The requirement is like this. Now I have a Dictionary.  Dictionary<int,string> dic = new Dictionary<int,string>(); //... some other operations Type t = typeof(Dictionary<int,string>);   Now I want to get the type int and string. How can I get the two? Thank you very much.  Update:  Thank you for the response. Actually my requirement is to create another generic class based on the two types, which were got from the dictionary type. Just like this.  PropertyType propertyType = typeof(Dictionary<int,string>); if (propertyType.Name.Contains("Dictionary")) {     Type keyType = propertyType.GetGenericArguments()[0];     Type valueType = propertyType.GetGenericArguments()[1];     propertyType = typeof(SerializableDictionary<keyType, valueType>); } //And after this, it will dynamically create a class and add the propery as one //of its properties   Now I cannot use propertyType = typeof(SerializableDictionary<keyType, valueType>). How should I update this statement? Thank you.


I started using Ubuntu on windows 10 and I've noticed that the default path /home/<user_created_during_installation> is located in   C:\Users\User\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\home\<user>   My question is, can I change that path (and if so, how?) or do I have to work on that path while I use Ubuntu on Windows?  Thanks in advance


Why is 1 divided by aleph null undefined?

So recently I have been thinking about infinity, and one of the things that I thought of was if you were able to get a defined value for the reciprocal of a transfinite (cardinal) number. So, I plugged $\frac{1}{א_0}$ into WolframAlpha and it said the following: Why is this the case? Shouldn't this be similar to this case? $$\lim_{x\to\infty} \frac{1}{x} =0$$ Aren't $\infty$ and $א_0$ equal to the same value in this context? What am I missing here?


How is it possible to have linux config files and normal files as mountpoints

In my current project, seeing mount command output showing files as mountpoints mounted on tmpfs. tmpfs on /etc/hostname type tmpfs (rw,relatime,size=52724k) tmpfs on /etc/hosts type tmpfs (rw,relatime,size=52724k) tmpfs on /etc/passwd type tmpfs (rw,relatime,size=52724k) tmpfs on /etc/ntp.conf type tmpfs (rw,relatime,size=52724k) tmpfs on /etc/resolv.conf type tmpfs (rw,relatime,size=52724k)  By manpage description, mount takes only directory as mountpoints. I tried to mount the file as done in above way but its not working for me. root@raspberrypi:/home# file /tmp/agner /tmp/agner: ASCII text  root@raspberrypi:/home# mount -t tmpfs tmpfs /tmp/agner mount: mount point /tmp/agner is not a directory  Bind mounts syntax:  mount --bind olddir newdir  mount --rbind olddir newdir  '/tmp' directory is already mounted into tmpfs. tmpfs on /tmp type tmpfs (rw)  I attempted below combinations but getting 'fs' not exist error. root@raspberrypi:/home# mount --rbind tmpfs /tmp/agner mount: special device tmpfs does not exist root@raspberrypi:/home# mount --bind tmpfs /tmp/agner mount: special device tmpfs does not exist root@raspberrypi:/home# mount --bind /tmp/ /tmp/agner mount: mount point /tmp/agner is not a directory  When specifying '-t tmpfs' filesystem option in addition, then mount manpage is showing up. root@raspberrypi:/home# mount -t tmpfs --bind tmpfs /tmp/agner  So what option in mount command is required to achieve this.


Discoveryd Alternative to Replace mDNSResponder Argument?

This is a direct follow-on to . , I'd add the "-AlwaysAppendSearchDomains" argument to the mDNSResponder plist file so that all local resolver lookups added the search domains, regardless of whether there was a period in the label to be looked up. For example, whether I try to ssh to hostname foo.bar or foo, the search domain of baz.com should be tried, not only for the latter case, as was (and is) the default behavior.   Now, it looks like the mDNSResponder is gone, replaced with discoveryd. I cannot find a similar option to get it to always appending the search domain. Suggestions? I'd rather not go the route of using a non-default local resolver, but I'd consider it as an option. For now, I'll just type in the long FQDNs, but I'd really rather not.  Thanks, Pete


Can the 90/180 Schengen Visa for a US Citizen be staggered?

