Yesterday (Jan. 3, 2018), I installed an OS update (Ubuntu 16.04), using the Software Center. My system isn't working correctly now. When my mouse rolls over the Launch bar, it disappears, then any open window disappears, leaving me with only the desktop screensaver showing. I can't even shut the computer off using the settings button on the top.  I went into the Terminal and attempted to fix it using the following commands:  sudo apt-get dist-upgrade sudo apt-get autoremove   But I'm still having the same problem.  I have reinstalled Ubuntu 16.04 and when I accepted the update on install had the same problem.  I have reinstalled it a second time but have not done an OS update and everything seems to be working fine.    Found another user with the same problem:    Is it possible that the Meltdown security update is at fault?  I've read the update has been issued for 64-bit x86 architecture ();  I'm running a 32 bit i386 architecture.  Could that be an issue and is there a way to correct it?

The latest updates (4/1/2018) make my laptop constantly crash the GUI/Unity:  (Intel Pentium su4100 processor)  syslog:  Jan  5 11:38:53 1810 kernel: [ 1850.327738] compiz[11911]: segfault at 0 ip 00007f6c7baf0c16 sp 00007ffd5ec71c60 error 4 in i965_dri.so[7f6c7b513000+82d000]   After login I end up with an empty desktop, just a wallpaper, GUI/Unity are in a crash loop:   No panel.  No dash.  Can't start a program. Launcher disappears. Sidebar disappears. System crash. Windows key not working. The key combination Alt+Tab not working.   Simply, the computer is not usable. Same for guest login. The only thing working: open up a terminal CTRL+ALT+T to examine log files.  I somehow forced  to let me log in and file the bug, but still lots of problems:   Dash not working Alt+Tab not working Sometimes windows all disappear for a few seconds     Any ideas for a solution or workaround?   UPDATE     If you have the same/ very similar problems, follow the link to my    report and mark there that you're affected too. Or file your own. Please leave a comment   if you wish, or upvote - this is a nasty problem - but an answer should   offer a fix or a workaround so users can use their computer again.    Without , Ubuntu can't fix issues.


I was reading an example about final for Java, and saw something like :  Counter c = new Counter() {   public int count() {     super.count();        return super.count();   } } c.count(); // now count 2   Is there a name for such construct? Is this ever used in practice? Is yes, it is considered a good OOD? A reference or a blog article would be appreciated.

What is the use of anonymous classes in Java? Can we say that usage of anonymous class is one of the advantages of Java?


Let $E = \left\{\frac{m}{2^{n}}\right\}$ where $m,n$ are integers, then $0$ is the only limit point of this set.  $($true$/$false$) ?$  I think the $0$ is the only limit point of this set. Since, as $n \to \infty$ terms of this sequence come nearer to $0$.   But the statement is false according to answer key.

I came across the following problem that says:     The set of limit points of the sequence $1,\dfrac12,\dfrac14,\dfrac34,\dfrac18,\dfrac38,\dfrac58,\dfrac78,\dfrac1{16},\dfrac3{16},\dfrac5{16},\dfrac7{16},\dfrac9{16},\ldots$ is which of the following?   (a) $[0,1]$   (b) $(0,1]$   (c) the set of all rational numbers in $[0,1]$   (d) the set of all rational numbers in $[0,1]$ and of the form $m/2^n$ where $m$ and $n$   are integers.   Please help. Thanks in advance for your time.


My shape is composed of 7 polygons which are supposed to be adjacent (ie sharing sharing same nodes). Would like to join the polygons by their nodes and make sure there is no space in between two polygons. But the 7 polygons maintained separately. Is there a way to do that?

I have a set of polygons representing administrative districts.  The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching. How can I have the polygons snap together, removing the spaces?


What is the best place to save a xindy style file (.xdy)? I read about XINDY_SEARCHPATH but what if I can’t change it because I’m only the developer and have no access to the users settings or when I want to publish a style via CTAN. Is there any place for such files?  Furthermore the file should not be deleted if the distribution is updated.

I’m developing a (non-public) custom class which has a comparing Xindy style file (.xdy). I’m installing the class feels etc. according to TDS with a script (or by unzipping to the right directories). But I couldn’t figure out a robust way to install the Xindy file, since it doesn’t use kpsewhich. So what is the best place to save such a style? It should   work with TeX Live and MikTeX be as easy as possible ideally not requiring to change .profile or something like that   I don’t know what systems the users have. But I guess most of them are basic users without any knowledge about installing packages or using the Terminal/Bash/…  Deployment via CTAN is not possible since the class/style is exclusive and non-public.


I am trying to download Ubuntu 18.04.3 LTS. I observed that I am downloading a .rar file instead of an .iso file. The official tutorial  assumes that the file is an iso.   I am an amateur. This had happened when I tried to install Kali for fun. So I copied the contents of the folder of the download into my pen drive and booted from it. I am now greeted with a GRUB command line instead of the expected live environment.  Is it expected to download a rar file? If so, am I doing the right thing?  Edit:    Apparently Windows is telling me it's a rar archive even though the extension is .iso.

I've never used Ubuntu before. Just heard from some friends. "IT'S GREAT!!!", they used to say. So i decided to try it. I downloaded WUBI, and ran it but 'twas takin' too much time. So I decided to download the .ISO Image file separately. It couldn't download more after 150 mB, and got interrupted (and cancelled) itself. I just went to , and further went to , and searched for my question. After having found a related one, which told     "try the torrent way"   So I downloaded it through the torrent. And after that when I opened the .rar file, there wasn't any .ISO image file; just some folders with names like .disc, boot, ISOLINUX, etc. I searched for the .ISO file but nothin' there: ANYONE HELP ME, PLEASE!!! or this will drive me into never thinkin' about Ubuntu again.


I've played with  to jazz up my prompt, but is there a way to change the color of what I type after said prompt to make my commands a little more distinctive in the scrollback?  I can leave an open color code tag which sort-of works (not really); it bleeds up to the first colored bit in the output (which may or may not exist).

One thing I liked about Mint was that the terminal would usually show two colors: everything from the left to the $ would be one color, and everything past the $ would be another.   Is there a way to have this setup with Ubuntu?


I would like to understand how an Internet Box, based on Linux, is designed. It's  made by a quite big operator in France; .  I'm sure I cannot post it to , but which is an appropriate site to ask this question? Reverse Engineering?

Is there a general discussion section for curious questions? Or are we simply left to swallow such curiosity because the results of it may or may not benefit a big crowd? Sample question There's an idiom, "It costs a moon". As of now NASA hasn't revealed if the Moon has precious elements. This brings some curious thoughts to me... What if the Moon has precious metals, gas, etc.? Does anyone own the moon or other planets in our solar system? Like Americans? Russians, Germans, Japanese, Chinese or British? Are there any constitutions that refrain anyone from such access or ownership to solar elements (either research wise or commercial wise)?


I'm trying to query my database and display in a combo box. But I constantly get the same error, so Im not sure now where the problem is exactly, I get java.lang.NullPointerException everytime I click on the combobox  this is my code:  ``    public Sell_Tick()    {      initComponents();      FillRouteCombo();     con = CreateDB.getConnection();          if(con!=null)     {         System.out.println("Successful DB Connection");     }  } private void FillRouteCombo()     {         try          {             pst=con.prepareStatement("select * from routes");             rst= pst.executeQuery();             while(rst.next())             {                 String getroutes=rst.getString("destfrom");                  destfrom.addItem(getroutes);               }         } catch (Exception e) {             System.out.println(e);         e.printStackTrace();         }      }   The error i get is this  java.lang.NullPointerException      Successful DB Connection     at Sell_Tick.FillRouteCombo(Sell_Tick.java:47)     at Sell_Tick.<init>(Sell_Tick.java:34)     at StartPage.TicketOperationActionPerformed(StartPage.java:1710)     at StartPage.access$5300(StartPage.java:52)     at StartPage$33.actionPerformed(StartPage.java:1121)  and line 47 is pst=con.prepareStatement("select * from routes");

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


I currently have some array lists and am trying to transfer some elements into a different array.   Here's what I have so far:  //create array separate from user input to remove duplicates  ArrayList<String> idsWithoutDuplicates  = new ArrayList<String>(); for (int i = 0; i < missionIds.size(); i++){     if (idsWithoutDuplicates.contains(missionIds.get(i))== false)         idsWithoutDuplicates.add(missionIds.get(i));  }  //search for mission numbers within array of array  for (int k = 0; k < idsWithoutDuplicates.size(); k++ ){     int idSize=0;     for (int employeeName = 0; employeeName <ids.size(); employeeName++){         for (int employeeId = 0; employeeId <ids.get(employeeName).size(); employeeId++){             /* when id is located, use the employee array to locate the other missions to               * which they belong */             if (ids.get(employeeName).get(employeeId).equals(idsWithoutDuplicates.get(k))){                 for (employeeId = 0; employeeId < ids.get(employeeName).size(); employeeId++){                     ArrayList<String> count  = new ArrayList<String>(); // ---> separate array for each employees total missions                     if (ids.get(employeeName).get(employeeId).equals(idsWithoutDuplicates.get(k)) == false &&                          count.contains(ids.get(employeeName).get(employeeId))== false){                         count.add(ids.get(employeeName).get(employeeId));                           idSize += count.size();                           for (int i= 0; i < count.size(); i++){                             System.out.print(count.get(i));                         }                     }                 }             }         }     }     System.out.println(idsWithoutDuplicates.get(k) + "\t    " + idSize);  }   The last if statement is trying to eliminate any duplicates with the contains condition, but this doesn't seem to work. I've tried converting 'count' to a set but this didn't work either.

I have an ArrayList<String>, and I want to remove repeated strings from it. How can I do this?


Show that 2|n(n+1) using induction   I tried but im stuck , it still (n+1)(n+2)   Two successive numbers   It's simple using the the methode that n=2k or n=2k+1   Can someone help or give a hint ?

Use induction to prove that, for all $n \in \mathbb{Z}^+$, $2\mid (n^2 − n)$.   That is, I am supposed to use induction to prove that $(n^2 − n)$ can be divided by $2$ when $n$ is a positive integer.  I've tried the following: $$\begin{split} (n+1)^2 − (n+1) &= (n+1)(n+1) - (n+1)\\ &=(n+1)(n-1)+2 - (n+1)\\ &=n^2 +n -n -1 +2 -n -1\\ &=n^2 -n, \end{split}$$ but I'm not particularly good at maths so I have no idea if this is even correct, and if it is, what it even means.


How correctly to rewrite domain to a subfolder with HTTPS ?  This will just redirect all request to subfolder1  RewriteCond %{HTTP_HOST} ^(www.)?example1.com$    RewriteRule !^subfolder1/ subfolder1%{REQUEST_URI} [L]   If I change to   RewriteCond %{HTTP_HOST} ^(www.)?example1.com$    RewriteRule !^subfolder1/ https://subfolder1%{REQUEST_URI} [L]   then it will generate a loop  The problem is if I navigate to this url: example.com  , then I want it to redirect to HTTPS, and to not change the url to something like: example.com/subfolder1   I want to make the above to work with HTTPS.

