I am trying to understand non-interactive zero-knowledge protocols (NIZK). But, I encountered single theorem adaptive and non-adaptive NIZK protocols. According to my understanding,   In adaptive NIZK protocols, simulator ($S$) is divided into two stages ($S_1,S_2$) where in first stage it generates the common reference string and in second stage, it generates the proof for any input using common reference string generated in first phase.  In non-adaptive NIZK protocols, given an input, simulator outputs common reference string along with the proof.  Is this understanding correct?  Is there any way to covert a non-adaptive NIZK protocol to adaptive NIZK?  What is difference between single-theorem and multi-theorem NIZK?

Group Signature schemes are used to provide anonymity of the signers. During signature generation, signers provide a NIZK proof to prove that they are certified group members. Verifiers check whether the proof is valid during verification of signature. Can we use non-adaptive NIZK proof to prove signer is a certified group member?


I have read the question  and confirmed that my configuration works fine with valid non-Freetype font names as passed to, e.g., xfontsel. However, I would like to use Freetype fonts instead.  With urxvt I specify my font as xft:Source Code Pro:size=9 in my X resources; the same specification works fine when given directly with the -fn command line option.  However, if I use the same specification with the -f option to cssh or the terminal_font setting in .clusterssh/config I get an error message:  Fatal: Unrecognised font used (xft:Source Code Pro:size=9). Please amend $HOME/.clusterssh/config with a valid font (see man page).   How can I specify this font to ClusterSSH?  (For those whom might be helped by a look at the source code, the error originates in the get_font_size() function of /usr/share/perl5/App/ClusterSSH.pm on my system; I suspect it's the $xdisplay->QueryFont($font); call that's failing.)

In my cssh config file, I have:  terminal_font=6x13   this default font is too small for me.   man cssh says, I can specify other font size with the -f argument, while using "standard X font notation".  is a wikipedia page containing some other fonts types. Unfortunately, none of these work for me:  $ cssh host1 host2 -f "7x14" Fatal: Unrecognised font used (7x14). Please amend $HOME/.clusterssh/config with a valid font (see man page).   Why does "7x14" not work?  How can I use bigger fonts with cssh ?


When during a casting of a spell with a long casting time do you actually need the target to be present and valid?  This was brought up because of the question

The new School of Invention tradition for Wizards () while still in playtesting (and indeed a bit silly in my opinion, more of a "chaos wizard"), got me thinking about its reckless casting ability. This allows the caster to cast magic they do not have prepared and get a random result. The random spells have different targeting criteria (Wall of Stone, Fireball, Feign Death , Mass Cure Wounds) and so it is not possible to decide the target of the spell until it has been cast, as you don't know what you are going to get until it is cast.  This suggests that the designer of the subclass has made the assumption that you don't actually target until you have cast the spell and release it, which makes sense from one point of view, strongly supported by the way a prepared action casting works, PHB p.193 where you cast the spell and hold the energy until the condition is met for the readied action at which point you target the spell.  While the Unearthed Arcana is not RAW or finalized and released, my question is not about this subclass, but about the official rules as a whole.  Is there was any direct RAW, or other supporting or opposing RAW, that states at what point a caster defines the target of a spell?  As a sub-question: are there any circumstances where it actually matters, other than the already defined Readied Action spell casting, in the official rules?


I read this story in the 70s or 80s (it might however be older). I think it was a short story, and not a novel.  These are two scenes I remember:  In the beginning of the story a guy (lets call him Albert, not the real name) sits in a room, when suddenly a disk appears and somebody (Balbert) drops through it (it turns out it is Albert himself). Soon after this a third guy (Calbert, again an older version of Albert) appears, they all struggle a bit and then Albert falls through the disk (and into the past to appear as Balbert).   Somewhere in the story he reaches some kind of far future where he meets an old man (which later turns out to be Albert again) who explains him how to operate the machines.

Years ago I read short story about a man sitting in his room. Suddenly appears the same man but from the future and gives him an advice about the future. Original man seems to agree to follow that advice. Man from the future goes away. Then another version of that man from another future comes and gives a completely opposite advice and begs original man to follow it. Then this second version of this man from future also left. Original man stays alone not knowing which advice from future he must follow.


Why is the RMS voltage applied to the secondary not 3.3 V in Multisim? 120/36 = 3.3 V

What would be the calculation for the output voltage of this full wave bridge rectifier?    Thank you.


I was helping my sister with her server commands when I got stumped on this. I want to find if the player has a specific potion with this:  /testfor @a[team=Sandwings] {Inventory:[{id:"minecraft:splash_potion"}]}   and this:  {Potion:"minecraft:poison"}   But I don't know how to combine them.

I am making a Minecraft Mini Game adventure map, and one of the levels has a /setblock command, I am using the command in a way to spawn an item in a chest (Wooden Button) I need the wooden button to have CanPlaceOn tag so it can be placed on a log. I have tried this command: setblock 294 5 -1251 minecraft:chest 0 replace {Items:[{Count:1,Slot:0,id:minecraft:wooden_button,CanPlaceOn:[log]}]}`


Suppose we want the derivative of $f(x,y)$ in the direction of $\langle 1,1\rangle$. We must convert this to a unit vector: $\langle 1/\sqrt2, 1/\sqrt2\rangle$ in order to use the formula. So I don’t find it intuitive that the partial $x$ must be multiplied by $1/\sqrt2$ and the partial $y$ must be multiplied by $1/\sqrt2$, take the sum, and that’s your derivative in the direction $\langle 1, 1\rangle$.

Given a function f(x, y), the directional derivative is defined to be a(∂f/∂x)+b(∂f/∂y), with being a vector of unit length designating the direction in which we wish to take the derivative. I understand how we go from the limit definition of a derivative in the direction of unit vector to a(∂f/∂x)+b(∂f/∂y), but I do not understand how to interpret this theorem (Df(x, y) = a(∂f/∂x)+b(∂f/∂y)) GRAPHICALLY. It is hard for me to visualize the derivative at a given point (x, y) in the direction of  being a(∂f/∂x)+b(∂f/∂y). For example, evaluating f(x, y) at directional vector <1, 0> yields the derivative ∂f/∂x. I find it difficult visualizing what is happening when we evaluate the directional derivative at, say, f(1, 1) in the direction <1/√2, 1/√2>. I can't quite visualize why the partial derivative with respect to x at point f(1, 1) multiplied by the x component plus the partial derivative with respect to y at point f(1, 1) multiplied by the y component ends up being derivative at f(1, 1) in the direction of the vector. Can you explain what is happening?


This is making me go nuts. Whenever I'm trying to go to the numpad view, instead of going into the 2D and showing only 2 axis, it's trying to show and think about the depth of the third axis. This is how it should look:  This is how it looks instead:  Please help me, it has been bothering me for a while but I can't even find anywhere how to fix this (oh also the background isn't full of cubes either.. :(

I'm working on a scene that, currently, is much more convenient when the view is.. not the correct perspective. There's a word for this, but I have no idea how to phrase it and my tries to look it up has all come up with weird results. (usually directions on how to make your view point from a certain direction) This has probably already been answered here, so please bear with me; I just cannot find anything that has to do with the problem I'm having. I drew a photo to make it easy: (excuse my crappy mouse-drawing skills)  Thanks!


Let $f: \left[0,\infty\right)$ $\rightarrow\left[0,\infty\right)$ be a continuous function so that $f(f(x))=x^2,  \forall x\in \left[0,\infty\right).$ Show that: $$\int_{0}^{1}f^2\left(x\right)dx\geq\frac{3}{13} $$ I noticed $f$ is injective, so it is strictly monotone. Also, $f^2(x)=f(x^2), \forall x \geq 0$, but by substituting $x^2$ I'm getting nowhere. Do you have any ideas?

Let $f: [0,\infty) \to [0,\infty)$ be a continuous function such that $f(f(x)) = x^2, \forall x \in [0,\infty)$. Prove that $\displaystyle{\int_{0}^{1}{(f(x))^2dx} \geq \frac{3}{13}}$.  All I know about this function is that $f$ is bijective, it is strictly increasing*, $f(0) = 0, f(1) = 1, f(x^2) = (f(x))^2, \forall x \in [0, \infty)$ and $f(x) \leq x, \forall x \in [0, 1]$**. With all these, I am not able to show that  $\displaystyle{\int_{0}^{1}{(f(x))^2dx} \geq \frac{3}{13}}$.  *Suppose that $f$ is strictly decreasing. Then, $\forall x \in (0,1), x^2 < x \implies f(x^2) > f(x) \iff (f(x))^2 > f(x) \iff f(x) > 1$, which is false because, if we substitute $x$ with $0$ and with $1$ in $f(x^2) = (f(x))^2$ we get that $f(0) \in \{0,1\}$ and $f(1) \in \{0,1\}$. So $f$ is strictly increasing.  **Suppose that there exists $x_0 \in [0, 1]$ such that $f(x_0) > x_0$. Then, $x_0^2 = f(f(x_0)) > f(x_0) > x_0$, which is false. Then $f(x) \leq x, \forall x \in [0,1]$.  Edit:  I have come up with an idea to use Riemann sums, but I reach a point where I cannot continue.  Let $\epsilon < 1$. Then $f(\epsilon) = x_1$ and $f(x_1) = \epsilon^2$. And now $(f(\epsilon))^2 = f(\epsilon^2) = x_2$ and so on. Now we will use the Riemann sum:  We will take the partition $\Delta = (1 > \epsilon > \epsilon ^2 > ... \epsilon ^{2^n} >0 ) $and the intermediate points will be the left margin of each interval. Then we have:  $\displaystyle{\int_{0}^{1}{(f(x))^2 dx}}  = \displaystyle{ \lim_{\epsilon \to 1}{\lim_{n \to \infty}{\sum_{k = 0}^{n}{(\epsilon^{2^k} - \epsilon^{2^{k+1}})\epsilon^{2^{k+1}}}}}}$  I do not know how to compute this.


I launch script.sh and inside it i want to know what is his name   Is there a standard procedure to know the scripts name ? the idea is to be able to extract the name from teh full path + name contained in $0  Thanks

How can I determine the name of the Bash script file inside the script itself?  Like if my script is in file runme.sh, then how would I make it to display "You are running runme.sh" message without hardcoding that?


