Group in which all elements are conjugate

Two elements $a$ and $b$ of a group $G$ are conjugate if there is an element $g$ in the group such that $b = g^{–1}ag$.   I was going through the  on conjugacy classes and was curious about this:   What can we say about a group $G$ in which all its elements are conjugate? Does it have any special properties? Can there exist such a non-trivial group $G$?


We don't get much snow in the UK, so I don't have much experience photographing it, and when I tried photographing falling snow last year I found it very hard to capture the snowflakes in the air — they either didn't show up or were just streaks. Is there a shutter speed that is best for this? I don't want to use flash to do so.  Any other snow photography tips welcome from those in snowier places!


Windows 8 People app without a delete option

I'm trying to delete contacts in my People app and when I right click, there isn't an option to delete.  Only pin to start or edit.  Where did it go?  How do I delete these contacts?


Converting lat/long to northing/easting given data from a .prj file

I have been given the a file containing a bunch of lat long coordinates along with this information that came from a ".prj" file alongside a ".shp" file: GEOGCS["GCS_GDA_1994",DATUM["D_GDA_1994",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]] I need to convert the lat/long coordinates which I've parsed out of the ".shp" file to northing/easting coordinates, but I don't understand this data - I'm a software engineer with very little knowledge of GIS, and I'm unsure where to start, and as far as I can tell, the above WKT isn't enough to perform the conversion. I have some other data which is already in northing/easting format, and I need to make sure the two are aligned. I'm using the NetTopologySuite.Proj4Net library.


Cannot rename a file with name too long (no 8+3 name)

I copied some directories from a now-defunct Mac laptop. I am trying to open one of the files (a PDF), but Acrobat won't open it because the name is too long.  I am trying to rename the file to a shorter name, but I cannot. Explorer won't let me, again, because of the long name.  I tried renaming it in cmd.exe using the 8+3 name, but none of the files from Mac have 8+3 names. That means that there is no way to rename it using the short name.  What else I can do?


With the following code, iI am able to draw a parabola y=x^2, but unable to draw parabola x=y^2, showing some error

With the following code, I am able to draw a parabola y=x^2, but unable to draw parabola x=y^2, showing some error, please help.   \documentclass{article} \usepackage{tikz,pgfplots} %\usepackage[x11names]{xcolor} \usepackage{tikz} \usetikzlibrary{intersections} \pgfdeclarelayer{bg}    % declare background \pgfsetlayers{bg,main}  % order of layers (main = standard layer) \pgfplotsset{compat=1.13} \usepackage{amsmath} \usetikzlibrary{positioning}      \begin{document}    \begin{tikzpicture}[domain=0:2, scale = 0.75] \draw(-4,0)--(4,0); \draw (0,-4)--(0,4); \draw[black, line width = 0.50mm]   plot[smooth,domain=-2:2] (\x, {(\x)^2});  \draw[black, line width = 0.50mm]   plot[smooth,domain= -2:2] (\y,  {(\y)^2}); \end{tikzpicture} \end{document}


What should be used to represent creature tokens when the printed token card isn't available?

Many spells or abilities cause one or more creatures to join the battlefield (i.e. 1/1 white Soldier creature tokens, 3/3 green Beast creature tokens, etc.). These token cards are not included with the cards that require them.  What do MtG players use instead to represent token creatures?  A quick search shows you can buy packs of such cards, but I'm wondering what convenient ways exist to represent these tokens without actually having to buy more cards?


In my Android application, when I rotate the device (slide out the keyboard) then my Activity is restarted (onCreate is called). Now, this is probably how it's supposed to be, but I do a lot of initial setting up in the onCreate method, so I need either:   Put all the initial setting up in another function so it's not all lost on device rotation or Make it so onCreate is not called again and the layout just adjusts or Limit the app to just portrait so that onCreate is not called.


How do I display data from a django rest get request in a react-leaflet using onEachFeature?

I imported shapefiles into my PostgreSQL database with PostGIS extension and created a REST API using Django which has a GET response like this: [ {     "objectid": 1,     "id_field": 5543,     "county_nam": "B1",     "const_code": 288,     "constituen": "KAM",     "county_cod": 47,     "shape_leng": 1.55978672217,     "shape_area": 0.057422949 }, {     "objectid": 2,     "id_field": 6634,     "county_nam": "B2",     "const_code": 3,     "constituen": "KIS",     "county_cod": 1,     "shape_leng": 0.88558616055,     "shape_area": 0.02332510618 }, {     "objectid": 3,     "id_field": 6600,     "county_nam": "B3",     "const_code": 10,     "constituen": "KIN",     "county_cod": 2,     "shape_leng": 4.28418177601,     "shape_area": 0.75826601303 }, {     "objectid": 4,     "id_field": 6731,     "county_nam": "B4",     "const_code": 13,     "constituen": "KAL",     "county_cod": 3,     "shape_leng": 5.33308007101,     "shape_area": 1.02533838151 }, ...  How do I display this response into a React Leaflet?    async componentDidMount() {     const rawcurrentuser = JSON.parse(localStorage.getItem("currentUser"));      await axios.get('/api/gis/counties/')       .then((response) => {         this.setState({ county: response.data });       })       .catch(function (error) {         console.log(error);       });   }  When I display as below, the data is not displayed. <Map center={position} zoom={7} ref={this.mapRef}>  {this.state.county && (         <GeoJSON           data={this.state.county}         />       )}  </Map>  Displaying with Django view works fine using onEachFeature: myLayer = new L.geoJson(data, {   onEachFeature: function (feature, layer) {           layer.bindPopup('<font size="4">' + feature.properties.county_nam)         },         style: countStyle  }).addTo(count).addTo(map);  How do I use the same concept in my current React scenario?


Independence of linear combination of multivariate distribution

$X$ is multivariate normal distributed with $\mu = (2, 2)$ and $\Sigma = (1, 0 ; 0, 1)$ and I have 2 vectors $A = (1, 1)$ and $B = (1, -1)$. How can I than show that the linear combinations $AX$ and $BX$ are independent?


What's the symbol for the curly D used to denote a dissection for a Riemann integral?

In an analysis lecture today the lecturer used the following curly D symbol to denote a dissection (for a Riemann integral):    How can I get this symbol with LaTeX? I've tried to find it in the comprehensive symbol list, as well as with Detexify, but haven't succeeded.


Get a notification when a exe is not running anymore

I have a synchronization running in the background. I thought I'll find the answer within seconds, but somehow I am not able to do so.  I would like to get a notification when that program closes or is terminated, i.e. is not running for whatever reason.  I thought it should be possible to use the task scheduler for that with a trigger "when a specific event is logged", here the exe is closed. But is there an event logged when a process is terminated? If yes where do I find it?


Strange behaviour of Stack Exchange websites

The webiste of Stack Overflow (and all its subsites, even this meta.stackexchange website too) always has a drop down box open, and also the shape of website is quite out of the layout.  At first I thought, it may be because of a slow Internet connection, but I am using a 4 Mbit/s broadband connection. Further, I am seeing on both my Windows and Linux systems. I have used Ctrl + F5, but I am seeing the same results. A screenshot is attached which is also appearing too large on my screen:


Hello, I made an object(left one) and I duplicated it and scaled by -1 in x direction(right one) to have it symmetric. Then i applied "Apply to Location, Scale&rotation and Origin to Geometry" But as in the picture, it is shaded improperly. What can problem be and how can I fix it ?


How can I transfer large files from Linux to iPad over a cable or wifi?

I am looking for a way to transfer large files to the iPad without using iTunes or pushing to and pulling from a remote server.  I run an Ubuntu laptop as my only OS at the moment and want to be able to transfer movies to my iPad.  I currently transfer most of my files by way of the dropbox app which works well for small files but is quite slow for larger files and eats up my bandwidth.  Ideally I'd like to be able to transfer over a cable or through WiFi.  Thanks for any tips.


What is the command of double parentheses in Latex?

What is the command of . in Latex? Thanks!


onclick of button navidate to another lightning component

I am not able to open a lightning component using "e.force:navigateToComponent"  this is the error when i click on the button:   this is my 1st component:  <aura:component controller="RecruitmentClass" implements="force:appHostable" access="global"> <aura:attribute name="LoginName" type="String"/> <aura:attribute name="LoginPwd" type="String"/> <aura:attribute type="Interviewee__c" name="Candidate1"/>
     <lightning:card title="" >
Login

         <ui:inputText label="Enter your name " value="{!v.LoginName}"/>
         <ui:inputText label="Enter your password " value="{!v.LoginPwd}"/>
         <lightning:button  label='Login' onclick="{!c.myAction}"/>
     </lightning:card>
     this is my js controller:  ({ myAction : function(component, event, helper) {     var name=component.get('v.LoginName');     var pwd=component.get('v.LoginPwd');      var action=component.get("c.Login");     action.setParams({         n:name,         p:pwd     });     action.setCallback(this,function(response){         if(response.getState()==='SUCCESS'){             var c=response.getReturnValue();             component.set('v.Candidate1',c);              //this is where im facing problems             var evt = $A.get("e.force:navigateToComponent");             evt.setParams({                 componentDef : "c:RecruitmentApp2ParentComponent",                 componentAttributes: {    Candidate : c                                       }             });             alert('succesful'+evt+'candidate: '+c);             evt.fire();          }         else {             alert('error something happend');         }     });     $A.enqueueAction(action);  }   })


An interesting problem with "decomposing" natural numbers.

Consider the following one-person game:  A player starts with score $0$ and writes the number $20$ on an empty whiteboard. At each step, she may erase any one integer (call it $a$) and writes two positive integers (call them $b$ and $c$) such that $b + c = a$. The player then adds $b × c$ to her score. She repeats the step several times until she ends up with all $1$s on the whiteboard. Then the game is over, and the final score is calculated.  Example: At the first step, a player erases $20$ and writes $14$ and $6$, and gets a score of $14 × 6 = 84$. In the next step, she erases $14$, writes $9$ and $5$, and adds $9 × 5 = 45$ to her score. Her score is now $84 + 45 = 129$. In the next step, she may erase any of the remaining numbers on the whiteboard: $5$, $6$ or $9$. She continues until the game is over. Alya and Bob play the game separately. Alya manages to get the highest possible final score. Bob, however, manages to get the lowest possible final score. What is the difference between Alya’s and Bob’s final scores? I tried to "decompose" into a few numbers and I get the same scores. I am not sure how to prove the conjecture that any numbers will yield the same score no matter which path is taken.


Can a bullet shot through a glass make a clean hole?

One can often see (hopefully only in the movies) that a bullet shot through a pane of window glass leaves a hole in it, but overall the glass is left largely intact. However, a low-speed projectile, e.g., a stone thrown into a window would probably shatter the glass completely. Is there a critical speed below which a bullet would shatter the whole window pane instead of piercing a hole?


Do browsers really only display images at 72 pixels per inch?

