Problem  The picture is just an example of my case, but I am left with blank space on the left when I load all the tiles and I get error message in the console:   Failed to load resource: the server responded with a status of 404 (Not Found) http://path/to/the/tile//base/8/6/53.png  etc.     I could guess and limit the extent of the layer, but I would really like to know is there any way to calculate it and also be able to get rid of the error message.  What I know about the tiles?   Originally they are served as TMS They represent png images 256*256 They are in projection: EPSG:3857 In OpenLayers2 they were called like TMS layer In OpenLayers3 (v.3.8.2) they are called like XYZ layer (that includes -y):     var baseLayer = new ol.layer.Tile({   source: new ol.source.XYZ({     url: 'http://path/to/the/tiles/base/{z}/{x}/{-y}.png'   }) });   Thoughts and questions   How can I calculate extent of the tiles? Or in another words how can I find out zmin zmax xmin ymin xmax ymax or whole range of x/y?  What does x/y really represent? Are they coordinates of the left bottom corner or center of the tile? In which direction does x/y increase? How can I figure out x/y of at least one of the tile, for example left bottom one?    (I have modified the question for better understanding of the problem)


$\lim\limits_{n\rightarrow\infty}\root n\of{a_n}=\lim\limits_{n\rightarrow\infty} {a_{n+1}\over a_n}$

Let $(a_n)$ a sequence of positive terms, show that  if $\lim\limits_{n\rightarrow\infty} {a_{n+1}\over a_n}$ exists, then so does $\lim\limits_{n\rightarrow\infty}\root n\of{a_n}$ and the two limits are equal.


I'd like to ask how to denest the nested radical $\sqrt{5^{\frac{1}{3}}-4^{\frac{1}{3}}}$?


How to make a bootable ISO image from a bootable DVD?

I want to make a .iso image of a bootable OS DVD, to use in VirutalBox.    Nautilus can make a .iso, but only of data files, it seems. The .iso it created was not bootable.  What is available to make a bootable .iso from a bootable DVD?


recently everywhere I go online I will find little snippets of text replaced with   "It's a Trap!"   It seemed to start with yahoo.com, but it has expanded to biblegateway, google, and much more! I don't know why its doing this, what type of virus remover to get, or what to do in general. Anyone else having this problem? Thanks!


I am an engineer and not a physicist. I am unable to understand why SuperNova happen.  I understand that when the core is composed of high atomic number of elements like Iron and further fusion is not possible. The core collapses under its gravity.  At this point the outer layer burst in a huge supernova. I am unable to understand why the outer layer just burst out in this supernova. Leaving behind a Neutron star or a black hole.


How do I give an answer an additional 50 bounty?

I thought that I could give an additional 50 bounty points for an answer if I wanted to, but it would appear that I am restricted to only giving an additional 100.  Could someone please tell me why this is so?  Is there way around this restriction?


I would like to typeset something like     f \colon X \leftrightarrows \mcolon g   where \mcolon is a mirror-image of \colon as regards spacing. How would I do this?


"Some of your past questions have not been well-received". How to count the endpoint?

I got a warning notification "Some of your past questions have not been well-received, and you're in danger of being blocked from asking any more." and I'm afraid to ask my next question, because I don't know if somebody downvote, no one will answer or flag question. How can it counts, I mean where is the border of "well-received questions"? It is total score of my questions or how system count when is enough to be blocked?  P.S. So sorry, if it is a little stupid question, but this is my first question on Meta and really want to understand it better. Thanks.


The problem is how to print the following math symbol.  I cannot find it among the Greek symbols.    here is where the "o" i find. I guess it's a special mathfont , and your anwser is very well and i will adopt your solution, but we can go head and find the best solution. thanks again.


Difficult alphabetic sorting with BibTeX

I added a new entry type to my book, article and incollection functions called abbreviation. This way, dictionaries appear in the bibliography as my publisher wants them to appear :      TLIO = Beltrami, Pietro G./Leonardi, Lino (dir.),Tesoro della Lingua Italiana delle Origini,Florence, CNR, 1998-., [URL = .   My problem now is that, in the bibliography, these entries are sorted alphabetically by the author, not by the abbreviation:      Casula Cant. Enn. = Antioco Casula,Boghes de Barbagia. Cantigos d’Ennargentu.ed.Giovanni Pirodda, Nuoro, Ilisso, 1999.      Ax, Wolfram,Zellmer, E., Die lateinischen Wörter auf -ura, Indogermanische Forschungen, 82(1977), 302-307.      TLIO = Beltrami, Pietro G./Leonardi, Lino (dir.),Tesoro della Lingua   Italiana delle Origini,Florence, CNR, 1998-., [URL =   .      Buchi, Éva,Where Caesar’s Latin does not belong : a comparative   grammar based ap-proach to Romance etymology   I need my bibliography to consider the abbreviation  for the alphabetic sorting instead of the author, each time there is such an entry for a reference, but I don't know how to modify my bibliographystyle so that it will do this.  Any help would be very welcome !   A simplified version of my code is:   \documentclass[openany,ngerman]{book} \usepackage[small]{dgruyter} \usepackage{microtype}  \usepackage{fontspec} \usepackage[main=french,italian, spanish, portuguese, latin, greek]{babel} \usepackage[round]{natbib} \usepackage{amsmath,amsfonts,amssymb} \usepackage{graphicx} \usepackage{lmodern}  \begin{document} Cf. \cite{DCECH}\\  \bibliographystyle{Bianca} \bibliography{bibliographie}  \end{document}   And you can find my bibliographystyle here :


NGINX 301 and 302 serving small nginx document body. Any way to remove this behaviour?

We have noticed that when using nginx internal 301 and 302 handling, nginx will serve a small document body with the appropriate Location: ... header.  Something along the lines of (in html): 301 redirect - nginx.  As appropriate in the above behaviour, a content-type text/html and content-length header is also sent.  We do a lot of 302 and some 301 redirects, the above behaviour is wasted bandwidth in our opinion.  Any way to disable this behaviour?  One idea that crossed our mind was to set error_page 301 302 to an empty text file. We have not tested this yet, but I am assuming even with the above, the content-type and content-length (0) headers will be sent.  So, is there a clean way to send a "body-less" 301/302 redirect with nginx?


When and why did ^ and $ take on their meanings of "beginning of line" and "end of line?"

Many command-line tools (grep, flex, etc.) use the ^ symbol to denote "beginning of line" and the $ symbol to denote "end of line." When did this convention arise? It seems perfectly reasonable to reserve two characters for these purposes, but it's a bit odd that on modern keyboards the $ symbol is to the left of the ^ symbol.  Is this a completely arbitrary decision? Does this come from some older keyboard layout? Is this convention used because some older tool decided to do things this way?  Regardless of the answer, are there primary sources that document this?


How to prevent “invoked too many times per second” error

The main requirement is to find travel time with traffic data between two locations or zip-code.  Inputs parameters would be from Location, destination, arrival time(this is between 6AM 8AM), mode of transportation, traffic model.  Based on the above input parameters in my google script function it should return travel time but I'm getting an error that      Service invoked too many times for one day: route. (line 40).    and I'm using the custom function below and there are 40 rows in my sheet:      function GetDurationNormal(location1, location2, mode) {   //var arrive = new Date(new Date().getTime() + (10 * 60 * 60 * 1000));//arrive in ten hours from now  // var arrive=new Date(2019, 09, 07, 06);// 7th of September 2019 06:00 am   var arrive = new Date();   arrive.setHours(9,0,0,0);   var directions  = Maps.newDirectionFinder().setArrive(arrive)   .setOrigin(location1)   .setDestination(location2)   .setMode(Maps.DirectionFinder.Mode[mode])   .getDirections();   // Get a script lock, because we're about to modify a shared resource.   var lock = LockService.getScriptLock();   // Wait for up to 30 seconds for other processes to finish.   lock.waitLock(20000);   Utilities.sleep(1000);  return directions.routes[0].legs[0].duration.text;


PDO Deadlocks Galore on the Semaphore table

I experience frequent deadlocks on the semaphore table that look like this:     PDOException: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when trying to get lock; try restarting transaction: DELETE FROM {semaphore} WHERE (name = :db_condition_placeholder_0) AND (value = :db_condition_placeholder_1) AND (expire <= :db_condition_placeholder_2) ; Array ( [:db_condition_placeholder_0] => variable_init [:db_condition_placeholder_1] => 298999494f343fc583c3e2.30542255 [:db_condition_placeholder_2] => 1328824262.5293 ) in lock_may_be_available() (line 181 of /var/www/drupal/includes/lock.inc).   This site sees fairly heavy traffic. Is the load the cause of this? Is this due to a faulty module? Is this something in Drupal core?  Most importantly, are there precautionary measures I can take to avoid this?


How to generate word document in Rails 2.3.5?  Is their any gem available?


Can CMOS Checksum error damage my computer

At time of booting i saw the CMOS check sum error. if this is battery related & it is not replaced, can it damage my computer?


Why did the Death Star not target this location at the end of “Rogue One?”

During Rogue One, we saw that the Death Star was able to aim and directly target      the city of Jedha.   So why, an the end of the movie, did they not      fire directly at the archive? They hit what seems to be a location far out in the water, next to the island.


Can Death Note be used to indirectly kill more than one person by killing the driver of a train/bus/plane?

If you state "Jack Hare" will die at precisely 15:00 12/03/14 without stating the location, and you write this without knowing where they will be at the time, and the person goes to work as per normal, can this be used to kill more than one person?


I Have the following code in Student.h  #ifndef _student_h_ #define _student_h_  template  <class T> class Student { public:     Student();     ~Student();     void setWage(float hourlyWage);     void addHours(float hoursWorked);     bool pay();     bool writeCheck(float value);     float getTotalEarnings();     float getStudentCut();     float getSwauCut();     float getWage(); private:     float wage;     float hours;     float swauCut;     float studentCut;     float totalEarnings; }; #include "student.tpp" //Works with .tpp, errors with .cpp  #endif   As im trying to separate my code I attempted to place the following code into both a .cpp and a .tpp for testing.   #pragma once #include "stdafx.h" #include "Student.h"  template <class T> Student<T>::Student() {     wage = 0.0f;     hours = 0.0f;     swauCut = 0.0f;     studentCut = 0.0f;     totalEarnings = 0.0f; }  template <class T> Student<T>::~Student() { }  template <class T> void Student<T>::setWage(float hourlyWage) {     wage = hourlyWage; }  template <class T> void Student<T>::addHours(float hoursWorked) {     hours += hoursWorked; } template <class T> bool Student<T>::pay() {     if (hours == 0 || wage == 0)         return false;     studentCut += .25*(hours * wage);     swauCut += .75*(hours * wage);     totalEarnings += hours * wage;     hours = 0.0f;     return true; } template <class T> bool Student<T>::writeCheck(float value) {     if (value < studentCut){         studentCut -= value;         return true;     }      return false; } template <class T> float Student<T>::getTotalEarnings() {     return totalEarnings; } template <class T> float Student<T>::getStudentCut() {     return studentCut; } template <class T> float Student<T>::getSwauCut() {     return swauCut; } template <class T> float Student<T>::getWage() {     return wage; }   My issue is that if I use the .cpp file and comment out the tpp file I get all sorts of errors. However if I just #include Student.tpp the files compile fine and work. I was under the impression that cpp and tpp were relatively the same?   The errors im getting are:  Error1  error C2995: 'Student<T>::Student(void)' : function template has already been defined   c:\users\aurelib.cs\desktop\studentproject\studentproject\student.cpp   13  1   StudentProject Error2  error C2995: 'Student<T>::~Student(void)' : function template has already been defined  c:\users\aurelib.cs\desktop\studentproject\studentproject\student.cpp   18  1   StudentProject   .... for all the functions.  If I remove the #include "Student.h" from the .cpp file I get Syntax errors.   I am using Visual Studios. And like I said I have no problem when I #include "Student.tpp" at the bottom of the template. But when I use the same code and #include "Student.cpp" instead.  Thanks so much in advance!