This is a  about Apache's mod_rewrite.   Changing a request URL or redirecting users to a different URL than the one they originally requested is done using mod_rewrite. This includes such things as:   Changing HTTP to HTTPS (or the other way around) Changing a request to a page which no longer exist to a new replacement. Modifying a URL format (such as ?id=3433 to /id/3433 ) Presenting a different page based on the browser, based on the referrer, based on anything possible under the moon and sun. Anything you want to mess around with URL   Everything You Ever Wanted to Know about Mod_Rewrite Rules but Were Afraid to Ask!  How can I become an expert at writing mod_rewrite rules?   What is the fundamental format and structure of mod_rewrite rules? What form/flavor of regular expressions do I need to have a solid grasp of? What are the most common mistakes/pitfalls when writing rewrite rules? What is a good method for testing and verifying mod_rewrite rules? Are there SEO or performance implications of mod_rewrite rules I should be aware of? Are there common situations where mod_rewrite might seem like the right tool for the job but isn't? What are some common examples?   A place to test your rules  The  web site is a great place to play around with your rules and test them. It even shows the debug output so you can see what matched and what did not.


I've been reading about algorithmic trading, which involves using complicated mathematical and statistical models to profit from market inefficiencies. Usually the gains from each trade are small, but when added together, they can generate huge returns. But why don't these trading firms simply buy a good stock, and hold the position until they make a profit? (1) Pick a stock with good long-term fundamentals and strong short-term momentum. (2) Set the price target at 1% higher than the current price (1% is pretty easy to achieve, because of short-term price fluctuation and the fact that the stock has upwards momentum). (3) Buy the stock, and wait until the price hits the target. (4) Sell the stock, rinse and repeat. While gaining 1% per trade may not seem to be much, but when added together, they can generate huge profits. So why don't trading firms simply do this? It seems to be a much more easier strategy than using complicated algorithms to look for small arbitrage opportunities or whatever. EDIT: Someone asked a similar question on Quora, but the answers are not what I am looking for......

Suppose I have 50,000 in a tracker.  Because it's an aggregate of the share index, it can obviously go up or down but what it certainly does is fluctuate up or down.   What is the problem, if any, of selling when it goes up 2% and then buying back in when it goes down 2%? Every time you clear 1000 allows you to then buy more shares. Surely you could do this many times a year? Barring crashes in the market, which means you hold for recovery, I can't see a downside myself. Any older, wiser heads out there?


I'm talking about the suggestions you (usually) get after you hold a key down for a few seconds. See image:    For some reason they suddenly stopped working for me. I honestly don't recall changing some preference directly related to this.  I would to re-enable it again but I cannot find a way to do it. Does someone know how to accomplish this?

Before upgrading to macOS Sierra, I really liked the Character Accent Menu by doing a long press on a key (for example, the character e) and being able to add an accent on it.   However, this functionality seems to not work anymore, and so far, I can't find out why?   Also, before, doing a long press on the delete button, would repeatly delete characters. Now, it is doing only one character deletion disregarding how long I'm pressing the key. So if I want to erase 10 characters, I need to press the delete button 10 times...  Also, I am not able to log off or shut down. When doing it, all applications are closed, status bar disappears but nothing happens. The dock remains here. I have no way to shut down or log out without doing a long press on the power button.  Is someone facing the same issue?  EDIT : Logging with a new user account or guest account fix all the problems. But I still would like to know what, in my user account, became corrupted during the upgrade.


I'm using Ubuntu 14.04 and I recently bought a . I want Ubuntu to automatically switch audio output to this device when I plug it in as opposed to me having to manually set it every time. Is there any way to do this? Thanks.

I have to plugin my USB Audio adapter ( 4300054 Gigawire USB Audio Adapter) for audio input because has a combo-input-output port for voice.  After I do this, I have go open Sound Settings and manually select the USB Audio adapter for Input and Output, if I do not, the system default remains selected.  Is there anyway, I can make Ubuntu to automatically select the USB Audio Adapter as the default as soon as I plug-in?


I'm trying to write a function in C that takes a struct array (of structs that hold employee information) as an argument and prints each member of each struct. For some reason my code isn't producing any output. Could anyone tell me where I am going wrong? Thanks.  Here it is:  #include <stdio.h> #include <stdlib.h>  typedef struct Employee {     int number;     char name[20];     char department[15];     double salary; }Employee;  void employeePrint(Employee arr[]);  main() {     Employee e1 = {101,"John Smith\0","Accounting\0",54926.25};     Employee e2 = {102,"Jane Q. Public\0","Retail\0",54926.24};     Employee e3 = {103,"George Washington\0","Tech\0",70417.76};      Employee empArr[3] = {e1,e2,e3};     employeePrint(empArr); }  void employeePrint(Employee arr[]) {     int i;     for(i = 0; i < sizeof(arr)/sizeof(arr[0]); ++i)     {         printf("Number: %-4d\n",arr[i].number);         printf("Name: %-6s\n",arr[i].name);         printf("Department: %s\n",arr[i].department);         printf("Salary: $%-2.2lf",arr[i].salary);         printf("----------------");     } }

How do I determine the size of my array in C?   That is, the number of elements the array can hold?


So as you can see here:    My fonts messed up for some reason. It was fine yesterday though.  I've already tried sfc /scannow which didn't do anything and I can't change the font via appearances because... I can't read what it says when the window opens..  Any help would be very appreciated :)  Edit: I did some more digging, and according to InDesign I'm simply just missing 90% of my fonts? I don't know if that helps though.

My windows 10 show garbage characters, I guess I didn't do anything special, but when I start my computer, it looks like this now. is there anything I can do right now?


This is not duplicate As I wanted to check why my argument is not working,Please have a look     $\mathbb Z[\frac{1+\sqrt{-7}}{2}]$ is euclidean domain.   My attempt:  I had thought following proof for $\mathbb Z[\frac{1+\sqrt{-3}}{2}]$ but there is problem to use same method to show $\mathbb Z[\frac{1+\sqrt{-7}}{2}]$ is ED. So I thought is my attempt is wrong?  $a,b\in  \mathbb Z[\frac{1+\sqrt{-3}}{2}]$  Consider $\frac{a}{b}=r+s(\frac{1+\sqrt{-3}}{2})$ where $r,s \in \mathbb Q$  So choose $m,n \in \mathbb Z$ such that $-1/2N(b)\leq r-m\leq 1/2N(b)$ and $|n-s|\leq 1/2N(b)$  So $a=mb+nb(\frac{1+\sqrt{-3}}{2})+r_1+r_2(\frac{1+\sqrt{-3}}{2})$ where $r_1+mb=r$ and $r_2+nb=s$  Now $N(r_1+r_2(\frac{1+\sqrt{-3}}{2})$=$r_1^2+r_1r_2+r_2^2\leq 3/4N(b)<N(b)$  Hence Done  Similar proof I tried for   $\mathbb Z[\frac{1+\sqrt{-7}}{2}]$  but last step I get $N(r_1+r_2(\frac{1+\sqrt{-7}}{2})\leq N(b)$  So I could not conclude.  I would thankful if someone help me out

Is the ring $\displaystyle A=\mathbb{Z} \left[ \frac{1+i \sqrt{7}}{2} \right]$ euclidean?  If $N : z \mapsto z \overline{z}$, then for all $z \in \mathbb{C}$ there exists $a \in A$ such that $N(z-a)<1$, except when $z$ has the form $\displaystyle \left(n+\frac{1}{2} \right)+ \left(m+ \frac{1}{2} \right) \frac{1+i \sqrt{7}}{2}$; in this case, you can only find a large inequality. So $A$ is "almost" euclidean, but is it actually euclidean?


Let there be a random sample $X_1,\cdots,X_n \sim f(x|\boldsymbol{\theta})=\frac{1}{\theta_2}exp[\frac{-(x-\theta_1)}{\theta_2}], x > \theta_1, -\infty<\theta_1<\infty,0<\theta_2<\infty$. How can I find the MLE of $\boldsymbol{\theta}=(\theta_1,\theta_2)$?  My work:  $L(\boldsymbol{\theta})=\frac{1}{\theta_2^n}exp[\frac{-1}{\theta_2}\sum(x_i-\theta_1)]1_{\{\theta_1,\infty\}}(x_{(1)})$  $log(L(\boldsymbol{\theta}))=l(\boldsymbol{\theta})=-nlog(\theta_2)-\frac{1}{\theta_2}(\sum (x_i)-n\theta_1)+log(1_{\{\theta_1,\infty\}}(x_{(1)}))$  $\frac{\partial l(\boldsymbol{\theta})}{\partial \theta_2}=\frac{-n}{\theta_2}-\frac{\sum(x_i)-n\theta_1}{\theta_2^2}=0$ implies that $\hat{\theta_1}=-\frac{(n+\sum x_i)}{n}$  $\frac{\partial l(\boldsymbol{\theta})}{\partial \theta_1}=\frac{n}{\theta_2}+\frac{1}{1_{\{\theta_1,\infty\}}(x_{(1)})}=0$  Where do I go from here? I do not think that I did the second partial derivative correctly for $\theta_1$.  Updated work based on provided link to show $lnL(\hat{\mu},\hat{\sigma}) > lnL(\mu,\sigma), \forall (\mu,\sigma)$:  So, $\hat{\theta_1}=X_{(1)}$ and $\hat{\theta_2}=\frac{1}{n}\sum(x_i-x_{(1)})$  $lnL(\hat{\mu},\hat{\sigma}) > lnL(\mu,\sigma)$  $(\frac{n}{\sum(x_i-x_{(1)})})^nexp[\frac{-n}{\sum(x_i-x_{(1)})}\sum(x_i-x_{(1)})]>\frac{1}{\theta_2^n}exp[\frac{-1}{\theta_2}\sum(x_i-\theta_1)]$  $(\frac{n\theta_2}{\sum(x_i-x_{(1)})})^nexp[\frac{-n}{\sum(x_i-x_{(1)})}\sum(x_i-x_{(1)})+\frac{1}{\theta_2}\sum(x_i-\theta_1)]>1$

Let $x_1, x_2... x_n$ be a random sample from a distribution with pdf:  $$f(x;\mu,\sigma)=\frac1{\sigma}\exp\left({-\frac{x-\mu}{\sigma}}\right)\,,-\infty<\mu<\infty;\, \sigma>0;\, x\ge\mu$$  How do I find the MLE for the parameters if both parameters are unknown?  I tried using the usual MLE with likelihood function:  $$L(\mu,\sigma|x_1...x_n)=\frac{1}{\sigma^n}\exp\left({-\frac{\sum{x_i}-n\mu}{\sigma}}\right)$$ But the derivative of this with respect of $\mu$ is a dead end.   I do know that if $\sigma$ is known, the MLE for $\mu$ is $\frac{\sum{x_i}}{n}$ and if $\mu$ is known, the MLE for $\sigma$ is $\frac{\sum{x_i}-n\mu}{n}$.   Do these help? What should be the approach?