In the book HTML and CSS, I came across the following quote:     The web browsers on most desktop computers display images at a resolution of 72 pixels per inch (ppi).    So is it really useless to create an image larger than 72 ppi if the browser will only render it at 72 ppi? After all, the larger the file, the slower it is to load and don't want to slow load time for nothing.   My monitor has a resolution of 1680 x 1050 yet according to this book, when I open up Firefox and view images, they will only be viewed at 72 ppi.


Assumptions:   Computer architecture: Describes how the different modules of a processor interact with each other. A computer architecture is defined using vhdl files Computer Organization: Describes the physical layout of the processor modules on silicon. A computer organization is defined using a set of photo masks (and manufacturing process eg chemical, that goes at each step) Computer Organization, therefore, requires that the fab process be taken into account. ARM is not in the fabrication business, therefore it does not sell photo masks.     My question(s):   What exactly is ARM selling to a vendor (eg: freescale)? For a SoC (System On Chip), (eg: ), which part is ARM and which is Freescale? Who did the integration?


Specific compilation Error " Dimension too large!"

When I compile the following document, I get the error   ! Dimension too large. <to be read again>                     \relax  l.22 ...le[arc=l,size=0.30 cm, font=\tiny](m',O,m)  ?    When I press H to get help, I receive the following message  I can't work with sizes bigger than about 19 feet. Continue and I'll use the largest value I can.  ?    How I can solve this problem?  \documentclass{article} \usepackage{tikz} \usepackage{tkz-euclide} \usetkzobj{all}%IMPORTANT--recognizes points, lines, circles, etc \usetikzlibrary{angles,quotes,bending}  \begin{document}   \begin{center} \begin{tikzpicture}[scale=1]  \tkzDefPoint(0,0){O}  \tkzDefPoint(1,0){u} \tkzDefPoint(-2, 1){v}   \tkzDefLine[bisector](u,O,v) \tkzGetPoint{m} \tkzDefLine[bisector](m,O,v) \tkzGetPoint{m"} \tkzDefLine[bisector](u,O,m) \tkzGetPoint{m'}  \tkzMarkAngle[arc=l,size=0.30 cm, font=\tiny](m',O,m) \end{tikzpicture} \end{center} \end{document}


How to read the numbers on electrical wiring to run within walls

I am wondering how to read the numbers on electrical wiring separated by slashes such as 12/2. What do the numbers refer to? What other numbers should I watch out for when purchasing wires to be run within the walls and sockets of a home? P Thanks.


Is it okay to write i.e. at the beginning of a sentence?

Is it aceptable to write "i.e." at the begining of a sencnce?  For example:     Does the above formula equal 2?   i.e. does (insert simple formula here) equal 10?   or should it be     Does the above formula equal 2?   I.e. does (insert simple formula here) equal 10?   or both capitalised?     Does the above formula equal 2?   I.E. does (insert simple formula here) equal 10?   Or would it be better to write     Does the above formula equal 2?   By that I mean does (insert simple formula here) equal 10?   or     Does the above formula equal 2?   That is, does (insert simple formula here) equal 10?


How to determine a Python variable's type?

How do I see the type of a variable whether it is unsigned 32 bit, signed 16 bit, etc.?  How do I view it?


How can I use perl 5.12 in Ubuntu? There is no distribution package on Ubuntu.  I have to use feature 'unicode_strings'; in my perl code, and this is available from 5.12. I try to install perl on Ubuntu by apt-get install perl, but 5.10 is the latest version.  How can I deal with this? Or is there any code in 5.10 can replace the code feature 'unicode_strings';?  Thanks.


Linear Algebra: Let U, V be non-zero subspaces of R3, and let W = U ∪ V be the set of vectors which lie in either U or V (or both).

Is this statement true or false? Let U, V be non-zero subspaces of R3, and let W = U ∪ V be the set of vectors which lie in either U or V (or both). Then W is a subspace of R3 .


How long does the ubuntu installation take and what to do after it?

I've got a HP probook 4515s, AMD Sempron SI-42 (2,1 Ghz), ATI Radeon HD 3200, only 1GB ram.  I'm installing Ubuntu 12.04 with a CD right now, and it seems to take about 20 minutes since.  And its also my first time I use ubuntu and I wanted to know how to set up wlan ( a friend told me it doesnt work on my pc) And maybe a link to a site telling my which things I need to install and what I should know and stuff.


C# look up type by source name and get source name for type

I need to fetch a C# type by name, where the interface should be pretty much identical to typeof except that the string is named at runtime instead of the type being named at compilation time- i.e. typeof(x) == runtime_typeof("x") for all x. Fairly critically, I also need to deal with various generic situations like generic definitions and generic types.  I've seen some other solutions in C# for getting type by name but they all seem to involve CLR mangled names rather than C# source names.  Furthermore, I need to retrieve a source name for a given Type object that should be of the same form.  How can I look up types by C# source name and retrieve a C# source name from a type?  Edit: Assembly qualified names and C# source names are not the same thing. Hence the explicitness in the question.  What I'm really looking for is that the names should be identical to the names you would use to reference them from C# source code- so IEnumerable<T> or IEnumerable<>, rather than IEnumerable[1]` or whatever. Requiring the full namespace is fine for me and I already know what assemblies to look in, so it's mostly an issue of what happens when generics and name mangling are involved.


How to ensure OpenVPN connection uses specific DNS?

I'm using OpenVPN through Tunnelblick on MacOS X Lion.  I need to set specific DNS (with local IP, which works only when VPN is up) for the duration of this VPN session only.  I do not have access to the OpenVPN server configuration. Only client config. Also, DNS from the server doesn't work.  So it works like this: I connect to VPN, go the Network preferences and manually set DNS. After VPN is disconnected, I switch back to default. It works, but it needs to be automatic.  After some exploration I found that OpenVPN up- and down- scripts might help me with that. Unfortunately, I haven't found any specific documentation about how exactly it can be done.  How it can or can't be done? Any advice would be appreciated!


Force Windows 8 to use UTC when dealing with BIOS clock

I have Arch Linux + Windows 8 on my laptop.  In previous versions of Windows, there is a DWORD in the registry (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal) that switches between localtime and UTC, but this doesn't seem to be working in Windows 8 anymore.  I am now getting UTC time in Windows since it thinks BIOS gives it localtime which is actually UTC time, and after reboot into Arch Linux, the clock becomes localtime-0400, because Arch thinks BIOS is having the correct UTC time.  I do not want to let Arch Linux use localtime.  Under this prerequisite, is there any possible solution?


Values are always returning null after building object

The idea is to print out a simple line saying the book title, author, and price. However, I cannot seem to return any value even after constructing a Book object.  I'm building a Book class, an Author class, and using a Tester to run the program.  Here's what I'm looking at:  package book;  public class Book {      String title;     Author author;     double price;      public Book(String title, Author author, double price){}      public Book(){}      public void setbookTitle(String title) {         this.title = title;     }      public void setPrice(double price) {         this.price = price;     }      public String getTitle() {         return title;     }      public Author getAuthor() {         return author;     }      public double getPrice() {         return price;     }  }   package book;  public class Author {      String name;     String email;     char gender;      public Author(String name, String email, char gender){     }      public String getName() {         return name;     }      public String getEmail(){         return email;     }      public char getGender(){         return gender;     }      public void setName(String name) {         this.name = name;     }      public void setEmail(String email) {         this.email = email;     }      public void setGender(char gender) {         this.gender = gender;     }      @Override     public String toString(){         return name;     }    }    package book;  public class BookTester {      public static void main(String[] args) {      Author author1 = new Author("Horstmann", "horstmann@gmail.com", 'm');     Book book1 = new Book("Big Java", author1, 60);      Double number = book1.getPrice();         System.out.println(number);      System.out.println ("The Book information is: ");     System.out.println(book1.getTitle() + book1.getAuthor() + book1.getPrice());       }  }   Any advice would be appreciated!


Age  12-17  18-24   25-34   35-44   45-54   55-64   65+ Category 1       5   16  14  44  13  12  0 2       0   1   3   0   0   0   0 3       3   2   6   1   0   1   0 4       27  3   3   13  0   3   2 5       0   4   4   9   6   7   4   The above is results of questionnaire data, I was going to use the chi^2 test on this but as it has very small values and values of zero, it is not appropriate.  I would like to test the if there is a relationship between age and category (which is about where the shop, i.e five 12-17 year olds shop at category 1).  What test if any could I use?  thanks


Select Distinct Not In Select Distinct Returning 0 Rows, Should be almost 1000

Select Distinct FileId From dbo.Files    returns 3415 rows  Select Distinct FileId From dbo.SyncHistory Where Date > '2015/7/1'    returns 2483 rows.  Select Distinct FileId From dbo.Files  Where FileId In (Select Distinct FileId From dbo.SyncHistory Where Date > '2015/7/1')   returns 2482 rows. Okay so someone synced this month but then deleted their file I assume.  BUT:  Select Distinct FileId From dbo.Files  Where FileId NOT In (Select Distinct FileId From dbo.SyncHistory Where Date > '2015/7/1')   Returns 0 rows.  I thought my connection was broken but I've run and rerun it and the results are consistent if also consistently wrong. Is this a sql bug? What am I missing here?


As a very confused newbie, what's up with the IF statement and [ ], [[ ]], ( ), (( )) why is if [ $jengnr -eq 1 ]; then  correct, but here it's double: if [[ -f "$jdir$object.eng.dat" ]]; then  and then I read that a nested if inside an if should be (( )) (not my code) #!/bin/bash # Nested if statements if [ $1 -gt 100 ] then echo Hey that\'s a large number. if (( $1 % 2 == 0 )) then echo And is also an even number. fi fi  but I used [[ ]] in an if statement that was inside an if [[ ]] statement, and that worked to? Can somebody please explain what, who and why there are 4 different if? .. and when to use them correctly?


How can I selectively override some A records on a Bind DNS Server?

I'm guessing there has to be a reasonable way to solve my issue but I'm trying to get some advice on a best practice to implement.  I have recently moved to a Web Design company and we need to be able to spoof DNS entries for websites we're working on. However we want to only override certain A records, but keep the others so the site seems to work.  i.e:  We want to make "support.abcd.com" resolve locally, but everything else go to the real site. This would allow us to design/demo a fully functioning site with only the work in progress locally.  We have an internal BIND DNS server (9.9.5.dfsg-3).   What should my zone file look for "abcd.com" based on the example above?  Edit: Would this work?            IN ns1 abcd.com. IN NS ns1 support.abcd.com. IN A 192.168.1.1 faq.abcd.com.     IN A 192.168.1.1 *.abcd.com.       IN NS abcd.com     <- External?