Working on an SMS app, which crashes upon reciept of a new message. The issue seems to lie in the Broadcast Receiver for incoming SMS but I can't figure out why.  The Broadcast Receiver:  public class SMSBroadcastReceiver extends BroadcastReceiver {       public static final String SMS_BUNDLE = "pdu";       public void onReceive(Context context, Intent intent) {          Bundle intentExtras = intent.getExtras();           if (intentExtras != null) {              Object[] sms = (Object[]) intentExtras.get(SMS_BUNDLE);              String smsMessageStr = "";              for (int i = 0; i < sms.length; ++i) {     //Line 24                  String format = intentExtras.getString("format");                  SmsMessage smsMessage = SmsMessage.createFromPdu((byte[]) sms[i], format);                   String smsBody = smsMessage.getMessageBody().toString();                  String address = smsMessage.getOriginatingAddress();                   smsMessageStr += "SMS From: " + address + "\n";                  smsMessageStr += smsBody + "\n";              }               Toast.makeText(context, "Message Received!", Toast.LENGTH_SHORT).show();               if (MainActivity.active) {                  MainActivity inst = MainActivity.instance();                  inst.updateInbox(smsMessageStr);              } else {                  Intent i = new Intent(context, MainActivity.class);                  i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);                  context.startActivity(i);               }          }      }  }   I labeled line 24 where the exception gets called.  The Error:  E/AndroidRuntime: FATAL EXCEPTION: main     Process: com.example.haltaar.texting, PID: 15909     java.lang.RuntimeException: Unable to start receiver com.example.haltaar.texting.SMSBroadcastReceiver: java.lang.NullPointerException: Attempt to get length of null array       at android.app.ActivityThread.handleReceiver(ActivityThread.java:3194)       at android.app.ActivityThread.-wrap17(Unknown Source:0)       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1672)       at android.os.Handler.dispatchMessage(Handler.java:106)       at android.os.Looper.loop(Looper.java:164)       at android.app.ActivityThread.main(ActivityThread.java:6494)       at java.lang.reflect.Method.invoke(Native Method)       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)     Caused by: java.lang.NullPointerException: Attempt to get length of null array       at com.example.haltaar.texting.SMSBroadcastReceiver.onReceive(SMSBroadcastReceiver.java:24)       at android.app.ActivityThread.handleReceiver(ActivityThread.java:3187)       at android.app.ActivityThread.-wrap17(Unknown Source:0)        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1672)        at android.os.Handler.dispatchMessage(Handler.java:106)        at android.os.Looper.loop(Looper.java:164)        at android.app.ActivityThread.main(ActivityThread.java:6494)        at java.lang.reflect.Method.invoke(Native Method)        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)    Can anyone help shed some light on this? AFAIK all permissions are being called correctly, and the check to see if intentExtras is null should stop the sms object from being null when checked? Or am I missing something?

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?


Alright so most of the people have their desktop having some missing icons but i'm not really having this problem, the real problem is that all the apps in finder are missing icons and sometimes they reappear weirdly...    DolphinEMU's icon is the most inactive.  When i look up on finder... this happens...    Yes it's french, but almost all my apps have no icon and they reappear sometimes. they still run perfectly.

I've been having this problem for a while now and it really starts to bother me. Every once in a while, a lot of my app icons go missing in the dock, launchpad, finder, cmd-tab switcher, just everywhere.   Some pictures:      Obviously this is really annoying. I already tried a lot of stuff to solve it.   I tried relaunching the Finder I tried relaunching the Dock (terminal: killall Dock) I tried clearing icon cache   The only way I can (temporarily) solve this by doing the following:   Reboot, now the icons have reloaded in finder and launchpad, dock icons are still missing go to Library/preferences/com.apple.dock.plist & delete the file open terminal: killall Dock   This way everything is fixed, but I have to rearrange my dock again since I removed the preferences file. It is only a temporary fix though, the issue keeps coming back and I always have to do this, which is very annoying.  Does anyone know what causes this? How could I solve it permanently? It’s really getting frustrating!  Thanks a lot!


So, you've got a new user.  They ask a really poor question (P.SE ) poorly written, off topic, or any other number of other things.  There is no way to redeem such a question on the site, it falls into the embarrassingly bad category and got deleted. There is only so much down voting and trying to help in the comments can be done (comments are a poor way to educate someone about the fundamentals of asking a question on Stack Exchange... but thats another matter).  in this particular anecdote, the person came to MSE and asked, and was given the advice to ask on the .  However, the question was asked on  and then .  One difficulty in this entire process is that it means that without that sympathy up vote on the misasked question on the main site, the OP is completely unable to ask on the per site meta.  Help > Privileges >      Participate In Meta   Privilege Type: Communication Privilege   Awarded At: 5 Reputation   And so, the person who asks a really poor question can't get to meta to ask why its really poor without a sympathy up vote.  And so, without excess bouncing of a person through the meta bureaucracy, how can we actually get someone to be able to ask on meta with only 1 rep?  Ok... so the reasoning behind this is:     Because we allow anonymous participation, we require a small bit of parent site reputation to prevent spam, and ensure that meta is for active, engaged members of the community.   Unfortunately, I don't know how often other sites get meta spam... or how prevalent it was in days before this permission was put in place.  Proposal:   Is the requirement of 5 rep or a registered user sufficient to keep away the meta spam while allowing people who genuinely need help the ability to post on meta (without coming over to MSE where the question is off topic)?

We currently require that new users have 5+ reputation to participate in meta support discussions (bugs, feedback, governance, etc). This is primarily because the use case for meta is not intrinsically obvious, so we require a modicum of "experience" with the site before jumping into it.   But that blocks new users with legitimate questions about their own posts.  Setting aside any arguments about new-users-are-evil-and-suck-the-life-out-of-our-community, I would like to propose a very specific path for new users to ask about their own question provisionally.  Instead of blocking a new user with this message:     You must have at least 5 reputation on <site> to ask a question on meta.   We can change this to:     You must have at least 5 reputation on <site> to post on meta, but you may ask a question about your own post specifically.      Link to your post:                                                                                ask about this post   cancel    The system will check whether the linked question provided belongs to the author. . The user can then proceed with the post provided they leave the template (below) intact:     Title                                                                                <!--Do not remove-->   <!--Note: Questions not about your post will be deleted-->      I have a question about the post:       <!-- Your question below: -->         Not only is this a great and gentle introduction to the proper use of meta, but it stands to help new users just when they need it most (learning to use the community).   Of course this doesn't 100% guarantee that someone won't get it wrong on occasion. But this is an awful lot of in-your-face guidance without simply telling people "read our FAQ" (which they never do). And if a user manages to step over all that guidance and still manages to misuse meta, I have no compunction about summarily removing a question they should never have posted.   But this just-in-time learning is a very effective way of learning a new site in a gentle and thoughtful way. If this is abused more often than not, it is easy to disable. But it's better than assuming clueless newbie every time.


I want to find a number or string in a very large database. Is there any way to make an SQL Query that searches the entire database, and not just a single table?  I'm looking for something like:  select * from *;

Given a number, how do I discover in what table and column it could be found within? I don't care if it's fast, it just needs to work.


I'm an absolute newbie at Blender and 3d, and I'm trying to build a scene using geometry nodes.  My problem is that this grass intersects the trees. Is it possible to mix point distribution nodes to substract the tree points from the distribution density of the grass points? It would be cooler with less grass under the trees because the lack of light under the trees doesn't allow grasses to grow as well.

I have an issue with a rig (this is my first time rigging) where it requires the subtraction of the weights of many different Vertex Groups from the head (root) vertex group to make the rig function properly.    Here is an image showing what I wish to accomplish:    The result image is an inversion of the middle image. Do keep in mind that inversion will not cut it, since I have to remove more things from the head (root) vertex group other than just the jaw itself.  Using the remove button in the vertex group tab gives me this result    This is not satisfactory, as it removes the vertices from the vertex group, but does not subtract the weight values from it.  Google has not turned up anything so far.  Normalizing solves nothing as it still causes deformation when moving parts with Children i.e. opening and closing the jaw deforms the lower lip bones.  Removing the influence of the head (root) bone will also cause irregular behavior as well since Blender treats all weights which aren't zero as one regardless of the weight assigned due to the vertices needing a weight of one.


At the bottom of man pcregrep, there is a message:  SEE ALSO         pcrepattern(3), pcresyntax(3), pcretest(1).   However, when I try to view man pcresyntax I get:  $ man pcresyntax No manual entry for pcresyntax $ man 3 pcresyntax No entry for pcresyntax in section 3 of the manual $ man -k pcre pcre-config          (1)  - program to return PCRE configuration pcregrep             (1)  - a grep with Perl-compatible regular expressions pcre_table           (5)  - format of Postfix PCRE tables pcretest             (1)  - a program for testing Perl-compatible regular expressions   I tried yum info pcresyntax and even yum search pcresyntax and got nothing.  At the suggestion of some comments posted below, I tried yum provides pcresyntax and yum whatprovides pcresyntax and got no results.  (This box is running CentOS 6.6.)  What package includes the man page pcresyntax?  More importantly, how can I find out what package includes a man page that I am missing?  (This is primarily for missing man pages that are mentioned in other man pages, rather than missing man pages for an installed command.  In other words, man pages that are not obviously associated with a given command.)    NOTE: I work with Linux professionally and I am interested in broadly applicable answers, as well as answers specific to any of the major package managers.  pcresyntax is just a specific example of a missing man page, not the end-all of my question.  Currently at work I primarily use yum, mostly on RHEL/CentOS 6, and I asked the title question rather than "where can I find the pcresyntax man page?" because I would like to know as much as possible about how to find and install missing man pages, for professional use both now (RHEL/CentOS) and in the future (Ubuntu/Debian, OpenSUSE, ...?)  Since asking this question I also found the  which answered all my immediate questions about PCRE.  ;)

On Debian systems (and derivatives):  $ dpkg --search /bin/ls coreutils: /bin/ls   That is, the file /bin/ls belongs to the Debian package named coreutils.  But this only works if the package is installed. What if it's not?


We frequently see blocking on our SSRS box which houses both front-end Report Manager ReportingService and the SQL database engine with ReportServer & ReportServerTempDB Catalog databases  Blocking session:     Database name: ReportServer     Application name: Report Server     Host name: SSRS01     OS User name: SYSTEM     Database User name: NT AUTHORITY\SYSTEM     First 2KB of SQL: CREATE PROCEDURE [dbo].[CheckSessionLock] @SessionID as varchar(32), @LockVersion  int OUTPUT AS DECLARE @Selected nvarchar(32) SELECT @Selected=SessionID, @LockVersion = LockVersion FROM [ReportServerTempDB].dbo.SessionLock WITH (ROWLOCK) WHERE SessionID = @SessionID  Blocked session:     Database name: ReportServer     Application name: Report Server     Host name: SSRS01     OS User name: SYSTEM     Database User name: NT AUTHORITY\SYSTEM     First 2KB of SQL: CREATE PROCEDURE [dbo].[CheckSessionLock] @SessionID as varchar(32), @LockVersion  int OUTPUT AS DECLARE @Selected nvarchar(32) SELECT @Selected=SessionID, @LockVersion = LockVersion FROM [ReportServerTempDB].dbo.SessionLock WITH (ROWLOCK) WHERE SessionID = @SessionID   Anyone else experience this, and fix it ?