So, I wanted to use Linux instead of Windows and chose to install it in dual mode so I can switch back. Linux suddenly stopped recognizing wifi and is on airplane mode, even if I turn it off it keeps going back on to airplane mode. I'm only a beginner coder who barely knows the basics of Python. I just want to use my computer again - before all of my college papers are due! Please help! I don't have a windows disk or an Ubuntu and I can't download the boot-manager. I have windows 8.1 and installed Ubuntu 14.01.

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


I guess this is sort of an odd question, but consider this scenario.   table classes (id_pk) table students (id_pk) table students_classes_map (students_id_fk_pk, classes_id_fk_pk, finalExamScore decimal, finalGrade decimal ...)   I am using unique combinations of foreign keys to map students to all classes that they ever took. Standard practice. But, say that I wanted to store some statistics for students and their classes, statistics that didn't change after a class ended.  Is what I did ok practice or should map tables simply map m2m relations and not include any other columns? I.e. should I create a new table called player_classes with an autoinc int pk as a one to many table that holds some data for a user in a particular class? (Grade, attendance, etc) and separate this data from the student_class_map table

I searched but did not find any discussions on this topic. Are there any pros and cons on creating many extra columns on joined table? Does it affect speed of data retrieval because we are joining 3 tables?  As far as what I think, it may slow tiny bit but it is necessary otherwise how can we save additional data about many-to-many relationships. Or is there any other way of which I am not aware of?


I have a problem with rounding rectangle. I know how to round a cube, but not how to evenly round a rectangular prism. When I use bevel, it does not seem to bevel evenly. But I want to do it correctly. Please see the following pictures for an example:  This is my model comparison. Here you can see my model is not rounded evenly.   And this is standard cube, that you can see when program starts. It's rounded evenly, but when you will scale it, you can see, that it will round not evenly, like my model (But my model was created not on this method)

I'll preface this by saying I'm very new to Blender - I'm trying to put a bevel on an edge, looks something like this:    As you can see, the vertical side is much longer than the horizontal side.  When I apply to bevel to the edge there, the bevel stretches proportionally - so there's 'more' bevel on the longer side.  I want to bevel without any 'ratio' like that - just a 45-degree bevel, if that makes any sense.  Do I have to put in a loop cut to make the side lengths equal?  I tried using a sub-surf modifier, but it applies on a bunch of nearby edges, when I just want to round this one corner.


User Experience is a practice which has historic roots in multiple other disciplines, uniting and combining them to provide something new. What are the building blocks of UX and what role do they contribute to the whole?

Is there a number of responsibilities that fall under UX (for example, graphic design, usability etc), or is UX a sub responsibility of design?


Hint for finding the $\sum_{n\geq1} \frac{n^p}{n!},p\in \mathbb{N} $ I would appreciate a hint or several hints if I can solve this problem in different ways.

Using some matlab (I know it's cheating) I found that: $$k=0 => Result=1$$ $$k=1 => Result=1$$ $$k=2 => Result=2$$ $$k=3 => Result=5$$ $$k=4 => Result=15$$ $$k=5 => Result=52$$ $$k=6 => Result=203$$  This sequence is puzzling...


ould someone please give me an idea as to how the solve the following.   $$T(1) = 1$$ $$T(n+1) = T(n) + \lfloor\sqrt{n+1}\rfloor$$  I converted the recurrence to $T(n) = T(n-1) + \lfloor\sqrt{n}\rfloor$ and then tried to solve it using the method taught in the "" at MIT and got the solution as $T(n) = n^\left(3/2\right) + 1$.  But the page I found this problem in asks for $T(n^2)$ and gives the answer as $\frac n6\left(4n^2 - 3n + 5\right)$, which I'm not able to derive.  Can someone please help me solve this recurrence?  Thanks

$T(n+1)=T(n)+\lfloor \sqrt{n+1} \rfloor$ $\forall n\geq 1$    $T(1)=1$   The value of $T(m^2)$ for m ≥ 1 is?   Clearly you cannot apply master theorem because it is not of the form $T(n)=aT(\frac{n}{b})+f(n)$ So I tried Back Substitution: $T(n)=T(n-1)+\sqrt{n}$ $T(n-1)=T(n-2)+\sqrt{n-1}$ therefore, $T(n)=T(n-2)+\sqrt{n-1}+\sqrt{n}$ $T(n)=T(n-3)+\sqrt{n-2}+\sqrt{n-1}+\sqrt{n}$ . . $T(n)=T(n-(n-1))+...T(n-k)+\sqrt{n-(k-1)}+...+\sqrt{n-2}+\sqrt{n-1}+\sqrt{n}$ . . $T(n)=T(1)+...T(n-k)+\sqrt{n-(k-1)}+...+\sqrt{n-2}+\sqrt{n-1}+\sqrt{n}$ $T(n)=T(1)+...+\sqrt{n-2}+\sqrt{n-1}+\sqrt{n}$ I'm stuck up here, how to solve this ahead?


Bluetooth headsets in general (or just most of them?) can only do one of the following:  Play stereo sound (or "high quality" sound in general) Play mono/restricted sound and take mic input  but not both. This means that when I get a call for example, the rest of the system is effectively muted while the communications program is using the HandsFree driver of the headset. I'd like an option to allow the system to automatically switch back and forth between modes. So that:  If some application requires the mic, default everything to the mono driver If no applications require the mic, default to the stereo/good driver

I have a Plantronics BackBeat Sense SE bluetooth headset. When Connecting it to Windows 10, it installs two profiles in Playback devices list:    PLT_BBTSENSE Hands-Free. PLT_BBTSENSE Stereo.   The Second one (Stereo) is set to be the "Default Device" and the "Default Communication Device" on the system.   At this point the sound works great and normally. The problem happens when I want to use the mic. When I start any program that uses the mic (recorder, chat, VoIP Calls, gaming, etc.) The sound suddenly stops working And I can only use the mic until I stop the recorder or the call.   The thing that kind of fixes the problem is setting the (Hands-Free) as the default device. I can hear the sound when I do that and it works with the mic but it becomes Very bad quality.  What I became to understand is that bluetooth had different profiles for sound and mic: A2DP and HSP. The first handle the voice(High Quality) but the latter handles the mic and reduces the sound quality.  Is this really the case? Is there anyway to make them work simultaneously? Is there any solution to this problem at all?


I got a Samsung T7 SSD drive knowing that it can handle 1GB/s read or write, but if I used  rsync -a --progress --stats --human-readable file1.m4v /Volumes/T7/file1.m4v   to tell the speed of copying a file, it only can go up to 180MB/s or at most 220MB/s (and cp feels slow as well).  But if I open up two Finder windows and drag and drop the file over, it really feels like 5 seconds to copy a 5GB iTunes movie file. (I then used a stopwatch to find out copying 16.5GB needed about 19 seconds).  (I think why the UI drag and drop can copy so much faster is due to rsync or cp using one processor core, and it is limited to one core's speed.)  So if I use the UI's drag and drop way of copying, is there a way to tell the copy speed? Or alternatively, if I use any command in Bash, can it copy a file at the maximum speed of the SSD and be able to tell the speed?

I accidentally stumbled upon this issue:  Copying a 119 MB zip file took 4 times longer in Terminal (cp) than in Finder!  I copied a file of 119 MB size in Terminal with  time cp file.zip file2.zip and it took about 20 seconds.  As this seemed quite slow to me, I went to the Finder, selected the same file and hit Cmd-D (duplicate) and it took less than 5 seconds to create the copy, that is only 25% of the time it took with cp!  Is there an explanation for it - might this be systematic?  Used Hard-/Software   MacBook 13" white (2007) OS X 10.6.8 Internal hard disk WDC WD10JPVT-00A1YT0         it really seems to be a cache issue: I tried the opposite order with another file and copied it first in Finder and then in Terminal, and in this case also the second copying was much faster.


I am tired of always trying to guess, if I should escape special characters like '()[]{}|' etc. when using many implementations of regexps.  It is different with, for example, Python, sed, grep, awk, Perl, rename, Apache, find and so on. Is there any rule set which tells when I should, and when I should not, escape special characters? Does it depend on the regexp type, like PCRE, POSIX or extended regexps?


I'm having troubles converting a time string to datetime object: And i know this question has been asked a couple of times but i haven't been able to find a solution for my question.  Here is my code:  order['created'] = 2018-12-22T00:41:30.926932Z created_at = datetime.datetime.strptime(order['created'],'%m/%d/%Y %H:%M:%S.%f').replace(tzinfo=pytz.utc).astimezone(local_tz)   and this is the error message I get     ValueError: time data '2018-12-22T00:41:30.926932Z' does not match   format '%m/%d/%Y %H:%M:%S.%f'

I need to parse  strings like "2008-09-03T20:56:35.450686Z" into Python's datetime type.  I have found  in the Python standard library, but it is not very convenient.  What is the best way to do this?


Out of an impulse buy - I now have a complete ebike kit with battery. Originally I wanted this to be put on a mountain bike but upon seeing how little the rim is - I don't think any mountain bike tyres will fit in there. I measured the rim (where the tyre will go) and it was roughly 2cm, slightly less in fact, does that mean that this kit is designed to go on a road bike/hybrid bike and only that? The diameter is 26 inches - any help appreciated thanks

We often get questions on bicycles.stackexchange about fitting wider or narrower tires to bicycles. We have a large number of these with answers suiting the specific bike or style of bicycle in question, but I have been unable to find one that provides a generic answer covering off all things that need to be considered. For most bicycles, the answer is the same regardless of the specific style and sizes of tires in question.   This is intended as a canonical question that we can point closed questions to.


.   Can you Refreeze bake/cooked chicken?   How long is cooked meat good in refrigerator?

What are the general rules regarding when can you refreeze food that was frozen and then thawed in the fridge? and what are the reasons behind them? (Hygiene? Food quality?). Let's assume for the sake of the argument that the items were in a non-frozen state only a few hours.  To be more specific, I'm interested in the application of these rules for  - Ginger garlic paste - Dough - Indian Curries - Green Chilly paste - Frozen green peas


Apologise for the bad title, I didn't succeed in summarizing what I mean.  I use the acronym package.  I set up a list of acronyms like  \begin{acronym}[AWGN]  \acro{UK}{United Kingdom}  \acro{USA}{United States of America} \end{acronym}   that I recall using, for example:  \ac{UK}   When I use one particular acronym for the first time, it also shows its definition. For example, this text  London is the capital of \ac{UK}.   is shown as     London is the capital of United Kingdom (UK).   But I only want     London is the capital of UK.   How can I do that?