The company I work for runs a series of ecommerce stores on a VPS. It's a WAMP stack, 50gb storage.  We use an archaic piece of ecommerce software which operates almost entirely client-side. When an order is taken, it writes it to disk and then we schedule a task to download the orders once every 10 minutes.  A few days ago, we ran out of disk space, which caused orders to fail to be written. I quickly hopped on to delete some old logs from the mailserver and freed up a couple of GB pretty quickly, but I wondered how we could fill up 50gb will nothing much more than logs.  Turns out, we didn't. Hidden deep within the c:\System Volume Information directory, we have a stack of pirated videos, which seem to have appeared (looking at the timestamps) over the past three weeks. Porn, American Sports, Australian cooking shows. A very odd collection. Doesn't look like an individual's personal tastes - more like the VPS is being used as a mule.  We have a 5-attempts and you're blocked policy on our FTP server (plus, there is no FTP account with access to that directory), and the windows user account has had it's password changed recently. The main avenues are sealed - and logs can verify that. I thought I'd watch and see if it happened again, and yes, another cooking show has appeared this morning.  I am the only one to know of this problem at my company, and only one of two with access to the VPS (the other being my boss, but no - it's not him).  So how is this happening?  Is there a vulnerability in some of the software on the VPS? Are the VPS owners peddling warez across our rented space? (can they do this?)  I don't want to delete the warez in case it is seen as a hostile action against this outside force, and they choose to retaliate.  What should I do? How do I troubleshoot this? Has this happened to anyone else before?


(Posted here as probably applies to all sites).  I was examining my reputation gain yesterday on Stack Overflow: 190. I believe I should have hit the 200 cap. Mainly due to         Respectively, I had 10, 7, 3, and 2 upvotes on those questions alone. There are a couple of other minnows in the list but the above alone should enable me to hit the cap.  There was a user removed sometime yesterday which knocked off 10 points (and possibly accounts for the disparity) but I think (1) the cap should have been recalibrated and (2) I answered (3) after this event before turning in for the night.  I checked all the usual suspects: the reputation graph on your profile and  the achievements tab, but they are all showing 190.


If $f$ is continuous on $[a , b]$ and $\int_a^b f(x) p(x)dx = 0$ then $f = 0$

Show that if $f$ is a continuous function on the interval $[a , b]$ and if $\int_a^b f(x) p(x)dx = 0$ for every polynomial $p$ then $f$ must be the zero function.   Attempt:  By the Weierstrass Approximation Theorem, we know there is a sequence $\{p_j\}$ such that $p_j \rightarrow f$ uniformly on $[a,b]$. (The Theorem states: "Let $f$ be a continuous function on an interval $[a,b]$. Then there is a sequence of polynomias $p_j(x)$ with the property that the sequence $p_j$ converges uniformly on $[a,b]$ to $f$.")  Then since $p_j$ is integrable on $[a,b]$ and since $p_j \rightarrow f$ uniformly on $[a,b]$. Then we know $f$ is integrable on $[a,b]$ and $\lim_{j \to \infty} \int_a^b p_{j}(x) dx = \int_a^b f(x) dx $.  But how do I know $f(x) = 0$ ?


I'm logged in as minime.  I don't understand why it doesn't allow me to chown file that I own without su privileges. Obviously I can use sudo, but I'd like to understand why? because of www-data group?  chown minime:www-data user-functions.php  ls -lh  -rw-r--r--  1 minime minime    24K Jan  6 16:11 user-functions.php  Error:  chown: changing ownership of `user-functions.php': Operation not permitted


Is this 'inversion' common in spoken English?

While I was listening to a guided meditation by Jon Kabat-Zinn (who is a Native English-Speaker) I bumped into an expression that appears to contain a sort of inversion in an affirmative sentence.  I've looked it up in the  and it seems this is something not linked to the presence of be likely to.     Only if you know, or even suspect that it actually does, are you likely to have enough energy for the discipline of formal practice.


Index notation Lorentz transfromation matrix

A Lorentz transformation between two different coordinate systems is given by:  $$(x')^\mu = {\Lambda^\mu}_\nu~ x^\nu$$  where $\Lambda$ is the Lorentz transformation matrix. I am a bit confused by the ordering of the indices using this notation, that is why do we write ${\Lambda^\mu}_\nu$ instead of $\Lambda^\mu_\nu$ or ${\Lambda_\nu}^\mu$. Is there an explicit convention of which index comes first in the left-to-right ordering? Is ${\Lambda_\nu}^\mu$ different from ${\Lambda^\mu}_\nu$ and if yes, how do they relate to each other.  What about the ordering of the indices from left to right of the general tensor? Does the order here just specify which position in the "N-dimensional matrix" we are considering, i. e. first index gives the row, second the column, third the "depth", etc.?  Any help in clarifying these points will be greatly appreciated.


This is a selection from my dmesg:  rtl8192cu 1-3:1.0 wlx10bef501e1cd: renamed from wlan0 wlx10bef501e1cd: authenticate with 90:94:e4:e7:99:cc wlx10bef501e1cd: send auth to 90:94:e4:e7:99:cc (try 1/3) wlx10bef501e1cd: authenticated wlx10bef501e1cd: aborting authentication with 90:94:e4:e7:99:cc by local choice (Reason: 3=DEAUTH_LEAVING)   Where that particular error is linked to device names being too long a string, as probably emerges by this attempt at connection:  ___@DESK:~$ sudo iwconfig wlx10bef501e1cd essid dlink_DIR-506L key s:___{pass}___ Error for wireless request "Set Encode" (8B2A) :     SET failed on device wlx10bef501e1cd ; Invalid argument.   The dongle as in the output of lsusb is a:  Bus 001 Device 002: ID 2001:3308 D-Link Corp. DWA-121 802.11n Wireless N 150 Pico Adapter [Realtek RTL8188CUS]   At the same time, that device (a wifi usb dongle) was used to successfully install Debian as a net install, with the same long string being the id showed by the installation GUI during download of the packages.  I tried to rename the device by creating a rule in /etc/udev/rules.d/70-persistent-net.rules without success (I used at the output of udevadm info and saved the attempt below amongst others, where "1-3" is the third device on bus one).  SUBSYSTEM=="usb",ACTION=="add",DRIVERS=="usb",ATTRS{product}=="802.11n WLAN Adapter",ATTR{dev_id}=="0x0",ATTR{type}=="1",KERNEL=="1-3",NAME="wlan1"     Why is that device being renamed to such a problematic id in the first place? Instead of trying to patch the situation later down the line is there a way I can just avoid wlan0 to be renamed?    After accepting an answer for this question I realized the answers for  include the solution for this problem, but the process described there also include steps that are not strictly required to solve this question.  I'm not sure if this qualifies as a duplicate or not.


Saving a list in a recursive function call

I am generating all binary strings of a given length and am trying to store them in a list which I am having trouble with. Here is the code: def generateAllBinaryStrings(n, arr, l, i):        if i == n:          l.append(arr)          print(arr)         return      arr[i] = 0     generateAllBinaryStrings(n, arr, l, i + 1)        arr[i] = 1     generateAllBinaryStrings(n, arr, l, i + 1)        return l  n = 3 l = []   arr = [None] * n  generateAllBinaryStrings(n, arr, l, 0)    i.e. first creating all possible strings with the starting bit as 0 and then all strings with the starting bit as 1. arr stores strings and am trying to append them into a list l. The following print result is right for print(arr) statement but l is not correct. May I know where I went wrong?: [0, 0, 0] [0, 0, 1] [0, 1, 0] [0, 1, 1] [1, 0, 0] [1, 0, 1] [1, 1, 0] [1, 1, 1]  [[1, 1, 1], [1, 1, 1], [1, 1, 1], [1, 1, 1], [1, 1, 1], [1, 1, 1], [1, 1, 1], [1, 1, 1]]


Any point to downvoting already closed questions?

That question of mine was closed a long time ago (relatively, to me at least).  However, from time to time I still get downvotes for it.  That got me thinking: is there any reason to still downvote closed questions?


"It isn't" vs "It is not" (Google suggestion) - which one is more common?

Everyone agrees that:     Semantically "It's not" and "It isn't" mean the same thing: "It is   not".   No doubt here. See:   The reason why I'm asking is because Google is suggesting one way regardless the fact the one other one has more hits, see:  and     In general: which one is more common and what examples where it makes difference come to your mind?


Why is password confirmation common in password resets and updates?

I've seen multiple websites with only one field for the password during registration, whereas there are two fields – Enter Password and Confirm Password – for password reset and update tasks.


WCF - have client check for service availability

I have a client-server system, both sides written by me, and I would like to put the clients in an 'offline' state when the server disconnects/dies, and then automatically bring them back 'online' when the server is available again.  For the first part, I listen for channel faulted events and handle that by setting the client to offline. I then start calling a 'ping' service on the server (every 30 sec.) which just returns a bool if it is alive. Once it is alive the client gets the bool and switches back online.   This all works, the problem I am having is that when the client calls the ping service and the server is down, no response is sent (obviously) and eventually, after about 2mins I get an endpoint not found exception. By this time I have already tried 3-4 more pings and hence have 3-4 exceptions brewing.  My question is, how can I deal with the ping service more gracefully? Ideally I would like to periodically call a service that lets me know if it is online, and instantly lets me know if it is not.


Applying Playfair's axiom when the point does not lie on the given line

Playfair's axiom states:     Through any point in the plane, there is at most one straight line   parallel to a given straight line.   This axiom is equivalent to the parallel postulate.  Intuitively, we know that if the point $P$ does not lie on the given straight line $\mathcal{l}$, there is exactly one straight line through $P$ that is parallel to $\mathcal{l}$. But how do we prove this? From Playfair's axiom, we know that there is at most one such straight line. But how do we conclude, from the first four postulates, that there is at least one?  Note: My question is different from . I have provided an answer to my own question.


Why do some tactile switches have 4 terminals?

I am wondering why some tactile switches have 4 terminals instead of two? For example, take a look at , like the image below:   (source: )    What is the use of the two remaining pins? If the pins of the exact opposite side are always shorted then why don't they have just 2 pins?


Given that $abc=1$, prove that $\frac{b}{c} + \frac{c}{a}+ \frac{a}{b} \ge \frac{1}{a} + \frac{1}{b} +\frac{1}{c}$.

I have tried to do a bunch of different versions of AM-GM on this and the equivalent versions that come from substituting in $abc=1$ and I always flip the inequality by doing it.   Help is greatly appreciated.


Can and should Stack Overflow automatically rewrite bit.ly links?

Quite a few people paste in bit.ly links into comments or answers, sometimes even for linking to other pages (or answers within the same page) on Stack Overflow. This way, you do not see where the link is pointing to.  Assuming that there is an API to do this, should the site automatically rewrite the links to point at the original URL?   Are there any benefits to leave them at bit.ly?   Why are people pasting them through bit.ly in the first place? Stack Overflow displays shortened URL anyway, so formatting should not be a concern.


how do we compile and run a haskell program on terminal?

I have my program saved as prog.c  how do I compile it and run it?


Can one replace/add a ship part in orbit?

I have a reusable ship in orbit and wish to add some parts to it (e.g. parachutes, heat shield, Mono-Fuel ...).  Is it possible?   Is there a mod that lets an engineer to do it?


Removing selection area from canvas when no layer is available or selected

I am new to QGIS 3 and I can not figure out the way to remove the selection from empty canvas or with Google Maps layers selected this area can not be removed. I tried to remove it by selecting a layer but still not successful.


