something or cat /sys/something, not checking for kernel version or config parameter or the like.


How to start my id column from 1 ?  My tabel is :   id |   origin    | destination | duration ----+-------------+-------------+----------   6 | Paris       | New York    | 540   7 | Tokyo       | Shanghai    | 185   8 | Seoul       | Mexico City | 825   9 | Mexico City | Lima        | 350  10 | Hong Kong   | Shanghai    | 130   Here id is my SERIAL KEY and PRIMARY KEY.  And I am using PostgreSQL.

I ran into the problem that my primary key sequence is not in sync with my table rows.   That is, when I insert a new row I get a duplicate key error because the sequence implied in the serial datatype returns a number that already exists.  It seems to be caused by import/restores not maintaining the sequence properly.


I want to perform automatic backups of a specific folder, F, in my home directory. To prevent malicious software from removing backups in the repository, however, I have created another user whose sole purpose it is to regularly perform these backups. It has the authority over the repository and obviously needs full read access to F. However, this turned out to be harder than I thought:  Using setfacl to  for F works for existing and new files, but seems to fail for files that are copied or moved to the folder. This is obviously not a sensible solution for a folder that is subject to frequent changes. Using bindfs with --force-user=backup and -p 0000:u=rD as root to automatically mount F at a location that the backup user has acces to works in principle, but leads to falsified owner and permission information. The backup software will adopt these forced values and fail to restore the actual metadata. This is obviously not an option either.  Is it possible to mount the folder in such a way that the backup user has read-only access to all files contained in F, but that the metadata remain unaltered? Please note that it would be nice to even get access to the files that my main user does not currently have access to. Or more specifically: If I use the -r option that bindfs offers, can I somehow tell Linux to completely ignore ACLs when my backup user tries to access any file within F?

I am new to system administration and I have a permission related query. I have a group called administration. Inside the administration group, I have the users user1, user2, user3, superuser. All the users are in the administration group. Now, I need to give permissions to the user superuser to be able to view the /home directory of the other users. However, I do not want user1, user2, user3 to see the home of any other user other than himself. (That is, user1 should be able to see only user1's home and so on).   I have created the users and groups and assigned all the users to the group. How should I specify the permissions for the superuser now?   In other words, I'm thinking of having two groups (say NormalUsers and Superuser). The NormalUsers group will have the users user1, user2 and user3. The Superuser group will only have the user Superuser. Now, I need the Superuser to have full access on the files of users in the group NormalUsers. Is this possible in Linux?


I have a 3p12s 18650 Li-ion battery pack that I use for my e-bike. I charge it with a balance charger. I know that charging with too high current is bad for battery life. But is it "the lower the better"? If not, is there any recommended minimal charging current? Is charging at 0.1 C safe? My only goal is to prolong the battery life (number of cycles). I charge it only at night so I don't care about it taking long time.  In the data sheet of the cells I use (Sony US18650V3) there is only specified maximum charge current 1 C. It says nothing about minimum charge current. What's more, I've never seen any batteries data sheet mentioning "minimum charge current".

I need a rechargeable battery pack for my project, I need to know what is the minimum charging current for NCR18650 li-ion battery?  In the datasheet, it says max charge current is 2A. what is the minimum charge current?  I use tp4056 module for charging, I can change the charging current   is 300mA to 600mA ok for charge current? will it damage the battery or affect badly for a battery lifetime?  Delaying in charging time is not a problem for my application .


I want to change in the table of contents the look of the parts. I reproduced on Word what I want :     I've looked into the site if the question was already answered but I didn't found what I want.   All I want is to center the part name in the TOC and also get rid of the page number. I am using the book class and I don't want to use other document classes.   Thank you.   EDIT. Here is my MWE :   \documentclass{book} \begin{document} \tableofcontents \part{First part} \chapter{A first chapter} \chapter{A second one} \part{Second part} \chapter{A third one} \chapter{The last one} \end{document}   Here is my preambule with titlesec :  \documentclass{book}  %Redifining paragraph spacing and thus spacing in the TOC \usepackage{titlesec} \usepackage{parskip} \setlength{\parskip}{ 0.4\baselineskip} \titlespacing\section{0pt}{9pt plus 4pt minus 2pt}{5pt plus 2pt minus 2pt} \titlespacing\subsection{0pt}{9pt plus 4pt minus 2pt}{2pt plus 2pt minus  2pt} \titlespacing\subsubsection{0pt}{9pt plus 4pt minus 2pt}{2pt plus 2pt minus 2pt} \setlength\parindent{0pt}  % Here the code of Christian Hupfer \usepackage{tocloft} \renewcommand\cftpartpresnum{\hfill} \renewcommand\cftpartleader{\hfill}  \begin{document} \tableofcontents \part{First part} \chapter{A first chapter} \chapter{A second one} \part{Second part} \chapter{A third one} \chapter{The last one} \end{document}

I'm trying to create a toc in a large Latex document which uses the KOMA script.  In the toc I would like to center the parts and remove all other components (pagenumber, partnumber). I use tocloft (a hard requirement for other reasons).  While I managed to remove the pagenumber, the partnumber is still there and the parts are very much on the right site instead of being centered.  A simplified example is:  \documentclass{scrbook} \usepackage[ngerman]{babel}  \usepackage{lipsum}  \usepackage{tocloft} \renewcommand{\cftpartfont}{\hfill\Large\bfseries} \renewcommand{\cftpartaftersnum}{\hfill} \addtocontents{toc}{\cftpagenumbersoff{part}}  \begin{document} \tableofcontents \part{A} \section{a} \lipsum \part{B} \section{b} \lipsum  \end{document}   I have adapted the commands for the centering from an example of the tocloft manual, where      \renewcommand{\cftZtitlefont}{\hfill\Large\bfseries} together with   \renewcommand{\cftafterZtitle}{\hfill} will give a centered Large   bold title.   was used to center the title (instead of the parts).   So my question, how can I center the parts and remove the partnumber?


I have just seen an approval for a Suggested Edit that takes the cake, and makes me wonder exactly how much attention some people are paying to what they do.  In  the editor changed the word auction to action. As far as I can see this edit was incorrect, however by the time I rejected it and typed an explanatory rejection message it had been approved.   So we have at least two people who don't pay attention to what they are approving. What can we do to stop this sort of thing happening? Note that this is not the most egregious example I've seen, but enough is enough - crap edit approvals don't make the site a better place (I've rolled back this edit).

A worryingly high number of bad suggested edits get accepted. For example:             (These are just examples of a few common patterns. The  exists too.)  What can we do to educate reviewers to do a better job?  This is an open question, not a feature request, because I don't have a good answer. Some possibilities:   Provide a way to notify the reviewers (“hey, check that proposed tag wikis aren't plagiarised”). Make the workflow for approval as long as the workflow for rejection, so that people don't blindly approve just because it's less work. (I don't know if some reviewers tend to do that.)


Here's an expression I am struggling to evaluate: $$\LARGE   {\sqrt{2}^{\sqrt{2}^{\sqrt{2}^{\:\cdot^{\:\cdot^{\:\cdot}}}}}} $$  The value turns out be $2$, but I don't understand how do we get it. Can anyone give the solution?  EDIT: The original problem is as follows:   If $y(x)= { x }^{ { x }^{ { x }^{ { x }^{.  } } } }$, then evaluate $y(\sqrt { 2 })$.

Find $x$ in   $$ \Large 2 = x^{x^{x^{\:\cdot^{\:\cdot^{\:\cdot}}}}}$$   A trick to solve this is to see that $$\large 2 = x^{x^{x^{\:\cdot^{\:\cdot^{\:\cdot}}}}} \quad\implies\quad 2 = x^{\Big(x^{x^{x^{\:\cdot^{\:\cdot^{\:\cdot}}}}}\Big)} = x^2 \quad\implies\quad x = \pm \sqrt{2} $$  Are these solutions correct? If not, why? If yes, are there other solutions?    PS: An extension of this discussion can be found in


I know that the series b. converges as $\sum \frac{1}{n^p}$ converges for $p>1$, So a. also converges. I want to know the sum.          a.$1+\frac{1}{9}+\frac{1}{25}+\frac{1}{49}+.....$          $b.1+\frac{1}{4}+\frac{1}{9}+\frac{1}{16}+.....$

As I have heard people did not trust Euler when he first discovered the formula (solution of the ) $$\zeta(2)=\sum_{k=1}^\infty \frac{1}{k^2}=\frac{\pi^2}{6}.$$ However, Euler was Euler and he gave other proofs.   I believe many of you know some nice proofs of this, can you please share it with us?


Given a Subset $S$ (not necessarily a subspace) of a vector space $V$, $\operatorname{Span}(S)$ indicate the smallest subspace containing  $S$. I need a hint to solve the problem   $$\operatorname{Span}(\operatorname{Span}(S)) = \operatorname{Span}(S)$$

My definition of span:   Suppose a vector space $(V,+,\cdot)$, and       $$S = \{u_1,\cdots,u_n\}$$      (and $S$ is a subset of $V$, not a subspace)      $$[S]=:\bigcap_{W\subset V, W\supseteq S} W$$      In other words, $[S]$ is, by definition, the intersection of all $W$,   such that $W$ is a subspace of $V$ and $W$ contains $S$.   Well, then I need to prove that   $$[S] = [[S]]$$  My strategy:  $[[S]]$ means the intersection of all subspaces that contain $[S]$. If all the subspaces contains $[S]$, so does their intersection. Therefore, $[S]\subset[[S]]$  However, I'm having trouble proving the converse:  $$[[S]]\subset[S]$$  Any hints?