How does one parse ${!i} (and what does it mean)?

I came across ${!i} in the body of a for-loop of the form  for ((i=$#; i>0; i--)); do     # ...     if <SOME_TEST>; then         # ...         accumulator="${!i}:${accumulator}"         # ...     fi     # ... done   Given this range of possible values, my guess is that ${!i} means something like "expand as the i-th positional argument".  Be that as it may, I'd like to know more about this notation.  (In particular, is ${!i} a special case for $@, or is it a particular instance of a syntax applicable to any array?  This is why I'm curious about how the expression gets parsed.)  I can't find documentation for this notation, though.  If I search the bash man page for the sequence ${!, I find only the following strings     ${!name[@]}    ${!name[*]}    ${!prefix*}    ${!prefix@}   ...and I can't fit the documentation surrounding these occurrences to the code I'm puzzling over.  (Actually, if possible, please quote any relevant documentation in your answer, so that I can sort out why I missed it.)    EDIT: For my original post I copied the wrong for-line from the original code.  I've fixed it now.  (The interpretation is the same, though.)


Can I play PS Plus free downloaded games after trial period ends?

I recently bought a PS4 and got 14 days trial activated on it. So, as PS Plus members get free monthly games, I downloaded Mad Max and Trackmania Turbo, so does it mean I will be unable to play both these game after my trial period ends? Is there any workaround for it if I am unable to play after the trial period ends?


Windows upgraded itself (from 8.1) without uninstalling Blender, but Blender wouldn't correctly work after this (look at the error message below).   Video won't show.  Does Blender work with Windows 10? What's the proper way to install it?  Here's the message:   It might be a matter of my hardware not being correctly detected by the new Windows, but anyway it's a good question. Does Blender work in Windows 10? Has anybody succeeded installing any version?


Teen horror book involving a girl and her boyfriend on their way to an abortion being killed by a nightmarish girl with a pitchfork

I have vague memories of reading this in the 90s. It was a paperback, possibly an R.L. Stine book (it seems like the right sort of plot and I have this vague memory of it being similar cover art). The main character is a girl who's pregnant. She and her boyfriend go to an abortion clinic (a legal one, not back-alley). That's where things get a little jumbled in my head. I remember the girl bleeding out on the operation chair due to a botched procedure. I also remember her and her boyfriend being stalked by a girl of the same age including a part where the protagonist gets stabbed through the stomach with a pitchfork. I want to say that the sequence of events was that they got stalked by the girl, she got stabbed, and the scene then cut to her bleeding out on the chair with the implication being that it was either just a dying dream, or that the girl who killed her was the unborn baby trying to get revenge.  The reason I see it as either sci-fi or fantasy was that the scene played out like a nightmare where no matter where they turned, their pursuer was behind them with the scenery changing malevolently against them. I want to say that they died a few times during the story, each time with them waking up from a seeming nightmare only to get killed again in a different way.


Looking for a word - thing that wastes a lot of time

I am looking for a words for a thing in which you invest a lot of time but don't gain anything. For example using whatsapp.


Standard definition of group isomorphism

ProofWiki  as a bijective homomorphism. In Topics in Algebra 2$\varepsilon$, Herstein defines a group isomorphism as an injective homomorphism:     Definition. A homomorphism $\phi$ from $G$ into $\bar{G}$ is said to be an isomorphism if $\phi$ is one-to-one.   Herstein does not define a homomorphism to be surjective, so the definition on ProofWiki and the definition in Topics in Algebra 2$\varepsilon$ contradict. Which definition is standard?


I'm not good in html, css, i want to apply boarder to dev, which contains image in right     .amount-2 {     border: 3px solid #4CAF50;     padding: 5px;     width: 70%;     float:left; }  .sample {     float: right;     width: 30%;     margin-top: -100px; }
 Files must be less than 2 MB. Allowed file types: png gif jpg jpeg. Images must be between 200x200 and 800x1400 pixels. Web page addresses and e-mail addresses turn into links automatically. Lines and paragraphs break automatically.
     I dont want to fix the heights


We have a live communication modern site, and i want to duplicate this site and all its content into a test site so i can test things before modifying the live. so is this possible inside SharePoint online? or are there any free tools to achieve this?


I've been looking into the getrusage function, which I see a prototype for within the file /include/linux/resource.h. I've tried to trace the directives to find where the actual function is, but I haven't found it. Does anyone know where it is?


Problems with \ref when using soul for highlighting

Here is a minimal example showing the problem.  \documentclass[10pt]{article} \usepackage[usenames,dvipsnames]{color} \usepackage{soul} %\soulregister{\ref}{1} \begin{document}  \section*{x}\label{x}  \section*{y} \hl{ Some text.   Section~\ref{x}. } \end{document}   I'm getting the error  LaTeX Warning: Reference `{x}' on page 0 undefined on input line 12.  ! Argument of \ref has an extra }.   The problem is with \ref. Commenting out the line beginning with "Subsection" makes the error disappear. \soulregister is intended for font commands. I don't know if \ref is a font command, but I could not get \soulregister to fix the problem (see the commented line above).


I have a laptop running Ubuntu 14.04 with no internet connection. I want to use Synaptic to install software and packages to it, referring to . The problem is, I do not have synaptic installed on the laptop, so I need to download the Synaptic package and all of its dependencies (deb files) on another PC and then transfer them to the laptop. I found the deb files , but I can only download one file at a time. Is there a way that I could download Synaptic and all of its dependencies at once?


I have an EC2 instance running Ubuntu 12.10 and I'd like to install Flash Player on it. However, when I try to install it as follows, I'm unable to. Some hint on how I could proceed? Thanks.  $ sudo apt-get install flashplugin-installer Reading package lists... Done Building dependency tree        Reading state information... Done Package flashplugin-installer is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'flashplugin-installer' has no installation candidate   I haven't set up VNC yet, so I'd very much prefer a CLI solution for the same.


shell command 'var="[a-p]"; echo $var' has as output "h", any explanation?

bash version:  $ bash -version GNU bash, version 4.3.11(1)-release (x86_64-pc-linux-gnu) Copyright (C) 2013 Free Software Foundation, Inc.   License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>  This is free software; you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.   command:  $ var="[a-p]"; echo $var h   Anyone has an idea what's the reason for this kind of interpretation.  For context I'm parsing a config file using shell and looking for patterns to grab sections names  [section-foo] foo=bar   while reading the file, if a section row for example is [a-p] it will get that weird behavior.


ATI Radeon 5770 Eyefinity - three monitors

How do I setup  to support three monitors on a Radeon  card? Currently I can setup only two at once in any combination.  Monitors are connected as DVI-DVI-HDMI.


The integral is:$$\int\sqrt{1+\sin x} dx$$  My first attempt was to multiply by:  $$\frac{\sqrt{1-\sin x}}{\sqrt{1-\sin x}}$$  giving: $$\int\frac{\sqrt{1-\sin^2(x)}}{\sqrt{1-\sin x}}dx$$ which is: $$\int\frac{\cos x}{\sqrt{1-\sin x}}dx$$ then make the substitution: $$u=1-\sin x$$ which gives $$\int\frac{-1}{\sqrt{u}}du$$ which gives: $$-2\sqrt{u}+c$$ so: $$I=-2\sqrt{1-\sin x}+c$$ but I am not sure if this is correct.  Also sorry if the formatting is a bit rubbish


MacOS Terminal ; Replace String in File With Another String

I'm writing a script and currently need to automate the processes of change a line in a file from     <policy domain="path" rights="none" pattern="@*"/>   to     <policy domain="path" rights="all" pattern="@*"/>   (changing "none" to "all") while maintaining spacing. What's the easiest way of doing this from the command line without using a ton of external packages?


Let’s say I write: “Just send me those documents as is”. Is that correct? Should the "as is" idiom be pluralised into “as are”, which sounds so wrong to me? Or are they both incorrect, in which case I may write “as they are”?


how to delete account and remove resume from Careers.stackoverflow.com?

Is there a way a registered user can remove his/her resume from careers.stackoverflow.com?


Mouse cursor size is tiny in Chromium (Ubuntu 18.04)

I'm running Ubuntu 18.04 with default gnome and I installed Tweaks to change my themes. I'm using theme DMZ White for my cursors.  Everything is OK except for Chromium (Version 69.0.3497.81 (Official Build) snap (64-bit)). The mouse cursor is tiny!  I have checked Slack, Postman, System Monitor and Calculator and the cursor is fine on those apps.  I've tried the instructions here to no avail:   How can I change my mouse cursor to a normal size in Chromium?


How to simply delete duplicate records in SQL Server?

In my table I have a few duplicate records. I want to simply delete them and leave one entry in the table.  Columns which matching is [SourceGradeId] from table A.  Can anyone show me a very simple delete query rather altering the table?


Jquery - Cloning a div which includes input unordered lists. How to get the dropdown to work in the cloned row?

I was using the answer to this question ->  to create select box dropdowns. I am wanting to clone a row and reuse the dropdowns that are included in it. I have got it to clone the row, but the dropdowns in the cloned version doesn't work. The clicks do not register. I have also added a class 'hide' to the 2nd dropdown in row 1. I only want to show the 2nd dropdown if the first option is selected, so I remove the class if the 1st option is selected in dropdown 1. This is why I cloned the row outside the function, as when the row is cloned, i want the 2nd dropdown to remain hidden and have the 'hide' class. How can I clone the row (row1) and have the dropdown work in the cloned row?  HTML

     <input type="text" disabled placeholder="Select n1">

Business

Hair

     <input type="text" disabled placeholder="new test">

test

option 2

     <input type="text" disabled placeholder="Select n2">

Something

Else

 click me

  CSS * {   margin: 0;   padding: 0; }  /* ugly reset */  .cselect {   position: relative; }  .cselect input {   background: #fff; }  .cselect ul {   display: none;   position: absolute;   z-index: 999;   left: 0;   top: 1.2rem;   margin: 0;   width: 100%;   background: #fff;   border: 1px solid #d6d6d6; }  .cselect li {   padding: 10px 5%;   list-style: none; }  .cselect li:hover {   background: rgba(41, 128, 185, 0.2); }  .hide{   display:none; }  JS $(function() { // DOM ready     $(".cselect").each(function() {      var $input = $(this).find("input");     var $dropDown = $(this).find("ul");      $(this).on("click", function() {       $dropDown.stop().slideToggle();     });      $dropDown.on("click", "li", function() {       $input.val($(this).text());     });    });  });  var newnewid = 0; var $cloneplayerclause = jQuery(".row1").clone(true);  function clonerow(){      newnewid++;   var $sectionClone = $cloneplayerclause.attr("id", newnewid).clone(true);   $('.rows').append($sectionClone);       }  function unhideoption2(){  $(".option").removeClass('selected');  $(this).addClass('selected');  if($('.option1').hasClass('selected')){  $('.options2').removeClass('hide');  }  }  $(".option").on("click", unhideoption2); $(".clonerow").on("click", clonerow);   ** EDIT ** The question was closed as it is linked to event delegation ->  I use the .on for my click event $(".option").on("click", unhideoption2);  but with each parent/static selector i add in, it still doesn't register any clicks on the cloned versions e.g $(".optionlist").on("click", ".option", unhideoption2);  or $(".cselect").on("click", ".option", unhideoption2);  or $(".row1").on("click", ".option", unhideoption2);  Where am i going wrong with the event delegation?