I stayed for two months from March 10th to April 27 (almost 2 months). Would the remaining month I didn't use still be available for me if I were to return in July?


How to format an external 64GB SD card (exfat) using command line?

I have an microSD card with 64GB capacity which has exFAT file system. If I insert it to my card reader, it is mounted automatically. But I am looking for a command to format the card. I installed exfat-fuse and exfat-utils, but could not find proper command to format my microSD card.


Java Buffered Reader string comparison gives wrong output

This is my Java code to read text from a text file  import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException;  public class checking { public static void main(String[] args) throws IOException {  // Create a BufferedReader from a FileReader. BufferedReader reader = new BufferedReader(new FileReader("pw.txt"));  // Loop over lines in the file and print them. while (true) {     String line = reader.readLine();     if (line == null) {     break;     }      System.out.println(line); // The output is abc     if(line=="abc"){         System.out.println("true");     } else {         System.out.println("false"); //However it show false...     } }  // Close the BufferedReader. reader.close(); } }   Inside pw.txt, there is only one line which the only text in there was abc.  I did an if statement to check if the line is equal to "abc" however the output was false... which I don't quite understand. Did I made any stupid mistakes?


USB locked: how do I reinitialize layout of the whole device

I installed Ubuntu 16.04 onto a USB stick. I installed Ubuntu onto my laptop. When I try to format the USB stick, I get this error message:  This partition cannot be modified because it contains a partition table; please reinitialize layout of the whole device. (udisks-error-quark, 11)   How do I fix this, so my USB stick is usable again.


"Jump to case label" error when using vectors inside switch statement.

This is the code, where I get several errors, when I add the other case or a deafult. I can't find any basic error like a missing semicolon or so, and the code works properly when I have only one case. I searched trough switch tutorials, but I didn't find anything about vectors and switch statements mixed is a problem.     int main() { int r;  while (cin >> r) {     switch (r)      {        case 3:     int y = 0;     cout << "Please enter some numbers, and I will put them in order." << endl;      vector<int> nums;     int x;     while(cin >> x)     {         nums.push_back(x);         y++;     }     sort(nums.begin(), nums.end());     int z = 0;     while(z < y)     {         cout << nums[z] << ", ";         z++;         if(z > 23)             cout << "\n" << "User... What r u doin... User... STAHP!" << endl;     }     cout << "\n" << "You entered "<< nums.size() << " numbers." << endl;     cout << "Here you go!" << endl;     break;      //In the following line I get the "jump to case label" error.      //I use Dev C++ software.         case 4:     cout << "it works!!!" << endl;     break;      } } system ("PAUSE"); return 0; }   What am I missing?


There are many red and black spots in my photos,what are those?

I am using canon 60d for more than 1year.few months ago i suddenly saw these dots were appeared in my photos.i have tried manual sensor cleaning several number of times,but this didn't work for me.what do i need to do to get rid of this problem? A photo of the camera screen is given below....


mid-level quality stock photography - adobe Stock vs iStock... or anyone else worth mentioning

I'm about to go on a search for a dozen or so stock photos representing our target audience and user-base (for a high-tech, B2B SaaS product). these will be used in marketing collateral as well as emails/landing-pages and other web pages. Our brand has not historically used a lot of photography so the few times we've need photos, we've gone to ShutterStock. I started my search there and while they have a vast selection and they are fairly inexpensive, a lot of their images are a bit too generic for our tastes...  after not too long they start looking like the horrible, happy-techy-people-working-in-offices that were so horribly, horribly overused (imo) back in the late 90s/early 2000s. I'd like to step the quality up a little bit... find something a decent set resembling more of a "portrait" (with evocative qualities) than a cheap stock photo (even that's what it is). Looking quickly, both Adobe Stock and iStock seem like they're closer to the quality I'm in search of. For purposes of uniqueness and again, that evocative quality, does anyone recommend 1 over the other... or perhaps have another in their price range to suggest?