How to fill a mesh inner geometry to make a completely solid model

My mesh object is based on a CT bone scan so there are many inner geometries due to natural spaces in human bones. But I need a model that has no inner geometries. How do I fill inner holes and spaces with completely solid mesh?  Thanks  Update: I attached a screenshot of the "holes" in my mesh after boolean op.    booleaned:    original:


PostgreSQL PostGIS ST_Point_Inside_Circle() radius in meters

I'd like to begin by saying that I have very little knowledge and understanding when it comes to GIS (despite extensive experience with Google Maps API). PostGIS appears to be a whole new ball game on its own.  I've recently installed PostGIS (v2.1.5) with my PostgreSQL (v9.4) instance in order to begin storing and working with GIS data. I'm currently using Google Maps API v3's DrawingManager to draw polygons, circles, rectangles and markers which need to be stored in the database, and later retrieved to display the polygons again on Google Maps; These shapes will also be used for various aggregate queries.  I currently have two tables. The one is called "locations" which will store the polygons, circles and rectangles created with Google Maps' DrawingManager. The second, called "rawdata" will contain a set of records with a POINT (lat, long) inside of it.  First and foremost, I do not entirely understand the concept of projections and how they work, but, based on what I've read online is that calculations and accuracy may vary, significantly. I understand that Google Maps works with the Web Mercator projection which I believe is officially known as the EPSG:3857 projection (or CRS), while the preferred method for storing and working with geometry() shapes in PostGIS is in the EPSG:4326. As such and in reference to my create table statements below, I have chosen to store my geometry data in EPSG:4326 in the tables.  An easier method would to be store my geometry in the newer geographic format, but I do not wish to impose those performance and lack of functionality drawbacks as I will be working with a significant amount of data (hundreds of thousands, if not millions of records).  I am trying to test the ST_Point_Inside_Circle() function but this appears to be inaccurate and I can only assume so because the function expects degrees as the radius parameter, yet Google Maps supplies me with a radius in meters. In reference to , I have tried converting meters to degrees by multiplying meters by 0.00001. However, the greater the radius in meters, the more inaccurate it appears to be. What can I do to achieve an accurate result?  SELECT ST_Point_Inside_Circle(ST_SetSRID(ST_MakePoint(28.239418677985668, -25.75443387513752), 4326), 28.241967111825943, -25.759674774140656, (583 * 0.00001));  Google Maps reports the distance in meters between the two points (center of circle and point) as 637 meters, yet ST_Point_Inside_Circle returns true when trying to convert 583 to degrees. This leads me to the assumption that one cannot convert meters to degrees using 0.00001.  What is the correct way to determine the radius with meters?


I understand that when you put your tongue on frozen metal, your tongue sticks to the metal but how does having a layer of ice covering the metal prevent your tongue from sticking?


How does Huygens Principle explain interference?

How exactly does  about the propagation of wavefronts account for interference?


Having problems vertically and horizontally centering div

I'm having a little trouble centering a div both horizontally and vertically. I've had a quick look around and can't really make much sense of other answers, so I thought I would post my own question.  What I am looking to do is center my div with text horizontally and vertically however I need the container div to stay perfectly sized to the window.  Here is the css I'm having trouble with.  body{margin:0 auto;}  div#section1 {height: 100vh;background: black;}   Also, here's a link to , I couldn't post HTML in here for some reason, the "Post" button would grey out.  Thanks


How to put text below some text in an equation

Please refer the attached image. I want to write \omega \in \mathbb{R} below sup as shown in the equation in the image. How should I do it?


I am facing some login problem for accessing instance. While login to the server console (its a live server) it shows as Permission denied (publickey), Also am accessing with sudo also same issue persists. AWS instance, should reboot, no change while login issue persists. Please reply at earliest to solve this issue ASAP.


Okay, so the formula for Gravitational Potential Energy (GPE) of satellites is: $$ U=-GmM/d$$ Mass and distance can't be negative, and $G$ is constant that is not negative.  Why is a satellite's GPE negative?  For other objects, like a ball, the GPE is calculated as: U=mgh  Correct me if I am wrong, but this is what I think:   Satellite's GPE is measured relative to earth's center, while a ball's GPE is measured relative to earth's surface. The satellite was sent to its orbit with energy from the fuel, and it was launched from the earth's surface. While for the ball, it was sent to its height with energy (say, from a human body) and it was carried from the earth's surface.   So is a satellite's GPE negative because: Energy needed to bring the satellite to earth's center is greater than the energy expended when it was sent to orbit?


Non-orientable one dimensional manifold.

I was trying to solve a question from Hatcher's book in section 3.3.  Question is:  Show that there exist a non-orientable 1-dimensional manifold if Hausdroff condition is droped from the definition of manifold.  I know real line with two origin is a 1-dimensional non-Hausdroff manifold. But I don't know how to show that this is orientable or not? I will apprecite if somebody explain this to me using the local homology definition of orientability.


I would like some help with exercise 3.39 from Fulton & Harris' 'Representation Theory A First Course':  Let $V_0$ be a real vector space on which $G$ acts irreducibly, $V=V_0 \otimes \mathbb{C}$ is a complex representation of $G$. Show that if $V$ is not irreducible, then it has two irreducible factors, and they are conjugate complex representations of $G$.  First of all I would like to remark that conjugate complex representations were not covered before in the book, but after a bit of research I believe the statement in the exercise is equivalent to: $V=W \oplus W^*$ for some (complex) irreducible sub-representation $W \subset V$. If I am mistaken please do correct me!  This question was asked here: , but the post got bogged down with notations and since it was so old I decided to ask it again here. It was suggested in the comments of that post that we consider a irreducible (proper) sub-representation $W \subset V$, let $V=W \oplus U$, and show that $U=W^*$, but I don't really see how we can go on...  The only way I have learnt to compute the amount of irreducible factors inside a representation $V$ is by computing $(\chi_V,\chi_V)=\frac{1}{|G|} \sum_{g \in G} |\chi_V(g)|^2$, but since we don't have a corresponding formula (not one that I am aware of) in the real case, I'm not sure how we can prove there are 2 irreducible factors in $V$ here. I am also failing to see how the second statement about the relation between the two factors can follow from the first part.  Any help is appreciated!


Relating the normal bundle and trivial bundles of $S^n$ to the tautological and trivial line bundles of $\mathbb{R}P^n$

On page $10$ of Hatcher's , he gives a proof that the Whitney sum of the trivial line bundle over $\mathbb{R}P^n$ and the tangent bundle is equal to the Whitney sum of copies of the tautological line bundle.  A summary of the proof is   1) The image of the tangent bundle of the sphere under the quotient is the tangent bundle of real projective space, and the image of the normal bundle is the trivial line bundle over real projective space.  2) He says the sum of the tangent bundle and normal bundle of the sphere is trivial.  3) He then proves that the trivial line bundle over the sphere is isomorphic to the normal bundle and proves that the normal bundle under the quotient is mapped to the tautological line bundle over real projective space.  But this doesn't make any sense because he claimed earlier that the image of the normal bundle is trivial and the tautological bundle is NOT trivial. Could someone please clarify what has happened? Is the image of the normal bundle of the sphere under the quotient the tautological bundle or the trivial bundle?


Product of all elements of a finite group with an unique element of order 2

Well be with you, gentlemen. I have the following problem from Aluffi's Algebra:  given a finite group $G$ with an unique element $f$ of order $2$, show that \begin{equation} \prod_{g\in G}g=f \end{equation} My reasoning is the following. Since $f$ is the unique element of order $2$, for each $g\in G$ such that $g\neq e$ and $g\neq f$, it must be that $g^{-1}\neq g$. So we can concoct a particular product coupling the elements with their inverses: \begin{equation} e\cdot f\cdot (g_1\cdot g_1^{-1})\cdot(g_2\cdot g_2^{-1})\cdots (g_n\cdot g_n^{-1}) \end{equation} which is really just $f$ in the end. My question is: how can I show that the order of the factors in this product really does not matter? I cannot see a way out.


I'm kinda new to OpenGL, I am currently trying to make a class which can handle drawing vertices into the screen and it doesn't seem to work, it doesn't draw anything. I know that this problem has nothing to do with shaders cz It works when I do it without a class (directly in the main.cpp file). Model.h #include <glad/glad.h> class Model { private:     GLuint VAO, VBO, EBO;  public:     Model(float vertices[], unsigned int indices[]);     void Draw(); };  Model.cpp #include "Model.h" Model::Model(float vertices[], unsigned int indices[]) {     glGenVertexArrays(1, &this->VAO);     glGenBuffers(1, &this->VBO);     glGenBuffers(1, &this->EBO);      glBindVertexArray(this->VAO);      glBindBuffer(GL_ARRAY_BUFFER, this->VBO);     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);      glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, this->EBO);     glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);      glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);     glEnableVertexAttribArray(0);      glBindBuffer(GL_ARRAY_BUFFER, 0);     glBindVertexArray(0); }  void Model::Draw() {     glBindVertexArray(VAO);     glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); }  Main.cpp #include <iostream> #include "Model.h" #include "Shader.h" #include "Window.h"  int main() { std::cout << "Start" << std::endl;  float vertices[] = {      0.5f,  0.5f, 0.0f,      0.5f, -0.5f, 0.0f,     -0.5f, -0.5f, 0.0f,     -0.5f,  0.5f, 0.0f }; unsigned int indices[] = {     0, 1, 3,     1, 2, 3 };  Window window("MyWindow", 800, 600); window.Show();  Model square(vertices, indices);  Shader testShader("testVertexShader.glsl", "testFragmentShader.glsl");  glViewport(0, 0, 800, 600);  while (!window.ShouldClose()) {     /*glClearColor(0.2f, 0.3f, 0.3f, 1.0f);     glClear(GL_COLOR_BUFFER_BIT);*/           testShader.Use();     square.Draw();      window.Update(); }  testShader.Delete(); window.Close();  std::cout << "End" << std::endl;  return 0;  }


I am planning to create a new user in Disco Dingo, How do you create a new user in Disco Dingo?                                                                  Any risks involved? How to delete the account?                                                                                What are the differences from the admin account-no power on sudo.


How to remove/eject non-existing External devices from Disk Utility?