If Co-variance (X, Y) = 0, does this necessarily mean that X and Y are independent?  I have read in previous posts that Co-variance equal to 0 implies that (1) X and Y are independent AND (2) X and Y could be independent, but are not necessarily so.  These two interpretations, however, are obviously contradictory.


What is the syntactical equivalent to switch/case in Python?

Programming languages like C/C++, C#, Java, JavaScript and Pascal () have a combination of switch and case statements (sometimes also called select or inspect) which allow you to check one value against several conditions to perform certain actions. my_value = 10; switch(my_value) {     case 10:         print("The number is ten");     case 2*10:         print("The number is the double of ten");     case 100:         print("The number is one hundred");     default:         print("The number is none of 10, 2*10 or 100"); }  Pseudo-Code to depict the special syntax of the switch-case construct. Being aware of functional equivalents like , is there a purely syntactical equivalent to the above programming construct?


What to do when you do not get an answer after 1 year

I am in the situation where I submitted an article 1 year and 4 months ago. I already asked to editors about the status nearly five months ago and they replied they are still waiting for the referee answer and that they were going to ask to expedite the process.  I didn’t receive other news since them, and I don’t know if it will be time to contact them again. Would it be considered impolite? What is your suggestion?


Product in finite abelian groups  Let $a\in A$ where $A$ is a finite abelian group.     How do I prove that $\Pi_{x\in A}ax=\Pi_{x\in A}x$?   Thoughts: If every element is not its own inverse, we see that $\Pi_{x\in A}x=e$. If there are elements that are their own inverse, then it is the product of these elements. How do I get the identity above?


Can any monomorphism of a subfield of a splitting field be extended to an automorphism?

It's a common theorem in field theory that if $\varphi: F\to\overline{F}$ is a field isomorphism, and if $E$ and $\overline{E}$ are splitting fields of monic polynomials $f(x)$ and $\overline{f}(x)$, respectively, where $\overline{f}$ is the image of $f$ under $\varphi$, then $\varphi$ can be extended to an isomorphism of $E$ and $\overline{E}$.   I'm wondering about the following: Suppose $E$ is a splitting field of a polynomial $f(x)$, and $k$ is a subfield of $E/F$. Can any monomorphism of $\varphi:k\hookrightarrow E$ be extended to a field isomorphism of $E$? Defining $\overline{k}:=\varphi(k)$, I get the case that $\varphi:k\to\overline{k}$ is a field isomorphism, and $f(x)$ and $\overline{f}(x)$ both  split over $E$, when regarded as polynomials in $k$ and $\overline{k}$. But is $E$ still a splitting field of $f(x)$ and $\overline{f}(x)$ as polynomials in $k$ and $\overline{k}$, or is it possibly too big to be a splitting field?  If it is a splitting field, then I suppose it would follow that any monomorphism on a subfield can be extended to an isomorphism of the splitting field.


How do you animate image texture materials in blender cycles with keyframes?

I have an image texture material on a mesh already in blender cycles 2.75... I was wondering how to change the material with keyframes so it changes to different pictures in the animation... I tried image sequence, but that doesn't seem to be what I am trying to achieve, neither does pressing "i" on the image source in the materials tab, it just says that the name property can not be animated ... Could someone help?


Installing Firefox in Ubuntu 12.04: configure no such file

I have downloaded a tarball for installing Firefox. Once it’s unpacked, the /configure command does not work. I happened to notice that the unpacked folder contains configure, read me, or install files, but the error says      configure no such file   What should I do?


The electrons in an atom have a certain configuration and we can predict in which space the electrons can be present of a certain energy level (s-orbitals have a sphere-shape,....).  Recently I read that there are  for nuclei: special configurations of the nuclei that makes them more stable (the magic numbers are 2, 8, 20, 28, 34, 50, 82, and 126) - so there are definitely  in a nucleus. I was wondering : do the neutrons and protons form certain geometric structures in these sub-shells of the nucleus?  Or are they all stacked closely on each other?


Returning removed feature (merged title/menu/top bar)

I want ubuntu 16 merged top/title and menu bar, back. what should I do?


What is the time and topic etiquette for a first meeting with a professor to discuss research?

I am meeting with a biology professor to discuss opportunities for an undergraduate research assistantship. I initiated the contact by introducing myself via email and sending him my CV and general areas of interest. He agreed to meet with me to discuss research opportunities, but I am wondering what is the expected length of a meeting like this? Also, are there any materials (e.g. printed copy of my CV) that I should bring? Should I come prepared with questions about his research (which would require hours and hours of critical reading, because while his work seems interesting to me, it's also very difficult to fully understand) or simply honestly tell him that I'm not as knowledgeable about his work as I would like to be but it sounds very interesting to me and I want to be involved? Lastly, is casual clothing appropriate?  Any answers are appreciated. Thank you.


Automatically export history at end of powershell session

I can export my Powershell history using the scripts outlined in ,   Get-History | Export-Clixml ~\PowerShell\history.xml   and I can automatically load up the saved history when I start a Powershell session using this line in my powershell profile,  Import-Clixml ~\PowerShell\history.xml | Add-History   But is there any way that my history can be automatically saved when I exit the session? I'm using  as my console.


Shortcut for quickly toggling between cameras (in a similar way the Alt+Tab works for OS tabs)?

Shortcut for quickly toggling between cameras (in a similar way the Alt+Tab works for OS tabs) ?    Assuming the function exists...  If it doesn't, it should lol.


If AC is constantly changing direction, how does it ever move?

I know this is probably really basic, but it's very confusing to me.


why does the PEWDIEPIE'S TUBE SIMULATOR didn't save the current game?

When I am playing the pewdiepie's game, I already reach the level 11 of the game and suddenly I decided to restart my phone due to the laggy thing of the phone, then when I try to open it up again (the app) I didn't see the level 11 game that I played before, it starts again in the beginning. What should I do and why does this error happens?


I'm completely new to Python and thus a bit confused about the flow of a program in Python. If my understanding is correct, for a single .py file, if we add the line  if __name__ =="__main__": main()   The interpreter finds the main function and starts executing from there. This, since Python execution goes sequentially line after line.  My question is if there are multiple .py files and 1 such file has the main function, like Java/C++ is there a way the python interpreter can know ad start executing the main function?


I keep hearing "I say 1 for the money and 2 for the show" (or variants of it) in various songs (rap specifically though I have heard it in other songs) . Can anyone tell me why it is used so much and where did it come from? Thanks. (If this helps, I hear it mainly in K-rap and I think it has something to do with "Show Me The Money")


Can you please tell me about convergence of the sequence $X_n=\frac{\left(n+1\right)}{2^{n+1}}\sum _{x=1}^n\frac{2^x}{x}$?

What can we say about convergence of a sequence whose $n$-th term $X_n$ is as follows? $$\frac{\left(n+1\right)}{2^{n+1}}\sum _{x=1}^n\frac{2^x}{x}$$ I have tried to compute limit, apply ratio test and Sandwich theorem, I also tried to use the property monotonic bounded sequences are convergent but I am unable to come up with a solution.


How to get a different Unity Launcher with different icons on each workspace?

I read through the various answers to having separate desktop folders in each Workspace using Screenlets, devilspie, or CCSM ... but that's not the answer to my question.  I installed 14.04 LTS a few days ago and have had good success getting most of my apps and some new ones to run.  What I would like is to have 4 separate workspaces, each with some different icons for the environments I run. For example,   Workspace 1 – dedicated to science and math apps Workspace 2 – dedicated to music tools Workspace 3 – for electronic circuits and simulations Workspace 4 – for web browsing and general computing   Think of an Android tablet where each screen can contain separate icons.  It must be obvious how to do this, but I can't find an answer.  I am 4 days old on Ubuntu, so please don't assume I know what I'm doing!


Everything was working fine, when I start my laptop today, wifi section was missing and I could connect only from wired connection. But wifi is still missing. Im new to linux, if anything Im doing wrong please help. $ lspci | grep Network 3d:00.0 Network controller: **Intel Corporation Wi-Fi 6 AX200 (rev 1a)**  $ dhclient wlan0 Cannot find device "wlan0"  $ cd Downloads $ cd iwlwifi-cc-46.3cfab8da.0 $ ls iwlwifi-cc-a0-46.ucode    README.iwlwifi-cc.ucode LICENSE.iwlwifi-cc.ucode $ sudo cp iwlwifi* /lib/firmware $ sudo modprobe iwlwifi $ dmesg | grep iwlwifi [    4.589179] iwlwifi 0000:3d:00.0: enabling device (0000 -> 0002) [    5.063474] iwlwifi: probe of 0000:3d:00.0 failed with error -110  And its weird it works on somedays.


E: Type' ://ppa.launchpad.net/bisigi/ppa/ubuntu' is not known on line 2 in source list/etc/apt/sources.list.d/bisigi-ppa-maverick.list  E:Unable to lock the list directory   This is blocking me from entering the Synaptic Package Manager! What is going on?  Help!


A question about causality and Quantum Field Theory from improper Lorentz transformation

Related post   In Peskin and Schroeder's QFT p28, the authors tried to show causality is preserved in scalar field theory.  Consider commutator $$ [ \phi(x), \phi(y) ] = D(x-y) - D(y-x) \tag{2.53} $$ where $D(x-y)$ is the two-point correlation function,  $$D(x-y):= \langle 0 | \phi(x) \phi(y) | 0 \rangle  = \int \frac{d^3 p}{ (2\pi)^3} \frac{1}{ 2E_{\mathbf{p}}} e^{-ip(x-y)}\tag{2.50}$$  P&S argued that each term in the right-hand-side of (2.53) is Lorentz invariant, since $$\int \frac{d^3p }{ (2\pi)^3} \frac{1}{2E_{\mathbf{p}}} = \int \frac{ d^4 p }{ (2\pi)^4} (2\pi) \delta(p^2-m^2)|_{p^0>0} \tag{2.40}$$ is Lorentz invariant.  Since there exists a continuous Lorentz transformation in the spacelike interval $(x-y)^2<0 $ such that $(x-y) \rightarrow - (x-y) $ and $D(y-x)=D(x-y)$, (2.53) equals zero in the spacelike interval. In timelike interval, since such continuous Lorentz transformation does not exist, (2.53) is non-zero in general.  My question is, consider a non-continuous Lorentz transmation in the timelike interval, $PT$, namely time reversal times parity transformation. I can also let  $(x-y) \rightarrow - (x-y) $. Why (2.53) in the timelike interval is non-zero?  I guess $PT$ will let (2.40) go to $p^0<0$ branch. But I am not sure if it breaks the Lorentz invariant of (2.40) and (2.50).