In C++ language is there any disadvantage to declare a variable global?   void foo() {   int a;   a=10; }  int a; void foo() {   a=10; }   Any differences between them?

In C/C++, are global variables as bad as my professor thinks they are?


Recently, I want to transfer some files and folders from my Windows computer to the VirtualBox. However, I just find that the function of copy and paste is not working, but I am sure that I have enabled this function on my computer. I don't know why. This problem has caused a lot of troubles for me. It is very inconvenient for me to work between my Windows computer and the VirtualBox. What can I do to solve this question?

Where is the configuration option for sharing clipboards (copy & paste) between the host OS and the guest OS?


I have a UITextField. I'd like to restrict the maximum allowed input value in the field to be 10.  That is, when the user is inputting the number inside, once the input value is larger than 10, the value in the input field won't be updated anymore unless the user is inputting a value less than or equal to 10.

How can I set the maximum amount of characters in a UITextField on the iPhone SDK when I load up a UIView?


If $x,y \in \mathbb{R}.$ Then the equation $3x^4-2(19y+8)x^2+361y^2+2(100+y^4)+64=2(190y+2y^2)$ represent in rectangular cartesian system  Options  $(a)$ Circle   $\;\;\;\;\;(b)$ Parabola $\;\;\;\;\;\; (c)$ Ellipse $\;\;(d)$ Hyperbola  Try:  From $$3x^4-2(19y+8)x^2++2y^4+357y^2-380y+264=0$$ For real roots, its discriminant always $\geq 0$ $$4(19y+8)^2-4\cdot 3 \cdot (2y^4+357y^2-380y+264)\geq 0$$ $$361y^2+64+304y-6y^4-1125y^2+1140y-792\geq 0$$ So $$6y^4+764y^2-1444y+728\leq 0$$ I am struck at that point. did not how to solve  further $\bf{Added}:$ I have seems that it can be convert into sum of square of numbers like $()^2+()^2+()^2+\cdots =0$ Could some help me to convert it , thanks


i want to remove wine1.7 from my Ubuntu 14.04 trusty tahr. But when i typed in sudo apt-get purge wineit didn't worked i gives me package not installed so i typed sudo apt-get purge wine(tab)and it showed the packages so i did sudo apt-get purge wine1.7 wine1.7-amd64 wine1.7-i386 wine-gecko2.34 wine-mono4.5.4 winetricks   i uninstalled wine but told me to do sudo apt-get autoremove  to remove the orphaned packages but when i did autoremove it broke my system.Fortunetly i had a clonezilla partition backup so i got back my OS from a week ago but it had wine installed so im back to where i started.So my question is how to remove wine and its dependencies without breaking my system ? and here are the packages that are orphaned according to apt but as i said when i do sudo apt-get autoremove it breaks my system here are the packages The following packages were automatically installed and are no longer required:   fonts-horai-umefont gcc-4.8-base:i386 gnome-exe-thumbnailer icoutils   libasn1-8-heimdal:i386 libasound2:i386 libasound2-plugins:i386   libasyncns0:i386 libavahi-client3:i386 libavahi-common-data:i386   libavahi-common3:i386 libcapi20-3 libcapi20-3:i386 libcups2:i386   libdrm-intel1:i386 libdrm-nouveau2:i386 libdrm-radeon1:i386 libelf1:i386   libexif12:i386 libexpat1:i386 libffi6:i386 libflac8:i386 libfontconfig1:i386   libfreetype6:i386 libgcrypt11:i386 libgd3:i386 libgif4:i386   libgl1-mesa-dri:i386 libgl1-mesa-glx:i386 libglapi-mesa:i386   libglib2.0-0:i386 libglu1-mesa:i386 libgnutls26:i386 libgpg-error0:i386   libgphoto2-6:i386 libgphoto2-port10:i386 libgssapi-krb5-2:i386   libgssapi3-heimdal:i386 libgstreamer-plugins-base0.10-0:i386   libgstreamer0.10-0:i386 libhcrypto4-heimdal:i386 libheimbase1-heimdal:i386   libheimntlm0-heimdal:i386 libhx509-5-heimdal:i386 libice6:i386   libieee1284-3:i386 libjack-jackd2-0:i386 libjbig0:i386 libjpeg-turbo8:i386   libjpeg8:i386 libk5crypto3:i386 libkeyutils1:i386 libkrb5-26-heimdal:i386   libkrb5-3:i386 libkrb5support0:i386 liblcms2-2:i386 libldap-2.4-2:i386   libllvm3.4:i386 libltdl7:i386 libmpg123-0 libmpg123-0:i386 libodbc1   libogg0:i386 libopenal1:i386 liborc-0.4-0:i386 libosmesa6 libosmesa6:i386   libp11-kit0:i386 libpcap0.8:i386 libpciaccess0:i386 libpng12-0:i386   libpulse0:i386 libroken18-heimdal:i386 libsamplerate0:i386 libsane:i386   libsasl2-2:i386 libsasl2-modules:i386 libsasl2-modules-db:i386 libsm6:i386   libsndfile1:i386 libspeexdsp1:i386 libsqlite3-0:i386 libssl1.0.0:i386   libstdc++6:i386 libtasn1-6:i386 libtiff5:i386 libtxc-dxtn-s2tc0:i386   libusb-1.0-0:i386 libv4l-0:i386 libv4lconvert0:i386 libvorbis0a:i386   libvorbisenc2:i386 libvpx1:i386 libwind0-heimdal:i386 libwrap0:i386   libx11-6:i386 libx11-xcb1:i386 libxau6:i386 libxcb-dri2-0:i386   libxcb-dri3-0:i386 libxcb-glx0:i386 libxcb-present0:i386 libxcb-sync1:i386   libxcb1:i386 libxcomposite1:i386 libxcursor1:i386 libxdamage1:i386   libxdmcp6:i386 libxext6:i386 libxfixes3:i386 libxi6:i386 libxinerama1:i386   libxml2:i386 libxpm4:i386 libxrandr2:i386 libxrender1:i386   libxshmfence1:i386 libxslt1.1:i386 libxt6:i386 libxxf86vm1:i386   ocl-icd-libopencl1:i386 odbcinst odbcinst1debian2 p11-kit-modules:i386 p7zip   unixodbc wine-gecko2.34:i386 Use 'apt-get autoremove' to remove them.

How can I remove the wine folder and all the applications in that folder?  I've tried via synaptic but it keeps showing up in the application menu.


My question      is about a conjectured injection from exceptional   $abc$-triplets $(a,b,c)\mapsto a^2+b^2$, but this question is about a conjectured injection from exceptional $abc$-triplets $(a,b,c)\mapsto a+2b$. It's similar   but not a duplicate.     The numbers $\,a,b,c\,$ is a $abc$-triplet if they are coprime and $a+b=c$. One version of the abc-conjecture is then:     For all $\varepsilon>0$ the set $E_\varepsilon$ of all $abc$-triplets with    $c>\text{rad}(a\cdot b\cdot c)^{1+\varepsilon}$ is finite.   where $\,\text{rad}(p_1^{n1}\cdots p_k^{n_k})=p_1\cdots p_k$ and $\,p_1,\dots ,p_k$ are arbitrary primes.   But it is known that $E_0$ is infinite. Conjecture:     For $abc$-triplets, where $a<b$,   $(a,b,c),(a',b',c')\in E_0\,$ and    $\,a+2b=a'+2b'\implies \{a,b\}=\{a',b'\}$    So far tested for all $a,b$ less than $100,000$. Can this be proved?    There is no uniqueness for $a+b$, $a-b$ or $2a+b$.

The numbers $\,a,b,c\,$ is a $abc$-triplet if they are coprime and $a+b=c$. One version of the abc-conjecture is then:     For all $\varepsilon>0$ the set $E_\varepsilon$ of all $abc$-triplets with    $c>\text{rad}(a\cdot b\cdot c)^{1+\varepsilon}$ is finite.   where $\,\text{rad}(p_1^{n1}\cdots p_k^{n_k})=p_1\cdots p_k$ and $\,p_1,\dots ,p_k$ are arbitrary primes.   But it is known that $E_0$ is infinite. Conjecture:     For $abc$-triplets,   $(a,b,c),(a',b',c')\in E_0\,$ and    $\,a^2+b^2=a'^2+b'^2\implies \{a,b\}=\{a',b'\}$    So far tested for all $a,b$ less than $10^5$. Can this be proved?    Diagram for the 9 exceptional abc-triplets with least distance to origo: $(1,8),(5,27),(1,48),(32,49),(1,63),(1,80),(4,121),(3,125),(81,175)$


I do not understand what happens with my paragraph. I have a few math expressions that I put between dollar signs, but the whole expression is bleeding out of the page:  \input{preamble.tex}  \begin{document}  \title{Problem 6: Förhållande mellan triangel areor} %http://www.forkosh.com/latex/ltx-138.html, hanterar headings \thispagestyle{empty}  \begin{center} {\LARGE \bf Problem 6: Förhållande mellan triangel areor}\\ \small \today \\  \end{center} \vspace{0.2in} %där tar min title import slut    \section{Problembeskrivning:}   I triangel \triangle $ABC$ är $D$ den punkt på sidan $AB$ för vilken $|BD|=4|AD|$, och $E$ är den punkt på sidan $BC$ för vilken $|CE|=4|BE|$.   Låt F vara skärningspunkten mellan DE och medianen från B. Sätt $\overrightarrow{u}=\overline{AB}$ och $\overrightarrow{v}=\overline{AC}$. Uttryck $\overline{BE}$ och $\overline{BF}$ i $\overrightarrow{u}$ och $\overrightarrow{v}$. Visa också att triangel \triangle $BEF$ alltid upptar samma proportion av \triangel $ABC$, och ange förhållande mellan trianglarnas areor.   \end{document}

Some lines in my document are italicized, with no spaces between words, and continue after the edge of the document. The rest of the document is fine. Here is the beginning:  \documentclass[runningheads]{llncs} \usepackage{graphicx} \usepackage{float} \usepackage{tikz} \usetikzlibrary{arrows} \usepackage[explicit]{titlesec} \usepackage{amsmath,amssymb} % define this before the line numbering. \usepackage[width=122mm,left=12mm,paperwidth=146mm,height=193mm,top=12mm,paperheight=217mm]{geometry} \begin{document} \pagestyle{headings}   And then, for example:   \subsection{b)}\\  \\  Given that h(n) is admissible, the algorithm will be optimal for:\\  f(n)=(2-w)[g(n) + w/(2-w)h(n)]  \\  when w/(2-w) \leq 1, that is when w \leq 1 the algorithm is optimal.\\ It        behaves like an A* algorithm following the heuristic:  f(n) = g(n) + w/(2-w) h(n)   And below is the result:    Any help is appreciated!