I am referencing a table containing an acronym entry that has not been mentioned in the text before. I would like to print the acronym short form in the table (the acronym is used multiple times in the table) and print the long form when the acronym is used in the text for the first time. Here is my MWE:  \documentclass[a4paper,11pt,oneside,fleqn]{scrbook} \usepackage[ngerman,english]{babel} % language listed last is default setting \usepackage[utf8x]{inputenc}  \usepackage{mhchem}  \usepackage[acronym,toc]{glossaries} \makeglossaries  \newacronym{LAr}{L\ce{Ar}}{Liquid Argon}  \begin{document}  some text ... \ref{SampleTable} ...  \begin{table}[!h] \centering \begin{tabular}{|c|c|c|} \hline & & \\ \hline \hline \gls{LAr} & & \\ \hline \gls{LAr} & & \\ \hline & & \\ \hline & & \\ \hline & & \\ \hline & & \\ \hline \end{tabular} \caption{Sample Caption} \label{SampleTable} \end{table}  .... some text ... \gls{LAr}  \end{document}


taking in subnet and ip address, performing a logical AND to retrieve the network address. My question is, how do I return a list of four octets, rather than just have all of the values stored into a list.  Example, my function is printing ['1','1','1','1'...], where as I want to print ['11111111','11111111','11111100','11111111']  def logicalAnd(ip, subnet):  test = list() for ipOctect, subnetOctect in zip(ip, subnet):     for i,j in zip(ipOctect, subnetOctect):         octet = (i and j)         test.append(octet) print(test)

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


What is the meaning of the directory specified by '//'?  It can be accessed by typing in 'cd //' at the comand prompt.   I have tried this on mac 10.9.5 and Centos 6. It shows the contents for the root directory. In the prompt it shows '//' for the directory. Is this simply a glitch in the prompt code? I use \w to show the working directory.

In unix/linux, any number of consecutive forwardslashes in a path is generally equivalent to a single forwardslash. eg.  $ cd /home/shum $ pwd /home/shum $ cd /home//shum $ pwd /home/shum $ cd /home///shum $ pwd /home/shum   Yet for some reason two forwardslashes at the beginning of an absolute path is treated specially. eg.  $ cd ////home $ pwd /home $ cd /// $ pwd / $ cd // $ pwd // $ cd home//shum $ pwd //home/shum   Any other number of consecutive forwardslashes anywhere else in a patch gets truncated, but two at the beginning will remain, even if you then navigate around the filesystem relative to it.  Why is this? Is there any difference between /... and //... ?


I'm trying to convert a CSV file to Arff format following this guide. (link below)  This is for practice purposes, I just want to know how to convert this properly before building a bigger dataset.   CSV file  Name,points,rebounds,steals,assists Lebron James,17,10,1,7 Lebron James,29,5,2,8 Lebron James,30,4,0,8 Lebron James,24,4,1,3 Lebron James,25,1,0,11 Lebron James,22,4,2,9 Lebron James,21,3,2,2 Lebron James,27,7,1,14 Lebron James,41,5,0,5 Lebron James,35,2,2,2 Lebron James,18,4,3,4   Java file - Working off this site tutorial   import weka.core.Instances; import weka.core.converters.CSVLoader; import weka.core.converters.ArffSaver;  import java.io.File;  public class arffBBALL{     public static void main(String[] args) throws Exception{            //load CSV         CSVLoader loader = new CSVLoader();         loader.setSource(new File("Users/myname/Desktop/bball.csv"));         Instances data = loader.getDataSet();           //save ARFF         ArffSaver saver = new ArffSaver();         saver.setInstances(data); // set the dataset we want to convert         // save as ARFF         saver.setFile(new File("Users/myname/Desktop/nbball.arff"));         saver.writeBatch();     } }   This is the error I'm getting in Java  Exception in thread "main" java.lang.NullPointerException     at java.io.StreamTokenizer.<init>(StreamTokenizer.java:248)     at weka.core.converters.CSVLoader.getStructure(CSVLoader.java:593)     at weka.core.converters.CSVLoader.getDataSet(CSVLoader.java:628)     at arffBBALL.main(arffBBALL.java:15)   I loaded the Weka.jar file into the referenced Library, but I can't seem to convert the CSV file to arff.  I have the CSV file on my Desktop on my Mac.    Any help would be appreciated.  Thanks  EDIT:  Latest errors after adding absolute path:  ---Registering Weka Editors--- Trying to add database driver (JDBC): jdbc.idbDriver - Error, not in CLASSPATH? Exception in thread "main" java.io.IOException: wrong number of values. Read 2, expected 1, read Token[EOL], line 4     at weka.core.converters.ConverterUtils.errms(ConverterUtils.java:912)     at weka.core.converters.CSVLoader.getInstance(CSVLoader.java:824)     at weka.core.converters.CSVLoader.getDataSet(CSVLoader.java:646)     at arffBBALL.main(arffBBALL.java:15)

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


I wanted to edit 's title which is on Mathematics Meta Stack Exchange because it did not have anything to do with the question itself. However, I could not edit it. When I tried to edit it, it brought me this message:  Suggested edits are not allowed on non-tag-wiki posts on meta sites.  Then, someone else came to edit the question's title. He was not a moderator, he just had way more reputation than me (I had 159, and he had 10k+). You also cannot gain privileges in Meta. At least that was what I saw in the Activity tab. So do I have to get 2k reputation on the main site to edit it, or is there something wrong? I'm relatively new to the site, and I rarely use Meta.

I noticed that the reputation from the main site carried over to meta on Gaming (at least the first upvote), I guess that doesn't work the other way around, right?  Is it then impossible to have a meta reputation higher than the site reputation?


I understand that adding content to a tag wiki gets two reputation points.  Today, I appear to get four points (2 x 2) for    which I do not understand. Why the double allocation?

I noticed (now that  has been fixed) that you basically get two +2 rep bonuses for suggesting a tag wiki: one for the wiki, one for the wiki excerpt. Is this really intended? It seems odd to me, since I suggested both at the same time from the same screen. Does it work the same way with posts: do I get +2 for suggesting an edit to a post's title, another +2 for suggesting an edit to the body, and another +2 for suggesting an edit to the tags?


Im trying to use the hyperref package for creating a link to a website with a dynamic url. I have a script that outputs an id that should be used in the url.  I have been trying to wrap my head around this for hours trying to figure how to achieve this but as a fairly new user of TeX I must admit defeat now.  Here is an example of what I want to do:  \newcommand{\getid}[0] {     \input{|"get-id.sh"} }  \newcommand{\createlink}[0] {     \getid \\ % Just for debugging     \href{https://www.website.com/\getid}{MyLink} }   This produces the id correctly but on the next line there is nothing remotely what I want, more exactly just "\let\reserved@d=\bgroup\def{\@@par}".  I have also tried \edef\getid{\input{|"get-id.sh"}} with the same result even though I feel like that should evaluate the input before I try to use the variable.  Using \def\getid{MyStaticID} works just fine so the problem only appears when using \input.  Possible workarounds could be to write the value with TeX code to a file and then import it, alternatively pass it to the code using pdftex. I would however prefer to do it in the TeX file as I am trying to do but is it even possible or a limitation somewhere I will have to live with?  Thanks in advance.  Edit  I build the pdf with pdfTeX from the TeX Live system installed with MacTeX. I use latexmk for building and in my .latexmkrc I have the line  $pdflatex = 'pdflatex --shell-escape -synctex=1 -interaction=nonstopmode';   which should enable input from commands (which it does successfully at times, just not with URLs).  My main document looks like this (stripped from irrelevant stuff for ease of reading but with all packages):  \documentclass[a4paper, 11pt]{report}  \usepackage[utf8]{inputenc} \usepackage{graphicx} \usepackage{epstopdf} \usepackage{enumitem} \usepackage{hyperref} \usepackage{ifthen} \usepackage{pdfsync} \usepackage{titlesec} \usepackage{tocloft}  \newcommand{\getid}[0] {     \input{|"get-id.sh"} }  \newcommand{\createlink}[0] {     \getid \\ % Just for debugging     \href{https://www.website.com/\getid}{MyLink} }   \newcommand{\wordcount}[0] {    \input{|"texcount -sum -1 content/chapters/*"} }  \begin{document}   \wordcount{} \createlink{}  \end{document}   and the get-id.sh is currently just echoing git rev-parse HEAD.  The wordcount and first part of createlink works just fine so there must be something in the url or hyperref packages that breaks (or just doesn't work the way I want/expect it to).

Let's say I compile the following file with pdflatex -shell-escape test.tex:   \documentclass{minimal}  \begin{document}  File listing is:  \immediate\write18{ls /usr}  \end{document}   This will send the output of the command ls /usr to report/log of pdflatex (primarily to stdout).   There are then two cases I'd like to utilize:    The output of ls /usr being included directly in the document (LaTeX stream). The output of ls /usr becoming the contents of a \newcommand (by this I mean, that I'd like the script to be executed when the \newcommand is executed first - and upon subsequent calls to the new command, the shell code should not be executed anew).    I have read through , but I'm not sure if this "pipe input" can be applied to \newcommand.   I have also read through  - and it seems that Tex' file I/O should be used; but I'm quite disliking the fact that I'd still have to redirect the script output (actually, in this case, the ls /usr output) to a file, and then read it in, to have it as contents of a command.   So, is there an easier way to achieve what I'd want (hopefully, illustrated through an example based on the above code)?     EDIT: Ehm, I should have asked one more question earlier :) I'll try with an edit here, although it will probably get missed .. :)   I originally asked for a \newcommand that will execute shell code only upon its definition (i.e., in a sense it is "cached"); and the answer from @egreg does exactly that. But then - would it be possible to have a different \newcommand definition, such that each time this newcommand is called, the shell command is executed anew? I.e. executing something like \@@input|"cat tempfile" (which cannot be executed as such), where tempfile changes between calls?


I am building a javascript remote for Kodi, where i only send data if it is changed. I am stuck with this peace of code. It will check every x seconds for a value but i only want to do something if the value has changed. Can someone shed some light on this?  every((0.35).second(), function() {   var kodi_api_request = {"jsonrpc": "2.0", "method": "Player.GetActivePlayers", "id": 1};   var kodi = encodeURIComponent(JSON.stringify(kodi_api_request));   var previous = {};   var stuff = request   .get('http://localhost:8080/jsonrpc?request=' + kodi, function (error, response, data) {     var newdata = data     if (previous !== newdata) {       console.log('changed');       previous = newdata;       console.log(newdata);     } else {       console.log('Error!');     }   }); });

A strict equality operator will tell you if two object types are equal. However, is there a way to tell if two objects are equal, much like the hash code value in Java?  Stack Overflow question  is similar to this question, but requires a more academic answer. The scenario above demonstrates why it would be necessary to have one, and I'm wondering if there is any equivalent solution.


I am not a student of mathematics, and I have never studied number theory. I was looking at RSA recently. Euler Theorem is used here. I don't quiet understand $1(mod\quad n)$ in Euler Theorem$a^{\phi (n)}≡1\pmod n$.  Are $1\pmod n$ and $1\; mod\; n$ the same ?   Isn't $1\; mod\; n$ always one? Why is the $ed=1\pmod n$ equal to $d=e^{-1}\;mod\;\phi(n)$?