For some reason Disk Utility (16.0) didn't eject my HDDs correctly and show the list of ghosts external drives as per below image:    despite I've no any external hard drives connected. Ejecting them from contextual menu doesn't do anything.    I've tried to use diskutil to unmount these non-existing drives:  diskutil list diskutil unmountDisk /dev/disk2   but it didn't work.  Including this shell command to unmount them all:  $ while read disk _; do diskutil unmountDisk force $disk; done < <(diskutil list | grep external) Unmount of all volumes on disk2 was successful Unmount of all volumes on disk4 was successful Unmount of all volumes on disk5 was successful Unmount of all volumes on disk6 was successful Unmount of all volumes on disk7 was successful Unmount of all volumes on disk8 was successful Unmount of all volumes on disk9 was successful Unmount of all volumes on disk10 was successful   but the command doesn't take any (even with force) effect despite the successful message. So these disks are still showing after restarting Disk Utility as per below command:  $ diskutil list | grep external /dev/disk2 (external, physical): /dev/disk4 (external, physical): /dev/disk5 (external, physical): /dev/disk6 (external, physical): /dev/disk7 (external, physical): /dev/disk8 (external, physical): /dev/disk9 (external, physical): /dev/disk10 (external, physical):     The following log entries shows when unmounting a single disk:  $ log stream opendirectoryd: Client: <private>, UID: 501, EUID: 501, GID: 20, EGID: 20 opendirectoryd: <private> completed, delivered 1 result diskutil: (CoreFoundation) Loading Preferences From System CFPrefsD For Search List diskutil: (CoreFoundation) Loading Preferences From User CFPrefsD For Search List authd: (Security) SecTrustEvaluateIfNecessary trustd: [com.apple.securityd.policy] cert[2]: AnchorTrusted =(leaf)[force]> <CFBoolean 0x7fffcc25d578 [0x7fffcc25cbd0]>{value = false} authd: (Security) [com.apple.securityd.security_exception] CSSM Exception: -2147411889 CSSMERR_CL_UNKNOWN_TAG authd: (Security) [com.apple.securityd.security_exception] CSSM Exception: -2147411889 CSSMERR_CL_UNKNOWN_TAG authd: (Security) [com.apple.securityd.security_exception] CSSM Exception: -2147411889 CSSMERR_CL_UNKNOWN_TAG authd: (Security) [com.apple.securityd.security_exception] CSSM Exception: -2147411889 CSSMERR_CL_UNKNOWN_TAG authd: (Security) [com.apple.securityd.security_exception] CSSM Exception: -2147411889 CSSMERR_CL_UNKNOWN_TAG authd: (Security) [com.apple.securityd.security_exception] CSSM Exception: -2147411889 CSSMERR_CL_UNKNOWN_TAG opendirectoryd: Client: <private>, UID: 0, EUID: 0, GID: 0, EGID: 0 opendirectoryd: <private> completed, delivered 1 result opendirectoryd: Client: <private>, UID: 0, EUID: 0, GID: 0, EGID: 0 opendirectoryd: <private> completed, delivered 1 result opendirectoryd: Client: <private>, UID: 0, EUID: 0, GID: 0, EGID: 0 opendirectoryd: <private> completed, delivered 1 result authd: Succeeded authorizing right 'system.volume.external.unmount' by client '/usr/sbin/diskutil' [30724] for authorization created by '/usr/sbin/diskutil' [30724] (13,0) opendirectoryd: Client: <private>, UID: 0, EUID: 0, GID: 0, EGID: 0 opendirectoryd: <private> completed, delivered 1 result opendirectoryd: Client: <private>, UID: 0, EUID: 0, GID: 0, EGID: 0 opendirectoryd: <private> completed, delivered 1 result opendirectoryd: Client: <private>, UID: 0, EUID: 0, GID: 0, EGID: 0 opendirectoryd: <private> completed, delivered 1 result authd: Succeeded authorizing right 'system.volume.external.unmount' by client '/usr/libexec/diskarbitrationd' [97] for authorization created by '/usr/sbin/diskutil' [30724] (2,0) taskgated: (Security) [com.apple.securityd.security_exception] MacOS error: -67062 taskgated: (Security) [com.apple.securityd.security_exception] MacOS error: -67062     How do I get rid of these non-existing volumes without restarting the system?


install robot 3t :- usr/local/bin/robomongo/lib’: Directory not empty

I am trying to install robo3t in ubuntu 14.04 new in linux   Those commands work   wget https://download.robomongo.org/0.9.0/linux/robomongo-0.9.0-linux-x86_64-0786489.tar.gz tar -xvzf robomongo-0.9.0-linux-x86_64-0786489.tar.gz sudo mkdir /usr/local/bin/robomongo   But when I write this command   sudo mv  robomongo-0.9.0-linux-x86_64-0786489/* /usr/local/bin/robomongo   I get    error :- /usr/local/bin/robomongo/lib’: Directory not empty


Trying to suspend someone from chat for 0.02 hours results in an error page

I've attempted to suspend a user from chat for 1-2 minutes so I input 0.02 into the "hours" field. The result was


It seems that newer versions of bash have the &> operator, which (if I understand correctly), redirects both stdout and stderr to a file (&>> appends to the file instead, as Adrian clarified).   What's the simplest way to achieve the same thing, but instead piping to another command?  For example, in this line:  cmd-doesnt-respect-difference-between-stdout-and-stderr | grep -i SomeError   I'd like the grep to match on content both in stdout and stderr (effectively, have them combined into one stream).  Note: this question is asking about piping, not redirecting - so it is not a duplicate of the question it's currently marked as a duplicate of.


How can I duplicate Apple's tiny USB power adapter?

I'm designing a project that controls 110VAC (plug in, socket out), and also has a microprocessor inside.  I'd really like this project to not need a wall wart to get it's 5V, so I want to include a small DC power supply inside.    Apple's USB power adapter looks like a great small design that I can fit inside my case.  I'm guessing this is a switching power supply but I can't find any teardowns or schematics anywhere.  Does anyone know how this thing works?  I know I could make my own 110V->5VDC supply from a bridge rectifier and some caps, but I'd like to also be super safe.  What's in the Apple brick?


Did Kant and Satre have the same view on morality

So in Kantian morality, in each act, you act as if your choice should become a universal law.  And in Existentialism and Humanism Satre says that in every choice you choose for all man. Are they promoting the same sort of view, or are the similarities merely superficial?


How to redefine the section counter in amsart?

I'm using the document class amsart, which defines the section counter as follows:  \newcounter{section}   However, I want the section counter to reset to zero every time I start a new part. Thus, I put in the preamble of my document the following code:  \newcounter{section}[part]   However, since the section counter was already defined in amsart, I'm receiving the error message:  Command \c@section already defined.   What is the appropriate way to redefine the section counter?


Schengen tourist visa refused. Can I appeal for reconsideration?

My Schengen tourist visa was rejected by the German Consulate, Chennai stating that my date of flying from Chennai to Berlin (02-Nov-13) is not the same as the starting date of leave approval from my office (06-Nov-13).  But my company has sanctioned me leave considering the fact that 02-Nov-13 to 5-Nov-13 are office holidays. I wouldn't blame the consulate because they wouldn't know that and they consider mismatching dates to be a discrepancy.  Now, what could I do? Shall I appeal for a reconsideration without paying the visa fee again? If yes, how do I do that? And also, what is the probability that they would reconsider again?  Or, shall I reapply fresh again with a correction in my leave letter from the office? I have sent a mail to the consulate but they haven't replied.


How to fire function on file upload to directory?

Is their any way that whenever a user upload file via ftp a function fire automatically.I don't have any code.Search it on internet but not find any solution.


Delete All files except specific file in bash

I am trying to use rm -rf !(current) delete all folders in current path except current folder. But I am getting below error     bash: !: event not found   How do I get this functionality in bash?


Using induction to prove the inequality $n!\ge 2^{n-1}$

How would I go about proving that $n! \ge 2^{n-1}\ \forall n \ge 1$? The base case makes sense to me, but when I do the inductive step, I go here using the inductive step:  $$ n+ 1 = k+1 $$ $$ (k+1)! \ge 2^{(k+1)-1} $$ $$ (k+1)! = (k+1)\cdot k!$$ $$\ 2^{k-1+1} = 2^k = 2^{k-1} \cdot 2 $$ $$(k+1) \cdot k! \ge 2^{k-1} \cdot 2 $$ $$ \therefore (n+1) \cdot n! \ge 2^{n-1} \cdot 2$$  Is this a viable proof? If not, what do I need to do differently in order to make it correct? Have I not gone far enough?


Force LaTeX image to appear in the section in which it's declared

Possible Duplicates:           How can I force an image in a LaTeX documents to appear in the section in which I declared it?  I don't want that an image about "Section A" to appear in "Section F". :(  I actually include an image with  \begin{figure}[ht] \begin{center} \includegraphics[scale=0.7]{./img/RobotManipulator3D_WorkSpace.png} \end{center} \caption{3D View of the robotic workspace (in red).} \label{Img:3DRobotWorkspace} \end{figure}


How to truncate entire string if it will overrun the max character count?

I need to limit this string to max 320 characters but also make it truncate cleanly if it is going to overrun e.g  I want  Testing Item 1 | Testing Item 2 | Testing Item 3   Instead of  Testing Item 1 | Testing Item 2 | Testing Item 3 | Tes   Currently I have this function:  /**      * First filter out any empty values, strip any tags, then join each array item with a pipe | and limit it to 320 characters.      * @param $array      * @return string      */     public function limitStripAndJoin($array) {         // Removes any empty strings from the array e.g if there's no caption on an image, we want to remove the empty string         $filteredArray = array_filter($array, 'strlen');          return strip_tags(substr(join(" | ", $filteredArray), 0, 320));     }   I just need to know how stop going to the next item if it will overrun?


I was wondering if there's a way that I can download apps from google play to my external sd card because every time I try downloading a game or a app it says "sorry, there's not enough storage on the device" and I have a 32gb sd card in and I tried going to applacation manager and moving apps manualy but some don't allow  me to move to my sd card and i have my default write disk on sd card and I have a samsung galaxy s5 mini


How to impelement GetHashCode in class without any ID

For example I have class   class Person {     public string FirstName { get; set; }     public string LastName { get; set; } }   How to override GetHashCode in this class?


You are missing the following 32-bit libraries, and Steam may not run: libc.so.6

I have recently moved over from SteamOS which is Debian Wheazy. None of the other fixes have not worked, I tried getting steam both through Steam itself and the Ubuntu Center.


How can I remove the qed symbols from all lemma proofs?

the following code will only make the qed not appear in the second proof. However, it it possible to make the qed symbol never appear at the end of the proofs without having to specify it locally every time?  \documentclass{article} \usepackage{amsthm} \begin{document} \begin{proof} This has the QED symbol. \end{proof} \begin{proof}\renewcommand{\qedsymbol}{} This hasn't. \end{proof} \begin{proof} And this has it again. \end{proof} \end{document}


Why does an even subdivide change the displayed texture?

In my scene I have a default plane and scaled one edge along the x axis. I have a material that is just a tile texture that is mapped on with a UV map. Here is a screenshot of the setup.    This is far from what I would expect. I would expect that it would look like the tiles had been compressed. My expected result shows up as I subdivide the plane. What is subdivide doing that is fixing this mapping?  Here is 1 subdivision   Here is 3 subdivisions


6/2(2+1) = 9 or 6/2(2+1) = 1 I am not really sure which is the correct answer. I think the latter is much more correct than the former. If we assume the property of distribution then the latter can be made into this 6/2(2+1) = 6/(2*2 + 2*1) = 1.


What was Darth Vader's official role (or rank) in the Empire?