I see stale previously uninstalled packages in dpkg:  $ sudo dpkg -l *boost* Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name                      Version           Architecture       +++-=========================-=================-================= un  libboost1.42-dev          <none>            <none>   However, I cannot remove the entry.  $ sudo apt --purge remove libboost1.42-dev Reading package lists... Done Building dependency tree        Reading state information... Done Package 'libboost1.42-dev' is not installed, so not removed  $ sudo dpkg --purge libboost1.42-dev dpkg: warning: ignoring request to remove libboost1.42-dev which isn't installed   Running apt-cache shows:  $ sudo apt-cache policy libboost1.42-dev libboost1.42-dev:   Installed: (none)   Candidate: (none)   Version table:

To uninstall a package (Ex: tor) installed from repository one should use   sudo apt-get remove tor   I did this but dpkg -l | grep tor shown something against the package. Next I try   sudo apt-get purge tor   But when I check dpkg -l | grep tor I got,   reza@reza-N43JM:/$ dpkg -l tor     Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name           Version        Description +++-==============-==============-============================================ un  tor            <none>         (no description available)   I think when I uninstall any package I should not get anything in dpkg -l list. Is it true? Or apt-get remove or purge does another work but not uninstall?


in a cartesian closed category $\mathcal{C}$. if we have $f: A\to X$ and $g: B\to Y$   then because the functor $(\_)^A$ is continuous, we have $g':B^A\to Y^A$ composing $\text{id}\times f: Y^X\times A\to Y^X\times X$ and the evaluation map $\epsilon: Y^X\times X\to Y$ we have a function $Y^X\times A\to Y$ then we have induced a function $f': Y^X\to Y^A$ we have the pushout of the two function $f'$ and $g'$ denoted $(Y, B)^{(X, A)}$   it seems that in the arrow category $\text{Id}\downarrow \text{Id}$ of $\mathcal{C}$, the object of type $(Y, B)^{(X, A)}\to Y^A$ in the pushout diagram is the exponential object of the two object $f$ and $g$. but I cannot formalize it, is this true?  What if restirct $f$ and $g$ to be monomorphism and replace the arrow category with the category of monomorphism pairs? notice that in this situation the morphisms in arrow category is only determined by the lower one of the arrow pair

Assume I have simplicial sets $X:\Delta^{op}\rightarrow Set$ and $Y:\Delta^{op}\rightarrow Set$, then I can form the simplicial set  $\operatorname{Hom}(X,Y)_n := \operatorname{Hom}_{sSet}(\Delta^n\times X,Y)$ where $\Delta^n := \operatorname{Hom}_{\Delta}(\cdot,[n])$. Then I have the 'adjunction relation':   $\operatorname{Hom}(Z,\operatorname{Hom}(X,Y)) \simeq \operatorname{Hom}(Z\times X,Y)$   Can I do the same thing for simplicial topological spaces $X,Y:\Delta^{op}\rightarrow \operatorname{Top}$? Are there references on that or is that trivially the same thing? What would be $\Delta^n$ and what topologies do you take on the $\operatorname{Hom}(X,Y)_n$? In particular, I would like to have the same adjunction relation: $\operatorname{Hom}(Z,\operatorname{Hom}(X,Y)) \simeq \operatorname{Hom}(Z\times X,Y)$  but I can't figure out the details of how to construct the simplicial topological space $\operatorname{Hom}(X,Y)$.


In cartesian coordinates, $dA = dx\,dy$ . As $x=\rho \cos\phi\ $ and $y=\rho \sin \phi \ $,  then: $dx=  \cos\phi\, d\rho - \rho \sin\phi\, d\phi$ and $dy = \sin\phi\, d\rho + \rho \cos\phi \, d \phi  $.  So $dx\, dy = \rho\, d\rho\, d\phi(\cos^2\phi-\sin^2\phi) $, (ignoring second order terms in $d\rho$ and $d\phi$)  Why is this not equal to the correct result of $dA=\rho\, d\rho\, d\phi$?

It is changing the coordinate from one coordinate to another. There is an angle and radius on the right side. What is it? And why?  I got:  $2\,\mathrm dy\,\mathrm dx = r(\cos^2\alpha-\sin^2\alpha)\,\mathrm d\alpha \,\mathrm dr$,  where $x = r \cos(\alpha)$ and $y = r \sin(\alpha)$.  but cannot understand and get the right side. The problem emerged when trying to integrate $\displaystyle \int_0^\infty e^{\frac{-x^2}{n^2}}\,\mathrm dx$ where I tried to change the problem knowing $r^2=x^2+y^2$ but stuck to this part. What is the change in the title called and why is it so?


I am trying to study the convergence of the series:  $$\sum_{n =2}^{\infty} \frac{1}{(\ln n)^{\ln n}}$$ First I have failed to use the D'Alembert test  $$ \lim_{n\to \infty} \frac{(\ln (n+1))^{\ln (n+1)}}{(\ln n)^{\ln n}} =1.$$ So I can Conclude anything from here.  I have also tried the integral Comparaison test but it was not soo clear.

Could I have a hint for testing the convergence of the following series please?  $$\sum_{n=2}^\infty\frac{1}{(\ln n)^{\ln n}}$$  I am very appreciative for your help.


For anyone who is using Blender 2.8 right now, does anyone know how I can change the dimensions of the shapes in Blender 2.8.  Take the sphere for instance: I want to change the number of rings and grids on the sphere, which was a process I usually did in 2.79b. Does anyone know how I can do this in Blender 2.8?

The tutorial I read is based on 2.79. So I'm not sure if it's still the same name in 2.8. But I can't find anything providing similar functionalities.


There are some questions about how content, especially source code, on Stack Overflow is licensed and how it should be attributed (see below). There is even a Stack Overflow blog post about how to attribute republished content ().  Why isn't there a "cite" feature, for example next to "share" and "edit", that collects all relevant information (hyperlink to the original question, author names for every question and answer with links to profile pages, etc.)? This would make attribution as described in the blog post easier for the users.  Related Questions:

The  and  Stack Exchange sites have a great feature that allows a user to quickly . This is accomplished by clicking share and then clicking cite:    For ease of copying and pasting the cite feature even provides the  and  LaTeX formats (something which probably wouldn't be needed on other sites).  Currently I am working on a paper which has heavily referenced the  site. As such having the ability to quickly cite each question / answer would be incredibly helpful. While I agree the ability to easily cite is more applicable to certain SE sites, this seems like a frictionless feature with a lot of benefit.  Is there a reason this feature isn't available across the entire Stack Exchange network? Is this something that each Stack Exchange site needs to decide within its community (i.e. I need to move this discussion to meta.ux.se)? Can the ability to cite question and answers please be added to all other Stack Exchange sites?


How can I stop limited user of my computer from using the F2 or F12 keys to access my computer while I'm away? They will use them to start it in safe mode and while they are in there it bypasses my password and I don't want them deleting or moving my file around. In fact all I want them to be able to do is go on the internet. They don't need access to any thing else. Can I do that?

While turning on my laptop, I wanted to disable a possibility to use "F10" boot menu (maybe it's F12 on other models). I want that no-one should be able to enter my DESKTOP (Even though I'm also using user-account password at Windows login screen). So, if BOOT is available, someone might use LIVE-CD to access my pc.  How to do that?


I'm trying to export an fbx file as an obj, and to test whether it work I had to import it, but when I imported it it failed to load the textures. I have looked at all the other questions related to this but none of them seem to help. Thanks in advance.

I used node textures in a mesh I exported to .FBX.  I then imported it into Unreal Engine 4 and it didn't import any textures; I clicked the Upload Textures option in Unreal Engine.  Is there something I'm doing wrong or is it Blender?


My phone just managed to do a factory reset, all on its own. Can I somehow retrieve at least the portion of the lost data? On computer for both linux and windows there are programs that can recover parts of harddrive which have been marked empty but still contain data from deleted files.  Is there a way to do this on Samsung Galaxy with Android 4.1.2? Because I really need my contacts and some of my memo notes were really important.