Titles can have [on hold] in them, if the space used is non-breakable one. [on hold]

I discovered it by accident .  I guess I'm not the only one who fixed non-breakable unicode space U+00A0 to something like Alt+Space. So it's pretty easy to circumvent your prevention without even really trying. After all, non-breakable space simply makes sense there.  I think the solution is to:   Only test at the end of the title (only white characters and small misleading ones after [on hold] should allow the test to return positive and block posting) - this will allow discussions on meta to have it spelled properly (see linked question). Forbid all and every white characters and 0-width characters between [on and hold] - this would be a real fix.


How do I turn a String structured as an Array into a type Array?

I have a type String that looks like '["123", 123, "testing"]'.  How do I change that String into type Array?


How to export data as CSV format from SQL Server using sqlcmd?

I can quite easily dump data into a text file such as:  sqlcmd -S myServer -d myDB -E -Q "select col1, col2, col3 from SomeTable"       -o "MyData.txt"   However, I have looked at the help files for SQLCMD but have not seen an option specifically for CSV.   Is there a way to dump data from a table into a CSV text file using SQLCMD?


How to typeset subscript in usual text mode?

It's easy to make subscripts in math mode: $a_i$.   How do I make a subscript outside math environment, likethis?


Case insensitive Contains in LINQ without making ToLower or ToUpper

I'm trying to get the customers which Company contains currentSearchViewValue.I want the LINQ to be case insensitive. I write the following:  string currentSearchViewValue = searchView.Query; var currentCustomersSearched = customers.Where(x => x.Company.Contains(currentSearchViewValue, StringComparer.InvariantCultureIgnoreCase)).ToList();   When I build it says that Contains has no overloads that take 2 arguments. I've seen a lot of examples on internet and they are very long or don't work. Is there a way to do what I want in one line?


My Windows folder takes up too much space - how can I reduce it?

In typical PCs the Size of Windows Folder is 6 to 8 GB but in my Case its 25GB. How can I delete the unwanted files from the Windows Folder (which, in turn, will optimize my C Drive size).  My system is Windows 7 with 60 GB in C Drive with 59 GB occupied.


I am trying to compare the text of a button to decide on the course of action to take in this Android app I am making. I am getting some unexpected behavior that I do not understand.    clickMeButton.setOnClickListener(new View.OnClickListener() {         public void onClick(View v) {             if (v.getId() == R.id.btnLeft) {                 Button button = (Button) v;                 String click = new String("Click me");                 String look = new String(button.getText().toString());                 Boolean check = new Boolean(look == click);                 if (button.getText().toString() == "Click me") {   Variable check is returning false. Why? In debugger, both items have "Click me" listed next to them. The button I click in the emulator says "Click me" and its original text, "Click me" is specified by the xml.


Let's leave the memory issue for a moment, aside.  If I have two 64-cores AMD EPYC processors each, how many virtual machines (servers) can I run at the same time? Is that right that I can run 64 VMs at the same time? (assuming that each vm need 2 logic processors). My question was raised during reading the following article:


Who is Azor Azhai? Was Melisandre's entire life a lie? Throughout the show she has put forward:   Stannis Baratheon Daenerys Targaryen Jon Snow   But      Arya Stark ends up to be the one to end the Night King. Clearly she thinks that her purpose is over because she died after the battle, so the Night King isn't coming back anytime soon.    Who is the Prince who was Promised in light of the      NK's death?


I have a set of lines that were created as lines between point pairs. Now I need to know, which points the lines connect. I thus want to join the Ids of both points to the line.   So far I tried to use spatial join, but one ID is always right, while the other ID is always wrong. The lines were created from the points, so they mark the vertices of the lines. In the end I want to have a single ID, derived from both IDs. For this question I only need to know how to get 2 columns in the line table with the IDs from the vertice points.      How can I (spatial) join two points to one line?     I am using ArcGIS 10.3 on Windows 7.