We have a busy SSRS Reporting server (SQL Server 2008 R2) on which we see frequent blocking between the below processes:   [dbo].[CheckSessionLock]  [dbo].[WriteLockSession]   We are aware that some reports are running unacceptably slow. What I need to know is whether the blocking in the ReportServer database is symptomatic of an overloaded server or whether the blocking is causing the reports to run slow.   I am inclined to believe it is the first case but haven't been able to gather evidence prove it definitively as such.   I have read the thread at  in which the issue is loosely acknowledged but I cant get to the link cited for addressing this issue.  Has some out there got to the bottom of same problem with blocking in the ReportServer database?


I have a script that runs perfectly. Problem is I have to make this script not readable to users. I think i turned it to a binary file by executing:  cat script | bzip2 -c |  gzip -c > script.sh  But it is not running on that format. Any other way I can make this script not readable and still be able to execute it?

I'm running Ubuntu. I need to know any way to obfuscate .sh shell script file contents in order to make it very difficult to read.  Any suggestion are welcome, including using online obfuscator.


Are there any Mac apps that are very similar to Microsoft Paint besides Paintbrush and Paint.net? I've tried those apps but found a lot of quirkiness and am looking for something more polished and user friendly.

I tried out several image editors mentioned on  but some of them (like  and ) were very disappointing. These apps were too simple and low level.  What do you suggest for a (preferably free) image editor on OS X?  P.S: I was using  on Linux and also know that it was released for OS X too, but I want to find new good applications.


Can two or more instances of the following deadlock with one another?  START TRANSACTION SELECT mycolumn FROM mytable WHERE myid IN (list-of-ids) FOR UPDATE : COMMIT   Points to keep in mind:   mycolumn is indexed This is mariaDB/innoDB There is only one table involved (mytable)   Example A:  Thread 1:      START TRANSACTION     SELECT mycolumn FROM mytable WHERE myid IN (100,200) FOR UPDATE     :     COMMIT      Thread 2: (note that IN-list is in opposite order)      START TRANSACTION     SELECT mycolumn FROM mytable WHERE myid IN (200,100) FOR UPDATE     :     COMMIT       Could these threads possibly deadlock on the SELECT in mariaDB/innoDB?  Example B:  Thread 1:      START TRANSACTION     SELECT mycolumn FROM mytable WHERE myid IN (100,200) FOR UPDATE     :     COMMIT      Thread 2: (note that IN-list is in same order)      START TRANSACTION     SELECT mycolumn FROM mytable WHERE myid IN (100,200) FOR UPDATE     :     COMMIT       Could these threads possibly deadlock on the SELECT  in mariaDB/innoDB?  UPDATE: A traditional way of avoiding deadlocks is to be sure to acquire locks in the same order, so that you can't have Thread 1 owning lock A and waiting on lock B while Thread 2 owns lock B and is waiting on lock A. However, I've seen several posts suggesting that even getting a single lock can't be considered atomic, because there are asynchronous processes going on in the engine that could still result in deadlock (and as a corollary to this, advising developers to always expect deadlocks and recover from them by retrying the transaction). I'm really asking whether deadlock can be eliminated by using proper coding practices in innoDB.)

I am .  I am going to have to update a program to allow deadlocks. Is it possible that SELECT statement will produce deadlock errors? I know that it is only a read lock so multiple selects won't be a problem, but what if there is an INSERT, UPDATE or DELETE statement (with subqueries possible with joins) and a SELECT statement (possible with joins or subqueries)?   Is it possible that the error will be thrown on the SELECT instead of the INSERT, UPDATE or DELETE.


I am working at a governmental office and we are required to only produce accessible PDF files. In practice that means that generated PDFs have to pass Adobe's accessibility checker or the "PDF Accessibility Checker".  Since I have to write lots of technical documentation, I would really like to use Tex.  Is there any kind of workflow/tutorial on how to create accessible PDFs? The only thing I could find were this presentation (in German:  ) which references a thesis by Babette Schalitz, but these links are offline. Also, the presentation does not include any kind of tutorial on actually create a PDF.  Is this a lost cause?

Does anyone know of any LaTeX modules that makes the pdf output generated by pdflatex / compliant?  Specifics:   With regard to math. One simple solution is to embed the latex equation as an alt tag. Simpler, and IMO better than translating to MathML. With regard to graphics. I use dot to generate the graphics. A simple solution here is to embed the .dot file as an alt tag for the figure.   Is there any way to generate alt tags with pdflatex?


I've just run the Update Manager on Ubuntu 11 to upgrade to 12.   I was watching the 'terminal' output in the manager, with Thunderbird open in the background, when everything was hidden by my desktop backiground image. Or that is how it seems - every now and again I see the apps open, and then the bg covers them again.  Mouse is responding, no keyboard button seems to take effect (have not pressed ESC).  I've left it for an hour or so --- is this normal?  It's not a brand new machine, and although I don't know the specs, it is not terribly slow usually.  Any suggestions would be appreciated!  This was 11 - 11.4, I think but I may be wrong - to 12 - 12.4 I thought, but I may be wrong.  In any case, I am using the Update Manager to perform the task: this is my first time, and it's not my machine, so I thought I'd try the simplest thing that would keep as much intact as possible.

I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please?


I successfully installed Ubuntu Gnome 15.10 along with Windows 10 on my Satellite laptop, but after some boots Windows abruptly decided to put MBR on top of GRUB. No way to get back into Ubuntu, I tried to run a grub-update on live USB (after the relevant mounts) but nothing changed.   If I try to reinstall the GRUB following this  I get this error:  root@ubuntu-gnome:/# grub-install /dev/sda Installing for x86_64-efi platform. grub-install: error: cannot find EFI directory.   Here's my partition table, if it may help:  Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt Disk identifier: 9FEFCFA9-CD66-11E3-8DDC-CA6477994E64  Device          Start        End    Sectors   Size Type /dev/sda1        2048    2099199    2097152     1G Windows recovery environment /dev/sda2     2099200    2303999     204800   100M EFI System /dev/sda3     2304000    2566143     262144   128M Microsoft reserved /dev/sda4     2566144 1827946926 1825380783 870.4G Microsoft basic data /dev/sda5  1927376896 1929019391    1642496   802M Windows recovery environment /dev/sda6  1929019392 1953523885   24504494  11.7G Windows recovery environment /dev/sda7  1827948544 1914957823   87009280  41.5G Linux filesystem /dev/sda8  1914957824 1927376895   12419072   5.9G Linux swap

I have a Sony VAIO S series with Windows 8 preinstalled, and I installed Ubuntu 12.10 on a new partition. When the PC boots Grub is display, and I can choose between Windows 8 (didn't worked at the beginning, had to change Grub settings) and Ubuntu 12.10. When I select Ubuntu 12.10 everything is OK, but when I use Windows 8, and I restart Grub isn't displayed anymore (Windows 8 boots immediately).  I booted a Ubuntu 12.10 LiveUSB, used efibootmgr, and found out that Windows 8 (each time it boots) changes EFI default bootloader from Grub to Windows Boot Manager.  How do I change this in Windows 8? I read something about bcdedit, but it does not work or I don't know how to use it...


I am trying to change my theorem environment, and I played a little with MetaPost (that I don't know well, being more of a TiKz user). I ended with this layout (which I really like) with the help of , but the behavior doesn't fit : it uses the last \MPtext for all calls to the textbackground (see MWE below). When I place a big chunk of text and theorems in a bufer, the behavior is even worse. Is there a way to correctly handle this ? Thank you in advance, \startuseMPgraphic{mp:axiomframe}   begingroup;     numeric u; u := 1EmWidth;     for i=1 upto nofmultipars :       pair bl, br, ul, ur;       bl := llcorner multipars[i]; br := lrcorner multipars[i];       ul := ulcorner multipars[i]; ur := urcorner multipars[i];       % Draw the surrounding box       path p;       p := ( bl -- br -- ur -- ul -- cycle ) enlarged (-0.5u,0.5u) ;       fill p withcolor 0.95 white ;       draw p withcolor 0.8 white ;       draw (p cutbefore point 0 of p cutafter point 2 of p) withpen pencircle scaled 1.2bp withcolor 0.8 white ;       p := ( ul -- (ul shifted (0,-2u)) -- (ur shifted (0,-2u)) -- ur -- cycle) enlarged (-0.5u,0.5u);       picture lab;       lab = thelabel.lrt(\MPstring{TitreTh},ul) shifted (2u,u);       p := (llcorner lab -- lrcorner lab -- urcorner lab -- ulcorner lab -- cycle) enlarged (0.5u,0.5u);       draw p withpen pencircle scaled 1.2bp withcolor 0 white ;       fill p withcolor 0.8 white;       draw lab;      endfor ;   setbounds currentpicture to OverlayBox ;   endgroup; \stopuseMPgraphic  \definetextbackground   [theoremFrame]   [mp=mp:axiomframe,     location=always,     leftoffset=1em,rightoffset=1em,     topoffset=0ex,bottomoffset=0ex,     frameoffset=5\bodyfontsize,     before={\testpage[3]\blank},     after={\blank[medium]}]  \def\starttheorem[#1]{   \setMPtext {TitreTh} {\bf #1}   \starttextbackground[theoremFrame]   \vskip 1em } \def\stoptheorem{\flushsidefloats\stoptextbackground\\\blank[big]}   \starttext \starttheorem[Knuth]   \input knuth \stoptheorem  \vskip 2em  \starttheorem[A formula]   \startformula     a + c = x   \stopformula \stoptheorem \stoptext

How do you make an enumeration where the enumeration counter appears within a frame decorated with Metafun?  The idea is to have something similar to an example on pg. 144 of the Metafun manual:    Except that "Zapf (1)" would be a counter rather a manual label.  Here is the code that reproduces the example with the manual frame:  \startuseMPgraphic{FunnyFrame}   picture p ; numeric w, h, o ;   p := textext.rt(\MPstring{FunnyFrame}) ;   w := OverlayWidth ; h := OverlayHeight ; o := BodyFontSize ;   p := p shifted (2o,h-ypart center p) ; draw p ;   drawoptions (withpen pencircle scaled 1pt withcolor .625red) ;   draw (2o,h)--(0,h)--(0,0)--(w,0)--(w,h)--(xpart urcorner p,h) ;   draw boundingbox p ;   setbounds currentpicture to unitsquare xyscaled(w,h) ; \stopuseMPgraphic  \defineoverlay[FunnyFrame][\useMPgraphic{FunnyFrame}] \defineframedtext[FunnyText][frame=off,background=FunnyFrame] \def\StartFrame{\startFunnyText} \def\StopFrame {\stopFunnyText } \def\FrameTitle#1% {\setMPtext{FunnyFrame}{\hbox spread 1em{\hss\strut#1\hss}}} \setMPtext{FunnyFrame}{}  \starttext  \FrameTitle{Zapf (1)} \StartFrame Coming back to the use of typefaces in electronic publishing: many of the new typographers receive their knowledge and information about the rules of typography from books, from computer magazines or the instruction manuals which they get with the purchase of a PC or software. \StopFrame  \stoptext   I was able to make enough progress to add an answer to this problem, but I'm still unsure if it's the right way to go.