A person at a phone store reset all the contents of my Motorola Moto G Android phone, and I did not give them permission to do so. I had many important pictures and videos, but the even more important thing were the audio recordings I had created.  Is there ANY WAY to recover this data? I know it was reset, but I'm very stressed and would appreciate a pointer of a way to effectively recover some or all of the data without comprising it in the process. I am not using the phone, and had shut it off entirely. I'm aware that the more you use it, the more it overwrites the data. I NEVER had a backup, dumb, I know.  Thank you folks!  **Edit: I recovered most of my photos and videos just now through Google+, most of it was synced! But how can I recover my voice recordings ? That's what's most important to me. I used this app.   Unfortunately, my phone model never supported SD cards, so there's nothing there.


I understand that adding a multiple of one row to another in a matrix has no effect on the determinant, which seems to contradict something I learned earlier: if I understand correctly, for a $n\times n$ matrix with rows $[v_1, v_2, v_3,\ldots v_n]$,  $$\det[v_1+v_1', v_2, v_3,\ldots v_n]=\det[v_1, v_2, v_3,\ldots v_n]+\det[v_1', v_2, v_3,\ldots v_n].$$  Thanks for the clarification!

1) Switching two rows or columns causes the determinant to switch sign  2) Adding a multiple of one row to another causes the determinant to remain the same  3) Multiplying a row as a constant results in the determinant scaling by that constant.  Using the geometric definition of the determinant as the area spanned by the columns of the matrix, could someone give me a geometric interpretation of the above theorems? Thanks.


My five-year-old son will be six in August. It's been a rollercoaster ride since he's been two. I'm feeling lost and failed as a parent. Me and his father are divorced since he's been two and we keep a straight line raising him separate. I can say we both love and support him.   He's been in speech therapy since age two, by three he was still not talking clear. I moved forward with professional help, being concerned that he may have autism. I went through all the testing and came back no signs of it just a receptive, expressive speech delay.  He started kindergarten this year full time, doing his academics in the morning with his special teacher, going to lunch, then joining his general kindergarten class to finish the day.   He's been responding well to the routine and made intermittent improvements with his speech. Unfortunately, the last month his behavior declined sufficiently.   My son feeds on bad attention. No matter how much I redirect him or his teachers, he feels no remorse and continues to repeat these bad actions. He runs around the classroom, has a hard time sitting in his seat, lately has been hitting students and teachers, something he never did at home.   I'm constantly having the same conversations with him and repeatedly going back to disruptive behavior at school. I don't let him get away with this behavior but he's pushing it hard at school.   It's one thing after another, I just can't catch a break. I'm moving on to professional help and I pray the outcome is right for my child.   I just can't understand why he loves to misbehave. Is this normal?

My 5 year old son receives and fears punishment but repeatedly exhibits the same unacceptable behaviors.  He's always been strong-willed, and is usually the kind to view a statement like "Don't do that" as an open invitation to do it.  We've tried redirection or distraction tactics, but he is still so narrowly focused on doing the original behavior.  Even worse, he will typically do the prohibited behavior and flagrantly tell us or show us that he's done it.  Repeatedly, even after punishment.  (He's in time out right now for this very thing).  He's consistently punished, yet he continues down the same self-destructive path each time.  When he is punished, we explain what he did wrong, why he's being punished, and why he shouldn't do what he was told not to do.  Sometimes he'll even tell us first why he's in trouble, so it makes me wonder if he's acting out for the inevitable negative attention he gets.  I think he gets plenty of love and positive attention- he's an only child and stays with a relative during the day.  We're trying to give him a good, fun childhood, but we need to figure out how to effectively discipline him.    His repeated misbehavior includes:   Yelling at the top of his lungs in public (stores, friends' houses, etc) Running away from us (at parks, stores, parking lots, etc) Talking back and disrespecting authority figures Hurting animals even after we explain why it's wrong Repetitive nuisance behaviors (repeating himself, banging his fists, kicking walls, intentionally crumbling food on floors, etc) Repeatedly asking us why he can't do something even after it's been explained to him Basically, most bad behaviors that young children may do, but repeated over and over again, even after discipline   He gets a warning to stop the behavior, then depending on the severity of what he's done (and where we are), he'll either go to time out or lose a privilege (such as taking away a favorite movie or missing out on an activity).  Going to time outs and losing privileges really upset him, but still do not ultimately deter him from the bad behavior.  It's like he can't help himself.  My spouse and I are getting worn down.  We try to model good behavior and encourage him to be well-mannered and respectful.  This behavior mortifies us.  It seems we can't even enjoy life as a family because our son is so disruptive and unresponsive.  Most public outings have to be cut short or eliminated because he consistently misbehaves and doesn't respond to our discipline.  After he's misbehaved, when we try to have heart-to-heart talks with him about his behavior and why we expect him to mind us, he usually has a little trouble expressing himself, and a lot of times we get the same nonsensical responses from him (Us: Why did you do [bad behavior]?  Him: Because I didn't want to).  He also doesn't like to make eye contact.  We don't usually feel like we've gotten through to him.  Is there another discipline tactic we could try?  Or does it sound like we need to see a professional at this point?  We're at a loss, and don't want things to spiral further out of control as he gets older (and even begins school).  We just want him to understand that his behavior isn't always acceptable.  Thanks for reading.  Update (from comments below): My spouse and I disagree on spanking, as we had different experiences with it. He feels it's necessary sometimes. Since our son failed to improve after time outs and taking away items/privileges, I grew to agree with him and we used it for select bad behaviors. It didn't work any better. However, when he was spanked, he was always told why. I didn't mention that we have used it because I was afraid it would distract from the original question, but since it has already come up [in comments], yes, it has been explored, but with no better results than our other tactics.


While I haven't read through the entirety of , I've read enough to (IMHO) reasonably conclude that there's two large issues at work there.   People who are having their activities moderated need to be more civil about it, lest they be even further moderated. Chat moderation on StackExchange could use a bit of tweaking, to reduce the likelihood of outside users performing moderation that may not fit the current context or culture of the room.   The first isn't really something we can do much about - people who don't want to be civil (whether it be in general, or simply in certain situations) just won't. That's one of the reasons moderation exists in the first place.  However, I think there are some appropriate changes that can be made to address the second part.  Outside users may not be able (or simply may not be willing) to perform enough depth of review to put flagged content into its proper context before acting upon it. However, the room's current (or recent) participants are probably very familiar with the context and therefore logically the most appropriate people to pass judgment.  Given this, the most logical move (at first glance) may be to entirely restrict chat moderation to only the participants of the room. However, this could become a problem where there are not enough moderators or high-rep users (I'll collectively refer to these as "flag handlers") present to deal with flags within a reasonable amount of time.  However, if there are enough flag handlers around, why not give them a chance to handle the issue internally before getting all of the StackExchange flag handlers involved? This reduces flag noise for non-local flag handlers, increases the likelihood that context and local culture will be taken into account before a flag is handled, and still leaves the entire SE flag handling community available to handle flags that the local users can't deal with on their own.  Proposed modification:  Immediately when a flag is posted to chat.    Notify local flag handlers only. "Local" includes any flag handlers currently showing as present in the room. May also want to include any who are currently active elsewhere in chat, and have visited the room within X days. (I'd say X probably shouldn't be more than a couple weeks.)  After a delay, only if the flag has not already been handled.    Notify non-local flag handlers. I'm thinking somewhere within 1-2 minutes would be an appropriate delay. Certainly no longer than 5 minutes, and no shorter than 30 seconds. Maybe consider throttling the delay according to recent flag volume. (i.e.: More flags per minute across the past X amount of time - say, 15 minutes to an hour - means a shorter delay.) Also may want to consider eliminating this delay when the room has a low number of "local" (or recently-local) flag handlers available.

The offensive/spam flags in chat are shown to every moderator from a parent site (on chat.stackexchange.com that is every SE 2.0 moderator, more than 200 right now) and 10k chat users as well. This is potentially far more users than a flag on an SE site itself is shown to.   I don't think it is necessary to show the flag to so many users at once. This can lead to the impressive sight of an entire horde of moderators descending onto one chat room when some flagging is going on, but it often notifies far more people than necessary to act.  Another huge disadvantage of notifying so many users at once is that only the fastest users to act decide on the fate of the flag. If you read up on the context of the flagged message, odds are that by the time you're finished with that someone already validated or dismissed the flag. This leads to hasty decisions on those flags because the users that take their time won't get to decide on the flag.   I propose that the chat flags are first shown only to mods and users in the same chat room, if there are enough users present that the flag could be acted on (so either one moderator or six 10k+ users). If they don't act after a short while or not enough privileged users are present in the room, the flag should be escalated to the mods and users of the parent site. If those users don't act on the flag, it be shown to all moderators and users on Chat.SE.  The exact delay should be just long enough to allow present and active users to handle the flag. Given the high speed that flags are currently handled in many cases, 30-60 seconds might be enough. Though looking at some hard data on flag handling times might be a better way to come up with a useful length.   It might also be useful to increase the number of users that see the flag incrementally even at the stage where all 10k users and moderators are notified. You don't need all of them, and the wide exposure .  The advantages would be:   Not bothering users that are not needed to come to a quick decision Allows local differences in chat culture to be policed more consistently Higher chance of showing the flag to users that already know the context   But there is also a danger to this, if flags are handled locally and nobody outside the room can see them, the potential for abuse is much higher. This could allow a chat room to develop a very hostile culture, and just flag away anyone that complains, or just dismiss valid flags.   There should be an obvious way for a user to involve moderators from outside the chat room. This could be the "flag for a moderator" option, they would remain global by default and ignore the escalation system. That would also need some UI work as this option is currently rather well hidden and I suspect that many chat users don't even know that there are two types of flags. I've posted my ideas about this


Suppose we have a sequence of functions $f_n(x)$ that converge to a limiting function $f(x) = \lim_{n \to \infty} f_n(x)$ for $\forall x \in [a,b]$. I was wondering under what conditions the following holds? \begin{equation*} \lim_{n \to \infty} \inf_{x \in [a,b]} f_n(x) = \inf_{x \in [a,b]} f(x). \end{equation*}

I'm sure I'm having a notational misunderstanding. Anyway, suppose $(f_n)$ is a sequence of continuous functions from a metric space $X$ to $\mathbb{R}$. So, if $(f_n)$ converges uniformly to a function $f$, then  $$\lim_{n \to \infty} \inf_{x \in X} f_n(x) = \inf_{x \in X} \lim_{n \to \infty} f_n(x)$$  and  $$\lim_{n \to \infty} \sup_{x \in X} f_n(x) = \sup_{x \in X} \lim_{n \to \infty} f_n(x).$$  Can somebody explain to me why is that? Again, this might be really simple...