Discrepancy between calculated and simulated error propagation

Just curious if anyone knows why there is a tiny but definite difference between the standard deviation as calculated by the error propagation formula and the simulation. It is only a 0.2% difference and doesn't cause me any problems personally but I am curious which of the two would be considered more accurate?  Adding another zero to the rnorm function causes my computer to crash. But I repeated this code 10 times or so (very small variance)  and I am confident that the mean is in fact 0.2% higher than it should be.  # This takes about 6 seconds to run x <- rnorm(10000000,mean = 100, sd = 10) y <- rnorm(10000000,mean = 100, sd = 10) z <- x*y # SD of x*y using simulation sd(z) # SD  of x*y using formula (((10/100)^2+(10/100)^2)^.5)*(100*100)


Proof of contracting Christoffel Symbol Identity

I figured out the following:   $${\displaystyle \Gamma ^{i}{}_{ki}={\frac {1}{2}}g^{im}{\frac {\partial g_{im}}{\partial x^{k}}}={\frac {1}{2g}}{\frac {\partial g}{\partial x^{k}}}={\frac {\partial \log {\sqrt {|g|}}}{\partial x^{k}}}.}$$  However I can't figure out how to show the following identity:  $$g^{k\ell }\Gamma ^{i}{}_{k\ell }={\frac {-1}{\sqrt {|g|}}}\;{\frac {\partial \left({\sqrt {|g|}}\,g^{ik}\right)}{\partial x^{k}}}.$$  I plugged in the equation for the Christoffel Symbol but it didn't get me where I wanted. Can anybody offer clarity?


`\ifhtlatex` needed for running tex4ht with different code

It is much easier to write my texts in an editor with LaTeX, but often clients ask for a word file.   tex4ht does a good job, it produces html from a tex-file, which can be easily used. But there are some packages which cause errors, e.g. the §-sign of Linux Libertine. Is it possible to have a command which makes pdflatex have a look whether it is run by htlatex?  I'd like to write something like   \ifhtlatex \usepackage{lmodern} \else  \usepackage{libertine} \fi   There are more things that don't work with htlatex, e.g. the machinery to name and count exhibitions and to produce a list of them at documents end. So something like \ifhtlatex would be helpfull.  ==========  I dont't want to load the tex4ht package itself, so I've no idea, how this  could be helpfull...


expression for "the small letters" of the contract, as in the nuances and discalimers that will bite you?

Looking for an equivalent of the Hebrew expression "the small letters of the contract" - as in the small disclaimers / minutia / nuances of the contract that if you won't put on glasses and read will bite you afterwards? e.g. "what? you didn't read the small letters of your live organ donation certificate?!"


Make a document look like it's been redacted by the CIA?

I've produced notes collections for physics courses that I've taken that include problem set solutions.  Two Professors have said they are worried future students will use my notes to cheat (i.e. it's a lot of work to produce new problem sets).  I'm toying with the idea of making the default version for the notes of a couple of these classes a redacted version, with the full version available on request.  I've used a macro around the .tex contents that uses a boolean flag to expand to nothing when a redacted flag is true.  However, I thought there could be a more fun way of doing the same problem.  Is it feasible to make it look like large portions of text (and formulas, and perhaps images) have been gone over by the big black marker of an over-zealous CIA redaction officer, faced with the impossible task of obscuring how much they've spent financing terrorism and government coups around the world?   Here's an example with about 1/3 redaction:    If something could be done like this, with random content redacted in black up to some threshold, that would be a pretty fun way of obscuring the problem set solutions.