I am trying to write the Euclidean algorithm in the following way:  $A = \lfloor A \div B \rfloor \times B + (\text{remainder of}) \: A \div B $   Now is there any symbol I can use  to say "remainder of A $\div$ B"? I know that in the C programming language there is the operator % for modulus; is that a valid symbol in maths? Can I write A % B? Or is there some other way?


I have a mid 2012 Macbook Pro running macOS Mojave 10.14.4.  When I plug in the external monitor it detects the display however on the external monitor screen it say no input.  I have checked all connections and tested them they are working fine. MiniDisplay to HDMI cable tested and confirmed working on other another mac (mac mini mid 2013)  I checked the console when I plugged it in and am getting this error:  [ERROR] - Driver bug - rowBytes too small. Display 0x42732c0, ioModeID 0x8000100a, ioModeDepth 0x0, bytePerRow = 5120, width = 1680, bitsPerPixel = 32,  minRowBytes = 6720 stored width = 1680. Forcing minRowBytes (possibly still wrong).   also   [ERROR] - Unable to find display pipe for IOFB service: 18203   Can anyone explain this error to me? Could it be a driver error?  The monitor I'm using is a Hitachi LE24K318A  This question is different from the others because the other questions don't show console outputs. I'm also not getting a "blank screen", I'm getting no input and errors.

MacBook Pro (15-inch, 2016) with 2 USB-C to HDMI adapters. The setup works great if I start up in that configuration.   If I connect the adapters while the machine is running or simply sleeping, one of the monitors will never get a signal and stay in low power mode. The OS sees the monitor, it shows in the display arrangement settings and I can move the mouse into it, but until I restart, I can't see anything on it.  Once I have restarted I can let the machine sleep or whatever, and the display still works unless I disconnect the adapter. As soon as I do that a restart is required to use it again.   Using MacOS Sierra (10.12.4)  Using this adapter:


I know little bit C Programming and Java. I want to start hard study on Objective-C and all other stuff that needed for Apple App and Game development, But I don't have any MacBook or iMac where I can learn them with xCode. I have just a iPhone 5.  Can anyone please let me know, how can I process on my Windows/Ubuntu computer?  Thank you,  John

Is there any way to tinker with the iPhone SDK on a Windows machine? Are there plans for an iPhone SDK version for Windows?  The only other way I can think of doing this is to run a Mac VM image on a VMWare server running on Windows, although I'm not too sure how legal this is.


Searching "deleted:1" yielded 217,625 results.  I am not informed why my account is suspended. I have no question or answer history here:   Solution idea: a "deleted" tag. This would allow that tag to be searched or RSS albeit it's on a per-site basis as I think user IDs are not consistent on all sites.  I hate investing time into a question only to have it deleted and not being notified about it. But it seems like the site keeps the database entry, so I was wondering if I can grep/mget all my deleted posts.  . Maybe I can replace it like so:  $EXCHANGESITELIST . "/users/recently-deleted-answers/885719"  $EXCHANGESITELIST . "/users/recently-deleted-questions/885719"   and like flashGot.  But I wanted to ask you guys if this feature is implemented or perhaps I can set up an RSS feed to be notified.

I would really like to see all of my questions and answers on the profile page, even if some of them were deleted, and I don't have enough rep to see them on the site. (Note that some questions are  after 30 days or 1 year, and the author might be oblivious about what happened.)   , the "deleted recent [questions/answers]" links in one's own user profile now list all respective posts that were deleted in the past 60 days, rather than just those that were originally posted in the last 60 days. , users with the "access to moderator tools" privilege (10k+ on designed sites, 2k+ on beta and non-designed sites) can use the search operator deleted:1 to see all their own deleted posts. , deleted questions and answers that were posted in the past 60 days, can be seen using the "deleted recent questions" and "deleted recent answers" links on the questions and answers tabs (at the bottom of the tab) in your user profile. For older posts: as of 2013-04-23 you can  if you already have a link to them, but they still aren't linked from the user profiles (not even just for you). Nor do you see inbox notifications for comments on them if you come back a few hours later. You have to have thought to bookmark your question, or you have to go digging for it in your browser history.


I'm running CentOS 6.2, trying to run tasks through cron. I've verified crond is running  $ service crond status crond (pid  20553) is running...   I have no /etc/cron.allow file, but I do have an /etc/cron.deny file that is empty.  I've checked the /var/log/cron file only to find entries of EDIT and RELOAD sessions, nothing being executed.  I did have some trouble with my system clock earlier today, and I think I resolved it. $ date and $ uptime both give back the correct time, but I can't execute hwclock commands for other issues. Should I look into problems with the hardware clock as the cause for nothing being executed or is there something else I'm forgetting here?

This is a  about using cron & crontab.   You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is not answered below then the answers will help you gather information that will help the community help you. This information should be edited into your original question.  The answer for 'Why is my crontab not working, and how can I troubleshoot it?' can be seen below.  This addresses the cron system with the crontab highlighted.


I am a Moroccan citizen flying from Casablanca to New York via Lisbon (TAP Portugal). The layover is around 8 hours at Lisbon and I have no Schengen visa of any type.    Do I need an airport transit / transit visa for Lisbon?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


Following on from this question: , I have a 237GB SSD C: drive (almost full, nearly 4 years old) with Windows 10. I have a 1.8TB magnetic drive (D:), currently unused and empty. I want to mirror the C: drive to the D: drive, so if the C: drive blows up, I don't have downtime as I go through a restore process. How do I do this (using Windows 10 or otherwise)? Can I do it by creating a partition on the 1.8TB D: drive so I 'm not wasting all that space? (C: drive is only 237GB.)  Obviously backups are already in place.  Edit: This is not a duplicate of my linked question. They are about completely different things. That question was about installing, not mirroring, Windows 10 on another drive on the same machine using the same product key, which is what I prefer to do. Still waiting for an answer there, please have a crack, I'd really like to know how to do it, and have a bunch of related questions about it. This question is about mirroring an existing C: drive to a second drive (using Windows 10 tools or otherwise), because that was suggested in an answer to the first question, although it didn't actually answer the question.

Current Setup:  My machine has four hard drives:  A 237GB SSD C: drive (almost full, nearly 4 years old) with Windows 10. I've got the original Windows 8 installation CD.  Storage Space (Z: drive), for important files. This Storage Space is comprised of two magnetic 1.8TB hard drives.  1.8TB magnetic drive (D:), currently unused and empty. Had some VM hard disk files there but I've moved them to my Storage Space (Z:) to make way for a new OS.  I have a Maximus VI Hero motherboard and UEFI bios.  Background:  I'm worried my C: drive will fail at some point. I need to get up and running again very quickly if this happens. I can't spend any time installing all the programs I need to do my job, especially if there's something urgent I need to deal with. (I realise that something else in my machine could fail, in which case I'd need a redundant workstation. Getting one soon.)  Goal:  I want to install Windows 10 on my spare D: drive. So if I lose the C: drive, I can boot Windows 10 on the D: drive, which will have all the programs I need installed and set up, good to go.  Main questions:  How do I do this?   Can I install Windows 10 on another drive using the same product key or do I need to buy another copy?  Related Questions:  I've dual booted Ubuntu and Windows on laptops before, but that was only one drive. Will I get something like a menu like Grub where I can choose which OS I want? I think I've seen a OS selection menu on Windows computers before.  Do I have to unplug or replug any cables before or after installation?   Will I be able to see the Storage Space (Z:) drive from the new Windows 10 OS?


Most books I've consulted on this matter give the following statement of Noether's theorem:  If a Lagrangian has a continuous symmetry then there exists a current associated with that symmetry that is conserved when the equations of motion are satisfied.  In my notes, the theorem is stated rather differently: if the action $S[\Phi]$ is invariant to the first order with respect to infinitesimal trasformations $\Phi\to \Phi+\theta\Delta\Phi$ if and only if the parameter $\theta$ is global, then there exists a local conserved current $j^\mu(x)$. There is something I am not sure about. By the principle of stationary action, the action should be invariant (to first order) under a transformation $\Phi(x)\to \Phi(x)+\Delta\Phi(x)$; this is true for on-shell fields, that is, for fields that actually solve the resulting equations of motion. Therefore, on-shell, it should also be invariant when $\theta$ is a global parameter and so any action $S[\Phi]$ is trivially invariant under a transformation of the form $\Phi(x)\to \Phi(x)+\theta\Delta\Phi(x)$. In this version of Noether's theorem, should I assume the invariance to also hold off-shell, for any possible field $\Phi(x)$?

For any transformation of the fields,  $$\varphi\to\varphi'=\varphi+\delta\varphi$$ the change in the Lagrangian can be written as  $$\delta\mathcal L = \text{EoM} + \partial_\mu j^\mu\tag{1}$$where "EoM" represents the equations of motion (Euler-Lagrange equations) and all other terms can be written as a total derivative of some function $j^\mu$, which is a known function in terms of the Lagrangian.   I would like to distinguish the different realizations of transformations. Let's assume that the transformation (1) leaves the action invariant, $\delta S=0$.    $\delta\mathcal L=0$   EoM $=0$, "on-shell": Noether current is conserved, $\partial_\mu j^\mu=0$. EoM $=\partial_\mu b^\mu\neq0$, "off-shell": modified Noether current $J^\mu = j^\mu+b^\mu$ is conserved, $\partial_\mu J^\mu=0$.   $\delta\mathcal L =\partial_\mu a^\mu \neq 0$, "quasi-symmetry"   EoM $=0$, "on-shell": modified Noether current $J^\mu = j^\mu-a^\mu$ is conserved, $\partial_\mu J^\mu=0$.  EoM $=\partial_\mu b^\mu\neq0$, "off-shell": modified Noether current $J^\mu = j^\mu-a^\mu+b^\mu$ is conserved, $\partial_\mu J^\mu=0$.     Is this listing correct?      What roles do the terms "on/off-shell" and "(quasi) symmetry" play in Noether's theorem?   Related: , , , , .


I edited an older question and then people complained about bumping such an old question to the front page for a minor edit.  If such an edit is not worth bumping the question, I think this should not stop you from editing, but is a misfeature of the site to bump it to the front page. Either there should be a threshold when a questions is bumped (and maybe an age limit) or an option for the editor to prevent bumping.  Then questions can be improved without annoying somebody.  While there is a point in getting more reviews of edits, this prevents at least implicitly by discouraging them through complaining users drive by edits, where I for example cannot really help with the question, but correct some minor issues like wrong tags or spelling errors. I think nothing should prevent someone from improving a question or answer, but of course not everybody needs to see the question again just because some punctuation was changed.

Given that the Stack Overflow trilogy is to be a resource for googlers, I usually try to go back over my questions/answers and improve them in whatever way that I can. However, I feel this may be inappropriate if there is already an accepted answer because edits bump the (already answered) question to the front page I am wondering if I should refrain from this habit.  Is there any way that I can edit my posts without bumping them? If there isn't, I really think there should be a way to do this (hence the 'feature-request' tag).