Using itertools and permutation() to get all unique combinations of two lists is easy. For instance, if I had: ['a', 'b'] [1, 2]  I could easily get: [   [('a',1),('b',2)],   [('a',2),('b',1)] ]  However, what I really want is to allow duplicate pairings. Each item in the larger list will be unique, but the number of combinations would be exponential, since the same item in the first list could get assigned to multiple items in the second list. So for the two lists above, I would get: [   [('a',1),('a',2)],   [('a',1),('b',2)],   [('b',1),('a',2)]   [('b',1),('b',2)] ]  If I had three items in each of the two lists, I would end up with 27 results. What would be the best approach to this?

How can I get the Cartesian product (every possible combination of values) from a group of lists?  Input:   somelists = [    [1, 2, 3],    ['a', 'b'],    [4, 5] ]   Desired output:  [(1, 'a', 4), (1, 'a', 5), (1, 'b', 4), (1, 'b', 5), (2, 'a', 4), (2, 'a', 5) ...]


Is it possible to disable the animation when switching "spaces"?  The animation is jarring, and isn't really usable if used in high repetition.  Note: this question is specifically for OS X Yosemite

In Snow Leopard, I had the window switch animation disabled when I quick-key between spaces. Now that it's Mission Control in Lion, there's a long animation during which all my desktop icons disappear and I can't use anything. I'd really like to disable this, but .  How can I disable this needless animation in OS X Lion or later?


I am using the  in a DDPAK package as a 5V USB voltage regulator on 4-layer board.  The TAB of the package is internaly connected to pin 2 (OUTPUT).    I am not sure what to do with the copper area connected to the TAB. Which of the following options should I choose:   leave the copper area connected to the TAB floating connect the copper area connected to the TAB to pin 2 (OUTPUT) use the copper area connected to the TAB as a the primary OUTPUT connection, leave pin 2 floating

Take the classic LM1117 linear regulator   Pin 2 is Vout.  The tab is also Vout.  From a component layout perspective, it would be nice if I could connect the output capacitor to the tab instead of the pin.  What is the functional difference between the tab and the pin?  Does one have less current carrying capability than the other?  Can I leave the pin floating and instead connect the tab to the output capacitor?  Must I hook the output capacitor to the pin?  Can I just short the pin to the tab?


This is a True/False question. and the answer is given False.  A is symmetric and hence we can diagonalize A. say $DAD^{-1}$ gives our diagonal matrix $diag(a_1,a_2...a_r)$ , then by taking n-th power we easily get the $tr(A^n)= a_1^n+a_2^n+...a_r^n$ Now to show the claim is false I should play with $n$ right? In particular, if I put $n=1$, this gives no contradiction because there always exists such a symmetric matrix. I don't know where to go from here.

Does there exist a symmetric matrix $A$  such that $2^{\sqrt{n}}\le |\operatorname{Tr}(A^n)|\le2020 \cdot2^{\sqrt{n}}$ for all $n$? I think no. The trace of $A^n$ equals $\sum\limits_{i=1}^n\lambda_i^n$ where $\lambda_i$ are the eigenvalues of $A$. Now, if the absolute value of trace of $A$ is bounded below by $2$, then I think the trace of $A^n$ will grow infinitely. Am I right? Thanks beforehand.


When I lock my computer, the first monitor shows "Press CTRL + ALT + DELETE to unlock", and the secondary monitor is just black. But in some office I saw the second monitor showing the desktop background.  How can I accomplish this?

In 2000/XP/Vista it was easy to set a wallpaper for the logon screen, either manually through tools like Logonstudio or simple registry changes by hand on prepared installation images or through custom group policies.  In Windows 7 all this works as usual, but the secondary (or any additional) monitor is just black. The mouse pointer is visible on it but no matter what settings I can't get the logon wallpaper to tile (or stretch or fill or whatever) over onto it.  This makes it hard to OEM/company brand the installation for multi-monitor users. More annoying is the fact that it looks officially supported to brand the logon wallpaper in Windows 7 - as it's made extremely easy... apart from this little catch. XP and Vista has no problem tiling or stretching the logon wallpaper over multiple monitors.


How can I escape a backtick?  I've tried whatever is written in the "How to Format" rubric that's on the right of the page, but it didn't work: like _so_  I want the backtick to be written in a comment (This is why a code block isn't a solution)  Thank you.  Edit #1 (12:04 UTC):  By using CodeCaster's answer, I've managed to escape a backtick. But a funny thing happens when using the following two examples:  First example:  Code:  `like _so_\``   Result: `like so``  Second Example:  Code:  ``like _so_\`   Result: ``like so`

How do I escape a backtick ` within a code block?  This is probably a duplicate, since I'm sure it's a common concern, but I can't find a question that addresses this specifically.  How do I write List'1 with the "1" character still in the code-text format?


Incredibly, I couldn't find a single, consolidated and up-to-date answer for this question. All I found was people complaining about missing notifications, discussions about changes in the notification system, and questions about @replies.  So here is what I think I know:   If I ask a question, I get notified about all comments, on the question or on any answer. If I write an answer, I get notified about all comments on my answer. Otherwise, I'm only notified if the comment contains a @reference to me   Is that really how it works? Do I get automatic notifications in any other situation?

The  was once introduced because it became hard "to keep track of all your questions, answers, and comments across every site you participated on".   The small red number tells you how many new replies you have across the entire Stack Exchange network of websites. And by replies, I mean:  New answers to your questions New comments on your posts @replies to you in comments   However, it's been a while since 2010, and there are many more events triggering an inbox notification.


An 'free' electron accelerated in an electromagnetic field can both absorb and emit a photon. What about an election accelerating in a gravitational field?  Edit: Some users have suggested that the question is a duplicate. However, my question asks about photon absorption, not radiation of photons.

A charged particle undergoing an acceleration radiates photons.  Let's consider a charge in a freely falling frame of reference.  In such a frame, the local gravitational field is necessarily zero, and the particle does not accelerate or experience any force. Thus, this charge is free in such a frame. But, a free charge does not emit any photons. There seems to be a paradox. Does a freely falling charge in a gravitational field radiate?


Here's a working example of my big table with images on it:  \documentclass[a4paper,12pt]{book}  % Relevant packages \usepackage{graphicx} \usepackage{lscape}  % Other packages I'm using \usepackage[spanish,es-nodecimaldot]{babel} \usepackage[T1]{fontenc} \usepackage[table]{xcolor} \usepackage{amsfonts,subfig,sidecap}  \usepackage{setspace} \usepackage{geometry} \usepackage{fancyhdr} \usepackage{siunitx} \usepackage{booktabs,cancel,cleveref,colortbl,csquotes,multirow,listings,pgfplots} \usepackage{mathpazo} \usepackage{environ} \usepackage[section]{placeins} \usepackage{titlesec, blindtext} \usepackage[labelfont=sc]{caption}   \usepackage[backend=biber,style=authoryear,sorting=nyt,maxbibnames=99]{biblatex}  % Document \begin{document}  \begin{landscape}   \begin{table}[hbt]      \centering      \begin{tabular}{ccccc}          ~ & DJF & MAM & JJA & SON\\         (A) & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image}\\         (B) & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image}\\         (C) & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image}\\         (D) & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image} & \includegraphics[scale=0.25]{example-image}\\      \end{tabular}     \caption{The caption of this very long table.}     \label{tab:Longtable}    \end{table} \end{landscape}  \end{document}     As you can see, the text that appears next to the images ((A), (B), (C) and (D)) are not "vertically" aligned or centered with the figures next to them. How could I fix this?  And I'll ask a second question here since it's related to this one. The caption that appears in this table is "Cuadro 1" (Spanish for Table 1). Is there a way to change only this one caption to "Figura 1"(Figure 1)? I'm asking because I actually didn't want to do a table, but I didn't know how to produce this kind of graphics using the figure environment. And since I'm writing a very long document this would be a problem for referencing them later.  Thanks a lot in advance!  EDIT: Clarification. My problem with caption is the following. Since it's a table environment the caption is, as intended, a "Table" caption. However, I would love to change this caption to a "Figure" caption, as if I was making a caption on a Figure (but using a table environment).   So the idea would be to produce the same image as above, but instead of "Table X" show "Figure Y" (and get the number Y from the corresponding number of figure instead of the number of table.  Eg: If I had 3 tables and 5 figures in my document, I would like to produce the image above and caption it as "Figure 5" instead of "Table 3".