Q: sentence[:] Learn Python The Hard Way Ex. 41

I know there are many posts regarding this exercise from this heavily criticized book, but so far it helped me to start understanding things.  However, with every chapter there are questions, and while some I can answer myself, others are far more complicated.  import random from urllib import urlopen import sys  WORD_URL = "http://learncodethehardway.org/words.txt" WORDS = []  PHRASES = {     "class %%%(%%%):":        "Make a class named %%% that is-a %%%.",     "class %%%(object):\n\tdef __init__(self, ***)" :       "class %%% has-a __init__ that takes self and *** parameters.",     "class %%%(object):\n\tdef ***(self, @@@)":       "class %%% has-a function named *** that takes self and @@@ parameters.",     "*** = %%%()":       "Set *** to an instance of class %%%.",     "***.***(@@@)":       "From *** get the *** function, and call it with parameters self, @@@.",     "***.*** = '***'":       "From *** get the *** attribute and set it to '***'." }  # do they want to drill phrases first PHRASE_FIRST = False if len(sys.argv) == 2 and sys.argv[1] == "english":     PHRASE_FIRST = True  # load up the words from the website for word in urlopen(WORD_URL).readlines():     WORDS.append(word.strip())   def convert(snippet, phrase):     class_names = [w.capitalize() for w in                    random.sample(WORDS, snippet.count("%%%"))]     other_names = random.sample(WORDS, snippet.count("***"))     results = []     param_names = []      for i in range(0, snippet.count("@@@")):         param_count = random.randint(1,3)         param_names.append(', '.join(random.sample(WORDS, param_count)))      for sentence in snippet, phrase:         result = sentence[:]          # fake class names         for word in class_names:             result = result.replace("%%%", word, 1)          # fake other names         for word in other_names:             result = result.replace("***", word, 1)          # fake parameter lists         for word in param_names:            result = result.replace("@@@", word, 1)          results.append(result)      return results   # keep going until they hit CTRL-D try:     while True:         snippets = PHRASES.keys()         random.shuffle(snippets)          for snippet in snippets:             phrase = PHRASES[snippet]             question, answer = convert(snippet, phrase)             if PHRASE_FIRST:                 question, answer = answer, question              print question              raw_input("> ")             print "ANSWER:  %s\n\n" % answer except EOFError:     print "\nBye"    I don't understand this bit  for sentence in snippet, phrase:     result = sentence[:]   What does sentence[:] suppose to do? I tried the code without [:] and it worked, so I'm very confused. Perhaps it's just there to make things more confusing for no reasong? Because I also noticed, that   This code:  for i in range(0, snippet.count("@@@")):     param_count = random.randint(1,3)     param_names.append(', '.join(random.sample(WORDS, param_count)))   I can rewrite into something less confusing param_names = random.sample(WORDS, snippet.count("@@@")), which then also begs the question why to do in such way?  Sorry for the n00bish post, but a help would mean a lot!


I'm trying to programmatically model a damped harmonic spring for use in mobile UI animations (physics isn't my background, please pardon any misconceptions).  Having derived the parameters for the general case equation, I can iteratively calculate values until I reach a suitable threshold, though because this is bound to "simple" C math trig and exp functions on the CPU, the 4000-some-odd steps can cause about 0.25 seconds on slow devices lag while it calculates. I'd like to speed this up using my platform's super-optimized vector and BLAS/LAPACK functions.  The requirement for doing this is precalculating the number of steps necessary to reach my threshold value.  In the underdamped case, where the roots of the characteristic function of the differential equation are non-real, I can use algebraic tricks to get my values:  $$x(t) = c_{1}e^{r_{1}}\cos(i_{1}t) + c_{2}e^{r_{2}}\sin(i_{2}t)$$  (Given $r_{1}$, $i_{1}$, $r_{2}$, and $i_{2}$ are the real and irrational components of my two roots, respectively.)  Knowing that $r_{1} = r_{2}$ and $i_{1} = -i_{2}$, I can simplify to:  $$x(t) = c_{1}e^{r_{1}}\cos(i_{1}t)$$  And get my desired value of $t$ for my threshold $a$:  $$t = \arccos(a / c_{1} / e^{r_{1}}) / i_{1}$$  When the roots are real, the equation is a lot simpler:  $$x(t) = c_{1}e^{r_{1}} + c_{2}e^{r_{2}}$$  But I don't have my trig functions floating around to help me solve it (even if I did, the irrational components being 0 would cause problems, of course).  Take the concrete example on pages 3-4 of  (my bible during this process), since they at least solve cleanly:  $$x(t) = 1.5e^{-t} - 0.5e^{-3t}$$  I know how I would solve for $t$ to get my for when $x(t) = a$ on paper, by setting $x=e^{t}$, solving, and back substituting, but I don't have that luxury here.  How would I go about solving for my threshold value in this (supposedly) simplified case?


how to display very large tree (+ standalone vs. bussproofs)

I am looking at different options to typeset proof trees, and be helped by   A question I don't see any hint therein is about whether there are tools to display very large proof trees (hundreds of nodes).  I am speculating/dreaming  about a tool to navigate a proof tree up and down (kind of what we do with google maps). Is there anything you may think of which could be suitable for doing that? How would you go to get something workable?  -------- second update  Thanks to cfr, I learnt about varwidth (without which it seems we get error messages: Something's wrong--perhaps a missing \item. \begin{prooftree}, why so?). Still, for a large number of proof steps, I get a cropped proof tree. I understand I may adjust the border's value, by trial and error. Question is: is there a way to ask latex to calculate the best value, for each given proof tree? Or at least, is there a way to know such value somehow in advance? (for the example below, border=125pt is good enough)  \documentclass[border=10pt,varwidth]{standalone} \usepackage{bussproofs} \begin{document} \begin{prooftree} \AxiomC{A} \UnaryInfC{B} \AxiomC{C} \BinaryInfC{D} \AxiomC{E} \AxiomC{F} \BinaryInfC{G} \UnaryInfC{H} \BinaryInfC{J} \AxiomC{A} \UnaryInfC{B} \AxiomC{C} \BinaryInfC{D} \AxiomC{E} \AxiomC{F} \BinaryInfC{G} \UnaryInfC{H} \BinaryInfC{J} \BinaryInfC{JJ} \AxiomC{A} \UnaryInfC{B} \AxiomC{C} \BinaryInfC{D} \AxiomC{E} \AxiomC{F} \BinaryInfC{G} \UnaryInfC{H} \BinaryInfC{J} \AxiomC{A} \UnaryInfC{B} \AxiomC{C} \BinaryInfC{D} \AxiomC{E} \AxiomC{F} \BinaryInfC{G} \UnaryInfC{H} \BinaryInfC{J} \BinaryInfC{JJ} \BinaryInfC{JJJ} \end{prooftree} \end{document}


How to select a dissertation committee member wisely?

I'm currently developing my dissertation proposal, and am in the process of choosing my committee members.  I have heard that one should carefully choose their committee members, since they ultimately judge if and when your PhD work is done.  As far as I can tell, a committee member should at least have some expertise in my research topic.  I'm sure there's more to it than that, but I want to know what other qualities should I look out for?  What qualities in a committee member should I avoid?  I imagine these other qualities are subtle and difficult to judge at first.  Nonetheless, how do I know if they are a good fit for the success of my PhD?


I am doing a small course in SQL during my academic degree, I am very new with this material.    I saw  on StackOverflow, I tried to do INNER JOIN between my three tables, the INNER JOIN between the two tables are working well, but when I am adding the thired it's not working well, maybe I missed something?  this one is working:   SELECT Actors.FirstName,Actors.LastName  FROM Actors  INNER JOIN ActorsMovies  ON Actors.ActorID= ActorsMovies.ActorID;   this one doesn't work, I get an error message that something is missing:   SELECT Actors.FirstName,Actors.LastName  FROM Actors  INNER JOIN ActorsMovies  ON Actors.ActorID= ActorsMovies.ActorID  INNER JOIN GenresMovies ON ActorsMovies.MovieID=GenresMovies.MovieID;


Whether making changes from one of the answer is fine?

Recently i asked . there i got to know that if question is changed completely then a person with edit privilege can roll back the question to old one. Now my question is suppose a partial answer is given (of significance) then the OP makes changes from my answer to his code and waits for rest part of his solution. this makes my answer look irrelevant since already the changes that my answer suggested are reflected in question. so what can be done?


The SQL is  select xxx from xxx where region in (A , B , C)    explain the SQL, and I find the SQL does not use index region, when I change the SQL to  select xxx from xxx where region in (B , C) it can use index  The sum of A and B and C is 2000000+, A is 1000000+


Override merge without loosing commits in Git

In my master branch There are old commits which are important for me to not loose I have another branch named beta-release and it lost those old commits since I had to reset its head and then had to add all the changes and make a commit , resulting into a single commit of the whole branch which is the updated version of the whole app ! Now if I merge beta-release (into master) instead of deleting those files that are not present in the beta-release branch , it keeps them , basically just merging but I want to override without loosing commits of the master branch but making the single commit of the beta-release branch as the newer commit that replaces everything in master ]  I want to override master with beta release branch with history of old commits in master branch


How to make larger brackets in maths equations?

When I use regular brackets () in Overleaf, they come out a regular size, but the size doesn't change if I have larger than regular terms inside the brackets. Do you know how I can control the size of the brackets? Thank you.


Prove the series $\sum_{n\geq1} \frac{1}{1+z^n}$ is convengent if $|z|>1$.

Consider $$\sum_{n\geq1} \frac{1}{1+z^n}$$ with $z\in\mathbb{C}$; I have prove that series is NOT convergent when $|z|\leq1$ to it I applied Weierstrass' method. But I do not know how I can prove that series is convergent when $|z|>1$, someone could help?, thanks


What does the expression (i,j) in c signifies?

I tried executing the following c code:  #include <stdio.h> int main()  { int i=2000,j=100;  printf("%d",(j,i));  }   I gave different values to i and j and found the output. I always get the output as the value contained in the second variable. Does the expression always give the last variable as a result or does it have any other meaning?


Music notation via latex / pandoc markdown

I like how you can embed equations in pandoc-flavored markdown, by putting the equation in between dollar signs, like this: $$ \int^{+\infty}_0 \frac{\cos(x)}{\sqrt{x}} dx$$  (see how it renders here:  ) And then it can be converted to pdfs and html like this: pandoc -s inputfile.md -o outputfile.pdf pandoc -s --mathjax inputfile.md -o outputfile.html  Is there a similar thing for music notation, whereby you can enter something into your markdown file to produce musical notation? The music stack exchange seems to use ABCjs and jTab for scores and chord charts, but I don't know how to incorporate these things into my own markdown:


Recommended Source Control Directory Structure?

I am going to be using Subversion for source control on a new J2EE web application. What directory structure will you recommend for organizing code, tests and documentation?


This remains an old concern of mine, and something I have never been able to wrap my head around. For instance, I have never understood why using your own sentences that you have crafted without citing yourself counts as plagiarism. That being said- I am currently working on a paper and describing the data section, and the dataset is common enough that I see myself using it in the future for another paper. The efficient thing to do here would be to use the same description for both papers. This would, however, be considered as plagiarism. How can one reasonably be accused of plagiarism here? The data section is ancillary to both papers, is not based on a 'novel' idea, but is purely descriptive. To describe the data again using different words just for the sake of not plagiarizing from myself seems to be waste of time. Now imagine this happening to thousands of researchers over many years. It seems to me that productive hours that are wasted for such a strange, and honestly, unnecessary formality. Am I missing something here?


Grammatically, what is "It" in the following sentence?

I'm currently working at a private academy in Korea, and my boss just asked me a real head-scratcher.   In the sentence:     It doesn't have to be hot and humid for players to lose too much water from their bodies.    I'm aware that "It" is a subject pronoun replacing "The weather." Besides that, however, I'm unsure.   Is it a false subject? I wouldn't think so since it's a pronoun. Is it some crazy kind of indirect object?  Anyway, thank you all for your help!