I have some console utility installed. It's in /usr/local/bin/my_utility. I can call it as my_utility and it works well. I've created a cron task which runs a bash script. That bash script calls my_utility. The error which occurs only when I can the bash script via cron is "my_utility: command not found".   Why isn't it found? Running the bash script directly works well. Also, the script uses other env. variables with no failure.


If 3 points are taken on a circle, what is the probability that the triangle formed by joining these points is an obtuse angled triangle?

three points are randomly chosen on a circle. what the probability that  1.triangle formed is right angled triangle.  2.triangle formed is acute angled triangle.  3.triangle formed is obtuse angled triangle.


I am still learning how to shell script and I have been given a challenge to make it easier for me to echo "Name1" "Name2"..."Name15" and I'm not too sure where to start, I've had ideas but I don't want to look silly if I mess it up. Any help?  I haven't actually tried anything just yet it's all just been mostly thought.  #This is what I wrote to start   #!/bin/bash  echo "Name1" echo "Name2" echo "Name3" echo "Name4" echo "Name5" echo "Name6" echo "Name7" echo "Name8" echo "Name9" echo "Name10" echo "Name11" echo "Name12" echo "Name13" echo "Name14" echo "Name15"   My expected results are obviously just for it to output "Name1" "Name2" etc. But I'm looking for a more creative way to do it. If possible throw in a few ways to do it so I can learn. Thank you.

How do I iterate over a range of numbers in Bash when the range is given by a variable?  I know I can do this (called "sequence expression" in the Bash ):   for i in {1..5}; do echo $i; done   Which gives:     1    2    3    4    5   Yet, how can I replace either of the range endpoints with a variable? This doesn't work:  END=5 for i in {1..$END}; do echo $i; done   Which prints:     {1..5}


I have a namespace that gets built out of a .cpp and .h lots of classes use this namespace and call the template functions from within it  How do I fix all the undefined references during the linking process? Where would I put all the definitions of the template functions? could someone show me an example of a namespace that uses templates and then a class that uses that namespace and can successfully call one of the templated functions without error?

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I am using a Sigma 18-35mm f1.8 Art lens on a Nikon D7100. On appropriate settings, I see sharp images after pressing the zoom button once, but not before doing that. When I review them on a laptop, though, I can't find images that are as tack sharp as they appear as reviewed on LCD of camera, after pressing zoom.  There is no unnecessary mistakes in garden pictures in shade, with sweet spot, image size comes to 20 MB approx, image setting Raw or Large Fine.... Sometimes I get better image with Nikon 18-140mm.... I am worried but can't find the right solution.

I use a Canon EOS Rebel T3i (600D) with the kit lens. I have experimented a lot with different settings and modes, but I feel like I have wasted many good shots that could have looked amazing, if only they were a little bit sharper.  I use auto-focus on most of my pictures and make sure to choose the right focus point, but all of my photos are still a little bit out of focus. When I zoom in, I can see that the pixels are not very crisp or well-aligned.  I am not sure if this issue is caused by my equipment or skills.


Prove that $\sum_{k=1}^n k^2 \binom{n}{k}=n(n+1)2^{n-2}$  I tried like this:  I used induction on $n$. I took $n=2$ then $LHS= \sum_{k=1}^2 k^2\binom{n}{k}=1\times 2+4\times 1=6$ and $RHS=2(2+1)=6$  and so its verified.  Now we assume that $\sum_{k=1}^n k^2 \binom{n}{k}=n(n+1)2^{n-2}$ is tue. We prove it for $n+1$.  Now $\sum_{k=1}^{n+1} k^2 \binom{n+1}{k}=\sum_{k=1}^n k^2 \binom{n+1}{k}+(n+1)^2$.  I cant know  how to get $(n+2)(n+1)2^{n-1}$ from here.  Can someone please help me out?  I found an answer here  which is the best and efficient. Thank you all for your effort

I found crazy (for me at least) induction example, in fact it just would be nice to prove. (Even have problems with starting) Any hints are highly valued: $$0^2\binom{n}{0}+1^2\binom{n}{1}+2^2\binom{n}{2}+\cdots+n^2\binom{n}{n}=n(1+n)2^{n-2} $$


It's  that there exists irrational numbers $x$ and $y$ such that $x^y$ is rational, but that proof only proves that such numbers exist and does not specify what they are.   What is a constructive proof that there are two irrational numbers $x$, $y$ such that $x^y$ is rational, i.e. what are those numbers?

Can an irrational number raised to an irrational power be rational?  If it can be rational, how can one prove it?


I need to fabricate/develop an angled spacer.  13 inch wide by 10 inch long, by 3/4 inch to 1 3/8 inch thick. This spacer is needed to go under two of the posts of a hobbyist car lift in my garage. The garage floor is angled by the door where two of the four corner posts will go. These two rear posts need to be on a flat surface and at the same level as the two front posts.  Each post pad will need to handle approximately 2000 pounds. I was thinking of building a 4-sided mold where the column pads would be on the angled concrete and pouring some type of epoxy, resin, or cement into the mold. Which the metal plate from car lift posts would sit on. enter image description here


I'm trying to prove that if $M$ is a simple module over $M_n(D)$ where $D$ is a division algebra, then $M\cong D^n$. I know that if $M$ is a simple module over $R$ then it is isomorphic to $Rv=\{rv|r\in R\}$ for all $v\in M$. I'm trying to find a $M_n(D)$ module isomorphism $f:M_n(D)v\rightarrow D^n$. I've been told to try the map that maps $Xv\mapsto Xe_1$, where $e_1$ is the column vector with 1st entry 1 and the rest 0. I can prove that this is a homomorphism but I'm stuck on the injectivity. Any help would be well appreciated!

Define $D$ to be a division algebra over a field $k$ and $R=M_n(D)$ the $n\times n$ matrix ring over $D$. A simple $R$-module $M$ is the quotient of $R$. I can write $R=\bigoplus_j I_j$ where $I_j$ is the subring of $R$ all of whose columns except the $j$-th are zero.   Is it true that the induced map $R\to M$ induces an isomorphism between $M$ and some $I_j$?   Many thanks!


Disclaimer: I speak British English.  I've noticed a lot of differences between the way Americans and Brits pronounce numbers.1  Since the question concerns this, I thought it might be appropriate to draw attention to it case we inadvertently confuse each other.  My question is not about these differences, I just wish to highlight them in case they cause confusion.  1. You seem to happily call a quarter "a fourth" sometimes, we always call 131 "one hundred and thirty one", we pronounce double digits in phone numbers like 12449 as "one two double four nine", and I think we are much more likely to use expressions like "thirteen hundred" to mean 1300.    Question  When talking about fractions, I have frequently heard  1/2    a half 1/3    a third 1/4    a quarter 1/8    an eighth 1/64   a sixty fourth 1/56   a fifty sixth   etc.  Essentially the rule seems to be that, except for "a whole", "a half", and "a quarter", the word matches the ordinal number; that is to say:      Numeral       Ordinal         Fractional     one           first           whole     two           second          half     three         third           third     four          fourth          quarter     five          fifth           fifth     six           sixth           sixth     fifty-seven   fifty-seventh   fifty-seventh  Even though 1/4 is a quarter, 1/64 is a sixty-fourth.  So what’s 1/62?  A  sixty-twoth?  A sixty-second? Surely not a sixty-half!  I know that simply saying one over sixty-two can usually work, but I'm asking specifically for the word itself, i.e.  if I divide a huge pizza into 21 pieces, what are the pieces?  Other than baker’s twentieths.  Summary: Can anyone point me to any sources (whether style guides or common usage studies or anything else) that discuss the pronunciation of fractions; specifically one that discusses this separately from ordinal numbers, rather than how to form ordinal numbers in the first place.

I have come across the following three spoken variants for the fraction ⅞:   Seven by eight Seven over eight Seven into eight   I am also aware of seven-eighths but I don't want to use that as it isn't practical for larger numbers. As an Indian, the most common variant I have heard is the first one but somehow that doesn't seem right. Besides, since English isn't our native language, I wouldn't want to trust it. I want to know from native speakers what they use and what's the correct way to refer to such numbers.  To make things even more complicated, most Indians use the third variant to mean something like 7×8, which I guess should be more appropriately referred to as seven times eight.


Exercise: Show that every ideal $I$ of $\mathbb{Z}$ is principal.  Attempt: Since $I$ is principal, it can be generated by one element. Also, my tutor said that if $I \subset \mathbb{Z}$ is an ideal and we consider any $a \in I-\{ 0 \}$ with $|a|$ minimal, we need to show that $a$ generates $I$ (which I have trouble understanding). Thank you.

Let $\mathbb Z$ be the ring of integers. The question asks to show  that every ideal of $\mathbb Z$ is principal. I beg someone to help me because it is a new concept to me.


i am have problem. Actually i am working on some code and that code is written in python but i want to do same problem in java .i got everything but on collection some problem is coming.  i am storing values in dictionary in java :   Dictionary<String, Integer> dc=new Hashtable<String, Integer>();   String s[]={"red", "blue", "red", "green", "blue", "blue"};     for(String t: s){          if(dc.get(t)==null)             dc.put(t, 1);     else             dc.put(t, dc.get(t)+1); }   output:  {blue=3, green=1, red=2}   i want like:  {blue=3, red=2, green=1}   but this is not the output i want i want like python gave:  cnt = Counter() >>> for word in ['red', 'blue', 'red', 'green', 'blue', 'blue']: ...     cnt[word] += 1 >>> cnt Counter({'blue': 3, 'red': 2, 'green': 1})   can any one give me some idea ?

I am relatively new to Java, and often find that I need to sort a Map<Key, Value> on the values.  Since the values are not unique, I find myself converting the keySet into an array, and sorting that array through array sort with a custom comparator that sorts on the value associated with the key.  Is there an easier way?


It is possible to add a Menu Entry that when I click a picture it says "convert to JPG" and executes this command?  convert -format jpg {The right click file}  Because normally when I want to attach screenshots they are very heavy cause they are stored in PNG.  It will be very helpful.  Thanks!

I found a nautilus script I would like to use. How do I install it?