Darth Vader was a man of great importance. He carried out highly sensitive missions for the Emperor, ranging from killing Jedi in the  to retrieving the top secret Death Star plans in A New Hope. However, with his appearance and the fact that he doesn't try to hide his affiliation with the Empire, nor that he is a man of importance, he must have had some official role and/or rank within the Empire.   A few other questions have touched on this, for instance , ,  and , but none of them really answered what I was wondering, and some even raised more questions.    Public role  This was my initial question, what was his public role in the Empire? It seems to me that while he may not be present in the capital, or even seen with the Emperor, he should have an official role or some sort of title that the general public can use to identify him with. Calling him 'Lord Vader' could be enough, I guess. The Empire wasn't exactly a transparent ruler, so even if some people (like the rebels) realized that the title of 'Imperial Lord' didn't really cover his actual roles, they wouldn't be able to do anything about it. But did he have an official role in the Empire, and are there any canon/non-canon references that touches on this?  When I thought about this for a while, I realized that the real issue is in fact his...  Rank within the Empire  This is also somewhat related to . The most upvoted comment there suggests that Vader was outside the normal chain of command, which would make sense in A New Hope, but during the assault against the rebel base at Hoth in The Empire Strikes Back, Vader is clearly in charge. Is he a special case when it comes to rank and everyone just sort of obey him, or does the Emperor explicitly tell other officers when Vader is in charge?  If he is outside the chain of command, but still seen as a superior officer and a powerful member of the Emperor's inner circle, how could someone like , Death Star admiral and Chief of the Imperial Navy have the audacity to be disrespectful? I realize that the Force is seen as 'mumbo-jumbo' even by Imperials, but that aside, he must still be regarded as a high-ranking officer. If someone like Motti lacks faith, surely other Imperial officers must feel the same way? Was Motti just stupid enough to let it show?  If a high ranking officer was executing a crucial mission and Vader unexpectedly showed up and wanted to change his plans, would the officer be punished if he refused? Imagine the scenario being played out twice, one where the officer is right, and one where Vader is right. In general, what would be best for the officer to do?    To sum up, what is Vader's official/unofficial role and rank, and how much weight did his words actually carry within the Empire?


I tried to upgrade Linux from 18.04 to 20.04 but unfortunately my laptop battery got over. When I tried to reopen, it got crashed. Now on starting there are only three options: Ubuntu, advanced options and system manage. Only black screen appears there. Please help me out, I don't have knowledge of Linux as I had recently moved to linux.


why it result in a NullPointerException when Object is null?

when objec is null:  if(object != null && object.string.equals("")) {     System.out.println("no error"); }   it will result in NullPointerException, and why if it checks the first result is false, it still check the second instead of stop check and print "no error"?  sorry for my bad english -_-#


How do you make mini-planet photos like this one?   By Guido Radig (Own work) [CC BY 3.0 (, via Wikimedia Commons  Here are some examples of what I mean on Flickr:  - though I would be open to a better source of examples.


This has been raised many times, and marked duplicate, but  (I believe), and it is time to revisit the question with a different perspective... especially since there was debate in the linked MSO question as to whether the MSO question itself is/was appropriate. It seemed appropriate at the time, but, in retrospect, a lot of trouble, and a quicker and more appropriate response would have been available if a flag-the-moderator option in a logical place was available....  Without the flag-the-moderator, is the right answer to post to MSO?        Possible duplicates that have been previously closed as duplicates:    (Good question!)    (declined, not duplicate)  others.   In most cases (all?), the duplicate links point back to this question:         In that question, it is suggested that the 'flag user' is missing , and that moderators have the ability to flag the users, and not 'general' users.  The problem is: how do you get moderators to flag the user, when you can't easily notify the moderators?  The answer given in the question is that you should flag one of the 'abusive' things the user has done, a comment, post, chat message, etc. The assumptions are that:   the profile itself will not be the actual problem. there is some activity of that user to flag. the 'volume' of these incidents is small.   if there is no 'action' to flag, then flag a random post and give the details in the message. This seems convoluted.  Unfortunately, it is possible to use  tool.  The result is that, to report this problem, you have to flag some random post (another user's post), and then provide complicated details in the 'reason'.  There should be a better way to do this.... and a flag on the offending profile page is the right way. Even if the only option is: flag for moderator attention. Provide reason: .....  Special things to consider:   the offending person/profile can join any chat room regardless of their profile home-page so the profile's effect stretches beyond the home-site jurisdiction. They don't need to 'say' anything to be offensive the flag-user may be part of the 'privilege' escalation process, presumably like the existing flag-posts @ 15 threshold.   FYI:  Removed Image showing chat rooms since it is not appropriate in all places.... you can find the image at http://i.stack.imgur.com/aq4bW.png


Which is the best approach to make a 2D character to be able to use tons of different equipments when in action?

I want to create a 2D game but I'd like to have the character to wear tons of different equipments on different combinations, like a RPG or something.  So let's say the user changes his/her shoulders and pants, this must be shown to the player and all these different equipments must follow the different characters action (hitting, being hit, spelling magic, etc.).  I see a few problems that I'd like to know the best approach/algorithm/architecture to solve.  1 - Sprites or Animations  Should I create different sprites for each equipment in each action animation?  Is it better to just have the equipment sprite and animate it directly on code like rotating and translating (using something like tween on Flash)?  Is there any other better option? (I really don't like the ideas above)  2 - Positions  Let's say during one of the character's move he starts looking directly in front to the player's view but ends his movement showing his right side to the player (like if he swings his sword from one side to the other).  If we consider one part of the user, like his head for example, it starts in front and then turns left.  It means at least 3 different positions for each head equipment (helmet, cap, whatever).  This surely influence the answer of #1 question. How is the best way to achieve that?  3 - Layers  Let's consider a character move where he spins 360 degrees with his arms open. At the beginning of the animation, his right hand is close to the user's view and then, at the middle of the movement, this is probably behind the character's body on the animation.  Whatever is the option on #1 question, you surely needs to use some kind of layer model to make this sprite or animation to starts closer to the player's view and later change to far away from player's view.  Is there any good way to do that?  I know the question is quite long and difficult to understand. Let me know if you think it's better to have some drawings to try to explain which one and I'll try to do that.


In RSA, how does the CPU deal with this huge modulus (8192 bits)?

Whilst I understand how the RSA algorithm works, I don't understand how the CPU operates when it needs to use the mod function with a huge number $n$, for example.  $n = 8192$ bits; $c = m^e \mod n$;  In essence my question is how does the CPU deal with this huge modulus?


A transformation between two free group actions.

Let $A, B:G\to \mathrm{Aut}(X)$ be two free group actions, where $X$ is a set and $G$ a group. A group action, $A$, is free if for all $g\in G\setminus{e}$, $A(g)x\neq x$ for all $x\in X$.Then there exists a function $f:X\to X$ such that for all $g\in G, x\in X$ $$f(A(g)x)= B(g)f(x).$$    I've been completely stumped for some time! How ought one think about such a question? I can't even think of a candidate $f$ or of some simple properties it ought satisfy! I've managed to dig up that the action being free is equivalent to $(g, x)\mapsto (A(g)x, x)$, $G\times X \to X\times X$ being an injection, but haven't been able to make use of this fact.


Freezing a physics simulation and use a certain frame to go on with modelling

I am just modelling a small cup that I want to fill with sugar cubes. To make it look more realistic, I want to let the cubes drop into the cup. I have already physics enabled and the right collisions but I am just wondering how to freeze a single frame to take it as my initial frame. Everytime I switch back to the first frame, I lose my keyframe and the cubes are over the cup again.  I guess the answer is pretty easy but I couldn't find it in the manual yet.


It seems the X button on locked comment voting lost's it's X  Grab any locked post, such as  .  Scroll to the comments, and try to upvote any comment. And tada, greeted with a big Ã—


Find Neural Network Inputs Given Outputs

I've trained a neural network with two inputs, a single hidden layer with two neurons, and one output using a bipolar sigmoid activation function. If a single input is known, how would I determine the second input to create a desired output?  For example, let's say the neural network is trained to add two inputs to produce an output. So if input_1 = 3 and input_2 = 4, the output will be 7, (3 + 4 = 7). Given input_1 = 3 and the desired output is 7, I want to calculate the second input required to produce the desired output (the answer should be 4).  How would I do this for a network that is more complicated than basic addition and has multiple inputs/outputs? For example, for a network with four inputs and two outputs, how would I calculate input_3 and input_4 given input_1, input_2, output_1 and output_2?


Is every compact subset of $\Bbb{R}$ the support of some Borel measure?

I have tried to prove the exercise 2.12 in Rudin's RCA:     12 Show that every compact subset of $\Bbb{R}$ is the support of a Borel measure.   For perfect (i.e. no isolated point) compact $K$ with non-zero Lebesgue measure, we just take the Lebesgue measure. However I struck on the general case.  My attempt is as follows: For every compact $K$, we can find a decreasing sequence of open set $\langle W_n\rangle_n$ s.t. $\bigcap_n W_n =K$ and $m(W_n-K)<1/n$. Find a continuous function $h_n$ s.t.   $h_n(x) = 1$ for $x\in K$ and $h_n(x) = 0$ outside of $V_n$.   (such function exists by Urysohn's lemma.) For continuous function $f$ with compact support define $$\Lambda f = \lim_{n\to\infty}\frac{\int_\Bbb{R} fh_ndm}{\int_\Bbb{R} h_ndm}.$$  I can not certain that the $\Lambda$ is well-defined. But if it is well-defined, then it gives an regular Borel measure (by Riesz representation theorem) $\mu$ s.t. $\mu(K)=1$. I guess that the $\mu$ has a support $K$ but I don't know how to get it. Thanks for any help!


Im trying to use -exec to invoke a sed statement below: find '$path' -mtime +$daysold -exec sed -E -f redact.sed file.txt {} \;. what does {} do? and what goes inside {}?


Verify the following combinatorial identity: $\sum_{k=0}^{r} \binom{m}{k}\binom{n}{r-k} = \binom{m+n}{r}$

$$\sum_{k=0}^{r} \binom{m}{k}\binom{n}{r-k} = \binom{m+n}{r}$$  Nice, so I've proven some combinatorial identities before via induction, other more simple ones by committee selection models.... But this one is weird, induction doesn't even seem feasible here without things getting nasty, and the summation on the left is not making things easier. Can anyone help?


Why is the password requirement so strict for Stack Exchange OpenID?

Are the password restrictions really necessary? Are people storing their SSN and Bank Account info on Stack Overflow?


Template function that calls template class function pointers

I have a template function that takes a function pointer from a template class.  However, I am getting an undefined reference.  Here is my header file. template<class T> bool Function(double(T::*func)(),                double(T::*funcderiv)());                class Class { public:     Class();         ~Class() {};          double Func1() { /* does something */ }     double Func2() { /* does something */ } };  Here is my cpp file where I get my compiler undefined reference error. template<class T> bool Function(double(T::*func)(),                double(T::*funcderiv)()) {     /* does something */ }  Class::Class() {     double (Class::*F1)() = &Class::Func1;     double (Class::*F2)() = &Class::Func2;              Function<Class>( F1, F2 ); /* Undefined reference to this function */ }  Thankful for any help.