I want to create a table with multiple rows of the following form: a cell that contains text and then multiple cells that contain images. The text should be vertically centered and the contents of every column should also be centered horizontally. I am aware of the m{} column type but somehow this seems to fail if an image is contained in the row and determines the row height. Any ideas?  Minimal example:  \documentclass{article} \usepackage{graphicx} \usepackage{array} \begin{document} \begin{figure} \begin{tabular}{m{3cm}c} (a) & \includegraphics{some_picture.pdf}\\ \end{tabular} \end{figure}  \end{document}


I am on a Ubuntu 17.04 Server and when trying to install Icinga2 per the , I get a dependency error.  root@PC:~# apt-get install icinga2 Reading package lists... Done Building dependency tree     Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies.  icinga2 : Depends: icinga2-bin (= 2.6.3-1~ppa1~xenial1) but it is not going to be installed E: Unable to correct problems, you have held broken packages.   Tried running apt-get install icinga2-bin and get the following  The following packages have unmet dependencies: icinga2-bin : Depends: libicinga2 (= 2.6.3-1~ppa1~xenial1) but it is not going to be installed Depends: libboost-program-options1.58.0 but it is not installable Depends: libboost-system1.58.0 but it is not installable Depends: libboost-thread1.58.0 but it is not installable E: Unable to correct problems, you have held broken packages.

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


I want to display two 3d view windows at once. But I want one to be in Edit Mode, and the other in Object mode. However, when I change the mode of one window the other 3d view window automatically changes. How can I make it so changing the mode in one window does not affect the other window?

When I split screen in two and switch Edit/Object mode, they both change. How to change just one? The intention here is:  use one to modelling with numkey view with transparent wireframe and the other to see the progress in perspective, with solid mesh


Asking here because I'm having a bear of a time trying to Google this. Is there a name for the structure, often observed in spoken English, in which a sentence begins with a noun phrase followed by a comma and a pronoun that serves as the subject of the sentence, with the antecedent of the pronoun being the preceding noun phrase? It's similar to the way stress pronouns are often used in French (e.g. "Moi, je m'appelle..."). Here's an example of what I'm talking about: "Students with more than one major, they tend to have very little free time." Anyone aware of a consensus on the correctness of this structure in an informal register?

Is it now considered acceptable to follow a proper noun ... or any noun ... with a pronoun? E.g.      The President he issued a new executive order.


How can I resolve a shutter release button problem with a Nikon D5100? I dropped the camera on the floor and now it displays "Error: press shutter release button again."

The LCD on my Nikon D3000 is displaying the following error message:     Error. Press shutter release button again.   I have pressed the shutter release button but the camera still does not work.


Build a bijection $f: \mathbb{R} \to \mathbb{R}\setminus \mathbb{N}$.  What about $f(x)=\pi \cdot x?$

Find a bijection from $\mathbb R \to  \mathbb R-\mathbb N$. I want to set my function up such that all natural numbers get mapped to $n+.1$ and reals of the form $n+.1$ to $2n+.1$ is this correct?


In the seven Harry Potter books, the reader meets about two dozen of Hogwarts' teachers, but I don't remember any of them having either a spouse or children.  They are all grown adults, often even elderly, so this seems a bit surprising. After all, in the Muggle world, high-school teachers often happen to have a family life beside their job.  What have I found so far:   Remus Lupin marries Nymphadora Tonks and fathers Teddy. However, this happens several years after his one-year appointment as DADA teacher in Hogwarts. Hagrid develops a romance with Madame Maxime in GoF, but it is unclear how far it goes, and I can find no mention of her after their trip to Europe. Snape has been madly in love with Lily Potter all his life, but she has never reciprocated and we can reasonably infer that he never had any bond with anyone else. We  that at least three of the four Hogwarts founders (Slytherin, Hufflepuff and Ravenclaw) had children, but I am more interested in 20th century teachers. Among the ghosts, the Bloody Baron and the Grey Lady have, hum, a complicated history.    Is any teacher of Hogwarts known to be married or to have a child? If no, has any justification for this been advanced?  Any information about the non-teaching staff (Pomfrey, Filch, Pince...) or the former headmasters is also welcomed.

Do the teachers have any family (like husband, children and wife), or are they sacrificing their personal lives for the service of the school?


Null pointer Exception occurs. Help me to solve this  public static memberlogin extends HttpServlet {  static Connection con=null; static Connection getCon() throws ClassNotFoundException{      Class.forName("org.postgresql.Driver");     try {         con =DriverManager.getConnection("jdbc:postgresql://localhost:5432/postgres", "selva", "selva");         } catch (SQLException e) {         e.printStackTrace(); } return con;  } protected void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException {      res.setContentType("text/html");     PrintWriter pw = res.getWriter();     String uname = req.getParameter("uname");     String pass = req.getParameter("password");     if(uname!=null && pass != null) {         String sql = "SELECT * FROM public.memberdata WHERE username = '"+ uname +"'";         try {             Statement st = getCon().createStatement();             ResultSet rs = st.executeQuery(sql);             if(rs.next()) {                 String user= rs.getString("username");                 String pas=rs.getString("password");                 if(user.equalsIgnoreCase("uname") && pas.equalsIgnoreCase("pass")) {                     res.sendRedirect("welcomepage.html");                 }                 else {                     pw.println("username password mismatch");                 }             }             else {                 pw.println("invalid username");             }          } catch (ClassNotFoundException | SQLException e) {             e.printStackTrace();         }    } }   HTTP Status 500 ? Internal Server Error Type Exception Report  Description The server encountered an unexpected condition that prevented it from fulfilling the request.  Exception  java.lang.NullPointerException     memberlogin.doPost(memberlogin.java:38)     javax.servlet.http.HttpServlet.service(HttpServlet.java:660)     javax.servlet.http.HttpServlet.service(HttpServlet.java:741)     org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)   Note The full stack trace of the root cause is available in the server logs.

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


What is this notification icon that looks like 3 stacked horizontal bars?

I'm concerned about an app on my child's phone. I saw an app icon in the notification area that looked strange (Andy Android head, slightly tilted as its icon).  How can I find out what app it is from just having seen that icon in the notification bar?


l have table and want to display selected feature in layout (print version). When select other country (look image) show me these country data in print version. Mostly do this by copy and paste in layout. But l want to do this automatic. Does anyone know how to do this? Probably need script tool.  l have tried in this link () to get answer, but l could not identify what mean there.

I am using ArcMap 10.2 and I'm looking for a way to add  a table containing certain fields from select elements from a featureclass to my map. Ive tried the add table option from the attribute table, but it doesn't quite give what I want (the table must be editable to look a certain way).   Are there any options out there for 10.2 like arcpy.mapping.tableview or will upgrading to 10.3 so I can get access to the "graphic table element" function be best?


Should this be neither is or neither are?  Neither of these two books is suitable. Neither of these two books are suitable.  Which one is correct?

Bob: "Can I set the font color? Can I customize the text?"  Frank: "Neither of these options is available. Sorry!"    Is "neither is" always correct or should one use "neither are" in some cases and what are the exact rules?  of this-is-why-stackexchange-exists :P


I have series of numbers (versioning) like this:      1.6.8   1.9.7 (also with two digits in the middle)   How should I do to target only the middle numbers, the ones between dot and dot?  I tried something like that this:   \.\d+(?=\.)   and it is targeting the middle number, but also the first dot.

I want to match a portion of a string using a  and then access that parenthesized substring:  var myString = "something format_abc"; // I want "abc"  var arr = /(?:^|\s)format_(.*?)(?:\s|$)/.exec(myString);  console.log(arr);     // Prints: [" format_abc", "abc"] .. so far so good. console.log(arr[1]);  // Prints: undefined  (???) console.log(arr[0]);  // Prints: format_undefined (!!!)   What am I doing wrong?    I've discovered that there was nothing wrong with the regular expression code above: the actual string which I was testing against was this:  "date format_%A"   Reporting that "%A" is undefined seems a very strange behaviour, but it is not directly related to this question, so I've opened a new one, .    The issue was that console.log takes its parameters like a printf statement, and since the string I was logging ("%A") had a special value, it was trying to find the value of the next parameter.


Whenever my three year old son plays on his trampoline, it doesn't take very long for him to start building up a significant amount of static electricity.  His hair stands on end (which is quite amusing), but when I help him down we both get a nasty static shock (which is not amusing).  He finds the shock upsetting, and I'm concerned that it will discourage him from enjoying his trampoline.  How can I prevent the build-up?  One suggestion I have seen on a parenting forum is to ground the trampoline frame with a cable and a metal stake.  However my understanding is that this would enable him to discharge by touching the frame (rather than me), but it would not prevent the static occurring in the first place.  If it's relevant, it's  and is on a grass lawn.  My son bounces in his socks, no shoes.  In case of link rot, it is an 8ft trampoline with a net enclosure.

sometimes I get "charged" and the next thing I touch something that conducts electricity such as a person, a car, a motal door, etc I get shocked by .  I'm trying to avoid this so if I suspect being "charged" I try to touch something that does not conduct electricity (such as a wooden table) as soon as possible, in the belief that this will "uncharge me".   Is it true that touching wood will uncharge you? How and when do I get charged? I noticed that it happens only in parts of the years, and after I get out of the car...