I have found the articles describing the python scripts to automatically convert, but the scripts seem to have been deleted, presumably because they have stopped working.  For example, looking for materials_cycles_converter.py in the diffusion browser produces the message "This path does not exist at rBAC89bfa619831c. It was deleted in 7d7b8c7d3efc and last existed at rBAC3f433bbe91fd." Is there an alternative script that I haven't found?  Or a tutorial?  -- edit: I originally mistakenly used 'textures' where I should have used 'materials' in the title.

I know this may be a tough or confusing question, but I have numerous existing materials I created and reuse for a project, which were all prepared for Blender Internal.  Now, I want to start the transition to Cycles, but I've hit a roadblock. How can I transition my materials without completely starting over? Or should I just forget it and start with fresh materials?


Prove that $\mathbb Z^n$ is not isomorphic to $\mathbb Z^m$ for $m\neq n$.   My try:  Let $\mathbb Z^n\cong \mathbb Z^m $. To show that $m=n$.  Case 1: Let $m>n$. Now that $\mathbb Z^m$ has $m$ generators whereas $\mathbb Z^n$ has $n$  generators and an isomorphism takes a generator to generator ; that is the contradiction.  Please correct me if I am wrong.  The case  $m<n$ also follows similarly.

Let $m$ and $n$ be two nonnegative integers. Assume that there is a group isomorphism $\mathbb{Z}^m \cong \mathbb{Z}^n$. Prove that $m = n$.   I tried using a contrapositive, ($m \neq n$ implies $\mathbb{Z}^m \ncong \mathbb{Z}^n$), and I think the problem is that there won't be a homomorphism, but did not get anywhere. Is there a better approach to this problem?


I do not have access to the original data set. AB: Overall mean: 149.41   sd: 89.13 N: 2284 B: Subset  mean: 110.98    sd: 73.53 N:  917 I need to determine the original mean and standard deviation or variance of the original A set that is combined in the set AB In order to determine the mean of A given sd, and N of AB and B we can do: mean(AB-B) = (149.41*2284 - 110.98*917)/(2284-917) = 175.19 Is it possible to determine the standard deviation or variance of the set AB=(AB-B) given the limited data? Update: @WHuber suggested @Ben's post  which suggests:  I converted that to R, tested it and indeed it works. pooledSD=function(n1,n2,m1,m2,s1,s2) {     sqrt( 1/(n1+n2-1)*( (n1-1)*s1^2 + (n2-1)*s2^2 + (n1*n2)/(n1+n2)*(m1-m2)^2)) }  Testing the above on a synthetic data works perfectly for the union of sets. Using algebra and solving for s1^2, I get:  I  tested the above function now and it works! P.S. I appreciate the additional background that Ben gives below.

Say there are $m+n$ elements split into two groups ($m$ and $n$). The variance of the first group is $\sigma_m^2$ and the variance of the second group is $\sigma^2_n$. The elements themselves are assumed to be unknown but I know the means $\mu_m$ and $\mu_n$.  Is there a way to calculate the combined variance $\sigma^2_{(m+n)}$?   The variance doesn't have to be unbiased so denominator is $(m+n)$ and not $(m+n-1)$.


Trying quantum teleportation in   Succesful runs in 'qasm_simulator', but when switching to IBMQBackend('ibmqx2') I get IBMQJobFailError

I am trying to build a circuit for quantum teleportation. On the simulator, everything runs fine and according to expectations, however, I am not able to run the algorithm on the real quantum processor.  ERROR_RUNNING_JOB is returned without any other explanation. I tried to implement two different circuits, the first one with controlled X and Z gates, the second one with gates X and Z are controlled by a value in the classical register. Please find both circuits below.  I appreciate any help.  Thanks.


I have an input string of integers separated by space. string input = "116 119 220 250";  How do I split this string and store each number in vector of integers?

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


Is there a word for this action? The action could lead to a full on crying or not.

What do you call this facial expression that forms just before bursting into tears? (Especially when a baby has been treated in a way he/she didn't expect and consider it unfair or feels neglected. Of course this pitiful and sad expression with lower lip protrusion is most commonly seen in younger kids; and is not acceptable for adults or they will be considered to react childish.)  Actually I need to know the answer to complete these sentences :  "When the father yelled angrily at the baby, he (the baby) ..(?) and then burst into tears. "  "When the mom took the toy from the baby, he ...(?) and cried."      PS: We have a phrasal verb in Farsi for describing this state and we use it for kids or adults, but when we hear it about a kid we would definitely think of a baby with this facial expression specially with the protruded lower lip. For adults, we would think of them in the state just before bursting into tears, for example; some winners react like this when they recieve their awards or when they are about to make a speech.   Note: Since I need to complete those sentences and they are about kids, if I know the term used for talking about/ referring to this kids' facial expression or state, that would solve my problem.


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

I'm not asking about general syntactic rules for file names. I mean gotchas that jump out of nowhere and bite you. For example, trying to name a file "COM<n>" on Windows?


When I put this in my code in swift 3 with xcode :               myarray.append(99.1)    I have following result when I use print(myarray) command for my array:     99.099999999999994   I would like to have only 99.1 no more. How can I add a value like 99.1 without being transform to the longer value in an array?

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


How to prove $\Bbb Z[i]/(1+2i)\cong \Bbb Z_5$?   My method is   $$(1+2i)=\big\{a+bi丨a+2b≡0\pmod 5\big\},$$  So any $a+bi$ in $\Bbb Z(i)$,we got  $$a+bi=(b-2a)i+a(1+2i).$$  So $\Bbb Z[i]/(1+2i)=\big\{0,[i],[2i],[3i],[4i]\big\}$.  I know how to prove this ring is isomorphic to $\Bbb Z_5$, but how can I prove that $\Bbb Z[i]/(1+2i)$ equals to  $\Bbb Z_5$ directly? Any suggestion ia appreciated.

A very basic ring theory question, which I am not able to solve. How does one show that    $\mathbb{Z}[i]/(3-i) \cong \mathbb{Z}/10\mathbb{Z}$. Extending the result: $\mathbb{Z}[i]/(a-ib) \cong \mathbb{Z}/(a^{2}+b^{2})\mathbb{Z}$, if $a,b$ are relatively prime.   My attempt was to define a map, $\varphi:\mathbb{Z}[i] \to \mathbb{Z}/10\mathbb{Z}$ and show that the kernel is the ideal generated by $\langle{3-i\rangle}$. But I couldn't think of such a map. Anyhow, any ideas would be helpful.


I read this English young adult fiction book 5-6 years ago. This has probably a been brought out after 2000.  All I remember is that the main character-a boy visits a place where people are in some kind of induced-dream state. The "dream-world" offers them things that are not achievable in the real world. The caretaker of the place tells the protagonist that people prefer to be in that world rather than the real one.  Also I remember mentions of there being more than one sun .In another book of the same series,the main character gets treated to wellness in a tribal house-a girl tends to him there.There also is a contest of some sort in one of the books,the protagonist is the youngest person in it and yet he wins(something conducted for the entertainment of some other people).

I read this story about five years ago (so make it about 2009) and the book (from the library) was reasonably tattered, but I'd say only 5 to 10 years old (this is just a rough guess). This was a novel, I think about 300 pages, but again I don't recall it very well so that could also be completely wrong.  I do remember it wasn't a huge tome though.  Most importantly: the narrative.  This story involved a teenage boy who was recruited by a man on a motorbike to help in some expedition; I think they were part of a group involved in some sort of missions against an evil group (again I can't recall exactly what).  This man (who I think was his Uncle 'Bob' or something like that) took him to a subway station and they only just made it to a portal to another world.  I think I'm missing a huge portion of the story, but at the end I recall they ended up in another world (through a portal of some description).  It was an ice world with a pre-Industrial civilization.  The key part of this novel that was members of this group trying to thwart the antagonists could only use a dog whistle; nothing else from a different world/time period could be used in that place.  This was emphasized regularly and when the main character went to the ice world, he got into considerable grief with his mentor (the Uncle Bob character) for using a torch from his original time period.  I think it was set about the early 2000s.  One last piece of information I recall was that this guy was regularly going on about three girls who were perfect at everything they touched.  He had a crush on one called Courtney.  Sorry for the vague details at the beginning, but hopefully the narrative description could prove useful.  Thanks ;)


Recently I've published my recent WordPress post on my blog. Normally whenever I post something on my blog It gets indexed almost instantly. But that didn't happen with my recent post.  I've asked from some of my colleagues about this incident and they told google can take up to 4 to 5 days to index new content. So I checked after 3 days by searching site:mydomain.com and I got my new post in results. In fact, it was ranking on the first page with targeted keywords.  But now after a week, It is again removed from the Google index. even its not coming by typing site:example.com.  I think this post appears to be suspicious to google bot because of this paragraph:     After implementing this technique I had reduced the response time from   1.5  seconds to under 170 milliseconds. So you can expect a 94% reduction in server response time if you also have a response time of   1.5 seconds or above.   Also, I've tried requesting google to index the new post from google webmaster.  Not this question is not only about Google not indexing a page. Google did index this page but now it has been removed from the index.  Update The content in the post is 100 % unique.

This is a general, community wiki  question and answer pair intended to address any questions   concerning the reasons a site or specific site contents do not appear   in search engine results.      If your question was closed as a duplicate of this question and you   feel that the information provided here does not provide a sufficient   answer, please open a discussion on .   My site (or specific pages on my site) is not appearing in search engine results.  Why isn't my content indexed and what can I do about it?


I created a table using the following code:  \begin{tabular}{>{\centering\arraybackslash}c >{\centering\arraybackslash}p{3.5cm} p{7cm}}  Parameter& Value & Remark      \\   \hline \hline      $\alpha$            & $1[-]$   & Reference angle.          \\     \hline      $\alpha_{\scaleto{1}{3.5pt}}$       & $\beta_{\scaleto{1}{3.5pt}}$     &Inflow angle.  \\     \hline     $\delta$      & $\num{0.5894}c = \SI{0.59475}{\mm}$  $\num{9.87}  / c_{ax} = \num{5.874}$    & \multicolumn{1}{c}{$-$}           \\     \hline \end{tabular}   The output of which is:   I would like to center align only the text in the fourth row and third column vertically i.e., -. I want other entries in the third column to be left aligned. How can I achieve this?