When constructing $\mathbb{Q}$ as equivalence classes containing pairs of integers, a natural inclusion of $\mathbb{Z}$ in $\mathbb{Q}$ arises:  $$f: \mathbb{Z} \to \mathbb{Q}, \; n \to \frac{n}{1}. $$ This mapping is not surjective, but it is injective, and the function is well-defined. My question is: is injectivity required for us to conclude that $\mathbb{Z} \subset \mathbb{Q}$?   It seems to me that this isn't the case. I could assign two distinct integers to the same rational, and $\mathbb{Z}$ would still be embedded in $\mathbb{Q}$. I could assign every $n \in \mathbb{Z}$ to the rational $\frac{0}{1}$ and still prove the result.   Is this correct?   As a side question, when we talk about an inclusion map, must I map $\mathbb{Z}$ to $\mathbb{Q}$ or could I instead map $\mathbb{Q}$ to $\mathbb{Z}$ by the rule $\frac{n}{1} \to n$? In this case, perhaps it wouldn't work because the function would not be well-defined for all $\mathbb{Q}$. I'm interested in particular on how we defined an inclusion map.


My model is see-through with black lines

I'm pretty new to blender, so i apologize if this question is a little dumb, i was following a blender tutorial but i accidentally pressed a key and i don't know which one i pressed, and now my model is sort of see through, here's the picture


I'm interested in why dependent observations are a problem in statistics. Let's say you want to know if there is a difference in mean exam scores between two schools. You collect 50 observations in each school. These 50 observations are derived from 5 different classrooms in each school and there is dependence within classrooms. In this instance, how would the results of the t-test be affected and how might they lead to inaccurate conclusions?


I am trying to create form by putting form requirement and it's not working

I have an in input required. As I am using input type="submit" it is working fine but I am using input type button. When I used input type button the input requirement doesn't work. Please help When I used the code below with type submit the required is working <script> function validateForm() {   var x = document.forms["myForm"]["fname"].value;   if (x == "") {     alert("Name must be filled out");     return false;   } } </script>  <form name="add_name" id="add_name">   Name: <input type="text" name="fname" required>   <input type="submit" value="Submit"> </form>  But my form is as below. I am using input type button and the requirement is not working. How to solve it please. <form name="add_name" id="add_name"> Name: <input type="text" name="fname" required> <input type="button" value="Submit"> </form>


elementwise division of two columns loaded from different files

My next question follows on  where I asked how to sum up the data from different files.   In this case I have e.g. two data files, consisting of m (here e.g. m=3) columns and a fixed number of rows n (here e.g. n=3), seperated by a semicolon (see minimal example):  What I want to plot in a tikzpicture is an elementwise division, e.g  Yvalues(1)=D1(1,2)/D2(1,3) Yvalues(2)=D1(2,2)/D2(2,3) Yvalues(3)=D1(3,2)/D2(3,3) ... for all n rows   The Xvalues shoud be the first column of one of the two loaded files (they are the same).  Maybe someone can use the defined makro 'mergetables' from the link above. Maybe the document could look something like this:  \documentclass{article} \usepackage{pgfplots, pgfplotstable} \usepackage{filecontents}  \begin{filecontents}{D1.txt} 0.1;10;10 0.2;20;12 0.3;30;14 \end{filecontents}  \begin{filecontents}{D2.txt} 0.1;3;5 0.2;3.5;10 0.3;4;15 \end{filecontents}  \begin{document}  \begin{tikzpicture} \begin{axis}     \addplot [Xvalues=first column of any file (D1 or D2),               Yvalues= e.g. 2nd column of file D1 devided by 3rd column of file D2] \end{axis}  \end{tikzpicture}  \end{document}   edit:  My problem is to access to the single columns of each loaded file. In my oppinion the new command, lets call it again \mergetables, should look something like:  \mergetables{D1}{0,1}{D2}{2}..{Di}{col1,col2}{\datatable}   This command should create a new table \datatable with the first column D1(0), the second column D1(1) and the third column D2(2) seperated by a semicolon. Maybe each column of the new \datatable should have a columnname X,Y1,Y2,... so when I want to plot them I can call them using their columnames like:  \addplot table [x=X, y expr={Y1./Y2}] {\datatable};


Prove identity $\sum_{k}{n\brack k}{k\brace m}=\binom{n}{m}\frac{(n-1)!}{(m-1)!}$

I'm looking for a proof of this identity: $$ \sum_{k}{n\brack k}{k\brace m}=\binom{n}{m}\frac{(n-1)!}{(m-1)!} $$ I'm looking especially for a combinatorial proof (if such exists), but different method still will be fine.


