The idiom 'Cross your Ts and dot your Is' is often written with apostrophes as though they were in the possessive forms:     Cross your T's and dot your I's   It's ubiquitous online, even on dictionary websites. But I don't understand why the apostrophes and don't know the rule of grammar that permits it. Can someone please explain the correct rule that governs writing it to me?
When writing (a blog post, script, etc..) what is the proper way to indicate two or more instances of a single letter? For instance, in Monty Python's Bookshop Sketch:     C: I wonder if you might have a copy of "Rarnaby Budge"?      P: No, as I say, we're right out of Edmund Wells!      C: No, not Edmund Wells - Charles Dikkens.      P: (pause - eagerly) Charles Dickens??      C: Yes.      P: (excitedly) You mean "Barnaby Rudge"!      C: No, "Rarnaby Budge" by Charles Dikkens.  That's Dikkens with two Ks, the      well-known Dutch author.      P: (slight pause) No, well we don't have "Rarnaby Budge" by Charles Dikkens      with two Ks, the well-known Dutch author, and perhaps to save time I      should add that we don't have "Karnaby Fudge" by Darles Chickens, or      "Farmer of Sludge" by Marles Pickens, or even "Stickwick Stapers" by Farles      Wickens with four M's and a silent Q!!!!!  Why don't you try W. H. Smith's?      C: Ah did, They sent me here.   I had always believed that plural never uses an apostrophe before the 's' (it's only used for possession), but I have rarely seen in written material the format "four Ms". (On a side note, whoever wrote  also used "two Ks".)  On a side note, and perhaps this should be a separate question, if a Compact Disc is a CD, then two Compact Discs would be two CDs right? (I see "CD's" written everywhere)
What is a Superblock, Inode, Dentry and a File? From the article  by M. Tim Jones, I read that Linux views all the file systems from the perspective of a common set of objects and these objects are superblock, inode, dentry and file. Even though the rest of the paragraph explains the above, I was not that comfortable with that explanation. Could somebody explain to me these terms? So I am on my college network which requires me to sign in to the browser before I start using the internet. I do so succesfully but on a clean install of Ubuntu, when I try to do sudo apt update, I get the following output:  $ sudo apt update Get:1 http://in.archive.ubuntu.com/ubuntu xenial InRelease [2,847 B] Err:1 http://in.archive.ubuntu.com/ubuntu xenial InRelease                     Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?) Get:2 http://security.ubuntu.com/ubuntu xenial-security InRelease [2,854 B]     Err:2 http://security.ubuntu.com/ubuntu xenial-security InRelease              ... Get:3 http://in.archive.ubuntu.com/ubuntu xenial-updates InRelease [2,855 B]    Err:3 http://in.archive.ubuntu.com/ubuntu xenial-updates InRelease ... Get:4 http://in.archive.ubuntu.com/ubuntu xenial-backports InRelease [2,857 B] Err:4 http://in.archive.ubuntu.com/ubuntu xenial-backports InRelease Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?) Fetched 11.4 kB in 0s (18.3 kB/s) Reading package lists... Done E: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/xenial/InRelease  Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?) ... E: Some index files failed to download. They have been ignored, or old ones used instead.   But when I do wget http://in.archive.ubuntu.com/ubuntu/dists/xenial/InRelease, I get this output success:  2017-04-01 05:34:57  http://in.archive.ubuntu.com/ubuntu/dists/xenial/InRelease Resolving in.archive.ubuntu.com (in.archive.ubuntu.com)... 91.189.88.162, 91.189.88.149, 91.189.88.152, ... Connecting to in.archive.ubuntu.com (in.archive.ubuntu.com)|91.189.88.162|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 246846 (241K) Saving to: ‘InRelease.3’  InRelease.3         100%[===================&gt;] 241.06K   110KB/s    in 2.2s      2017-04-01 05:35:00 (110 KB/s) - ‘InRelease.3’ saved [246846/246846]   Clearly I have internet access from my browser and on wget but when I do sudo apt (or apt-get) update I get this error.  PS: This question is not similar to other threads as their solutions do not seem to work on mine        As I have found out, this problem is happening only to me, not others on the college network. Despite setting up the network according to instructions, this still happens. Any more help would be appreciated  EDIT: So as it turns out, 50% of us in the college are facing this issue, while 50% aren't despite having no issues with the hardware and sudo apt update before the last week. Thanks to @David Foerster for helping me throughout all this time.  