NE555 monostable timer circuit restart timer when trigger grounded in between

I had made an NE555 timer IC based delay circuit (monostable mode) which keeps output HIGH for 10 seconds when trigger pin is connected to ground momentarily. But what I want is if I ground trigger pin again (momentarily) within the ten seconds, it restart the ten-second timer i.e. start timer again from that moment and keep output pin HIGH for another ten seconds. Any way to do that?  Below is my circuit Diagram.    Update: actually i am trying to replace the Arduino in my motion sensing relay circuit. Arduino is programmed in such a way that if motion is detected it turns relay ON immediately and if motion is not there then turns relay OFF after 1 minute. Also if there is any motion detected within that minute then the timer restarts. I think using Arduino just for that is a waste. Please suggest.


What is the difference between "fit_transform" and "transform" methods when using "SimpleImputer"?

I have following code, I am not able to understand the difference between use of fit_transform() and transform() method in this case.  In the following code, when I am using fit_transform(X_valid) instead of transform(X_valid) it gives me different outputs.   from sklearn.impute import SimpleImputer  # Imputation my_imputer = SimpleImputer() imputed_X_train = pd.DataFrame(my_imputer.fit_transform(X_train)) imputed_X_valid = pd.DataFrame(my_imputer.transform(X_valid))


Name the sci fi story in which an administrator is promoted to teacher

I believe this was written to order by someone like Asimov, but I can't find it.  An administrator works and works and gets promoted, finally, to teacher -- the crown of a school career.


Help ID Australian novel. Sci Fi (soft) / Magical Realist / Slipstream. Published 1976 – circa late 1980s

Asking for a friend.   Length; Novel (possibly novella or novelette)  Publication Notes; Australian/Melbourne author (likely but not certain. It shows a lot of familiarity with Melbourne). Australian publication. May have been published overseas as well. Published circa 1976 to late 1980s* (*It was read in roughly that time frame AND there's a mention of Melbourne's Valhalla Cinema as still operating, and that was its time period. ).  Setting; Melbourne, Australia. Present day (late 1970s - 1980s).     Plot; Male protagonist. Marginalized by society. He is increasingly ignored. Eventually he actually disappears from our universe and enters an alternate version of Melbourne. While there he meets a girl, also marginalized, also from our universe. NOTE - It's possible that the alternate universe appears black and white to him.   Unknown elements; Unsure if the alternate Melbourne is unpopulated before he meets the  girl, but we think so. Can't remember if romance ensues, but it probably does otherwise what's the point? Can't remember the ending.    I'm asking for a friend, so there's probably not much more I can tell you.   Thanks for reading.


Should the "closed as duplicate" message be altered?

Here's what the closed-as-duplicate message looks like:  marked as duplicate by johndoe1, johndoe2, johndoe3, johndoe4, johndoe5 May 5 '55 at 5:55 This question has been asked before and already has an answer. If those answers do not fully address your question, please .  Or something like that. Anyway, 'has been asked before' implies that the other duplicate is older, while apparently . That means the newest question may be the one left open, and the older question marked 'has been asked before' with a link to a newer question. That doesn't look consistent. It seems like we could change it with a more accurate message. I'd try to think of one to propose, but that's not really my area of expertise. I know it isn't a big deal, but it bugs me.


How to attach multiple ipv6 ips to eth1 on debian

I've just got a new server with native ipv6. I want to attach multiple ipv6 ips to eth1, but the only way I can see to do so is to attach them individually:  i.e.  address 2607:f0d0:xxxx:xxxx::2 address 2607:f0d0:xxxx:xxxx::3 address 2607:f0d0:xxxx:xxxx::4   Is it possible to bind whole subnets of ipv6 to a single network interface on debian? My server host tells me I have 18,446,744,073,709,551,616 ipv6 addresses for that server, surely it gets to be a nightmare to manage if they all have to bound individually (plus ifconfig would look messy).  Does anyone have a solution?


I tried so much different things of installing ntpq or other stuff but nothing works.  I dont can change it to yes. I hope someone can help here.  I had Ubuntu 16.04  This is my terminal output of the Command timedatectl         Local time: Tue 2017-06-27 20:52:45 CEST   Universal time: Tue 2017-06-27 18:52:45 UTC         RTC time: n/a        Time zone: Europe/Berlin (CEST, +0200)  Network time on: yes NTP synchronized: no  RTC in local TZ: no   Also tried this tutorial:   But when i make sudo timedatectl set-ntp on it only changes Network time on: yes/no.  Also installed ntp. But from the command sudo ntpq -p i get this error  ntpq: read: Connection refused


My website is under a DDoS attack with bots. They are all coming in from different IPs so I can't block them all. Is it possible to make a CAPTCHA or a password just to connect to the site first for like small attacks. Maybe block IPs that connect to the site 100 times in like 30 seconds or 1 minute. Any scripts to use in .htaccess or anything just to block these bots to connect to my site.


Can I pipe stdout on one server to stdin on another server?

stdout on one CentOS server needs to be piped to stdin on another CentOS server. Is this possible?  Update  ScottPack, MikeyB and jofel all have valid answers. I awarded the answer to Scott because, even though my question didn't specify security as a requirement, it's always nice to be safe. However, the other two fellows' suggestions will also work.


Showing that the derivative operator is not bounded on $L^2 (\mathbb{R})$

If we define $D$ as the set of functions $f \in L^2 (\mathbb{R})$ such that $f' \in L^2 (\mathbb{R})$ too, then it can be shown (I think) that the linear operator $\frac{d}{dt}: D \rightarrow L^2 (\mathbb{R})$ is not bounded with respect to the norm on $L^2 (\mathbb{R})$, which is $||f|| = \sqrt{\int_{-\infty}^{\infty}|f(t)|^2 dt}$.   But I'm having trouble proving this. What I'd like to do is find a sequence $(f_n)$ in $D$ with $||f_n||=1$ $\forall n \in \mathbb{N}$ but with $||f_n '||$ increasing and becoming arbitrarily large with $n$.   I understand that if we were working with the space of continuous functions on $\mathbb{R}$ instead of $L^2 (\mathbb{R})$, with the nice supremum norm, we could just use $f_n (t) = \sin(nt)$, but that won't work here. I tried the sequence $f_n(t) = \sqrt{\frac{\sin(nt)}{t}}$ because that's got a handy $L^2$-norm of $\sqrt{\pi}$ for all $n\in\mathbb{N}$, but its derivative isn't in $L^2 (\mathbb{R})$ so I feel stuck.   I think I'm approaching the problem correctly, but the norm in question here isn't easy to work with -- is there a simple sequence I could use?


Edges on an even number of Hamilton cycles

Let $G$ be a graph in which every vertex has odd degree. Show that every edge of $G$ lies on an even number of Hamilton cycles.


Jquery .On('click') is being uncooperative

I have a delete button that is generated inside of a div. When clicked I want it to delete the itself and the div and everything inside of it.     $('#geography-save').click(function () {     $('.selected-criteria').prepend('
<button type="button" class="btn btn-danger remove-save"></button>
Geography Selection

'); }); $(document).ready(function(){     $('.remove-save').on('click', function () {         alert('test');         $(this).parent('div').remove();     }); }); <link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>  <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>  <button type="button" class="btn btn-success" id="geography-save" data-dismiss="modal">Save Search</button>


Can six "$1\times1\times1$ pyramids" fit inside a $1\times1\times1$ cube?

Consider the pyramid $\left \{ (x, y, z): x,y,z\geq 0, x+y+z\leq 1 \right \}$.  This is a pyramid that has $3$ pairwise-orthogonal edges, all of length $1$ (just like a corner of a room):   From now on I'll call it a "unit pyramid" (UP). One can easily check that the volume of a UP is exactly $\frac{1}{6}$. So that raises the question:     Can we take six UPs and fit them all perfectly inside a unit cube?   When I thought about it, my initial answer was an obvious yes. So I tried to imagine such arranging, but I couldn't. I was quite surprised since I usually have a very good spatial vision. Then I tried drawing a solution and failed.  Since I'm not tech-savvy enough to use a 3D graphics software, I decided to take this problem into the real world.  So here's a unit pyramid:    It's composed of 3 edges of length 1 (which I set to be $5$ cm) and 3 edges of length $\sqrt2$ ($\approx 7$ cm).  Now, there's only one reasonable way to attach another one to it, if our goal is a unit cube:     (since now we have our square base). Now I added all the edges necessary to form a cube:   And as your 3D mind can see, now we have four unit pyramids:   It's pretty hard to see the region that has stayed uncovered by our 4 UPs, so here it is, emphasized:   And what do you know - that's a ! A quick reality check: a regular tetrahedron with edges of length $\sqrt 2$ has a volume of $\sqrt 2 (\sqrt 2)^3/12=4/12=1/3$, which suits the fact that we entered 4 UPs inside.   But now, I'm pretty certain that you can't fit another 2 of them inside. To be sure, I constructed them seperately (last picture, I promise!):  On the left there's a UP, and on the right - our regular tetrahedron (would you believe that one is twice the volume of the other?) Now you'll just have to trust me that it won't fit.  Well, that convinced me that the mission of fitting 6 unit pyramids inside a unit cube is impossible, but of course I wouldn't call it a mathematical proof. Does anyone have a more mathematically-convincing argument? I'd be curious to hear your ideas and thoughts about this.  Thank you for your time reading the question!


If there is $\{P_n\}$ of partitions with $\lim_{n\to\infty}[U(f,P_n) - L(f,P_n)]=0,$then $f$ is Riemann integrable.

The following question is taken from Real Analysis by Royden, Chapter $4,$ question $5:$     Let $f$ be a bounded function on $[a,b].$       Suppose there is a sequence $\{P_n\}$ of partitions of $[a,b]$ for which $\lim_{n\to\infty}[U(f,P_n) - L(f,P_n)]=0.$       Show that $f$ is Riemann integrable over $[a,b].$   My attempt:  Let $\varepsilon>0$ be given.     Then there exists a partition $P_N$ of $[a,b]$ such that      $$U(f,P_N)-L(f,P_N) < \varepsilon.$$     Since $\varepsilon>0$ is arbitrary, therefore      $$U(f,P_N)\leq L(f,P_N) \leq \underline{\int}_{a}^b f.$$     Similarly,      $$\overline{\int}_a^b f \leq U(f,P_N) \leq  L(f,P_N) \leq \underline{\int}_a^b f.$$     Therefore, $f$ is Riemann integrable on $[a,b].$  Is my proof correct?