Why swapping is not working when I am using method to swap two collections

I come across one scenario where swapping is not working when I am using a method to swap two collections.   public static void main(String[] args) {     Stack<Integer> one= new Stack<>();     Stack<Integer> two= new Stack<>();     one.push(1);     one.push(2);     swap(one, two);     two.forEach(System.out::println); }  //swap two stack private static void swap(Stack<Integer> one, Stack<Integer> two) {     Stack<Integer> temp = new Stack<>();     temp = one;     one = two;     two = temp;  }   But When I swap two collections using below code, it does swap two collections.  public static void main(String[] args) {     Stack<Integer> one= new Stack<>();     Stack<Integer> two= new Stack<>();     one.push(1);     one.push(2);     Stack<Integer> temp = new Stack<>();     temp = one;     one = two;     two = temp;     two.forEach(System.out::println); }   I would really appreciate the help. Let me know if you want more clarification.


No reference images of my daughters face for modeling

It may be practical problem of the few beginners, the Problem i am facing is most of the tutorials are using reference images to model face, I also want to model my daughters face but i dont have the reference images like front view, side view, top view, etc also I do not know how to perfectly take photographs of my daughter face to model the same. Can someone shed some light on this problem.. Many thanks


How to prevent the citation in footnote appear not in order?

I use a quite complicated way to make my citation, as I need to use the same citation as a reference in different places in my text.   Now I got the correct way of showing the citation in footnote, but each citation has 2 numbers, and the number of the citation is not in order (the one with squared brackets). It comes out like   1[3], 2[1], 3[4], 4[2]    I want them show as (this problem has been solved with sorting=none)  [1],[2],[3],[4]   And how to remove the number 1 before [1]?  Is that possible to set the referenced citation also as superscript inside the text? In order to keep reference citation work, I keep the script for footpartcite and partcite.  Thank you!  \documentclass[a4paper, 12pt, headsepline,DIV=12,twoside]{report} \usepackage[english]{babel} \usepackage{mathptmx}  \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{parskip} \usepackage{filecontents} \usepackage[backend=bibtex,style=numeric,natbib=true]{biblatex} \usepackage{textcomp} \usepackage{csquotes}  \begin{filecontents}{\jobname.bib} @Electronic{unintentional, Title                    = {Accidents or Unintentional Injuries}, Author                   = {{National Center for Health Statistics}}, URL                      = {http://www.cdc.gov/nchs/fastats/accidental-  injury.htm}, urldate                  = {2016-08-10},} @Book{HP, Title                    = {Harry Potter and the Philosopher's Stone}, Author                   = {{Rowling,J. K. }}, Date                     = {1997}} @Misc{ASH, Title                    = {Automotive Safety Handbook}, Author                   = {{Seiffert, Ulrich; Wech, Lothar}}, Date                     = {2003}, Editor                   = {SAE International}, Note                     = {pp. 91, 96, 97}} @Electronic{CrashStatistic, Title                    = {Annual Global Road Crash Statistics}, Author                   = {{Association for Safe International Road Travel}}, Date                     = {2016-07-16}, Url                      = {https://asirt.org/initiatives/informing-road-users/road-safety-facts/road-crash-statistics}} \end{filecontents}  \usepackage{xcolor}  \usepackage{hyperref} \hypersetup{colorlinks,linkcolor={black},citecolor={blue!50!black}}  \DeclareCiteCommand{\footpartcite}[\mkbibfootnote] {\usebibmacro{prenote}} {\usebibmacro{citeindex}% \mkbibbrackets{\usebibmacro{cite}}% \setunit{\addnbspace} \printnames{labelname}% \setunit{\labelnamepunct} \printfield[citetitle]{title}}% {\addsemicolon\space} {\usebibmacro{postnote}}  \DeclareMultiCiteCommand{\footpartcites}[\mkbibfootnote]{\footpartcite}   {\addsemicolon\space}  \DeclareCiteCommand{\partcite} {\usebibmacro{prenote}} {\usebibmacro{citeindex}% \mkbibbrackets{\usebibmacro{cite}}% \setunit{\addnbspace} \printnames{labelname}% \setunit{\labelnamepunct} \printfield[citetitle]{title}% {\addsemicolon\space} {\usebibmacro{postnote}} \DeclareMultiCiteCommand{\partcites}{\partcite}{\addsemicolon\space}  \addbibresource{\jobname.bib} \begin{document} Each citation has two numbers.\footpartcite{unintentional} And the order of citation is not correct. \ref{ftn:unintentional}  I dont know how to put unsrtnat style inside my preamble, because the system said it´s not existing.\footnote{\label{ftn:unintentional}\partcite{unintentional}}  And I have tried to define natbib separately \ref{ftn:unintentional} But the system says I have already defined it with usepackage {biblatex}\footnote{\label{ftn:HP}\partcite{HP}}  The citation number inside text is not correct,\footpartcite{CrashStatistic} because only 4 citations have been used here \footpartcite{ASH}  Does anyone know how to solve them?\ref{ftn:HP}   \printbibliography \end{document}


The probability that exactly / at-least $k$ numbers are in the correct position

Given a sequence of $[1,\dots,n]$ in random order:   Let $P_k$ be the probability that exactly $k$ numbers are in the correct position Let $Q_k$ be the probability that at least $k$ numbers are in the correct position   How can we calculate $P_k$ and $Q_k$?  These are the facts that I've managed to establish so far:   $P_n=\frac{1}{n!}$ $P_{n-1}=0$ $P_k=Q_k-Q_{k+1}$ $Q_n=P_n$ $Q_{n-1}=Q_n$ $Q_k=\sum\limits_{i=k}^{n}P_i$   Partial answers (for example: $P_0,P_1,Q_1$) or any other insights will also be appreciated...  Thanks


this must be a very stupid question but i came to this site by accident and now i'm somehow interested in this but i dont know how to start or where to play! Is there a online game of this or is this only table top? Because some posts sound like there is an online version. And generally how and where to start playing this game.  Excuse my lack of knowledge and thank you for your help!


What is the time complexity when dividing by 2 until reaching 1?

i=100 while i>=1:   i=i//2   print(i)  What is the time complexity in upper bound for the following code?


SSD seems full, but file system says otherwise

I'm running CentOS and have a 100GB Micron RealSSD P300. It appears that the drive is almost full, as noted by running df:  Filesystem     1K-blocks     Used Available Use% Mounted on /dev/sda3       94753636 86002428   3937948  96% / tmpfs           12298364        0  12298364   0% /dev/shm /dev/sda1         253871    58571    182193  25% /boot   However, running du / tells another story:  6.9M    /bin 56M     /boot 188K    /dev 28M     /etc 3.3M    /home 251M    /lib 25M     /lib64 16K     /lost+found 4.0K    /media 4.0K    /mnt 8.0K    /opt 0       /proc 11M     /root 18M     /sbin 4.0K    /selinux 0       /service 4.0K    /srv 0       /sys 436K    /tmp 1.4G    /usr 1.9G    /var   What could be taking up all of these blocks that I can't see? Could the drive just be broken? I don't have too much experience working with SSDs, so perhaps there's an obvious step I'm missing?


Definite integral $\int_0^92\sqrt x\,\mathrm dx$

I am having trouble trying to solve this definite integral: $$\int_0^92\sqrt x\,\mathrm dx.$$  I already made this:   But I don't know how to proceed with this Riemann Summation. (I cant solve it using FTC, only Riemann Summation).


Ok  so  I've been  trying do  read an image and  resize it to a  specified dimension  and save it  into a  package directory,  everything   goes well  but  the image   still  keeps the same  dimensions as the external file,  and  don't  understand why   this is  my  method.       public boolean guardarImagen() {     boolean imgcreated = false;     MUbicaciones ub = (MUbicaciones) this.getObject();     File imagenFile = ub.getImagen();      //create img  dimensions (supposed to anyways)     BufferedImage bufim = new BufferedImage(300, 300,BufferedImage.TYPE_INT_RGB);     // asignar la imagen al bufim.     try {         bufim = ImageIO.read(imagenFile);     } catch (IOException e1) {         e1.printStackTrace();     }     // obtener las extensiones de los archivos.     String ff = imagenFile.getName();     String formatName = ff.replaceAll("^[\\w]+(\\s)?[^.]", "");     String fileExtension = ff.replaceAll("^[\\w]+.[^A-Za-z]", "");     // nuevo archivo que contiene la ubicacion donde se va a guardar la     // imagen.     newImageFile = new File(this.getDirImagen() + this.getNombreArchivo()             + formatName);           try {         // escribe la copia de la imagen en nuevo directorio.         ImageIO.write(bufim, fileExtension, newImageFile);         imgcreated = true;     } catch (IOException e) {         e.printStackTrace();     }     return imgcreated; }// guardar imagen


I understand the concepts of L1 and L2 loss (i.e. L1 loss will force some parameter coefficients to zero while L2 will only make them approach zero). What do these do when implemented in XGBoost? Does L1 loss prune the tree more significantly than L2 loss?


I am building a large array of Light Switched relays, and due to the size of the array i want to keep the part count down.  Each 'Pixel module' has a 12V SPDT, bulb and an activate-on-dark circuit. There is a strong spotlight on the device and the viewers shadow is obscuring the light in their shadow so the swing is large.  I have seen the obvious LDR-and-Pot circuits with a junction out to a NPN Transistor, and the more stable comparator alternative  I was looking at "solar cell" types of Photodiodes (PiN Type), and I can't see why I cannot just lay one across a PNP transistor (Collector to Base?) or something so it applies a Base voltage when lit up.  Can someone briefly explain to me why I am wrong?  I figure it would be all over the net if it was that easy, and i cant find any examples!  Is this possibly the cheapest way to make a light switched 12V relay driver?  Note: I prefer solutions using discrete circuitry, as I have a thing for human readability, visual components etc :P


What color codes can I use in my PS1 prompt?

I used several colors in my PS1 prompt such as   \033]01;31\] # pink \033]00m\]   # white \033]01;36\] # bold green \033]02;36\] # green \033]01;34\] # blue \033]01;33\] # bold yellow   Where can I find a list of the color codes I can use?  I looked at  but it didn't answer my question about a list of the actual codes.  It would be nice if there was a more readable form also.  See also


How can I move an object on a plane of two axis like XY?

Is it possible to move an object in the 3D View on a plane of two axis like XY, XZ, YZ?


I have a Ruby on Rails app with two sub-sites, www.example.com/site1 and www.example.com/site2. For demonstration purpose, we need to disable site2 and only show site1. So I made some redirects in my apache virtual host conf like this  Redirect 301 http://www.example.com/site2 http://www.example.com/site1 Redirect 301 http://www.example.com http://www.example.com/site1   to be sure to always redirect to site1. Now, it would be great, if we could kinda strip out the site1 from the url http://www.example.com/site1 so that it only shows http://www.example.com, but also can handle sub sites (e.g. the "original" site is http://www.example.com/site1/cat1 and it should be displayed as http://www.example.com/cat1).   Is this possible using apache's rewrite engine? And how? I'm not sure if I have to change something inside my app, or is the request URL (that my router picks up) not modified by apache? Another solution would be, to only show the domain in the users address bar. Is this possible, and how?