As it stands, the issue has been raised to our college's networking department :) Let $\alpha$ be a regular curve in $\mathbb{R}^2$ and let all of its tangent lines pass through the origin. Also, let $\beta$ be a regular curve in $\mathbb{R}^2$ and let all of its normal lines pass through the origin.   How can I show that $\alpha$ is contained in a straight line through the origin and that $\beta$ is contained in a circle around the origin?  I know that the tangent line $\alpha(t)$ is the line that points in the direction of the tangent vector $T(t)$ and that the normal line of $\beta(t)$ is the line that points in the direction of $N(t)$, but how can I put this all together to complete the proof? Supposing to have something like this:  #include &lt;map&gt; int main(){     std::map&lt;int,int&gt; m;     m[1] = 2;     m[2] = 4;     return 0; }   I would like to be able to inspect the contents of the map running the program from gdb. If I try using the subscript operator I get:    (gdb) p m[1] Attempt to take address of value not located in memory.   Using the find method does not yield better results:  (gdb) p m.find(1) Cannot evaluate function -- may be inlined   Is there a way to accomplish this? Is there a word for one side in a pair? Is there a word for one side in a pair? In a conversation it would the the interlocutor, but I'm looking for a generic term. How to redirect STDIN of background process? In my Ubuntu, i run java application in background. I use bash script to run it and now it looks like:  nohup java -jar app.jar &amp; exit 0   The problem that i want to be able to write an input string to my application, without making it foreground, from different terminals/sessions. Something like  echo "mytext" &gt; /appdir/in   How should i change my script? How can I tell which version of Windows 8 I am running? Standard, Pro, Enterprise, or RT? I have searched everywhere but cannot find how to tell which version of Windows 8 I am running.  I have the system properties on the screen but it just says "Windows 8," nothing else.  Is this the standard edition?  EDIT 04142015:  My new favorite way to do this is to go to the commnand prompt and issue (same with Windows 7):    wmic os get caption  Response:  Microsoft Windows 8.1 Pro libpng problems for QGIS I'm using ubuntu 18.04 and if I download QGIS 2.18 and I try to run it, I get this:  libpng warning: Application jmp_buf size changed Segmentation fault (core dumped)   If I try with QGIS 3.2, the error is:   libpng warning: Application was compiled with png.h from libpng-1.6.34 libpng warning: Application  is  running with png.c from libpng-1.2.56 libpng error: Incompatible libpng version in application and library   So it's clear that the problem is with libpng.   I purged libpng-dev and reinstall again but nothing changed.   I tried to purge libpng16-16 but I get:  sudo apt purge libpng16-16 Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  libgdk-pixbuf2.0-0 : Depends: libpng16-16 (&gt;= 1.6.2-1) but it is not going to be installed                       Recommends: libgdk-pixbuf2.0-bin  libgtk-3-0 : Depends: libcairo-gobject2 (&gt;= 1.10.0) but it is not going to be installed               Depends: libcairo2 (&gt;= 1.14.0) but it is not going to be installed               Depends: libfontconfig1 (&gt;= 2.12) but it is not going to be installed               Depends: libpango-1.0-0 (&gt;= 1.40.5) but it is not going to be installed               Depends: libpangocairo-1.0-0 (&gt;= 1.40.5) but it is not going to be installed               Depends: libpangoft2-1.0-0 (&gt;= 1.40.5) but it is not going to be installed               Depends: adwaita-icon-theme               Recommends: libgtk-3-bin E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.   and then:  ~$ sudo apt install libgdk-pixbuf2.0-bin libgtk-3-bin Reading package lists... Done Building dependency tree        Reading state information... Done libgdk-pixbuf2.0-bin is already the newest version (2.36.11-2). libgtk-3-bin is already the newest version (3.22.30-1ubuntu1). 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. ~$ sudo apt install libgtk-3-0 libgdk-pixbuf2.0-0 Reading package lists... Done Building dependency tree        Reading state information... Done libgdk-pixbuf2.0-0 is already the newest version (2.36.11-2). libgtk-3-0 is already the newest version (3.22.30-1ubuntu1). 