I have referred in my thesis 4 abstracts from the same author:   @inproceedings{quantin2019exomars,   title={ExoMars at Oxia Planum, probing the aqueous-related Noachian environments},   author={Quantin-Nataf, C and Carter, J and Mandon, L and Balme, M and Fawdon, P and Davis, J and Thollot, P and Dehouck, E and Pan, L and Volat, M and others},   booktitle={Ninth International Conference on Mars Abstracts},   volume={6317},   year={2019} } @inproceedings{quantin2018unique,   title={The unique and diverse record of Noachian aqueous activity in Oxia Planum, Mars},   author={Quantin-Nataf, C and Thollot, P and Carter, J and Mandon, L and Dehouck, E},   booktitle={Lunar and Planetary Science Conference},   volume={49},   year={2018} } @inproceedings{quantin2016oxia,   title={Oxia Planum, the landing site for ExoMars 2018},   author={Quantin, C and Carter, J and Thollot, P and Broyer, J and Lozach, L and Davis, Joel and Grindrod, Peter and Pajola, M and Baratti, E and Rossato, S and others},   booktitle={47th Lunar and Planetary Science Conference Abstracts, Abstract},   volume={2863},   year={2016} } @article{quantin2015oxia,   title={Oxia Planum: a suitable landing site for ExoMars 2018 Rover},   author={Quantin, C and Carter, J and Thollot, P and Broyer, J and Lozach, L and Davis, Joel and Grindrod, Peter and Pajola, M and Baratti, E and Rossato, S and others},   journal={EPSC Abstracts},   volume={10},   pages={EPSC2015--704},   year={2015} }   In my main.tex file for the bibliography I inserted:  \documentclass[12pt,twoside]{report}  \usepackage[utf8]{inputenc}   ........  \usepackage[style=authoryear,sorting=nyt]{biblatex} \addbibresource{references.bib}  \begin{document}   .........  \printbibliography  \end{document}   In the end I have this result:   except for the dash line, there are not even in a year order.

I use biblatex with style=authoryear and when there are two references of the same author in the bibliography there is just a dash. How can I get the full name in the second entry too?


My hp printer got detected, printed two pages. then suddenly it started saying "processing - rendering complete" then "Idle- rendering complete" Ubuntu 20.04

I am unable to print documents using my HP printer. However, I am able to print test pages.  What I tried:  I have tried removing and re-installing the printer from the system settings but I can only print once (the first task). Then all the following tasks get stuck at the "Rendering Completed" status.  I additionally tried restarting the computer which leads in the same task mentioned above.  Moreover, I logged into the CUPS system ( 1.6.2) from http://localhost:631  From there, I removed the printer, restarted it and re-installed with no sucess.  System Specifications:  System : Ubuntu GNOME 13.04  Memory: 3.9 GB  CPU : AMD Athlon(tm) 64 X2 Dual Core Processor 4200+ × 2   OS-type : 32 bit  Graphics: Gallium 0.4 on NVA3  Printer: HP Deskjet 2050 j510 Series  IP Adress: localhost  I had no problems with my previous OS which was Pinguy OS 11.04 ( a distro based on Ubuntu 11.04) and it's the first time I use my printer at this OS.  Screenshots:   My printer stuck at "Rendering Completed" status.     From the CUPS web interface; you can see that "Rendering Completed" is stuck at the state of the print process.  **EDIT:**I tried printing from the pdf.js pdf viewer of firefox: I wait for about 5 minutes for a 10 pages document to print, the document is printed like faded and sort of in bold font (I accuse rendering for that). Then the status of the printer gets stuck at 'Rendering Completed' but I can print later on. Again, for the next prints I wait for 5 minutes minimum ( I wait for the 'Rendering....' bar to fill ) and the printing is weird.


I am Bangladeshi passport holder. Travelling to Canada from Abu Dhabi via Zurich or Munich or Frankfruit do I need transit visa in those countries? Since I have Canada visa and will fly from Abu Dhabi to Toronto via Zurich or Munic without Sengen visa, is there any problem as I am Bangladeshi Passport holder?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


Humans have all but left Terra (Earth) and spread out over outer space.  It starts out with a man and women dis-formed and mutated. They go to a disreputable embryo dealer. And they are told it is the last pure blood Terran.  The child is raised on a planet of dactyl humanoids. When a slave circus comes to town, he sneaks in by climbing a wall. He is caught and made a slave.  There is a giant rock creature and other weird beings. Ultimately he makes his way to Terra, and almost dies there due to a lack of Terran antibodies.

A story from my [edit - son's] youth, so the description is sort of fragmented.   Humans are almost extinct, most that remain are mutated or cross-breeds. Earth's location is forgotten, but main characters find it. Earth surrounded by blockade of derelict ships. Aliens lack the ambition/survival drive of humans - a broken leg might be a fatal injury. Galactic civilization is decaying.


Evaluate: $$\prod_{i=1}^{89} \sin (i)$$  My attempt:We know that   $\sin \alpha \cdot \sin(90- \alpha)=\sin \alpha \cos \alpha=\frac{1}{2}\sin 2\alpha$  Then we have:  $$ (\sin1\cdot\sin89)(\sin2\cdot\sin88)\cdots (\sin44\cdot\sin46)\sin45 =\left(\frac{1}{2}\sin2\right)\cdots\left(\frac{1}{2}\sin88\right)\frac{\sqrt{2}}{2} $$  Factorize from $\frac{1}{2}$ then do the same thing again You will get:  $$ \frac{\sqrt{2}}{2^{67}}(\sin4\cdot\sin8\cdots\sin88) $$  Now what to do?Any hints?

Using $\text{n}^{\text{th}}$ root of unity  $$\large\left(e^{\frac{2ki\pi}{n}}\right)^{n} = 1$$  Prove that   $$\prod_{k=1}^{n-1}\sin\frac{k \pi}{n} = \frac{n}{2^{n-1}}$$


I am recalling the first day of integration class. The teacher taught us some history about how the particular symbols came into play. Let $y = f(x)$. Here is how he broke up $\int_a^b y$ $dx$: Draw two lines $x = a$ and $x = b$ and the polynomial $y = f(x)$. The area between the three equations and $x$-axis is the area that can be found using $\int_a^b y$ $dx$. Now split up the lines into rectangular strips of width $dx$. The integral is actually now the sum of the products of the lengths and $dx$. So it can be shown as $\Sigma_{x=a} ^b y$ $dx$. And he said that the integral sign is found by stretching (?) $\Sigma$ to $\int$. It did help me understand integration but the previous sentence went over my head. Is it true or was it a harmless prank by my teacher? Thanks in advance!

Title says it all (I think). I'm betting it's something to do with Standard Integrals though. What is this symbol "$\int$" called?


I try my best to use proper sentence construction and punctuation, and for my amusement, I've taken the quest to find meaningful situations where one might use the various conjunctions at the beginning of sentences. I was told that "because" was the only one that's worthy of being placed at the start of a complete sentence. However, I've taught myself to challenge what I've been taught by attempting to discover flaws or contradictions in the logic. Along my journey, I've noticed that English is full of opposite words thus maintaining harmony and balance. By now, you should see where I'm heading with this idea; I've set out to find the inverse to the word "because." I know of the obvious examples that come to mind such as "except," "albeit," and "not because." None of these seemed to suit a universal role, though, but I believe I have discovered a solution, and I would like to know if this would be acceptable for use in sophisticated writing:     But for the faint, guiding light in the distance, the hallway was completely dark.   Which would have the same meaning as the following statement:     The hallway was completely dark but for the faint, guiding light in the distance.   Here we have the same two clauses and the same idea, but in a different order. You might observe that the phrase "but for" can be a wide-use substitute for the three examples previously listed (not directly, but in combination with other words). Please keep in mind that I follow strict guidelines, and I strive to present myself as professional as possible when conveying my ideas through language, and as such, I would prefer it if your responses would take this proposal in the same perspective.

For a while, using but to start a sentence was largely frowned upon. But, I think it is possible to use but at the beginning of a sentence, as long as it isn't overused.  Am I right?


This should be a very simple question but I can't seem to figure it out. If we have a morphism of schemes $f: X \rightarrow Y$, I am trying to understand what fiber is above some $\operatorname{spec} \kappa(f(p))$ for $p$ a point in $X$. Let's just work with affine schemes for now. If we have an $A$-algebra $\phi: A \rightarrow B$ which induces a morphism of schemes $f: \operatorname{spec}B \rightarrow \operatorname{spec}A$. Then firstly, if $p \in \operatorname{spec}B$ is a point, then what does the pullback along the morphism $\operatorname{spec} \mathcal{O}_{f(p)} \rightarrow \operatorname{spec}A$ look like? If $\mathfrak{p}$ is the prime ideal of $B$ corresponding to the point $p$, then obviously the resulting scheme is the tensor product $\operatorname{spec}(B \otimes_{A} A_{\phi^{-1}(\mathfrak{p})})$. But what does this scheme actually correspond to? Is there some simplification of this? I used to wrongly think that this was the scheme $\operatorname{spec}\mathcal{O}_{p}$ but I have realised there is no reason to think that is true. So once I understand that, I would like to pullback further along the morphism $\operatorname{spec}\kappa(f(p)) \rightarrow \operatorname{spec}\mathcal{O}_{f(p)}$. I know this should be quite easy but I'm having trouble seeing it.

Suppose I am given a morphism of schemes $f: X \longrightarrow Y$ and suppose that for any point $y \in Y$, $\kappa(y)$ denotes the residue field. I would like to show that the fibered product $$X \times_{Y} \text{Spec}(\kappa(y))$$ is homeomorphic to the preimage $f^{-1}(y)$ in the induced topology.  The following is my attempt so far:  The question is obviously affine on the target, so without loss of generality we reduce to the case of a morphism $f: X \longrightarrow \text{Spec }A$. Then we have  $$ f^{-1}(\text{Spec }A) = \bigcup_{i \in I} \text{Spec }B_{i} $$ via morphisms $$ \phi_{i}: A \longrightarrow B_{i}. $$ We can then write, \begin{align*} f^{-1}(\text{Spec } A) \times_{\text{Spec } A}\text{Spec } \kappa(y) &= \bigcup_{i \in I} \left( \text{Spec } B_{i} \times_{\text{Spec }A} \text{Spec }\kappa(y) \right) \\  &= \bigcup_{i \in I} \text{Spec }  \left( B_{i} \otimes_{A} \kappa(y)  \right). \end{align*} Now let $\mathfrak{p}$ be the prime ideal of $A$ corresponding to the point $y \in \text{Spec } A$. Then $\kappa(y) = (A/ \mathfrak{p})_{\mathfrak{p}}$. Then for any of the $B$ (dropping the index for brevity), we have \begin{align*} B\otimes_{A} (A/ \mathfrak{p})_{\mathfrak{p}} &\simeq B \otimes_{A} A / \mathfrak{p} \otimes_{A} A_{\mathfrak{p}} \\ &\simeq B_{\mathfrak{p}} \otimes_{A} A / \mathfrak{p} \\ & \simeq B_{\mathfrak{p}} / \mathfrak{p}B_{\mathfrak{p}} \end{align*}  Now the prime ideals in $B_{\mathfrak{p}} / \mathfrak{p}B_{\mathfrak{p}}$ correspond precisely to the prime ideals of $B_{\mathfrak{p}}$ containing $\mathfrak{p}B_{\mathfrak{p}}$. Further, the prime ideals of $B_{\mathfrak{p}}$ correspond precisely to the prime ideals of $B$ contained in $\phi(\mathfrak{p})B$. That is, we have \begin{align} \text{Spec }B_{\mathfrak{p}} &= \{  \mathfrak{q} \subseteq B :  \phi^{-1}(\mathfrak{q})  \subseteq \mathfrak{p}  \} \\ &=  \{ \mathfrak{q} \subseteq B : f(\mathfrak{\mathfrak{q}}) \subseteq \mathfrak{p}      \}. \end{align} Note that in the very last line we have abused notation slightly: There is not really any notion of being "inside" $\mathfrak{p}$ when it is being treated as a point in the scheme. So really we mean that $f(\mathfrak{q})$ is a point in the scheme whose corresponding prime ideal is a subset of $\mathfrak{p}$. Now as we said above, the prime ideals of $B_{\mathfrak{p}}/\mathfrak{p}B_{\mathfrak{p}}$ are the following $$ \text{Spec }(B_{\mathfrak{p}}/\mathfrak{p}B_{\mathfrak{p}}) = \{ \mathfrak{q} \subseteq B : f(\mathfrak{\mathfrak{q}}) \subseteq \mathfrak{p}      \text{ and } ???  \} $$ This is the point at which I get stuck. Ideally I would like to make some argument from the statement "Now the prime ideals in $B_{\mathfrak{p}}/\mathfrak{p}B_{\mathfrak{p}}$ correspond precisely to the prime ideals of $B_{\mathfrak{p}}$ containing $\mathfrak{p}B_{\mathfrak{p}}$" to conclude that the question marks are the condition $\mathfrak{p} \subseteq f(\mathfrak{q})$. Could someone point me in the right direction as to how to get this condition?   Is the proof up until this point correct? Different sources online seem to do this many different ways, so it's difficult for me to check.