how can I put these two images beside each other, How can I do that?  code I tried  I am attaching figure it look like this.  \documentclass[tikz,border=3.14pt]{standalone} \usepackage{tikz-3dplot} \usetikzlibrary{arrows.meta}  %\usepackage{graphicx} %\usepackage{caption} %\usepackage{subcaption}  %\usepackage{xcolor}   \begin{document}  %\begin{figure}[!tbp] %    \begin{subfigure}[b] \tdplotsetmaincoords{60}{97} \begin{tikzpicture} [scale=2.0, line cap=round, line join=round, >=latex,tdplot_main_coords]  \draw[->] (0,0,0) -- (3,0,0)node[below]{$x$}; \draw[->] (0,0,0) -- (0,3,0)node[below]{$y$}; \draw[->] (0,0,0) -- (0,0,3.5)node[left]{$z$}; \draw[fill] (0,0,0) circle (0.5pt) node[above, left]{$o$};   \draw[thick] (2.5,1,0) -- (2.5,1.5,0) -- (1.5,1.7,0) -- (1.5,1.2,0) -- (2.5,1,0) -- (0,0.7,2)node[below]{$ $}; %cube lower square  \draw[thick] (0,1.2,1.7) -- (0,0.7,2) -- (0,1,2.8) -- (0,1.5,2.5) -- (0,1.2,1.7) node[below]{$ $}; %cube upper square  \draw[thick] (0,1.2,1.7) -- (2.5,1.5,0) node[below]{$ $}; \draw[thick] (0,1.5,2.5) -- (1.5,1.7,0) node[below]{$ $}; \draw[thick, dashed] (0,1,2.8) -- (1.5,1.2,0) node[below]{$ $};   \draw[fill] (0,1.18,2.3) circle (0.5pt) node[above, left]{$ $}; \draw[thick,->] (0,1.18,2.3) -- (0,1.18,3.6)node[below, left]{$\hat{k}$}; \draw[thick,->] (0,1.18,2.3) -- (0,2,3.6)node[below, right]{$\widehat{n_k}$};  \draw[thick] (0,1.18,3.2) .. controls (0,1.18,3.3) and (0,1.6,3.4) .. (0,1.74,3.2); %angle \draw[fill] (0,1.5,3.31) circle (0.05pt) node[above]{$ \gamma_k $};  %\draw (0,0) node[minimum size=2cm,draw] {square}; %\draw (0,-2) node[minimum size=2cm,draw,circle] {circle};    \end{tikzpicture} %\end{subfigure}   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  %\hfill % \begin{subfigure}[b] \tdplotsetmaincoords{60}{97} \begin{tikzpicture} [scale=2.0, line cap=round, line join=round, >=latex,tdplot_main_coords]  \draw[->] (0,0,0) -- (3,0,0)node[below]{$x$}; \draw[->] (0,0,0) -- (0,3,0)node[below]{$y$}; \draw[->] (0,0,0) -- (0,0,3.5)node[left]{$z$}; \draw[fill] (0,0,0) circle (0.5pt) node[above, left]{$o$};   \draw[thick] (2.5,1,0) -- (2.5,1.5,0) -- (1.5,1.7,0) -- (1.5,1.2,0) -- (2.5,1,0) -- (0,0.7,2)node[below]{$ $}; %cube lower square  \draw[thick, rotate=90] (0,1.9,-1.2) ellipse (18pt and 30pt);% upper circle \draw[thick, rotate=90] (0,-1.1,-1.27) ellipse (18pt and 30pt);% lower circle  %\draw[thick] (0,1.2,1.7) -- (0,0.7,2) -- (0,1,2.8) -- (0,1.5,2.5) -- (0,1.2,1.7) node[below]{$ $}; %cube upper square \draw[thick] (0,0.7,2) .. controls (0,1,2) and (0,1,2) .. (0,1.2,1.7); \draw[thick] (0,0.7,2) .. controls (0,0.7,1.8) and (0,0.7,2.4) .. (0,1,2.8); \draw[thick] (0,1,2.8) .. controls (0,1.1,2.8) and (0,1.2,2.8) .. (0,1.5,2.5); \draw[thick] (0,1.5,2.5) .. controls (0,1.4,2.3) and (0,1.3,2.4) .. (0,1.2,1.7);     \draw[thick] (0,1.2,1.7) -- (2.5,1.5,0) node[below]{$ $}; \draw[thick] (0,1.5,2.5) -- (1.5,1.7,0) node[below]{$ $}; \draw[thick, dashed] (0,1,2.8) -- (1.5,1.2,0) node[below]{$ $};   \draw[fill] (0,1.18,2.3) circle (0.5pt) node[above, left]{$ $}; \draw[thick,->] (0,1.18,2.3) -- (0,1.18,3.6)node[below, left]{$\hat{k}$}; \draw[thick,->] (0,1.18,2.3) -- (0,2,3.6)node[below, right]{$\widehat{n_k}$};  \draw[thick] (0,1.18,3.2) .. controls (0,1.18,3.3) and (0,1.6,3.4) .. (0,1.74,3.2); %angle   % Points \draw[fill] (0,1.5,2.5) circle (0.05pt) node[above, right]{$ \Delta{S_k} $};  \draw[fill] (2.5,1.24,0) circle (0.05pt) node[below]{$ \Delta{y_k} $}; \draw[fill] (2,1.6,0) circle (0.05pt) node[below, right]{$ \Delta{x_k} $}; \draw[fill] (1.7,1.16,0) circle (0.05pt) node[below]{$ \Delta{A_k} $}; \draw[fill] (2.96,0.6,0) circle (0.05pt) node[below]{$ R $}; \draw[fill] (0,0.4,1.7) circle (0.05pt) node[below]{$ S $}; \draw[fill] (0,1,2.6) circle (0.05pt) node[below, left]{$ (x_k,y_k,z_k) $};      %\draw (0,0) node[minimum size=2cm,draw] {square}; %\draw (0,-2) node[minimum size=2cm,draw,circle] {circle};    \end{tikzpicture}   %\end{subfigure} %  \caption{fig 11}  %\end{figure} \end{document}


If I have a horizontal (x) and a vertical (Y) element (axis, perhaps more in the geometrical sense) what would be a proper name for the other axis (Z)? Is there already something like horizontal, vertical adjectives in English for that third dimension?


How to install managed package using Salesforce DX CLI?

I am trying to follow the  and . I tried to push some of my Lightning components which depend on a managed package in App Exchange. I would like to know how to install a managed package using Salsforce DX CLI so that i can use that command in my travis.YML file for my CI integration.  Here is the script for my Travis file  sudo: true dist: trusty cache: false env: - URL=https://developer.salesforce.com/media/salesforce-cli/sfdx-linux- amd64.tar.xz before_install:  - export SFDX_AUTOUPDATE_DISABLE=true - export SFDX_USE_GENERIC_UNIX_KEYCHAIN=true - export SFDX_DOMAIN_RETRY=300 - wget -qO- $URL | tar xJf - - "./sfdx/install" - export PATH=./sfdx/$(pwd):$PATH - sfdx update - sfdx force:auth:jwt:grant --clientid $CONSUMERKEY --jwtkeyfile  assets/server.key --username $USERNAME --setdefaultdevhubusername -a DevHub script: - sfdx force:org:create -f config/project-scratch-def.json -s -a  PackageInstallation - sfdx force:org:list - sfdx force:org:display - sfdx force:user:password:generate -u PackageInstallation - sfdx force:org:display - sfdx force:org:open -u PackageInstallation - sfdx force:source:push -u PackageInstallation - sfdx force:apex:test:run -u PackageInstallation -c -r human   I get the following error as my components depend on the app exchange components:     No COMPONENT named markup://ldt:datatableDev found :


How much water does pasta absorb when it is cooked?

How much water will dry semolina pasta absorb when it is properly cooked?  For example, how much water would one pound of farfalle or spaghetti absorb?  I am guessing the shape of the pasta doesn't matter, just the absolute weight.  I am not looking for how much water is required to boil it, nor what temperature is required, just how much should be absorbed.  I like my pasta cooked a minute or so past the box "al dente" stage.  The application is single burner cooking (I only have one available).   I can make the sauce, then add additional water and pasta to cook directly in the sauce, making for only one burner being required, and only a single pot to clean.  I understand the actual amount will require due to the vagaries of how much evaporates, but I expect that to be a minor adjustment.


I have Kali linux installed on Virtualbox (4.2.12) and the host OS is windows 7. I have bridged the VM with the host OS.The problem is Kali is not able to detect the WiFi interface. I searched the internet and most of the  say that the virtual machine can only identify wireless devices connected via USB and the host machine's WiFi can not be detected by VM. Assuming that it is true I am wondering how am I able to connect to the internet from the VM when the host machine is only having an active WiFi connection and no wired connection? Any insights? P.S. I do not have the privilege to create a tag that is why I am tagging this with backtrack.


Why does the wheel of a car appear to be moving in opposite direction?

When a car is about to stop, the speed of its wheel reduces. Why do we see or feel that the wheel of the car is moving in the opposite direction?  This can also be observed of a fan at home.  So why is it?


I'm having some trouble with a Stack class. Everything looks fine to me, but I could be missing something. I thought it might be something with the makefile, seeing as I'm not all that great with makefiles.  I've also looked through a few different questions, but not found anything that fixed my problem.  Here is all the code I'm compiling plus the makefile.  Stack.h:  #ifndef STACK_H #define STACK_H  #include "Node.h"  template<class Type> class Stack { public:   Stack();   void push(Type );   Type pop();   bool isEmpty() const;  protected:   Node<Type> *head; };  #endif   Stack.cpp:  #include "Stack.h"  template<class Type> Stack<Type>::Stack() {   head = NULL; }  template<class Type> void Stack<Type>::push(Type element) {   Node<Type> *newNode;    newNode = new Node<Type>;   newNode->data = element;   newNode->next = head;   head = newNode; }  template<class Type> Type Stack<Type>::pop() {   Node<Type> *current = head;   Type element = current->data;    head = head->next;   delete current;    return element; }  template<class Type> bool Stack<Type>::isEmpty() const {   return head == NULL; }   Node.h:  #ifndef NODE_H #define NODE_H  #include "Matrix.h"  template<class Type> struct Node {   Type data;   Node<Type> *next; };  #endif   main.cpp:  #include "Stack.h" #include <iostream>  using namespace std;  int main() {   Matrix m1;   Matrix m2(1, 2, 3, 4);   Matrix m3;   m3 = m1 + m2;    Stack<Matrix> stack;   cout << stack.isEmpty() << endl;    return 0; }   Makefile:  all: matrix matrix: removal main.o Matrix.o Stack.o         g++ -o matrix main.o Matrix.o Stack.o main.o: main.cpp         g++ -c -g main.cpp Matrix.o: Matrix.cpp         g++ -c -g Matrix.cpp Stack.o: Stack.cpp         g++ -c -g Stack.cpp removal:         rm -f *.o   If you need to see Matrix.h/Matrix.cpp, let me know. They're just for doing math on matrices and aren't causing any problems as far as I'm aware (they've compiled just fine).


Hi I purchased and attempted to download MyCraft, but there was an error in the download.  No option to attempt another download, just offer to buy again.  Suggestions?


I am creating a IEEE paper, but all my references are displayed as [?]. Why is that? What can I do to get the references properly typeset?  Here is my code:  \documentclass[twocolumn,twoside]{IEEEtran} \usepackage{cite} \begin{document} \title{DDD} \author{AAA} \maketitle \begin{abstract}  hhh \end{abstract} \section{Introduction}  hghg \cite{vvv} \bibliographystyle{IEEEtran} \bibliography{myreference} \end{document}   and here is my .bib file:  @article{vvv,   author  = {xxx},   title   = {cryptography},   journal = {dddd},   year    = {2012},   volume  = {CS},   number  = {04},   pages   = {161} },


Seeking Mobile Data collection software recommendations?

What  software is available to do mobile data collection, with GPS positioning.  Map display not required. I'm looking across the board (platform wise).  I'm already aware of...              Any others you're aware of?


Binary Hamming code - number of words weight $i$

Define $A_i$ as the number of words in binary Hamming code of weight $i$. Prove:   $$A_1=0, A_0=1$$   $$(i+1)A_{i+1}+A_i+(n-i+1)A_{i-1}= {n \choose i}$$   I am a tad clueless as to how to proceed. I can show that for a given weight $i$, the number of columns of such weight of the parity-check matrix $H$ are precisely $n\choose i$. Every codeword $c$ of Ham must hold $c*H^t$. Furthermore, I can describe the generating matrix $G$ as being a matrix of the form [$A|I_{n-r}$], where there are $n\choose i$ rows in $A$ of weight $i$, for $2\le i \le n$.  I am certain the proof has to do with these two properties, yet I am unable to connect the points. Perhaps a proof with induction could be of use?  Any hints/direction towards the right way and what I should be looking at or focusing on will be extremely appreciated!