What is the difference between a Summit and an Apex?

Summit, Peak, and Apex are often interchanged. What is the difference between Summit vs Apex or Peak vs Summit


Can’t remove grayed out app icons on iPad 4

iPad 4 operating on iOS 10.3.3 has multiple grayed out icons that have “waiting...” under them. Have waited hours, no change. Did hard reboot, with and without WiFi, no change. Looking for suggestions on how to remove them.  Also, the App Store icon is missing. How do I restore it. Thanks.


$2 \times 3 = 5+1$ and $2+3 = 5 \times 1$. When else can we switch the operators like this?

I noticed the following: $$2 \times 3 = 5+1$$ If you switch the operators, it is still true: $$2+3 = 5 \times 1$$ There is another obvious/trivial example where you can swap the operators: $$2\times 2 = 2+2$$ I think these are the only solutions (for positive integers). Can anyone give an elegant proof?


Let $A$ be a finite set. Prove or disprove: the number of subsets of $A$ whose size is even is equal to the number of subsets of $A$ whose size is odd.   Example: $A = {1,2}$. The subsets of $A$ are {},{1},{2}, and {1,2}.  Since there are two subsets of odd size ({1} and {2}) and two subsets of even size ({} and {1,2}) the claim holds for this particular example.


Can a Paladin take levels of other classes?

In 3.5 D&D,  have severe restrictions on multiclassing:     Like a member of any other class, a paladin may be a multiclass character, but multiclass paladins face a special restriction. A paladin who gains a level in any class other than paladin may never again raise her paladin level, though she retains all her paladin abilities.   Because Pathfinder is based on 3.5 D&D, do Pathfinder paladins face the same restriction? That is, if a Paladin multiclasses to say, a fighter, can she take another level of Paladin later on?


Why do we need a Stack Overflow in Portuguese?

I have noticed there is a Stack Overflow in language differs from English which is global and mostly used by programmers.  I think there is no need for a site in other languages. Otherwise we will end up with 127 StackOverflow sites. I am afraid that we will lose the amount of people sharing data.


What is the equaton for ARIMAX(1,1,1) and how can I undifference the 1st differenced data to fit the equation?

I have generated the ARIMAX(1,1,1) model to predict the future Barramundi catch. In this model, there are two exogenous variables (price and streamflow) that affect Barramundi catch. I have used 1st differenced data to run this model as the data was not stationary at level. Could you please help me out to identify the equation for it and how can I use this equation for the future prediction of catch especially for the undifferenced data? Here, I have attached an excel file of my data.


Can we find positive integers $a$ and $k \geq 2$ with $2^n - 1 = a^k$?

I would appreciate if somebody could help me with the following problem:      For a given positive integer $n$, can we find positive integers $a$ and $k$ ($k\geq 2$) such that $2^n-1=a^k$?    The answer would be no, I  guess.  Please give me some ideas!


I have this values with DNS entries (The point at the end must be there): DOMAIN="_my-smtp.sub.domain.com." DOMAIN="_my-smtp.sub.domain.co.uk." DOMAIN="_my-smtp.sub.domain.eu."  Now I need two values. One is the subdomain and the other is just the domain Subdomain: sub.domain.com sub.domain.co.uk sub.domain.eu  Domain domain.com domain.co.uk domain.eu  For the subdomain I tried what works. SUB_DOMAIN=`echo $DOMAIN| perl -p0 -e 's|^_my-smtp\.||g' | perl -p0 -e 's|\.$||g'`  But there are many different domain endings (TLDs), sometimes with two (co.uk) TLDs and sometimes with one (com). How could I solve this?