I have the code:  \documentclass{article} \usepackage[a4paper]{geometry} \usepackage{tabularx} \usepackage{lipsum} \begin{document} \begin{tabularx}{\textwidth}{ | X | c | }   \hline   \lipsum[1] & top\\   \hline   \lipsum[1] & center\\   \hline   \lipsum[1] & bottom\\   \hline \end{tabularx} \end{document}   Gives this:    The top row is already aligned top. How can I vertically align the center row at the center? And the bottom row at the bottom?


Let $p$ be a fixed prime in $\Bbb Z$ and $Ab$ represent the category of abelian groups.  Define a functor $F : Ab \rightarrow Ab$ by $F(G) = G/pG$ and $F(f) = x + pG \rightarrow f(x) + pH$ (where $f:G \rightarrow H$ is a homomorphism)   What does $pG$ mean for an abelian group?  I am familiar with the notation $aG = \{ag : g \in G\}$, but $G$ isn't specified to be an integer group which would be compatible with a prime $p$.

Jack is trying to prove:     Let $G$ be an abelian group, and $n\in\Bbb Z$. Denote $nG = \{ng \mid g\in G\}$.      (1) Show that $nG$ is a subgroup in $G$.      (2) Show that if $G$ is a finitely generated abelian group, and $p$ is prime,    then $G/pG$ is a $p$-group (a group whose order is a power of $p$).   I think $G/pG$ is a $p$-group because it is a direct sum of cyclic groups of order $p$. But I cannot give a detailed proof.


This question is about datagram socket not tcp sockets, so please review it first before thinking its duplicate Is there a way to check the port before creating a new DatagramSocket. When the port is in use for example by another instance the code below throws SocketException      socket = new DatagramSocket(4446);   I would like to have it checked before I create the DatagramSocket object. So that if it is not available I can increment it and check again untill it becomes available and then I create the Socket ?

How do I programmatically determine the availability of a port in a given machine using Java?  i.e given a port number, determine whether it is already being used or not?.


Orcus, the demon lord of undeath, is listed in Mordenkainen's Tome of Foes on page 152-153. He has several lair actions, including the following:     Orcus's voice booms throughout the lair. His utterance causes one creature of his choice to be subjected to power word kill (save DC 23). Orcus needn't see the creature, but he must be aware that the individual is in the lair.   Power Word Kill, however, states:     You utter a word of power that can compel one creature you can see within range to die instantly. If the creature you chose has 100 hit points or fewer, it dies. Otherwise, the spell has no effect.   There is no save DC, that's the whole point of the spell (which is 9th level).  Why is there a save DC given for Orcus' lair action? Is it for balancing purposes, so that players don't have to deal with a "you most likely die now" feature every round? Or could it be a mistake from the developers? It would clearly be too strong without a save, but even with that, a DC of 23 makes success unlikely if you're not proficient and naturally good with the relevant save ability (which is not given and therefore unknown).  I'm specifically interested if there are other features with similar issues, and if there are any rulings/statements from official sources about it*.    Of course, if the given DC is not a mistake, but rather intentional, it raises the question which ability to use for the saving throw. CON would make sense, but RAW, none is given.    * I'm aware that developer intent is considered off-topic for some time now. Feel free to answer this question without designer quotes, though I don't see how this issue could be resolved without insight from a designer. Still, maybe you'll discover something I missed :)

In Out of the Abyss, Orcus has a number of Lair actions. One of those Lair actions has a confusing point:       Orcus's voice booms throughout the lair. His utterance causes one creature of his choice to be subjected to power word kill (save DC 23)   It is stated that there is a save with a DC of 23 but no specific type of saving throw. The spell it references doesn't have a saving throw either. Another of his Lair actions is properly specified as a strength saving throw, but not this one. What kind of saving throw is needed and how are we supposed to know?


I want to find an inequality between the to terms... Assuming all the $a_i $ to be positive, the one where $1$ is added to all the $a_i$ is bigger, but is there a real relationship? It doesn't have to be an inequality because I need something stronger than that...

Let $a_1,a_2,\dots,a_n$ $\in$ $\mathbb{R}^+$ and $a_1\cdot a_2\cdots a_n=1$, , prove that $(1+a_1) \cdot (1+a_2) \cdot \dots \cdot (1+a_n) \geq 2^n$ I have tried factorising but it just lead me to extremily complicated equation that were extremily difficult to understand... Could someone help me?


I have a form for cloning entries. Basically it works the same way as entry add form, it saves under brand new ID, but is pre-filled with data from existing entry.  For data like text and references, this is easy. Problem starts with images. I do not want to reference one image in multiple entries, it would not be convenient for reasons that are out of scope of this question. So I wrote simple function:  function _file_copy_by_id($fid) {   $source =  file_load($fid);   // Copy to the same place, let the Drupal care for renaming   $result = file_copy($source, $source->uri, FILE_EXISTS_RENAME);    return $result->fid; }   And in my form I made image field look like that:  'DimensionImageFile' => array(   '#type' => 'managed_file',   '#title' => t("Image"),   '#title_display' => 'invisible',   '#upload_validators' => array(     'file_validate_extensions' => array('gif png jpg jpeg'),     'file_validate_size' => array(variable_get('mymodule_image_size', 5 * 1024 * 1024)),   ),   '#upload_location' => 'public://mymodule/image',   '#theme' => 'preview_upload',   '#default_value' => _file_copy_by_id($product_data['DimensionImageFile']), ),   Now, it looks OK when form is rendered:    In the database, it looks OK too. Exported entry:  INSERT INTO `file_managed` (`fid`, `uid`, `filename`, `uri`, `filemime`, `filesize`, `status`, `timestamp`, `origname`) VALUES (426, 16, 'test.jpg', 'public://mymodule/image/test_3.jpg', 'image/jpeg', 37237, 1, 1391088561, 'test.jpg');   No entry in {file_usage} - just as expected.  File is there, with number added properly, but when I try to save, all I get is:     The file used in the Image field may not be referenced.     If I will add "fake" usage, like this:  function _file_copy_by_id($fid) {   $source =  file_load($fid);   // Copy to the same place, let the Drupal care for renaming   $result = file_copy($source, $source->uri, FILE_EXISTS_RENAME);   file_usage_add($result, 'mymodule', 'clone', 0, 1);   return $result->fid; }   form works all right. But files are reported as used. That's bad, because if user will decide to remove and replace them, cloned ones should get deleted as soon as possible, and the fact they are reported as being used prevents cleanup deletion.

I am having some issues with the  type. Whenever I try to edit and save a form that has a managed_file element in it an error occurs: The file  used in the Picture field may not be referenced.  This is the code I'm using:  function foo_form ($form, &$form_state, $foo) {     ...        $form['file'] = array(     '#type' => 'managed_file',     '#title' => t('Picture'),     '#default_value' => (isset($foo->file->fid) ? $banner->foo->fid : ''),     '#upload_location' => variable_get('foo_upload_location'),   );    if (isset($foo->file)) {     $form['current_file'] = array(       '#type' => 'hidden',       '#value' => $foo->file->fid,     );   }   ...   $form['submit'] = array(     '#type' => 'submit',     '#value' => t('Save'),   );   return $form;  }  function foo_form_submit ($form, &$form_state) {   $foo = (object)$form_state['values'];    $current_file_set = isset($form_state['values']['current_file']);    if ($form_state['values']['file'] != 0 && !$current_file_set) {     // Load the file uploaded in the form.     $file = file_load($form_state['values']['file']);      $file->status = FILE_STATUS_PERMANENT;      file_save($file);      $foo->file = $file->fid;   } else if ($form_state['values']['file'] != 0 && $current_file_set) {      // If we are uploading a different picture, delete the old one and save the     // new one. If not, don't do anything.     if ($form_state['values']['current_file'] != $form_state['values']['file']) {       file_delete(file_load($form_state['values']['current_file']));       // Load the file uploaded in the form.       $file = file_load($form_state['values']['file']);        $file->status = FILE_STATUS_PERMANENT;        file_save($file);        $foo->file = $file->fid;     }   } else {     file_delete(file_load($form_state['values']['current_file']));     $foo->file = null;   }    ... }   I traced the error back to the  function in modules/file/file.module but don't know anything about the file references.


i've downloaded the last 64 bit version of ubuntu on my macbook pro. Now i want to create a bootable usb/dvd for install ubuntu on my pc, but i'm on a mac. My pc is formatted, so i can't use it. Please help!

Not sure if the title is specific enough, so here we go:  I crashed my Windows pc, and now I want to install Ubuntu on that computer. I'm currently using my Mac, as it is the only operable computer I have left. I have downloaded the .iso. I guess my question is; How do I go about installing Ubuntu on my crashed computer from the external harddrive? I've used Ubuntu before, but I used to install it from a CD-rom. I tried reading the instructions, but couldn't really understand them. Please help  Edit: As Tom mentioned, I only want to install Ubuntu on the (formerly) Windows machine.  Anyways, thanks for the quick responses, I think I've got it from here. Cheers


I'd like to buy a new 1TB disk to replace my old 150GB disk. Is there an easy way to copy my Ubuntu installation with   my home folder content,  system settings,  applications,  and so on...   so at the end I can just unplug my old disk and plug the new one without having to re-install everything?

The HDD I have my Ubuntu installed is about to fail. I would rather not lose 3 years worth of data, customisation and apps. I am looking for a way to move the complete system (SWAP included, because I'm not sure if I can relink the system to a new SWAP partition) to another HDD. But not the complete HDD< only the partition containing Ubuntu, to a partition on a different HDD. Basically I'd like to do what I've been able to do with Norton Ghost for my Windows install. I thought about using Clonezilla but I think I would have issues with GRUB (Especially trying to boot from a different UUID than what is in the conf file). do you know of any way this could be done?  PS, my home directory is encrypted but that's not really an issue, because I can work around that.  EDIT: changed the explanation to make it clearer


Could anyone give an example for a bijective and continuous map $X \rightarrow  X$ that is not open (and thus not is a homeomorphism)? The topology on $X$ must be se same.  I suppose there must be some simple examples, but I wasn't able to find one yet.   Some things I tried and that cannot work: The topology must be infinite. Linear maps even on infinite dimensional Banach spaces cannot work (Open Mapping Theorem). Maps $\mathbb R \rightarrow \mathbb R$ in the real numbers cannot work either.  Thank you for answers.