Columnname : Meta Data["1. Information"] String column = columnname.replaceAll(".","\\.").replaceAll("\"", "\\\\\"");  I am trying to escape both double quotes and dot character,How can i do this?

Does Java have a built-in way to escape arbitrary text so that it can be included in a regular expression? For example, if my users enter "$5", I'd like to match that exactly rather than a "5" after the end of input.


I have to set JAVA_HOME on /usr/lib/jvm/java-8-oracle or /usr/lib/jvm/java-8-oracle/bin/??

I've installed a version of Java. How can we set the $JAVA_HOME environment variable correctly?


I’m going to China and want to access my Gmail/Facebook account from time to time. Can somebody recommend a VPN provider or protocol that is not blocked by the Chinese firewall.  I have a private VPN based on OpenVPN and I’m not sure if I can use it in China. As I read, in the recent months they start blocking the OpenVPN protocol completely.  It would be helpful if somebody who is in China now and uses a VPN could give me some advice. Links to blog post older than a month are not helpful.

I will soon be spending a few months travelling across China and want to get a VPN service to get around the Golden Firewall.   When I was in China in 2014/15 the general consensus was that Astrill offered the most reliable service, but I heard that they have been targeted quite strongly by the government over the last year.   Therefore, I am wondering what is the best VPN for China these days? Is Astrill still as good as it used to be?   Any recent experiences would be very helpful!


I have a php function for getting info out of my database. When they go to   I want to create a fake test.txt (text is dynamic) and download it. It's contents should be the equivalent of executing foreach(databaseContent() as $content)  { echo $content . '<br/>' } inside of it.  How can I get started on this? (Using php)

What code do you need to add in PHP to automatically have the browser download a file to the local machine when a link is visited?  I am specifically thinking of functionality similar to that of download sites that prompt the user to save a file to disk once you click on the name of the software?


'Ago' would be an adverb if it told time, but it seems only to be a kind of modifier of adverbs that tell time or to require some other free-standing word to tell time. It cannot stand alone, which seems to me to disqualify it from being considered an adverb. The closest it comes to telling time itself is when it is combined with 'long' as in 'long ago'. Could it be that 'ago' is just a particle or a function word like 'than' and isn't really a part of speech or even a word at all unless it is combined with some other free-standing word? German has things like this that are particles of verbs as separable prefixes. They look like words in print and are separated when spoken, but do not exist without the verbs to which they are attached in the infinitive form. (wehtun - to feel sorry, or bad. Tut das weh? Does that hurt? To which I can only say, Oy vay!)

I was informed earlier today that the word ago is actually a postposition and the only one  of its kind in English. Is this correct? If so, why do  not use this classification and prefer to  instead?


Do we have to fill out a different visa form for each applicant for a UK visa? Can it be filled in with the same id or does every form need a different id? Actually, I am applying for the first time.

I stay in US on a valid visa and my wife stays in India along with our daughter who is less than 1 year old. While travelling to US from India, we are planning to visit my brother who has been living in the UK for around 6 years. I am planning to get Visitor visa for my family and myself. Here are the questions I have:   Do I need to fill out , one for myself, one for my wife, and one for my daughter? As I am in the US and my family is in India, will we be able to select different centers (San Francisco for myself and Hyderabad/Chennai for my wife and daughter)?  Do I need to book the flights before submitting the application(s)?


I'm programming a function that requests the user for input, and I would like the function to automatically terminate if the user takes too long to enter the input. For example, a simplified version of my code is of the following: user_input = input('Please enter "yes" or "no" below: ')  if user_input.lower() == 'yes':      # executes some code elif user_input.lower() == 'no':      # executes some code else:      # executes some code  Right now the program will wait for the user to input the result before executing anything else and as stated above, I would like the program to automatically stop running if the user takes too long to input the answer. I'd appreciate any help!

I'm calling a function in Python which I know may stall and force me to restart the script.   How do I call the function or what do I wrap it in so that if it takes longer than 5 seconds the script cancels it and does something else?


I want to mimmick this layout:    But I do not have access to the source code. My best guess is that this is a tabular environment with brackets typeset arround it.

How do we add a matrix to a LaTeX document?


I'm doing a project which requires me to match URLs . I'm horrible at regex. But i believe the structure goes as follows -    letters and symbols , except space that that can be repeated 1 to any number of times, immediately followed by a dot 0 or 1 times, followed by letters and symbols , except space, 1 to many times, followed by a dot " ." , followed by a list of valid extensions (like com ,org,in (will be specified here)) followed by a "/" 0 or 1 times  if 0, then immediately followed by space if 1 , then words and symbols except      how do I form the regex for this

How can I check if a given string is a valid URL address?  My knowledge of regular expressions is basic and doesn't allow me to choose from the hundreds of regular expressions I've already seen on the web.


I am converting my word document to LaTeX document and now I have stopped at a point where I have to list all the citations to bibliography. I have refrences in APA format in word document. One option is that I individually copy citation from Google Scholar to LaTeX, but I am sure that there should be a shorter way of doing this, where I can get the BibTeX for all the citations all at once.  Thanks  I think I was not clear enough and therefore, I am reformatting my question below:  I have 50 references and I would like to have them in .bib format. Is there a easy way (like a website or tool) which can provided the .bib formatted references? OR do I have to get it from Google scholar, one by one?

I have the following list of publications in a text plain file:  [1] Heikki Ailisto, Petteri Alahuhta, Ville Haataja, Vesa Kyllönen, and Mikko Lindholm. Structuring context aware applications: Five-layer model and example case. In Proceedings of the Workshop on Concepts and Models for Ubiquitous Computing, pages 1–5, Goteborg, Sweden, 2002.  [2] Chris Allan, Pavel Avgustinov, Aske Simon Christensen, Laurie Hendren, Sascha Kuzins, Ondrej Lhoták, Oege de Moor, Damien Sereni, Ganesh Sittampalam, and Julian Tibble. Adding trace matching with free variables to AspectJ. In Proceedings of the 20th ACM SIGPLAN Conference on Object-Oriented Programming Systems, Languages and Applications (OOPSLA 2005), pages 345–364, San Diego, California, USA, October 2005. ACM Press. ACM SIGPLAN Notices, 40(11).  [3] Malte Appeltauer, Robert Hirschfeld, Michael Haupt, and Hidehiko Masuhara. ContextJ: Context-oriented programming with Java. Information and Media Technologies, 6(2):399–419, 2011.   and I need to generate a bib file (or any other kind of reference database).  To sum up, I need to generate a reference database from a text plain file. Is it possible?  Best,


[Edit] Complete restatement of the problem: My system freezes when I plug a memory device into a USB port. I have just upgraded from 18.04 LTS to 20.04 LTS.  All of this hardware has worked without issue for months before the upgrade. Symptoms of the freeze:  Mouse cursor will move, cannot pick anything, no scrolling or right click.  Keyboard doesn't respond.  Alt-F2 will not bring up a terminal, cntrl-alt-T will not bring up a terminal.  sysreq-alt-R-E-I-S-U-B will reboot.  control-alt-F1 will log the user out.  During a freeze, $top stops displaying new information.  The clock freezes at the current time. The freeze can be reliably initiated by: plugging any of several thumbdrives into any USB port plugging a particular microSD memory card into a USB memory card reader The freeze does not initiate when A Logitech Unifying reciever plugged into USB seems to have no problems. Plugging one of several different thumb drives into the USB ports. plugging a different microSD card into a memory card reader. I have two users set up.  One of them is on "Desktop: Gnome" and "Session: Gnome-XORG", and has the freeze problem. The other is on "Desktop: XDG_CURRENT_DESKTOP" and "Session: Ubuntu".  This user does not experience the freeze problem. I'm into stuff I don't really understand here so I don't know what the impact of that means. I have: Uninstalled Nautilus, confirmed the problem happens when Nautilus isn't installed.  Re-installed after sudo apt update and sudo apt upgrade Removed Radeon video card and installed an Nvidia card, problem still occurs Removed the memory sticks, tried installing them one at a time, problem still occurs Done a BIOS memory and hardware test with no problems found. [EDIT] I have Universe, Multiverse, and Restricted repositories enabled. So far all hardware tests and memory tests have checked out OK. Here is some more information that may or may not be relevant: sudo dmidecode -s bios-version A12 ~$ free -h               total        used        free      shared  buff/cache   available  Mem:           31Gi       3.1Gi        11Gi        73Mi        16Gi        27Gi  Swap:         2.0Gi          0B       2.0Gi ~$ ls -al /usr/share/gnome-shell/extensions total 20 drwxr-xr-x 5 root root 4096 Sep 29 12:56 .  drwxr-xr-x 7 root root 4096 Sep 29 12:59 ..  drwxr-xr-x 2 root root 4096 Sep 29 12:56 desktop-icons@csoriano  drwxr-xr-x 3 root root 4096 Sep 29 11:51 ubuntu-appindicators@ubuntu.com  drwxr-xr-x 3 root root 4096 Sep 29 11:51 ubuntu-dock@ubuntu.com  ~$ lspci | grep VGA Thrice 03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] R600 [Radeon HD 2900 PRO/XT]

All operating systems freeze sometimes, and Ubuntu is no exception. What should I do to regain control when...   just one program stops responding? nothing at all responds to mouse clicks or key presses? the mouse stops moving entirely? I have an    In what order should I try various solutions before deciding to pull the power plug?  What should I do when starting up Ubuntu fails?  Is there a diagnostic procedure I can follow?