Would a group of molecules in a container, settle down after a long time? (considering that no gravity acts on them)

Because, every time they collide, don't they emit radiation? As in, losing energy in the form of this radiation, So eventually, won't they lose all of their kinetic energy? Of course the time taken might be very long


The covariance of a gaussian random variable and another one in its variance linear combination

Assume $y$ is a Gaussian random variable with $\text{Var}(y)= \sigma_y^2=\sum_i a_i^2\sigma_i^2$, where $\sigma_i$ corresponds to $x_i$, all $x_i$ are independent. $\mu_y = \sum a_i\mu_i$. I want to derive a formula for $\text{Cov}(y,x_i)$. I have tried the following: $\text{Cov}(y,x_i) = \mathbb{E}[x_iy] - \mathbb{E}[x_i]\mathbb{E}[y]$. The last term is trivial to get. $\mathbb{E}[x_iy] \approx \mathbb{E}_z[\int \exp[-.5 (((x - \mu_i)^2)/\sigma_i ^2 + ((z/x - \mu_y)^2)/\sigma_y^2 )]/|x| dx]$, which is untractable I am afraind. So, I am wondering if there is a way to tackle this problem?


I use some russian text in my file and when I compile it to pdf text becomes diffuse and transparent. How can I fix it? (To compile source file I use latex + dvipdfm, MikTex version 2.9)  This is my code:  \documentclass[12pt]{article}  \usepackage[russian,english]{babel}  \usepackage[landscape, left=0.7cm, right=0cm, top=1.5cm, bottom=0.4cm]{geometry}  \usepackage{fancyhdr} \pagestyle{fancy} \fancyhf{} \fancyhead[L]{Left} \fancyhead[R]{Right} \fancyheadoffset{-0.5cm}  \begin{document} \selectlanguage{russian}  Hello world!  Привет мир!  \end{document}


Is $\exists x \in A ~:~ P(x)$ the same as $\exists x ~:~ x \in A \implies P(x)$

If we wish to convert a statement of the form $\exists x \in A ~:~ P(x)$ into the form of an implication, would the correct conversion be  $$\exists x ~:~ x \in A \implies P(x)$$  Thanks


Celebrities database with multiple parent categories and children categories?

I am creating a React/Laravel web application that will allow the user to search and navigate through celebrities based on their 'categories'. I have set up a Categories table using MySQL like so:  *CATEGORIES_TABLE* id      name                   parent_category_ids     children_category_ids 1       Music                  0                       23,24,25,26,27,28,29,30,31... 2       Sport                  0                       45,46,47,48,49,50,51...  ... continued ...  23      Pop Music               1                       120,121..  ... continued ...  45      Soccer                  2                       180,181...  ... continued ...  180     Club Teams              45,2...                  250,251,252... 181     International Teams     45,2...                  301,302,303...  ... continued ...  250     Real Madrid FC          180,45,2                 1045,1046,1047,1048,1049,1050... 251     Barcelona FC            180,45,2                 1080,1082,1083,1084,1085,1086..     *CELEBRITIES_TABLE* id      name                   category_ids 1       Justin Bieber          1,17,18... 2       Christiano Ronaldo     2,24,32,34...   As you can see, categories can have multiple parents and multiple children, and celebrities can have multiple categories.  My issue is that I'm not that experienced in Database Design so I'm not sure if this will work. I am worried that this setup will be hard to maintain and it won't be efficient at inserting/deleting new categories and celebrities etc.  Any thoughts on this would be much appreciated, I don't want to get stuck into it for it to not work, thank you!


How was the Chosen One meant to bring balance to the Force?

The legend of the Chosen One foretold the coming of a being who would restore balance to the Force.  Now we know that Anakin Skywalker was the Chosen One, but how exactly was he supposed to restore balance?  Is a balance to the Force:   eliminating all Dark Side users so that only the Light Side remains?   reducing the Dark Side's influence to almost nothing, but still leaving some Dark Side users so that there is a balance of energies? (End of Episode VI, there are still Dark Side users in Legends) creating an equal presence on both sides? (for example, at the end of Episode III it appears that there are two Sith [Sidious and Vader] and two Jedi [Yoda and Obi-Wan]) Any other way not mentioned above?   And whichever the legend means, has the prophecy been completed? Has the Chosen One restored balance to the Force at one point, or did he fail to fulfill the prophecy?  So in short, What is the meaning of 'balance' when it is said that "The Chosen One will bring balance to the Force", and did he fulfill the prophecy?