I hope this doesn't turn out to be a silly question.  There are lots of nice examples of continuous bijections $X\to Y$ between topological spaces that are not homeomorphisms.  But in the examples I know, either $X$ and $Y$ are not homeomorphic to one another, or they are (homeomorphic) disconnected spaces.    My Question: Is there a connected topological space $X$ and a continuous bijection $X\to X$ that is not a homeomorphism?    For the record, my example of a continuous bijection $X\to X$ that is not a homeomorphism is the following.  Roughly, the idea is to find an ordered family of topologies $\tau_i$ ( $i\in \mathbb Z$) on a set $S$ and use the shift map to create a continuous bijection from $\coprod_{i\in \mathbb Z} (S, \tau_i)$ to itself.  Let $S = \mathbb{Z} \coprod \mathbb Z$.  The topology $\tau_i$ is as follows: if $i<0$, then the left-hand copy of $\mathbb Z$ is topologized as the disjoint union of the discrete topology on $[-n, n]$ and the indiscrete topology on its complement, while the right-hand copy of $\mathbb Z$ is indiscrete.  The space $(S, \tau_0)$ is then indiscrete.  For $i>0$, the left-hand copy of $\mathbb Z$ is indiscrete, while the right-hand copy is the disjoint union of the indiscrete topology on $[-n, n]$ with the discrete topology on its complement.  Now the map $\coprod_{i\in \mathbb Z} (S, \tau_i)\to \coprod_{i\in \mathbb Z} (S, \tau_i)$ sending $(S, \tau_i) \to (S, \tau_{i+1})$ by the identity map of $S$ is a continuous bijection, but not a homeomorphism.


I know there is .bash_history file on the home directory that stores all of the commands whom user has interred them.   But I am looking for all thing which we see on the terminal. .bash_history file does not contain the result. I need both commands and commands' results. Or at least commands' result. So is there any way? by the way I do not like copy the screen:)

I'm trying to do some debugging in Android and I am running a live logcat in the Terminal, but the problem is that there is too much information generated so that when I am finished and try to copy all the information received by choosing "Select All" and then "Copy" a lot of the early output which is produced isn't copied. I was aware of history, but that just provides a list of commands that have previously been entered, not the output.  Can I see a history of all the output that the terminal gives, or perhaps can I have the terminal save as a text file all the output that it is producing?


I'm not sure if it was a series or a mini series but some kids get lost on a space ship and end up finding a long lost earth.  The ship might be called "Merlin" and it has an AI. They end up being noticed by the bad guys and they activate something called the "spear of influence". It detects any ship that passes the barrier of a huge area of space so they are trapped.  I remember one part of the plot was regarding the ship running out of water so they had to get more from an asteroid or a comet. If anyone remembers the name please let me know

I'm trying to identify a Disney TV movie from the late-80s to mid-90s.  The plot points that I can remember are:   3 teenagers on a spacecraft, all in recently in trouble at their (military?) academy so being sent somewhere the ship malfunctions no adults around, period they meet some alien woman who agrees to help them because she "thought they were much older warriors" rather than kids the kids somehow have mechs (they look exactly like the Battlech Timber Wolf/Mad Cat mech) harvesting ice on a planet for water, they encounter some gigantic worm creature that can sense heat


Years ago I read a fantasy trilogy, which I’ve since loaned to someone and never got back.  It was about a man who was developing a VR game which was entered via a sensory deprivation tank. Something happened and he got stuck in the game, where if you died you would also die in real life. It was a fantasy medieval kind of a game, where he was playing a bard.  In real life he had a wife and they were really good fencers. They’ve crashed a plane in France and he ended up having trouble with his leg and she ended up only as organs held together in a plastic case. At the end he sort of became his wife in game and had a child and I think she was evil(?)

I read this sometime in the late 90s, borrowed from the local library. The basic plot was that people couldn't exit the VR sim(s), so the authorities brought in one of the original designers of the fantasy realm (as that's where the trouble started) to get to the bottom of it all. (It was a fairly generic D&D/VR ripoff, but trying to remember it has been bugging me.)  Other bits I remember:   There were several VR realms, one of the others was a War sim - a general was mentioned as being trapped there. The main character's class was a bard, whereas normal users could only pick from warrior/wizard/rouge He was forced out of the VR company after creating the fantasy realm, and is reluctant to assist He's introduced in the book at a sword-fighting lesson (possibly fencing) He has a pegasus that's under the illusion of being an old nag He defeats a dragon by lassoing it's mouth shut on it's own fireball He has some root level systems access (a backdoor that he left in for himself), even within the sim The fantasy realm has some partial scenarios based on myths - he escapes from a snow white type scenario on his pegasus (which was depicted on the cover IIRC) VR tech was of the full body immersion tank type, with some sort of neural feedback At the start a bit character has his hand cut off in game, and on waking up can't feel anything in that hand The computer running the sim has achieved some sort of sentience and separated into id, ego and superego personas Someone was suffering from brain cancer IRL, so uploaded himself to the sim and suffers from persistent headaches. His attempts to hack the system from the inside using magic are probably the root cause of the problems.   Any ideas would be appreciated, my google-fu has failed me. (oh, and it's not the Otherland series — that's far more complex and interesting)


I need help improving my proof. It's a bit lacking in details, and I don't know how to phrase my reasoning.    For any homeomorphism, identities must map to each other. Therefore, any automorphism of $\mathbb{Z}/2\mathbb{Z}\times \mathbb{Z}/2\mathbb{Z}$ must map $(0,0) \mapsto (0,0)$.   This leaves three other elements, label them $1: (0,1), 2: (1,0), 3: (1,1)$.   Since all of these elements are order two, and the group action of any two will give the third, they can be interchanged with each other freely. So, any bijection of these three elements will result in an automorphism. Hence, there is a function between the automorphisms of $\mathbb{Z}/2\mathbb{Z}\times \mathbb{Z}/2\mathbb{Z}$ and the symmetric group $S_3$  To prove this is a homeomorphism, we show $\mu(g\circ h) = \mu(g)\cdot\mu(h)$. This is true because $g$ and $h$ are automorphisms, and the bijection above supports this property, and this is circular reasoning that I can't seem to articulate more clearly.  To prove this is a bijection, like before, the function maps the pairs to their labels. It's injective, because if two labels are equal, then their points are equal, and so it is with the functions inputs and outputs. It's also surjective because of labeling of inputs and outputs carrying over to functions.    Is "labeling" enough to prove bijection? I don't want to just enumerate all the functions, there has to be a better way. The reasoning for homeomorphism and bijection are both really lame, but I don't know what sort of reasoning I can employ to make this more concise.  This is in the "basic" Group Theory section of Paolo Aluffi's "Algebra: Chapter 0". I have not yet gotten to Rings, Fields, Modules, or any Linear Algebra.

So I believe I've finished the proof, but it all amounts to case-work and I really think (and hope) there's a better approach than this. Here's what I've done: Attempt: Within $\text{Aut}_\mathsf{Grp}(\mathbb{Z}/2\mathbb{Z} \times \mathbb{Z}/2\mathbb{Z})$ identities must be mapped to identities thus what defines each isomorphism is the bijective function between its last three elements: \begin{matrix} (0,0) & \mapsto & (0,0) \\ (0,1) & & (0,1) \\(1,0) & & (1,0) \\(1,1) & & (1,1) \\ \end{matrix} If every bijective function between these last three elements constitutes a homomorphism (including the first unchanged mapping of identities), then $\text{Aut}_\mathsf{Grp}(\mathbb{Z}/2\mathbb{Z} \times \mathbb{Z}/2\mathbb{Z}) \cong S_3$ in that isomorphisms in $\text{Aut}_\mathsf{Grp}(\mathbb{Z}/2\mathbb{Z} \times \mathbb{Z}/2\mathbb{Z})$ can be identified with permutations of three elements, which is exactly what $S_3$ is. I then, essentially go case-by-case showing every one of the six different bijections is a homomorphism. For two of those bijections (which are just compositions of other bijections I've already checked) I apply the following lemma:  If $\phi :G \to H$ and $\psi : H \to K$ are bijective homomorphisms, then $(\psi \circ \phi)$ is a homomorphism. As proof, assume the premise. We then have $\forall a,b \in G:$ $$\psi (\phi (ab))= \psi(\phi(a) \phi(b))=\psi (\phi(a))\psi (\phi(b))$$ $\implies (\psi \circ \phi)$ is a homomorphism.  So my questions are:  Is the proof that I have sufficient? Is there a better proof for this problem? (A hint towards it rather than complete give-away would be much more appreciated)  EDIT: I have indeed looked at , but the approach carried out there uses vector spaces which I have not been introduced to or am supposed to use to solve this problem.


$(B_t)_{t \in \mathbb R_0^+}$ are random variables on $(\Omega,\mathcal A,P)$.   $\forall r \le s, t > s, B_t-B_s,B_r$ are independent (i.e. $\sigma(B_t-B_s)$ and $\sigma(B_r)$ are independent, where with $\sigma(X)$ I denote the $\sigma$-algebra produced by the variable $X$).    Can one show that $B_t-B_s$ and $\sigma(\{B_i| r \le s\})=\sigma(\bigcup_{r \le s}\sigma(B_r))$ are independent?  Does one need to use the fact that any endless sequence of random variables from $(B_t)_{t \in \mathbb R_0^+}$ is multivariate normally distributed?

I have a question concerning the definiton of Brownian motion. Usually (e.g. on Wikipdia) one demands a brownian motion $\lbrace B_t\rbrace_{t\in[0,\infty)}$ to satisfy the following condition:  $\forall 0\leq t_0<t_1<...<t_m: B_{t_1}-B_{t_0},...,B_{t_m}-B_{t_{m-1}}$ are independent random variables.   But today I come across with formally another definition of Brownian motion! Instead of the above condition the book demands the following property:  $\forall t,h\geq 0$, $B_{t+h}-B_t$ is independent of $\lbrace B_u : 0\leq u\leq t \rbrace$.  Now I'm wondering whether both properties are indeed equivalent or not?! Hopefully someone can help me.


In most dictionaries "labeled" or "labelled" isn't recognized as an adjective but there are a few who do deem it to be an adjective.  Is this correct? Or is "labeled" merely the past tense of "label"?  Any input is as always greatly appreciated!

Consider the following sentence.     The blue page is stapled to the red page.   Although "stapled" is (apparently) past-tense, nonetheless the above sentence is clearly expressing something about the present. What gives? In particular, would it be wrong to label "stapled" as past-tense in that sentence?  (note: Er, actually the OP's question involves the difference between a passive construction and a construction with a predicative adjective -- F.E.)


Currently, pressing Enter after entering a partial simply refreshes the page. This should not happen. If I have not selected a site, then pressing Enter should do nothing. If I wanted to refresh, I can simply press F5.