NOTE: This issue was first brought up in , but since that post is now locked, I want to initiate a proper feature request to update this functionality.   The site search built into the new top-bar is a great feature, but as discussed in , it is incredibly unforgiving.  In particular you run into problems trying to find some sites by the URL.    When using the search, the feature only looks in the site name and the subtitle/description for the site.  Where this becomes a problem is for sites that had graduated and have received their own name, and the URL no longer matches the site name.  For example, trying to find Gaming.SE:    If you know Gaming.SE existed, but did not know the name was "Arqade", you might run into problems.  "Gaming" yields no results.  If you searching for "game", you do find it because "videogamers" (sic) is part of the description, however, it buried under "Game Development", "Board & Card Games", and "Role-playing Games", so you don't see it unless you scroll down.  You encounter a similar problem with several other sites:    if you are searching for "Seasoned Advice", you won't find it with "Cooking" since it is not referenced in the site's description. In fact, this one is impossible to find as "food" isn't mentioned either.  The only cooking term that you could find the site by is "Chef". "Mi Yodeya" also has the same problem since "Judaism" is not mentioned anywhere but the URL.  "Jewish" is mentioned in the description, but has virtually no characters in common with Judaism save the "J". Amateur Radio's URL is Ham.SE, so that's another tough one to find. Mathematics has a closely related problem since most users who learned UK English might search for "maths", which does not return anything either.   Not all sites have the same problem since the name is close to the URL or the URL is mentioned in the description (for example "Ask Different" references "Apple", "Home Improvement" references "DIY" in the description), but this can make finding specific sites problematic for users who might not be familiar with the boutique name of the site and only know it by the URL.  Can the search be updated to reference the URL, or at least the descriptions also include some reference to the URL Name for all sites to make it easier to find.

I wanted to switch to  in the handy dandy site switcher in the new top bar. Entering "cook" brings up nothing:     ... so I have to remember that the boutique title of the site is "Seasoned Advice":     ... in which case the site switcher also thinks that maybe I was thinking of heading over to  to see what's up. So the site switcher searches site names and descriptions, but not subdomains. This is unexpected behavior - I believe it should search all three.


I want to make a model for a game with Blender, right now I am making an escape pod for a spaceship, just the basic mesh structure that will have a texture (which I will figure out if there's any problems later), but here's the problem, I am getting an unwanted corner mesh when making the doorway into the pod.  Couldn't post a picture here, sorry  But I have tried making more cuts and they don't work when using them to cut down the mesh, here is the blend file:   PS:(It is happening to all four corners of the doorway so it'll most likely work for all if it works with one)   Here's a blend without all the cuts if it makes it easier:  NOTE: The nose cone isn't done in this version!

Probably an obvious answer, but I can't figure out why my mesh is causing such a weird crumpled up look with the subsurf modifier.  I've gone through to make sure there are no doubles or overlapping vertices, but it still looks weird when I apply the subsurf.  Any idea what I might be doing wrong?      Here is the .blend


If my memory is not playing me up this could be done with old versions of Ubuntu but I can't find a way of doing it with 18.04.   Is there a way of doing it?

Ubuntu 16.04 I have 2 instances of Nautilus (file explorer) open - in different drives and or folders.  I want to create a LINK to a file.  It doesn't appear to be easily done - if I drag & drop the file it makes a copy. If I right-click the file the menu does have a 'Make Link', but it makes the link in the folder the file already is in (why would I want that?) - and I have to then drag the link to the place I want, which makes a copy of the link, and then I have to delete the link made in the place I don't want. Seems like very inefficient way. So, I'm probably missing something....?


is it legal to dribble the ball after rebounding your own miss when the ball only hit the backboard?

In this video, a college basketball player steals the ball, races down court, and avoids the defender by throwing a pass to himself off the backboard.    In all the (disorganized) basketball games I've played in, a shot had to hit the rim before the shooter was allowed to rebound. And that looks like a shot to me.  Obviously the officials allowed it, but I couldn't find an explicit mention in the . Is this ruled as a shot, and if so, why is it legal? I'd be interested in the answer for any level of basketball, though NCAA is the most relevant.


Let $f:[0, 1] \to \mathbb R$ be a continuous function and $g: [0, 1] \to \mathbb R$ be defined through $g(x) := \int_0^x(x - t)f(t)dt$. Prove that $g'' = f$ in $[0, 1]$.  My work so far: I've defined a function $h(t) = (x-t)f(t)$, so that now   $g(x) = \int_0^xh(t)dt$   and I can use the fundamental theorem of calculus to obtain:  $g'(x) = \frac{d}{dx}\int_0^xh(t)dt = H'(x) = h(x)$, where $H(x)$ is the antiderivative of $h(x)$. So $h$ is the antiderivative of $g$, meaning that   $g''(x) = h'(x)$ where $h'(t) = [(x - t)f(t)]' = -f(t) + (x-t)f'(t)$, so $g''(x) = -f(x)$.   I'm almost there, but I get a minus to the front... Where am I doing wrong? Thanks in advance!

Let $f:\mathbb R\to \mathbb R$ be a continuous function and $\Phi(x)=\int_0^x (x-t)f(t)\,dt$. Justify that $\Phi(x)$ is twice differentiable and calculate $\Phi''(x)$.   I'm having a hard time finding the first derivative of $\Phi(x)$. Here's what I tried so far:  Since $f$ is a continuous function and $x-t$ is a polynomial function, thus continuous, $f(t)(x-t)$ is the product of two continuous functions and is also continuous. Since $x$ and $0$ are differentiable functions, by the Fundamental Theorem of Calculus   $\Phi'(x)= (x-x)f(x)x' - (x-0)f(0)0'=0$  I checked the solution and this is wrong, the solution goes like this: $\Phi'(x) = (x\int_0^xf(t)dt - \int_0^xtf(t)dt)' = \int_0^xf(t)dt + xf(x) - xf(x) = \int_0^xf(t)dt$  So I tried to do it their way, expanding $(x-t)f(t) to xf(t) - tf(t)$ and I got this:  $\Phi'(x) = (\int_0^x (x-t)f(t)dt)' = (\int_0^x xf(t) - tf(t)dt)' = (x\int_0^xf(t)dt - \int_0^xtf(t)dt)' = xf(x)x' - xf(0)0' - (xf(x)x' - 0f(0)0') = xf(x) - xf(x) = 0$  $0$ again.  Another thing I didn't understand is why they put the $x$ outside the integral, I thought we were only supposed to do that with constants. As in, why is $\int_0^x xf(t)dt = x\int_0^x f(t)\,dt$  I understand the rest of the exercise, I just can't get this derivative right with the Fundamental Theorem of Calculus. The version I'm using says  Let $f$ be a continuous function and $a(x)$ and $b(x)$ be differentiable functions. If $$F(x) = \int_{a(x)}^{b(x)} f(t) \,dt$$ then $F'(x) = f(b(x))b'(x) - f(a(x))a'(x)$  Is this correct? Because if so I don't understand how the derivative of this exercise works.


I've made an animal model, which consists of two objects: eyes and a whole body. I decided to make them into one object. When I tried to do that with Ctrl  + J one eye joined to the body and the other disappeared. What's the problem?

I am attempting to make a tree but when I try to join the different components together ctrl J my decimated icospheres revert back to its original shape.  Any idea on how I can solve this?  I also forgot to mention that I am trying to create a low poly tree and that I am still in the learning stages.  The first image is the tree before joining and the second is the tree after joining


Here is a problem from Ernst Kunz's Introduction to Commutative Algebra and Algebraic Geometry:  Let $K$ be an infinite field, $V \subset \mathbb{A}^n(K)$ a finite set of points. It's ideal $\mathfrak{J}(V)$ in $K[X_1, ..., X_n]$ is generated by $n$ polynomials. Hint: Interpolation.  note:  $\mathfrak{J}(V)$ consists of all $F \in K[X_1, ..., X_n]$ with $F(x) = 0$ for all $x\in V$  A similar question can be found in . The solutions given above are not complete and satisfying. I've tried some simple cases: $n = 1$ and $V$ is a single point. For other cases, I don't have any accessible solutions.   Anyone can help? Prefect the solution in the link or give an alternative approach to the problem. Thank you!

I am reading Gathmann's free online notes on Algebraic Geometry. One exercise asks to show that     "Every affine variety in $\mathbb A^n$ consisting of finitely many points can be written as the zero locus of $n$ polynomials".    There is a hint says "interpolation". I don't know how to start with the hint.   If $n=2$, we can use interpolation to get 1 polynomial for finitely many points. But we need to show 2 polynomials instead. I am also not sure how to apply interpolation for higher dimensions. Anyone can help? Thank you!


I was reading a book about general relativity and I came across these two equations  $$    \begin{align}     \mathrm{g}^{\mu\nu}_{,\rho}+     \mathrm{g}^{\sigma\nu}{\Gamma}^{\mu}_{\sigma\rho}+     \mathrm{g}^{\mu\sigma}{\Gamma}^{\nu}_{\rho\sigma}     -\frac{1}{2}(     {\Gamma}^{\sigma}_{\sigma}+{{\Gamma}^{\sigma}_{\sigma\rho}}     )     \mathrm{g}^{\mu\nu}     &=0, \tag1   \\     \mathrm{g}^{[\mu\nu]}_{,\nu}     +\frac{1}{2}(     {\Gamma}^{\rho}_{\rho\nu}-{\Gamma}^{\rho}_{\nu\rho}     )     \mathrm{g}^{(\mu\nu)}     &=0, \tag2     \end{align} $$ Where the connection is not symmetric with respect to the lower Indices.  and it says that by contracting equation (1) once with respect to ($\mu,\rho$), then with respect to ($\nu,\rho$), then subtracting the resulting equations we can get equation (2), however I can't see how that's possible.