Is the function $\frac{\sin{x}}{x}$ continuous at $x=0$?

Here the function is $$f(x) =\frac{\sin{x}}{x}.$$ We see that the right hand limit equals the left hand limit but does $f(0)$ exist?


Where do I put this code to install Absynth 5?

I want to install absynth 5 on my computer. I found this code, here it is.   #!/bin/bash # Date : (2013-02-01) # Last revision : (2013-02-01) # Distribution used to test : Kubuntu 12.04 LTS # Author : DJYoshaBYD # Licence : GPLv3 # PlayOnLinux: 4.1.9  # CHANGELOG # [SuperPlumus] (2013-06-17 19-35) #   Update gettext message   [ "$PLAYONLINUX" = "" ] && exit 0 source "$PLAYONLINUX/lib/sources"  PREFIX="Absynth5" WINEVERSION="1.3.0" TITLE="Absynth 5" EDITOR="Native Instruments" GAME_URL="http://www.native-instruments.com" AUTHOR="DJYoshaBYD"  #Initialization POL_GetSetupImages "http://files.playonlinux.com/resources/setups/$PREFIX/top.jpg" "http://files.playonlinux.com/resources/setups/$PREFIX/left.jpg" "$TITLE" POL_SetupWindow_Init  POL_Debug_Init  # Presentation POL_SetupWindow_presentation "$TITLE" "$EDITOR" "$GAME_URL" "$AUTHOR" "$PREFIX"  # Create Prefix POL_SetupWindow_browse "$(eval_gettext 'Please select the setup file to run')" "$TITLE" POL_System_SetArch "x86" POL_Wine_SelectPrefix "$PREFIX" POL_Wine_PrefixCreate "$WINEVERSION"  #Dependencies  # Configuration Set_OS "winxp" Set_SoundDriver "alsa"  # Installation POL_Wine_WaitBefore "$TITLE" GC_DONT_GC=1 POL_Wine "$APP_ANSWER" POL_Wine_WaitExit "$TITLE"  # Create Shortcuts POL_Shortcut "Absynth\ 5.exe" "$TITLE"  POL_SetupWindow_message "$(eval_gettext 'NOTICE: For low-latency audio, look into WineASIO.')" "$TITLE"  POL_SetupWindow_Close exit 0   But I think it is supposed to go somewhere other than the Terminal because in the terminal after typing #!/bin/bash I still get a $ sign. Thank you in advance for all of your help.


If $\gcd(a,b) = 1$ and $a \mid c, b \mid c$, then $ab \mid c$

For integers $a,b$ that are relatively prime to one another, we have $a \mid t$ and $b \mid t$. It should follow that $ab \mid t$, but I cannot manage to prove this. Here is as far as I was able to get.  If $a \mid t$ and $b \mid t$, there exist integers $\beta, \alpha$ such that $$a \beta = t, \; b\alpha = t.$$ Hence, $$(a\beta)(b\alpha) = (ab)(\beta \alpha )=t^2,$$ so $ab \mid t^2$.  Why, though, does $ab$ divide $t^2$? Further, how do I even know that $ab \leq t$? Another idea was to use Bezouts identity and assert the existence of integers $x$ and $y$ such that $$ax + by = 1.$$ Multiply through by $\beta \alpha$ and reassociate: $$(a\beta)(x\alpha) = (b\alpha)(y\beta) = \alpha \beta,$$ but this doesn't appear to help me.


Prove trigonometry identity for $\cos A+\cos B+\cos C$

I humbly ask for help in the following problem.  If  \begin{equation} A+B+C=180 \end{equation} Then prove \begin{equation} \cos A+\cos B+\cos C=1+4\sin(A/2)\sin(B/2)\sin(C/2) \end{equation} How would I begin the problem I mean I think $\cos C $ can be $\cos(180-A+B)$. But I am unsure what to do next.


Did Harry Potter lose Voldemort's powers when he lost his connection to Voldemort?

Harry noted to Dumbledore that he had a number of things in common with Voldemort. And it was later revealed that some of Voldemort's power was transferred to Harry when Voldemort tried to kill him. So, what powers did Harry get from Voldemort (i.e. Parseltongue and others) and did they all leave him when he stopped being a horcrux?    Update In the Chamber of Secrets Dumbledore states that Harry has many qualities that Salazar Slytherin values in his hand picked students. Parseltongue - resourcefulness - determination - a certain disregard for rules.    So, does anyone know what specific powers Harry got from Voldemort and is there anyway to tell if he lost anything else besides Parseltongue?


Someone Activated My Playstation as Their Primary

i contact sony and they say that they do nothing for me ! and i must wait 6 months to deactive all consoles that connect to my psn account. after 6 month the other console that using my account will be baned or just dissconnect from my psn account ? if he will be baned witch ban ? (Console or his psn account)


Trusting p-values when errors are not normally distributed

Suppose I have a multiple linear regression model and the errors are not distributed normally.Does the central limit theorem hold true in this case? should i trust the p values of the coefficients of variables assuming the residuals are not skewed?  Will really appreciate any help on this, thank you :)


Can I roll over a 401(k) with my current employer into an IRA?

My wife has a 401(k) with her employer that she has been contributing to for years.  They recently switched administrators for the 401k, and the new outfit is simply terrible - bad fund choices and outrageous fees.  I would like to roll over her 401(k) into an IRA where I can manage the investment choices myself.  I know we can do that if she were to quit her job, but can we do it while she is still employed there?


I understand how to use the C++11 delete keyword to create classes that can't be copied or moved, but in Bjarne Stroustrup's The C++ Programming Language 4th edition, in section 3.3.4 Suppressing Operations, it says (emphasis mine):     Using the default copy or move for a class in a hierarchy is typically   a disaster: given only a pointer to a base, we simply don't know what   members the derived class has, so we can't know how to copy them.   Could anyone please provide a small example of this? Shouldn't the copy/move already be implemented if we are working with a pointer only to a base class?  Edit:   After I read the link provided by Igor Tandetmik, I found  (look at the "treacherous case") which gives a very clear answer to my question, on a different question about Object Slicing.


Help centre refers to review queues, a privilege, and a link that do not exist

The help centre for MSO states (on this page: ):     "The first queues you gain access to are Late Answers and First Posts. These and all other review queues are accessible from the "review" link that appears at the top of every page next to your user name."   At the top of this and most pages next to my user name I see only rep, badge count, "chat", "main", "about", "help", and a search bar, so to me that quote just looks wrong (and not very helpful).  I originally wrote up a question asking about how to get access to those review queues, and why I could not find the link, since I spent so long looking for them, but I was able to get to a page with list of 4 other review queues (through a link in the help centre), and I imagined there is only one review queue list page, so something strange must be going on.  Finally, before posting that question I came across a question () with critical information I did not see anywhere else in my hunt for the link and for the review cues I supposedly now had access to:     Here on Meta, for example, we 'only' have 4 of the queues, low   quality, suggested edits, reopen and close.   If this is true, it makes sense that I would not see a review link (as I do not have enough rep for any of the review queues that do exist), but can we please change the Meta help centre so that it stops referring to   queues that do not exist a privilege that does not exist a link that does not exist   ?  A lot of confusion could be avoided if the related privilege were removed from the list (and its help page were removed as well).    Update:  I see some of the reasons given for the current unfortunate set-up on another question ():   MSO has a "master privilege list" for all sites, so it can't be changed. MSO users with at least 500 rep do technically have access to the first posts and late answers queue...it's just that it does not exist.   "1." is apparently not true, as WendiKidd points out in the comments there.  Privilege lists are changed in new SE sites to allow for lower rep thresholds.  "2." is just very unintuitive (and cost me and potentially others much time sussing out the answer to how it all works).  If we still don't want to or can't fix things as I suggest above, though, I suggest we:   Start showing the "review" link on MSO starting at 500 rep regardless (as long as the help centre is saying it is there). On the review queue page, show placeholder messages for review queues that do not exist mentioning that they do not exist (so people do not think they are on a separate page somewhere).


Is a field with cyclic multiplicative group necessarily finite?

It is a standard result that finite fields have cyclic multiplicative groups (the nonzero elements with respect to field multiplication).  A recent discussion on  leads me to ask about the converse:     Is a field $F$ whose multiplicative group $F^*$ is cyclic necessarily finite?   Clearly the biggest a cyclic group can be is countable, and thus $F$ would also be at most countable.


Which one is grammatically correct?      She is the most talented teacher THAT I've ever known.    or      She is the most talented teacher I've ever known.


Which hardware should I concentrate on, when assembling a head node for an HPC cluster? The main task for the head node is to relay instructions to the compute nodes which will be running artificial intelligence algorithms.  Ubuntu 14.04 LTS will be running on the head node.  I would assume it should have a high bandwidth NIC such as the infiniband 50 Gbps card, but I'm relatively inexperienced in this area.  Thank you


Correct place of apostrophe: friend's or friends'

A quick Google search (actually I use Duckduckgo but "a quick Duck or DDG search" would sound weird...) showed that "friend's" was a bit more common, whereas a Google user manual or tutorial used "friends' " and I (maybe biasly) assume them to use (more) correct grammar. The sentence used in the Google user manual was: "See friends' locations on a map"  (see this link )


Is it possible to install Ubuntu on a Microsoft Surface (RT)?

I want to know if it's possible to install Ubuntu on a Microsoft Surface tablet (with Windows RT).  Please help me. I want to know because you can't install any desktop apps on it.


Gravity doesn't seem to work the way it is supposed to

This has been a bit of an awkward question that's been plaguing me ever since I started watching space documentaries on discovery about 10 years ago. I was saving this for the day I would ever meet Professor Brian Cox where I can point and say "HA!" see you can't explain that one (he probably can and so could someone here).  It's a simple question: when you get on a merry-go-round or something that rotates fast, then the force pushes you outward, but when they talk about things in space that rotate they refer to the force that pulls them inwards.  So which is it. If I spun something like a big beach ball really really fast then I'd still be thrown off it. If I took that into space should that suddenly keep me glued to it?  I apologise for my ignorance but I've never had this explained to me.


Edit a question (from other user) and get +2 rep?

There was  Question on SO this morning (GMT Time). I made an edit (I don't have enough rep to do it without peer review) and the changes I commited were    Change the Title Fix code Indent   After this happened, my changes were accepted, and I +1-ed the question and put it as a favorite.   Within 1 minute I got +2 reputation, I have done peer-review-ed editing at least twice before but nothing like that happened.   Is this a bug on the system or is it standard behaviour? Is there any link we can find the detailed behaviour of how the edit-system works? Do all edits (either peer-reviewed or not) give you some reputation ?  Thanks for your time. I hope question is inline with the rules.