At the moment in the new StackExchange top-bar, when you type a search term into stackexchange site search and press Enter, the page refreshes or something similar. I think it would be better if you actually went to the first listed site in the search.   For example, if I typed "statistic", this brings up cross validated, and if I press Enter I would like to go to cross validated.    Similarly, and perhaps this should be another suggestion, up and down cursor keys should move the selection to the list of sites, enabling you to for example, press down key twice and then enter to go to the second listed site.  It might also be better to have some specific visual indication that you have you the selection corresponds to the first hit (i.e., like the Facebook search box).  As a side point I realised after a bit that you can tab and enter, which arguably works fine, but it was not the keyboard interaction that I was expecting. So I still think supporting both modes of keyboard interaction might be good.


Is the differentiable point set of a function measurable？  Thanks in advance

If $f : \mathbb{R} \to \mathbb{R}$, define $C(f) = \{ x : f \text{ is continuous at } x \}$ and $D(f) = \{ x : f \text{ is differentiable at } x \}$. I have seen it proved that:   $C(f)$ is a $G_\delta$ set. For any $G_\delta$ set $A \subset \mathbb{R}$, there exists a function $f : \mathbb{R} \to \mathbb{R}$ such that $C(f)=A$.   I suspect there is a related characterization for $D(f)$. I see that a related question was asked at , where the accepted answer implies that $D(f)$ is a $G_{\delta \sigma \delta}$ set.   Is this optimal, that is, does there exist $f$ such that $D(f)$ is $G_{\delta \sigma \delta}$ and not $G_{\delta \sigma}$? If so, can an example be given? Conversely, given any $G_{\delta \sigma \delta}$ set $A \subset \mathbb{R}$, does there exist $f$ such that $D(f)=A$?


I am having a problem that I was not able to re-produce with a small self-contained example. That is, I wrote such an example (appears below), but the small example compiles, while the actual code does not.  I have a function template defined in the base:  template<class ExplicitSpace> struct ExplicitState {     ...     template<class Neighbor>     std::vector<Neighbor> successors() const {...}     ... };   I have the following in the deriving type:  template <typename CostType_> struct GridMapState: ExplicitState<GridMap<CostType_>> {     using Base = ExplicitState<GridMap<CostType_>>;     using Base::Base; // inherit constructors     using Base::successors; // this is supposed to do the trick      ...     std::vector<Neighbor> successors() const {         // return static_cast<const Base *>(this)->template successors<Neighbor>();           // the above commented version compiles         return successors<Neighbor>(); // this does not compile     }     ... };   As the comment indicates, I can explicitly call successors() of the base, but I cannot rely on using Base::successors; to make it visible.  gcc 4.8.2. gives the following:  GridMapState.h: In member function ‘std::vector<StateNeighbor<GridMapState<typename ExplicitState<GridMap<CostType_> >::CostType> > > GridMapState<CostType_>::successors() const’: GridMapState.h:20:35: error: expected primary-expression before ‘>’ token          return successors<Neighbor>();   Here is the small example that attempts to re-produce the problem, but it compiles just fine:  template <typename U> struct A {     template <typename T>     T f() {return T(0);} };  template <typename V> struct B : A<int> {     using MyT = int;     using Base = A<int>;     using Base::f;     MyT f() {return f<MyT>();} };  int main() {     B<int> b;     std::cout << b.f() << std::endl;     return 0; }

In templates, where and why do I have to put typename and template on dependent names? What exactly are dependent names anyway?    I have the following code:  template <typename T, typename Tail> // Tail will be a UnionNode too. struct UnionNode : public Tail {     // ...     template<typename U> struct inUnion {         // Q: where to add typename/template here?         typedef Tail::inUnion<U> dummy;      };     template< > struct inUnion<T> {     }; }; template <typename T> // For the last node Tn. struct UnionNode<T, void> {     // ...     template<typename U> struct inUnion {         char fail[ -2 + (sizeof(U)%2) ]; // Cannot be instantiated for any U     };     template< > struct inUnion<T> {     }; };   The problem I have is in the typedef Tail::inUnion<U> dummy line. I'm fairly certain that inUnion is a dependent name, and VC++ is quite right in choking on it. I also know that I should be able to add template somewhere to tell the compiler that inUnion is a template-id. But where exactly? And should it then assume that inUnion is a class template, i.e. inUnion<U> names a type and not a function?


I have seen the discussions of "to center on" vs "to center around", and usually the argument is that "to center X around Y" is illogical. The counter-argument is generally that it is an idiom and therefore does not have to be logical. However, I do not see why this phrase is illogical.  To me, there are clearly to ways that "to center" can be used:   Putting X in the center of Y. Putting the center of X on Y   The first meaning obviously doesn't make sense with "about". You can't center a picture around a page. But in the context of second meaning, I find it is perfectly logical to center X around Y, eg. "to center a circle around a point". "At" and "on" also make sense here, but so does "around".   So why is it necessary to invoke the argument of the idiom? Am I misunderstanding something?  -  Edit: This is not a duplicate of . Most answers there just state it is illogical, not why. The few that do only say that it is illogical since to center X is to put X in the center, which is only the first meaning I mentioned. The answer of user oosterwal comes close but only talks about a set of multiple.  I would like to know why it is illogical to center for example a hullahoop around a candle, i.e. putting the candle in the center of the hullahoop.  Moreover, even the idiomatic use seems logical to me, since for example arguments centered around a main point seem more meant in this second meaning, rather than them being in the center of something.

I have often heard presenters talking about something centered around another thing, but it seems a bit illogical and hence improper to talk like this. Am I right about this?


Some time ago, we had a problem with -type questions on Earth Science Stack Exchange. After some users , we closed and deleted 500 questions with some effort and we made them off-topic. We stopped coming up as the first entry for searches for "help identify my rock" on Google, and the flood of questions ended. However, we still receive some questions. We close them, but I realized that +2k users were not deleting them, so I made . I asked for help from a mod but they don't want to delete them unilaterally. My question is if we are at risk of appearing again at the top of Google searches if we don't delete them, because I am a bit tired of asking users to delete the questions. Apparently the problem is that delete votes don't put posts into a review queue and we don't have many +2k users using meta frequently. Does Google index closed questions? Should I continue battling for the deletion of these unwanted questions for this reason?

I was just wondering about that because it would influence how I deal with closed questions, e.g. whether they need to be improved (tagging, formatting, code samples) after closing, or if some should be deleted altogether.  However, I'm not asking for answers to these questions, I just want to know if Google (and/or other search engines) list closed questions in their search results. (I hope they don't.)


I have all the ingredients to make a dough except for the yeast, can I use baking soda or powder instead of using a yeast for making a bread dough (high gluten)?

I've read one cook say,  "I add baking soda when I make bread using buttermilk. The buttermilk is acidic enough that it interferes with the environment that commercial yeast needs to reproduce well, resulting in a somewhat dense, poorly risen loaf.  I add1/2 teaspoon of Baking Soda per 8 ounces of buttermilk, and the result is is a beautifully risen, light bread with beautiful color and texture. The Baking Soda neutralizes the acid in the buttermilk, producing CO2, which adds to the bread's leavening."  Does adding them all together(or one and yeast) really work that way, or is it overkill!? I have seen other recipes use all three and they also had buttermilk in the recipe. So is it the buttermilk that changes it all, to have to use all three(or one and yeast)?


Is $\mathbb{R}^2 = \mathbb{C}?$ are same set, metric space, vectorial space, field, etc? Thanks in advance.

Complex numbers are usually formally defined as pairs of real numbers. Although there are operations on $\mathbb{C}$, such as complex multiplication, which are not found in operations usually applied to $\mathbb{R}^2$, the sets themselves seem to be the same. Each consists of pairs of real numbers.  So is it okay to say that $\mathbb{C} = \mathbb{R}^2$? It seems formally correct, but something doesn't feel quite right about it.


let the integral equation is  $$\phi (x)-\frac{e}{2}\int_{-1}^{1}xe^{t}\phi(t)dt=f(x)$$  then  1).there exist a continous function $f:[-1,1]\to (0,\infty)$ for which solution exist. 2).there exist a continous function $f:[-1,1]\to (-\infty,0)$ for which solution exist. 3).for $f(x)=e^{-x}(1-3x^2)$ ,a solution exist 4).for $f(x)=e^{-x}(x+x^3+x^5)$ ,a solution exist  how to solve this question ,i can only solve simple questions in integral equations but this very tough , $\text{EDIT}$ After so much of reading of integral equation,i try to solve the question $\textbf{the solution i tried}$-$$\phi (x)=\frac{e}{2}\int_{-1}^{1}xe^{t}\phi(t)dt+f(x)$$ $$\phi (x)=\frac{e}{2}x\int_{-1}^{1}e^{t}\phi(t)dt +f(x)$$ $$\phi (x)=\frac{e}{2}xC+f(x)    \;\;\;\;\;\;\;....1$$ where $C=\int_{-1}^{1}e^{t}\phi(t)dt$ $\textbf{from (1)}$ $$C=\int_{-1}^{1}e^{t}(\frac{e}{2}tC+f(t))$$ $$C=\int_{-1}^{1}e^{t}\frac{e}{2}tCdt+\int_{-1}^1 e^tf(t)dt$$ $$C=\frac{e}{2}C\int_{-1}^{1}e^{t}tdt+\int_{-1}^1 e^tf(t)dt$$ further doing calculation i get $$C=C+\int_{-1}^1 e^tf(t)dt$$ $$\implies \int_{-1}^1 e^tf(t)dt=0$$ after that i pick the option  'c' and 'd' and they satisfied the integral so they are sutiable for $f(x)$ and my option are also right but still don't know how to work for option 'a' and 'b' please help. Thankyou

Consider the integral equation $\phi(x)-\frac{e}{2} \int_{-1}^{1} x e^{t} \phi(t) d t=f(x) .$ Then  there exists a continuous function $f:[-1,1] \rightarrow(0, \infty)$ for which solution exists there exists a continuous function $ f:[-1,1] \rightarrow(-\infty, 0)$ for which solution exists for $f(x)=e^{-x}\left(1-3 x^{2}\right)$, a solution exists for $f(x)=e^{-x}\left(x+x^{3}+x^{5}\right),$ a solution exists  what I tried $f(x)=f(x)+\frac{e}{2} \int_{-1}^{1} x e^{t} \phi(t) d t$ $\phi(x)=f(x)+\frac{e x}{2} \int_{-1}^{1} e^{t} \phi(t) d t$ $ \begin{array}{l}L e t \quad c=\int_{-1}^{1} e^{t} \phi(t) d t \\ \Rightarrow \phi(x)=f(x)+\frac{x e}{2} c\end{array} $ $c=\int_{-1}^{1} e^{t}\left(f(t)+\frac{c e}{2} t\right) d t$ $c=\int_{-1}^{1} e^{t} f(t)+\frac{\operatorname{ce}}{2} \int_{-1}^{1} t e^{t} d t$ $c=\int_{-1}^{1} e^{t}f( t)+\frac{\operatorname{ce}}{2}\left[t e^{t}-e^{t}\right]_{-1}^1$ $c=\int_{-1}^{1} e^{t} f(t)+\frac{c e}{2}\left(2 e^{-1}\right)$ $c=\int_{-1}^{1} e^{t} f(t) d t+c$ $\int_{-1}^{1} e^{t} f(t) d t=0$ Option (3) and (4) satisfies this Relation so, (3) and (4) seems true  to me.is i am right? I am stuck  for option (1) and (2)  is there any result or theorem ?