How can I run multiple instances of Telegram?

I am new to Linux and Ubuntu.  I need to run multiple instances of desktop Telegram. I saw the answers in   I do not understand how can I use the answer.   I extracted tsetup.1.1.23.tar.xz. and then opened the terminal and cd to that directory.   Also I created another administrator user named atk2 with no password.  I tried running telegram as another user like this:  sudo -u user2 ./Telegram   but it does not work. I get  No protocol specified QXcbConnection: Could not connect to display :0 ./Telegram(_ZN14SignalHandlers8internal7HandlerEiP7siginfoPv+0x175)[0xe52725] ./Telegram(_ZN14SignalHandlers8internal12DumpCallbackERKN15google_breakpad18MinidumpDescriptorEPvb+0x2e)[0xe52f7e] ./Telegram(_ZN15google_breakpad16ExceptionHandler12GenerateDumpEPNS0_12CrashContextE+0x3d4)[0x10b83e4] ./Telegram(_ZN15google_breakpad16ExceptionHandler13SignalHandlerEiP7siginfoPv+0x97)[0x10b86f7] /lib/x86_64-linux-gnu/libpthread.so.0(+0x13150)[0x7f6673f36150] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0xcb)[0x7f667360d0bb] /lib/x86_64-linux-gnu/libc.so.6(abort+0x16d)[0x7f667360ef5d] ./Telegram[0x1d6007e] ./Telegram(_ZN14QXcbConnectionC2EP19QXcbNativeInterfacebjPKc+0x97c)[0x1495bfc] ./Telegram(_ZN15QXcbIntegrationC1ERK11QStringListRiPPc+0x31e)[0x146971e] ./Telegram[0x14683bd] ./Telegram[0x1c3cb5d] ./Telegram[0x19810e5] ./Telegram[0x1981eb5] ./Telegram[0x1f1b63c] ./Telegram[0x198358c] ./Telegram[0x1657ad9] ./Telegram(_ZN11ApplicationC2ERiPPc+0x1e)[0xe5f13e] ./Telegram(main+0x8a)[0x8c94ea] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf1)[0x7f66735f71c1] ./Telegram[0x8e6b1d] Aborted   I also tried  mkdir ~/.telegram2ndprofile Telegram -many -workdir ~/.telegram2ndprofile   but I get this error in using telegram command.   # telegram -many -workdir ~/.telegram2ndprofile usage: telegram [-ynsr] user [ttyname] [message...]   What should I do to run multiple telegram instances?


On occasion I have bought sliced/chopped, pre-tenderized, frozen octopus from the local market and each time I attempt cooking it, it always is still a little chewy and smells like bay water. I suspect I'm not cleaning it right and boiling it too long but am unsure the right way to get a decent tasting octopus dish.  What is the best way to make a simply tasty octopus?


How to prove U•V = |U|•|V|cos(θ), if θ is the angle between |U| and |V|

This is a snippet from my book.    How did they get from |U|$^2$ = U • V = |U|•|V| |U|/|V| ?


How to calculate variance and expected value in R given some function f(x)

I was wondering how to calculate the expected value and variance of some function f(x). For the Expected value, I integrated x*f(x) and I'm confident that is correct, but I'm confused about how to calculate the variance using integrals and f(x). I was wondering if I should use:  where I would set a variable to the value of the expected value I found earlier and use that formula. Any help would be greatly appreciated.


It says specifically in this AWS readme documentation to make a .aws folder, and other folders of this type exist (.ext), but windows says "you must type a file name" in order to try and create a folder like this and won't let you.   I could be reading this wrong, so correct me if I am.  The \ is confusing and I am used to seeing this in commenting code, but not in actual file folders.   You need to set up your AWS security credentials before the sample code is able to connect to AWS. You can do this by creating a file named "credentials" at ~/.aws/  (C:\Users\USER_NAME\\.aws\ for Windows users) and saving the following lines in the file:  [default] aws_access_key_id = <your access key id> aws_secret_access_key = <your secret key>


Using TeXstudio's GUI, I would like to collapse the calls of \usepackage{} similar to what can be done for a \paragraph{}, a \section{} etc. The fact that some code can be collapsed in the GUI is identified with a little arrow pointing downward (if expanded) or to the right (if collapsed) next to the first line of code that can be collapsed (see below).    I've tried using  \documentclass[a4paper,12pt]{article} { % this allows collapsing in the GUI (1/2)     \usepackage{color} } % this allows collapsing in the GUI (2/2) \begin{document}     text \end{document}   which allows me to collapse the \usepackage{} calls but doesn't compile.   In short: I want code that compiles and allows me to collapse the code like show in the picture below (as identified by the gray arrow in line 4). So far, I can either get the code to compile (not using the { } around the \usepackage) or I am able to collapse the calls in the GUI.    Does anyone have a solution or idea?


Does Noether's theorem also give rise to quantities conserved over space?

Noether's theorem gives rise to quantities that are conserved over time. But does it also give rise to quantities that are conserved over space?


How did the WallstreetBet community know that Game Stop was shorted so heavily?

What I understand from the whole Game Stop soaring stock prices event is that Game Stop stocks were in essence shorted too heavily, there were more stocks borrowed/shorted than in existence. This enabled people from the WallstreetBet community and others to inflate the stock price massively by buying it. What I want to know is how/where the WallstreetBet community got the information that it was shorted so/too heavily. Were it just statements from big investors that they shorted heavily on Game Stop stocks? Or did/could they get information from other sources too about how much the stock was shorted?


This is problem 3B.12. from the afore mentioned book. It asks to show that, if $G$ is a solvable Frattini-free group (that is, $Φ(G)=1$) and $H$ is a subgroup of some maximal subgroup $M$ of $G$, then $G$ contains a subgroup of index $|M:H|$. It is easy to see that, if   $N \unlhd G$ and $M\cap N=1$, then $G=MN$, $M\cong G/N $ and $H\cong K/N $ for some $ K \leqslant G $, where $K$ contains $N$. Then $|G:K|=|G/N:K/N|=|M:H| $ and we are done. However, the hypothesis will not necessarily hold. But, if $N$ is minimal among normal subgroups of $G$ (in the sense of containment), then $N$ is elementary abelian, hence nilpotent, which implies that $M \cap N \lneq N_G(  M \cap N ) \cap N $. Thus, $M \lneq N_G(  M \cap N )$ and by the maximality of $M$ we deduce that $M \cap N \unlhd G$. So, for this particular $M$, if it is not true that there exists some normal subgroup of $G$ with which it intersects trivially, then $M \cap N = N$ by the minimality of $N$. Hence $M$ contains every minimal subgroup of $G$.     How should I proceed from here?


I would like to say something like     The boy, Adam's, favorite toy was a bike.   What is the proper way to say this?


Using a t-test with only 2 discrete values (without a mean)

Hypothetical example:  A researcher counts the number of persons entering a building over a one hour period and records this number.  The following day the researcher performs the same count during the same hour of the day.  Can these two numbers be compared for a statistically significant difference using a t-test, despite the fact that neither are means?  (Please ignore the fact that taking single readings and trying to infer meaningful findings is abhorrently bad science, this is intended as a statistical question.)


Force icon to stay outside notification tray

Using the mouse, I can drag an icon placed in the notification tray and move it outside.   Can I do that but from an automated script (so maybe using the Windows Registry), for an arbitrary program icon?


I am working on a long document in LaTeX with documentclass book. I need the page number to always be in the upper right corner of each page, even if that page is the first page of a chapter (right now on 1st pages of chapters, the page number is bottom-centered, on all other pages it's top-right).  I control the position of the page number with fancyhdr:  \usepackage{fancyhdr} \pagestyle{fancy} \lhead{} \chead{} \rhead{\thepage} \lfoot{} \cfoot{} \rfoot{} \renewcommand{\headrulewidth}{0pt}   Also, I don't know if the problem is related but my chapters do not start from the top of the page. There is a white area, then comes chapter X, then a newline with the chapter line. What I also want is the chapter to start from the top of the page.  The main question here is how I can get the page number to always appear in the upper right corner, I mention the thing with the chapter title position only in case that might be related.


Are there processes to deal with spam users that post no content?

I had a look at badges today, and in the list of recent badges I saw a display name that struck me as odd and spammy, that just got rewarded the .  I then took a look at users that recently got awarded this badge (check the above link), and noticed a lot of spammy accounts. These are 1 rep users, that just uploaded a (company)logo as their profile picture, and filled their about me with advertisement. Often accompanied by a link to some company in their website field.  These profiles where in multiple languages, and for companies from multiple locations. It almost looks an organised effort.  I manually flagged the first few users by raising a modflag on one of my own posts, by lack of content from the spammy users.  Taking into account the tremendous amount of flags that are recently being cast due to all the heated discussions here on MSE, I think it could take a while before my flags are handled, and I respect that. But are there any other, more automated processes, that deal with this type of users?


Hoping someone can help me here with this issue I'm having. Wine isn't working on my Ubuntu 14.04LTS so I want to completely remove it and install from the software manager  Code I'm using is as follows  sudo apt-get purge wine   Which shows  wine            wine1.6         wine1.6-amd64   wine1.6-i386    wine-gecko2.21  wine-gecko2.34  wine-mono0.0.8  wine-mono4.5.4  winetricks   So When I go to unistall using  sudo apt-get remove wine1.6 --purge --no-install-recommends   It uninstalls wine1.6 all fine but also then installs another version  The following NEW packages will be installed   wine1.8 wine1.8-amd64 wine1.8-i386:i386   My question is how can I prevent wine1.8 from being installed as I want wine removed completely. Sorry if this is really simple I'm new to ubuntu and learning slowly  Thanks, Youlethal


Why prefer poly() to I() ? Are they different?

A post "" used two ways to model the polynomial regression: (a) poly(..., ...); (b) I(...). Below is the example:  set.seed(20) q <- seq(from=0, to=20, by=0.1) y <- 500 + 0.4 * (q-10)^3 noise <- rnorm(length(q), mean=10, sd=80) noisy.y <- y + noise  # fitting polynomials #     two methods model_a <- lm(noisy.y ~ poly(q,3)) model_b <- lm(noisy.y ~ q + I(q^2) + I(q^3)) # their summary are all the same except the coefficients summary(model_a) summary(model_b)   The post said that:      q, I(q^2) and I(q^3) will be correlated and correlated variables can   cause problems. The use of poly() lets you avoid this by producing   orthogonal polynomials, therefore I’m going to use the first option (i.e., poly()).   I am confused that:  (1) Why does the q, I(q^2) and I(q^3) cause problems?  (2) According to summary(), these two models are all the same, except the Coefficients . Why the coefficients are different, while others are the same? Shouldn't they all different, or all the same?


Prove that maximal number of monomials ...

I stumbled across this problem and I realize that it's propably easy but somehow I can't imagine the problem properly. Prove that the maximal number of monomials (that are not similar) of polynomial $n$ variables of a degree $d$ is equal to $\binom{n+d}{n}$


How to view monitor refresh rate in macOS?