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   At this point I'm afraid of breaking something if I continue trying things, so I come here for advice before.  I deleted and reinstalled ubuntu. I installed first thing qgis and it was working. Afterwards I compiled gdal, from source to have it from python as stand alone. It might be this, but I had done this previously without any problems. In the Prisoner of Azkaban, Harry and Lupin could practice the patronus on the boggart, but when Harry was in the final task in the Goblet of Fire, he tried to use the patronus on the boggart, it didn't work and he then moved on to use ridikkilus.  Why could he use a patronus against the boggart, but then not in another? Calculate all integer solutions $(x,y,z)\in\mathbb{Z}^3$ of the equation $x^2+y^2+z^2 = 2xyz$.   My Attempt:  We will calculate for $x,y,z&gt;0$. Then, using the AM-GM Inequality, we have  $$ \begin{cases} x^2+y^2\geq 2xy\\ y^2+z^2\geq 2yz\\ z^2+x^2\geq 2zx\\ \end{cases} $$  So $x^2+y^2+z^2\geq xy+yz+zx$. How can I solve for $(x,y,z)$ after this? Changing permissions on serial port I want to load the new entries without reloading the page. I found a great solution for: The ajax script:  &lt;script&gt;     $(document).ready(function() {     var refreshId = setInterval(function()     {         $('#content').fadeOut("fast").load('http://neocsatblog.mblx.hu/new.php').fadeIn("fast");     }, 10000);      }); &lt;/script&gt;   And the php:  &lt;?php require_once("wp-blog-header.php"); ?&gt; &lt;div id="content" &lt;?php cyberchimps_filter_content_class(); ?&gt;&gt;          &lt;?php do_action( 'cyberchimps_before_content'); ?&gt;          &lt;?php if ( have_posts() ) : ?&gt;              &lt;?php while ( have_posts() ) : the_post(); ?&gt;                  &lt;?php get_template_part( 'content', get_post_format() ); ?&gt;              &lt;?php endwhile; ?&gt;          &lt;?php elseif ( current_user_can( 'edit_posts' ) ) : ?&gt;              &lt;?php get_template_part( 'no-results', 'index' ); ?&gt;          &lt;?php endif; ?&gt;          &lt;?php do_action( 'cyberchimps_after_content'); ?&gt;      &lt;/div&gt;   However, this is a special feature that works perfectly here:  However, the main page refuses to load new entries, I do not understand the reason for this, as we use everything the same. Is there a way to edit SVG files in Illustrator where you can specify a CSS class for each path?  I already know in Illustrator that if you give the layer name an actual name, Illustrator will use that name as the path's ID, which is fine if you don't plan on reusing the icon more than once on the same page.  My current workaround is to just use the IDs method, but then later convert the IDs to classes in my code editor, but it's pretty annoying to have to do every time I generate my SVG sprite.  If that's currently not possible in Illustrator, are there any other apps that will allow you to specify that? Or maybe a Grunt or Gulp package?  It looks like you might be able to do it with Inkscape with a , so I might look at that if there's no other good solutions out there. Many To Many Relationships How to implement "select all" check box in HTML? How to set programmatically multiple arguments for views contextual filters How to set programmatically multiple arguments for views contextual filters?  I can do it with one argument, it works great, but not with multiple arguments.  I want to select all nodes created by a list of people, but views only takes first in array into consideration:  $array = array(3250,32); $view = views_get_view('myview'); $view-&gt;set_display("myblock"); $view-&gt;set_arguments($array); $view-&gt;pre_execute(); $view-&gt;execute(); $content = $view-&gt;render();    Am I doing something wrong? Uniform convergence of alternating series SCP fails without error How to use downloaded fonts with pdfLaTeX on Ubuntu I want to use the  font in my pdfLatex document.  What steps should I do for using a downloaded font   Should I download the TTF or the OpenType version? Where should I store the font? Should any font processing be done? How can pdfLatex find this font?   I am using TexLive 2011 installed in a custom location (/somepath/texlive/2011) on Ubuntu How do you create a bootable USB stick using windows 7 I've downloaded Ubuntu desktop (the .iso file that is) on a windows 7 machine and want to create a bootable USB stick in order to install it onto a laptop which currently has no OS. Is there a way to do this?