I want to disable guest session in ubuntu 14.04. I did that in 12.04 before, however I can't find /etc/lightdm/lightdm.conf as in 12.04. I think 14.04 might replace it with /etc/lightdm/users.conf, which has the following code:  [UserAccounts] minimum-uid=500 hidden-users=nobody nobody4 noaccess hidden-shells=/bin/false /usr/sbin/nologin  Should I change hidden-users= to hidden-users=guest?

How do I disable the guest session in Ubuntu 11.10 or higher? I don't want people to be able to use my computer without using a password to log in!


In my page, I use this block of code to generate :  $.ajax({         url: '...' }).done(function (model) {     for (var i = 1; i <= model.numberOfPages; i++) {         html += ''+i+'&nbsp;';     }     $(".page_numbers").html(html); });   But when I try to add a click event on these a tags, nothing happen. Where did I go wrong?  $(document).ready(function (event) {     $('.page_number').click(function (event) {         //Some code here     }); });

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


For example, I'm hungry, but the Africa kids are much more (so I should not care about my hungry).

Wasn't really sure how to phrase this, but I'm thinking of an instance in which someone diminishes a problem by presenting one of larger scope - as a rather shoddy example, "x political problem in America doesn't matter because half the world's population is starving."  I honestly have no idea if this is considered fallacious or not, but for some odd reason I can't shake the feeling that someone has described it to me as a fallacy before. Am I crazy or is there something to this (or something similar)?


Is it possible to intuitively explain why conditional probability/expectation $(P(A|X)$ or $E[Y|X])$ depends on sigma algebra on which it is conditioned not the value of the random variable ?  Formally, it is due to Radon-Nykodin theorem. But in Breiman it says that the intuition behind this is that the relevant information contained in knowing $X(\omega)$ is the information regarding the location of $\omega$. What is the meaning of it.

Suppose for two random variables $X_1$ and $X_2$ $\sigma(X_1) = \sigma(X_2)$. Why $E[Y | X_1] = E[Y | X_2]$ a.e. ?  the set where $X_1= X_1(\omega)$ can be different from the set $X_2= X_2(\omega) $. How can then conditional expectation conditioned on the event can be equal ?


I have the following query  SELECT * FROM campaigns where campaign_id IN ( 'idStrOne', 'idStrTwo', 'idStrThree' );   The results of which are being ordered by the primary key of the table campaigns which is 'id'. This is not the order I want.   I want the results to come back in the same order as the arguments to the IN function. So in this case the order I want is   idStrOne, idStrTwo, idStrThree   How do I get this order?

I am wondering if there is away (possibly a better way) to order by the order of the values in an IN() clause.  The problem is that I have 2 queries, one that gets all of the IDs and the second that retrieves all the information. The first creates the order of the IDs which I want the second to order by. The IDs are put in an IN() clause in the correct order.  So it'd be something like (extremely simplified):  SELECT id FROM table1 WHERE ... ORDER BY display_order, name  SELECT name, description, ... WHERE id IN ([id's from first])   The issue is that the second query does not return the results in the same order that the IDs are put into the IN() clause.  One solution I have found is to put all of the IDs into a temp table with an auto incrementing field which is then joined into the second query.  Is there a better option?  Note: As the first query is run "by the user" and the second is run in a background process, there is no way to combine the 2 into 1 query using sub queries.  I am using MySQL, but I'm thinking it might be useful to have it noted what options there are for other DBs as well.


I am having a problem retrieving a data from mysql that has an apostrophe in it. I don't have problem in saving a data that has an apostrophe since that I am using mysqli_real_escape_string when inserting the data to the database but I get an error when retrieving it. My sample code in PHP for retrieving the data is mysqli_query($con,"SELECT column1data FROM Table1 WHERE column2data LIKE '".$data."' ")or die(mysqli_error($con)); and the $data is the one that has an apostrophe in it.

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I have a brand new system using Gigabyte B85M-D3H motherboard, 8 Gigs 1600Mhz Memory, Intel i3-4330 3.5 GHz processor, ADATA 128 GiG SSD, WD15EARS Hard Drive. I partioned the SSD into 90 Gig and 30 Gig partitions, hoping to create a dual-boot Windows 8.1 Pro and Ubuntu 14.04 64 bit systems. When I first downloaded an Ubuntu .iso, I was looking for a 64 bit Intel version and chose i386 instead of AMD.  The 1st install went seamlessly but I realized that Ubuntu was only 32 bit. I followed online discussions to remove Ubuntu, Create a Bootable CD for Ubuntu 64 bit and followed the same steps as I did the 1st time. This time however, Ubuntu 64 did not recognize the Windows 8.1 install and wanted to overwrite the 90Gig partition. I directed it to install to the WD15EARS which was previously partitioned into 2 750Gig volumes. When I was finished, the system booted into Ubuntu, ignoring Windows 8.1. I essentially ended up with 2 independent OS systems changeable through the bios. When I went into Window 8.1 and looked at the drives, a 350Mb chunk of Ubuntu thinks its a part of the SSD ADATA drive. In addition it says the WD15EARS drive is locked and inaccessible. There was some grub message error saying drive locked but I am new to linix and do not know command line instructions

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


The question that got my stuck is as follows: Prove that for all integers $a, b, c,$ $\gcd(a, b, c) = \gcd(\gcd(a, b), c)$. I have no idea on how to start or how to express $\gcd(a, b, c)$ into equations, please help, thank you.

Prove $\gcd(a,b,c)=\gcd(\gcd(a,b),c)$ for $0\ne a,b,c\in \Bbb{Z}$. I tried solving it with sets but I sense there are some details I am missing. I would truly appreciate your reference.


EDIT: My question is a duplicate but my answer here is a bit different than the answer in the linked duplicate above.  I cannot install, remove, or upgrade anything using APT because of this error:  $ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  guvcview : Depends: libguvcview-2.0-0 but it is not installed             Recommends: uvcdynctrl but it is not installed E: Unmet dependencies. Try using -f.   I'm certain I can find and fix this error. I'm more interested in knowing why the entirety of apt is broken because of one program having a problem.  Edit: I can't apt-get dist-upgrade either:  $ sudo apt-get dist-upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  guvcview : Depends: libguvcview-2.0-0 but it is not installed             Recommends: uvcdynctrl but it is not installed E: Unmet dependencies. Try using -f.   apt-get -f install is met with this error:  Preparing to unpack .../libguvcview-2.0-0_2.0.5+ubuntu2~ppa1+1418-0ubuntu1~201702081552~ubuntu16.10.1_amd64.deb ... Unpacking libguvcview-2.0-0:amd64 (2.0.5+ubuntu2~ppa1+1418-0ubuntu1~201702081552~ubuntu16.10.1) ... dpkg: error processing archive /var/cache/apt/archives/libguvcview-2.0-0_2.0.5+ubuntu2~ppa1+1418-0ubuntu1~201702081552~ubuntu16.10.1_amd64.deb (--unpack):  trying to overwrite '/usr/lib/x86_64-linux-gnu/libgviewaudio-2.0.so.2.0.0', which is also in package libguvcview-2.0-2:amd64 2.0.4+debian-1 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Errors were encountered while processing:  /var/cache/apt/archives/libguvcview-2.0-0_2.0.5+ubuntu2~ppa1+1418-0ubuntu1~201702081552~ubuntu16.10.1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   It should be noted that the file /usr/lib/x86_64-linux-gnu/libgviewaudio-2.0.so.2.0.0 does not exist on my system.  I can't do anything with APT because of this. I can't even remove an unrelated program. abiword is a text editor.  $ sudo apt-get remove abiword Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies:  guvcview : Depends: libguvcview-2.0-0 but it is not going to be installed             Recommends: uvcdynctrl but it is not going to be installed  lubuntu-desktop : Depends: abiword but it is not going to be installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).   OS: Lubuntu desktop (Ubuntu 16.10)

For example:  $ sudo apt-get install curl Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: bsh : Depends: libjline-java but it is not going to be installed groovy : Depends: libjline-java but it is not going to be installed rhino : Depends: libjline-java but it is not going to be installed E: Unmet dependencies.   Try 'apt-get -f install' with no packages (or specify a solution).   I get the same or similar errors when I attempt to install clojure1.3, leiningen, and several other packages.   When I try the suggestion made in the error message, this is what happens:  $ sudo apt-get -f install  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following packages were automatically installed and are no longer required:   diffstat linux-headers-3.2.0-26-generic linux-headers-3.2.0-26 dh-apparmor dkms html2text libmail-sendmail-perl libsys-hostname-long-perl Use 'apt-get autoremove' to remove them. The following extra packages will be installed:   libjline-java Suggested packages:   libjline-java-doc The following NEW packages will be installed:   libjline-java 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 23 not fully installed or removed. Need to get 0 B/72.0 kB of archives. After this operation, 129 kB of additional disk space will be used. Do you want to continue [Y/n]? Y (Reading database ... 226243 files and directories currently installed.) Unpacking libjline-java (from .../libjline-java_1.0-1_all.deb) ... dpkg: error processing /var/cache/apt/archives/libjline-java_1.0-1_all.deb (--unpack):  trying to overwrite '/usr/share/java/jline.jar', which is also in package scala 2.9.2-400 Errors were encountered while processing:  /var/cache/apt/archives/libjline-java_1.0-1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1)  $ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  bsh : Depends: libjline-java but it is not installed  groovy : Depends: libjline-java but it is not installed  rhino : Depends: libjline-java but it is not installed E: Unmet dependencies. Try using -f.


Let $M$ be a complex $n\times n$ matrix and $I$ the $n\times n$ identity matrix. The overline $\bar{M}$ denotes the complex conjugate. The determinant of $I+M\bar{M}$ is obviously real, because $\det(I+M\bar{M})=\det(I+\bar{M}M)=\overline{\det(I+M\bar{M})}$. I have no doubt that $$\det(I+M\bar{M})\geq 0,$$ but I do not have a proof. Can someone help me? Motivation: I need this to complete an answer at MO.

Let $A$ be non-singular $n\times n$ complex matrices and $x$ be negative eigenvalue of $A\overline{A}$. Show that algebraic multiplicity of $x$ is an even number. I show that the $\det(A\overline{A})>0$, so the number of negative eigenvalue is even. But I'm stuck to prove algebraic multiplicity of $x$ is an even number.