Does anyone know how to get from (1) to (2) in the system  $$    \begin{align}     \mathrm{g}^{\mu\nu}_{,\rho}+     \mathrm{g}^{\sigma\nu}{{\Gamma}}^{\mu}_{\sigma\rho}+     \mathrm{g}^{\mu\sigma}{{\Gamma}}^{\nu}_{\rho\sigma}     -\frac{1}{2}(     {{\Gamma}}^{\sigma}_{\rho\sigma}+{{\Gamma}}^{\sigma}_{\sigma\rho}     )     \mathrm{g}^{\mu\nu}     &=0, \tag1   \\     \mathrm{g}^{[\mu\nu]}_{,\nu}     +\frac{1}{2}(     {{\Gamma}}^{\rho}_{\rho\nu}-{{\Gamma}}^{\rho}_{\nu\rho}     )     \mathrm{g}^{(\mu\nu)}     &=0, \tag2     \end{align} $$  by contracting equation (1) once with respect to ($\mu,\rho$), then with respect to ($\nu,\rho$)?  Where $\Gamma$ is not symmetric with respect to the lower Indices.  My attempt so far to solve this problem is: Well, when contracting with respect to μ and ρ I get: $$ -\frac{1}{2} g^{\rho \nu } {\Gamma} _{a\rho}^{a}-\frac{1}{2} g^{\rho    \nu} \Gamma _{\rho a}^{a}+g^{a\nu} \Gamma _{a\rho}^{\rho}+g^{\rho a} \Gamma _{\rho a}^{\nu}+g_{,\rho}^{\rho\nu}=0 $$ and when contracting with respect to nu and ρ I get: $$ -\frac{1}{2} g^{\mu \rho } \Gamma _{a\rho}^a-\frac{1}{2} g^{\mu    \rho} \Gamma _{\rho a}^a+g_{}^{a\rho } \Gamma _{a\rho}^{\mu }+g^{\mu a} \Gamma _{\rho a}^{\rho    }+g_{,\rho }^{\mu \rho }=0 $$ when subtracting these two equations I get: $$ \frac{1}{2} g_{}^{\mu \rho } \Gamma _{a\rho }^a-\frac{1}{2} g_{}^{\rho    \nu } \Gamma _{a\rho }^a+\frac{1}{2} g_{}^{\mu \rho } \Gamma    _{\rho a}^a-\frac{1}{2} g_{}^{\rho \nu } \Gamma _{\rho    a}^a+g_{}^{a\nu } \Gamma _{a\rho }^{\rho    }-g_{}^{a\rho } \Gamma _{a\rho }^{\mu }-g_{}^{\mu a}    \Gamma _{\rho a}^{\rho }+g_{}^{\rho a} \Gamma _{\rho    a}^{\nu }-g_{,\rho }^{\mu \rho }+g_{,\rho }^{\rho \nu }=0 $$ I cant see how this is equal to equation (2)


let spaceship = {   homePlanet : 'Earth',   color : 'red' }; let tryReassignment = obj => {   obj = {     identified : false,      'transport type' : 'flying'   }   console.log(obj) // Prints {'identified': false, 'transport type': 'flying'}   }; tryReassignment(spaceship) // The attempt at reassignment does not work. spaceship // Still returns {homePlanet : 'Earth', color : 'red'};   spaceship = {   identified : false,    'transport type': 'flying' }; // Regular reassignment still works.    Let’s look at what happened in the code example: We declared this spaceship object with let. This allowed us to reassign it to a new object with identified and 'transport type' properties with no problems. When we tried the same thing using a function designed to reassign the object passed into it, the reassignment didn’t stick (even though calling console.log() on the object produced the expected result). When we passed spaceship into that function, obj became a reference to the memory location of the spaceship object, but not to the spaceship variable. This is because the obj parameter of the tryReassignment() function is a variable in its own right. The body of tryReassignment() has no knowledge of the spaceship variable at all! When we did the reassignment in the body of tryReassignment(), the obj variable came to refer to the memory location of the object {'identified' : false, 'transport type' : 'flying'}, while the spaceship variable was completely unchanged from its earlier value.

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


I am making a side project in Java where a Mobile will store a list (ArrayList) of apps and separate UI class to handle all input/ output and business related logic. The problem is in following block of Mobile class:  public App searchApp(String name) {     System.out.println(list);     for(App app: list) {         String appName = app.getName();          if(appName == name)         {             return app;         }    }     throw new IllegalStateException(); }   This function let person search for the app in the list. And here's how the search input is being taken from user:  public String inputSearch() {     System.out.println("Enter app name to search: ");     return sc.nextLine().trim(); }   And here's how the UI class is displaying result:  public void choices(int choice) {        switch(choice)     {         case 1:             String[] input = inputDetails();             mobile.addApp(input[0], input[1]);             break;          case 2:             String s = inputSearch();             App found = mobile.searchApp(s);             System.out.println("App found in search:");             System.out.println(found.toString());             break;              and so on...   The problem is in searchApp.   I am unable to figure out why if condition is not working even though both appName and name can be seen as equal upon printing (also have used trim() on both string types but still no success).

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


After installing Drupal 8 (via installation wizard), trying to run any drush command, getting below error:  drush en views_ui PDOException: SQLSTATE[HY000] [2002] No such file or directory in core/lib/Drupal/Component/DependencyInjection/PhpArrayContainer.php on line 79 Drush command terminated abnormally due to an unrecoverable error.   Drupal version: 8.2.x  Drush version:  8.1-dev

I installed Drush for the first time (so it may be a configuration error) and I'm trying to update to the latest core version of Drupal.  Drush is giving me this error - I'm on an OSX box.  dev5:clientnamedirectory my.name$ drush pm-update projects drupal-7.25
Additional uncaught exception thrown while handling exception.

Original

PDOException: SQLSTATE[HY000] [2002] No such file or directory in drupal_get_installed_schema_version() (line 155 of /Users/my.name/Sites/proface/includes/install.inc).

Additional

PDOException: SQLSTATE[HY000] [2002] No such file or directory in system_list() (line 165 of /Users/my.name/Sites/clientnamedirectory/includes/module.inc).

  Drush command terminated abnormally due to an unrecoverable error.


I've just read the proof of $\S4$ (iv) in Mumford's "Abelian Varieties", on page 42-43, which says that multiplication by $n$ not divisible by $p=\text{char}(k)$ on an abelian variety $X$ is surjective.  I can understand that it works (as in, I can follow the proof line by line), yet I don't have intuition for it. In particular, I don't understand why does passing to tangent spaces work. It may be my poor understanding of tangent spaces and differentials.  It seems to say something along the lines of "surjectivity of multiplication by $n$" can be checked on first order linear approximations". Does this make any sense? Would this make sense for more general isogenies? A reference where this is discussed in more detail would also be welcome.

According with Mumford the answer is yes, but there are some obscure points in the proof.  We know that there exists a very ample line bundle on $A$ since every abelian variety is projective. Hence, via some corollaries of the Theorem of the Cube, we get an ample line bundle whose restriction to the kernel of $n_A$ is both the trivial bundle and very ample. This should imply that the dimension of $\ker n_A$ is $0$.  Furthermore, Mumford says that the fact that the dimension of the kernel is $0$ implies the surjectivity of $n_A$.  Is anybody able to clarify these two points to me?  Thanks in advance!


So from my understanding of final you can't change the value of variable after. In the case of a private final foo HashSet<>() = new HashSet<>() I can use foo as a HashSet and edit the values in it but I can't reassign foo right?

I can't understand where the final keyword is really handy when it is used on method parameters.    If we exclude the usage of anonymous classes, readability and intent declaration then it seems almost worthless to me.   Enforcing that some data remains constant is not as strong as it seems.    If the parameter is a primitive then it will have no effect since the parameter is passed to the method as a value and changing it will have no effect outside the scope.  If we are passing a parameter by reference, then the reference itself is a local variable and if the reference is changed from within the method, that would not have any effect from outside of the method scope.    Consider the simple test example below. This test passes although the method changed the value of the reference given to it, it has no effect.  public void testNullify() {     Collection<Integer> c  = new ArrayList<Integer>();           nullify(c);     assertNotNull(c);            final Collection<Integer> c1 = c;     assertTrue(c1.equals(c));     change(c);     assertTrue(c1.equals(c)); }  private void change(Collection<Integer> c) {     c = new ArrayList<Integer>(); }  public void nullify(Collection<?> t) {     t = null; }


I have no idea how to approach this problem. Please help. Thanks.

I've been wondering about this one for a while; I find it a little weird how abruptly it happens. Basically, why do we need just three uniforms for $Z_n$ to smooth out like it does? And why does the smoothing-out happen so relatively quickly?  $Z_2$:     $Z_3$:    (images shamelessly stolen from John D. Cook's blog: )  Why doesn't it take, say, four uniforms? Or five? Or...?


I want to know, if is possible found the arithmetic progression of four square number, with the same common difference.  \begin{align} \ & a^2 +r = b^2 \\   & b^2 +r = c^2  \\   &  c^2 +r = d^2  \\  \end{align}  where a,b,c,d,r $\in\mathbb{N}$  Hence, I found only triple succession.  For example: 1,5,7 because  \begin{align} \ & 1^2 +24 = 5^2 \\   & 5^2 +24 = 7^2  \\  \end{align} where the ratio is 24.  but I can't found a example with four number and the same common difference. at worst. Could you demonstrate that nonexistent using reductio ad absurdum to this statement?.

It is easy to find 3 squares (of integers) in arithmetic progression. For example, $1^2,5^2,7^2$.  I've been told Fermat proved that there are no progressions of length 4 in the squares. Do you know of a proof of this result?   (Additionally, are there similar results for cubes, 4th powers, etc? If so, what would be a good reference for this type of material?)    Edit, March 30, 2012: The following  in MO is related and may be useful to people interested in the question I posted here.