I just purchased a Dell P2175Q monitor for my 15" MBP w/Touchbar. I'm connecting with a USB-C to DisplayPort cable, but when I go to Apple > System Preference > Displays, there is nothing about the Refresh Rate. Pressing the Option key does not show any additional options.  I've seen countless screenshots where this information should appear. Is there another way to check the refresh rate?  I'm on macOS 10.13.4  Thanks.


I corrected some wrong code  and the edit was rejected almost instantly. Could anyone explain why?


Let $$f(z) = \frac{1-e^{2iz}}{z^2}$$ and let R > r > $0$ Find $$\int_{-\infty}^{\infty}\frac{sin^2(t)}{t^2}dt$$ using $$\int_{\gamma}f(z)dz = 0$$ where $\gamma=L(-R,-r)\oplus - S(0,r)\oplus L(r,R) \oplus S(0,R)$ I have found that f(z) has a singularity at $0$ with a pole of order 1  and that Res(f,0)= -2i. where can I go from here?


Ordering the list (of questions) with the suitable knowledge matching to the users knowledge

There are different users with different knowledge. Professional users don't want to answer easy questions and amateur users are not able to answer difficult questions and so on.   If the questions were listed in order such that they were closest to the users knowledge then they could be more productive, because in this matter the user doesn't need to look through all questions to find one they can answer. The questions will be already listed specially for each user. So they log in; takes 1-2 minutes; and sees matching questions they can answer.


How is the reputation value formatted when it gets abbreviated?

The current reputation value (rep) of StackOverflow (SO) users is mostly shown in a short form beside their name on all possible occasions. I see values like 1, 23, 345, 12.3k or 456k. Just out of interest: what abbreviation rule works behind it?  I found a partial answer on this question  which leads to the conclusion that after 9,999 follows 10k, but that's just a guess, since 10,0k would also make sense, i.e. it's not clear how many digits will be shown and how/if rounding is involved (or truncating).  I think a tiny comment added to some help page should describe how the rep value is actually formatted in the SO pages?


ls -F OR ls -al - What does the red highlighting mean?

So I ran a ls -F or ls -al on my /usr/bin directory and some of my files showed up with a red background and white text.  What does this mean?


The following post has 'show 1 more comment' link, but, when I click it, there are no more comments:      Update: 8 hours later (02:15UTC), and there is still a 'broken' reference to 'show 1 more comment'    Clicked:


What is the intuitive sense behind the purpose and mechanics of Sufficient Statistics?

The definition of a sufficient statistic is: Let $X_1,...,X_n$ be a random sample from a distribution indexed by a parameter $\theta$. Let $T$ be a statistic. Suppose that, for every $\theta$ and every possible value $t$ of $T$, the conditional joint distribution of $X_1,...,X_n$ given that $T=t$ depends only on $t$ but not on $\theta$. Then, $T$ is a sufficient statistic for parameter $\theta$.   I feel like I know several pieces of the puzzle (like the factorization theorem) to understanding sufficient statistics but do not have the overall theory down.   My main questions are:  1) Why do they say that $T$ is a sufficient statistic for parameter $\theta$? If $\theta$ were the population mean of a normal distribution, say $\mu$, does it mean that anytime we want to find the probability of, say, $X_1,...,X_n$ occurring in a certain way, that we don't need the value of the mean of the population?  2) In real-life, why do we want to use a sufficient statistic? Is seems that just calculating the statistic shouldn't be that much work (such as the sum of X's) so why do we need it?   Thanks!


Chemmacros is not resetting the reactions counter in the new chapter

I have a problem with chemmacros counter. When I type the reaction in different chapter, the counter of the equation doesn't restart. See the example  \documentclass[twoside]{ecsthesis}       \graphicspath{{../Figures/}}   \usepackage[sort &compress]{natbib}   \usepackage[noprefix]{nomencl} \usepackage{chemmacros} \usepackage{longtable} \usepackage{wasysym} \usepackage{hyperref} \usepackage{cleveref} \usepackage{upgreek} \usepackage{epigraph} \usepackage{tipa} \usepackage{array}  \setlength\epigraphwidth{8cm} \setlength\epigraphrule{0pt}  \begin{document} \chapter{1}  \begin{reaction} A+C=B  \end{reaction}  \chapter{2}  \begin{reaction} A+C=B  \end{reaction}   \begin{reaction}  A+C=B   \end{reaction}   \chapter{3}   \begin{reaction}  A+C=B   \end{reaction}   \begin{reaction}  A+C=B   \end{reaction}  \end{document}   I think that changing something in the .sty file could help but I do not have a clue about it.


Why is the information paradox restricted to black holes?

I am reading Hawking's "Brief answers". He complained that black holes destroy information (and was trying to find a way to avoid this). What I don't understand: Isn't deleting information quite a normal process? Doesn't burning a written letter or deleting a hard disk accomplish the same?


Use the script to export values with offset by one column

I would like to use the exportRange Function and set the target to off center by one column.  How can I accomplish this?  function exportRange()      {    var import = SpreadsheetApp.openById('1KTvAvC6UCePjyEiOmyTlCokdiHMwYbKBJRAKDxaAIPQ');    var ss = import.getSheetByName('Business Division Master Contact List');     var SRange = ss.getRange(3,1,ss.getLastRow(), 16);         //Get full range of data    var A1Range = SRange.getA1Notation();    //get A1 notation id the range    var SData = SRange.getValues();          //get the data values in range     var tss = SpreadsheetApp.openById('1bfew3H4gluutxuo1tDRr8rwNCZHSuw16oHYthT_f8CM');    var ts = tss.getSheetByName('Business Contact List'); // ts = target sheet    ts.getRange(A1Range).setValues(SData);   //set the target to the source values   }


problem installing MS Office2010 (64 bit) in Ubuntu 14.04 Wine

I am using Ubuntu 14.04 and I could not install MS Office 2010 or any office version using wine. A message pop up says "Office encountered an error during setup" but other *.exe files run perfectly. How do I solve this problem?


I need to analyze data uploaded from vehicle GPS devices to detect travel patterns and then attempt to learn about the normal travel patterns for that vehicle so that predictions can be made about maintenance, refueling etc. Some vehicles are domestic (exhibiting normal home->work->home travel patterns) and some are commercial with scheduled routing. I have loaded the GPS lats and longs to a database, and then constructed an ST_LineString with the data points for each vehicle (approx 1k points per vehicle per day). Vehicles will never have identical travel patterns (GPS accuracy, irregular ping times etc) and the patterns will be visible as subsets of pings - for example a one hour commute between point A (home) and point B (work) between 8am and 9.30am each morning, mon-fri.  Now the difficult part - I am considering the options. I have to write this in a database procedural language using the usual toolbox of procedures, cursors, iteration etc. I could use Python if it is helpful - I'm a database guy trying to think laterally and spatially.  A travel pattern could be identified by  (i) a similar sequence of points that can differ by a tolerance (say +/- 300 meters)  (ii) parking locations - if a car is parked at the same location for 8 hours a day  (iii) temporal- the vehicle starts at trip at 0830 every day, +/- 10 minutes.  I am planning to write a procedure that checks for each of these patterns for each point (or set of n points) by comparing it with all other points (or set of points) by iterating through the pings for each day in sequence. The easiest use case is to find recurrences of a vehicle parked at the same place each day. Detecting similar movement patterns is more complex. Can anyone suggest a technique for this?  Thanks!


I recently upgraded skype 4.2 to 4.3 on ubuntu 12.04, but it is crashed within some seconds. This crash is happening each time. can any body suggest me some workaround.


How to avoid OS X downloading things while using tethering

When on the road, I would like to use my phone's LTE connection and tether it to my macbook.  However, I do not have an unlimited data plan, so I don't want the mac to download a bunch of stuff (OS X updates, Chrome updates, and so forth) and kill my monthly allowance.  As far as I know, when tethering from the mac side it looks like a regular wlan connection, so I am not sure if there is an easy way to do this. I use Little Snitch, so I was considering creating a restrictive profile there to block connections when in this mode. Is there an obvious way to do this that I am missing?


Work, Energy & Power - Body slides down a hemisphere

A small body of mass $m$ slides down from the top of a hemisphere of radius $r$. There is no friction between the surface of the block and the hemisphere. The height at which the body loses contact with the surface of the sphere is? This is how I understood the problem: First of all, the mass does not lose contact with the surface of the sphere at all, considering it is undergoing centripetal acceleration, where the centripetal force is provided by the component of the mass's weight towards the centre of the hemisphere ($mgcos\theta$, where $\theta$ is the angle between the vector of the mass's weight and its component acting towards the centre). Therefore, since only $mgcos\theta$ is responsible for the centripetal force, I can form a relationship like this:  $mgcos\theta\ =\ \large \frac{mv^2}{r}$ $ v\ =\ \sqrt{rgcos\theta}$ Taking 'h' as the height of the mass from the base of the hemisphere. $cos\theta\ =\ \large \frac{h}{r}$ Then the velocity of the mass becomes: $v\ =\ \sqrt{gh}$ The component of the mass's weight along the centre disappears only when $\theta$ becomes $90$ degrees. At this point, it leaves the surface of the hemisphere. Now, the energy of the mass at the topmost point is: $P.E\ =\ mgr$  As the body slides over the hemisphere's surface, it has a tangential velocity given by the expression I had just previously derived. So by the conservation of total mechanical energy of the body, its energy at any other point on the hemisphere is: $T.E\ =\ mgh + \frac{1}{2}mv^2$ $P.E\ =\ T.E$ $gr\ =\ gh + \frac{v^2}{2}$ $gr\ =\ gh + \frac{gh}{2}$ $h\ =\ \frac{2}{3}r$ But this would mean that the body does indeed leave the surface of the hemisphere. It just doesn't add up. Can someone please explain if my approach and assumptions are valid and how I got to this completely contradictory answer?


How to pass list of values as a parameter to OleDbCommand

I want to execute query  SELECT id, name FROM MyTable WHERE (id, name) IN ((1, 'One'), (2, 'Two'))   using OleDbConnection and OleDbCommand. Is it possible to pass the contents of IN clause as a parameter to command? If yes then what value should I pass a parameter value? List, IEnumerable or something else? If not then is it possible to pass the list of single values like for query  SELECT id, name FROM MyTable WHERE id IN (1, 2)


I'm having an issue with calculating the predicted linear angle a projectile needs to move in to intersect a moving enemy ship for my 2D game.  I've tried following the document , but what I've have come up with is simply awful.  protected Vector2 GetPredictedPosition(float angleToEnemy, ShipCompartment origin, ShipCompartment target) {     // Below obviously won't compile (document wants a Vector, not sure how to get that from a single float?)     Vector2 velocity = target.Thrust - 25f; // Closing velocity (25 is example projectile velocity)     Vector2 distance = target.Position - origin.Position; // Range to close     double time = distance.Length() / velocity.Length(); // Time      // Garbage code, doesn't compile, this method is incorrect     return target.Position + (target.Thrust * time); }   I would be grateful if the community can help point out how this is done correctly.  EDIT  Here is my (working) method following the advice given:  protected Vector2 GetPredictedPosition(ShipCompartment origin, ShipCompartment target, Ship enemyShip, Ship firingShip) {     Vector2 targetVelocity = enemyShip.Direction * enemyShip.Thrust;     Vector2 projectileVelocity = firingShip.Direction * 25f;      Vector2 velocity = targetVelocity - projectileVelocity; // Closing velocity     Vector2 distance = target.Position - origin.Position; // Range to close     double time = distance.Length() / velocity.Length(); // Time      return target.Position + new Vector2(Convert.ToSingle(targetVelocity.X * time), Convert.ToSingle(targetVelocity.Y * time)); }