Is it possible to override DateTime.ToString() function in C#

I would like to override the default behavior of the DateTime.ToSting() function so I can add it automatically the CultureInfo.  My final result is that if someone use the function like this:  DateTime.Now.ToString("g");   I can make it work like this:  DateTime.Now.ToString("g", new CultureInfo("en-US"));   It's a multi threaded application in .NET 4 Framework and I prefer not the set it on each thread.


Weird problem updating from 12.04 on chromebook

I installed ubuntu 12.04 using crouton on my chromebook. I'd like to update the distribution, because I can't always install the packages I'd like too. I followed various instructions online, and in chat, but I kept running into dead ends - for instance, I can't seem to find an update manager anywhere on the linux side of my system (I'm using xfce as my desktop, if that's relevant) which seems to be required for a lot of methods I found. I also tried the command sudo apt-get update && sudo apt-get full-upgrade, which went for about 30 seconds and outputted:  Reading package lists...Done Building dependency tree Reading state information...Done 0 upgraded, 0 newly installed, 0 to remove, and 0 not upgraded. E: Invalid operation full.   Before I decided that I wanted to update my distribution for sure, I tried to install the package nethack, and it gave the error E: package 'nethack' has no installation candidate.  If there's any more information anyone needs, I'd be glad to figure it out and get it for them; I didn't know what all information was needed. I am fairly new to Linux.  Any help would be appreciated. Thanks!  EDIT:  I read through (and tried) the various commands given at the page that this is supposed to be a duplicate of. The only one that seemed like it might help, the last one, gave an error of "command not found". This question is not solved by that answer.   Extra piece of information: as noted in the comments, I believe I have an ARM CPU.


How to check whether my system RAM is DDR2 or DDR3

I have a compac desktop computer and I want to update it with the 2 or 3 GB or RAM. I am confused that what type of RAM this system have whether DDR2 or DDR3. The processor in my computer is AMD Athlon.   So, if possible please let me know, the ways how can I check the type of RAM whether DDR2 or DDR3.  And how can I check by looking at the RAM that what type of this.


To show the direct limit, I know some ways but I wish to write this inductive limit using a new command, \limind? In other words, when writing this new command I want to see this: limind, not in italic form.  How can I achieve this?


Contacting prospective advisors before graduate school applications - courtesy or annoyance?

Last year, rather late during the MSc application cycle (after one round of funding was allocated - tardiness due to an abrupt change in my life situation), I emailed two professors from two schools that I most wanted to go to. I had perused their webpages and decided these professors had the specific research interests closest to my own.  My reason for contacting them before finishing my applications for their respective schools was that the applications included a large section for specific research questions that I wanted to investigate. So, I emailed these professors asking a bit about their work, because their webpages of course featured surface-level stuff.  One professor was very receptive and invited me to Skype with her so she could better explain herself and I could ask her questions. With her support, I was able to write an application that met her standards quite quickly.  The other professor told me - paraphrasing, of course - that he was too far into the process of choosing a new student for his research group to spend time helping me finish the application.  Let me be clear that the latter professor didn't say any harsh words and I have nothing bad to say about him. That said, the purpose of my question is to decide whether it's better for me as a prospective MSc student to email professors ahead of time like this. Was the latter's rejection likely due to my tardiness rather my emailing him? The more receptive professor made the point that she always wanted to have prospective MSc students write their own research proposals and get her approval before submitting the application. Is this common? If so, then I guess reaching out beforehand is a good thing to do, but earlier in the application cycle?  Thank you.


Blank Screen while upgrading 19.04 to 19.10

When i was upgrading ubuntu 19.04 to 19.10 while installing the upgrades, the screen went blank and its been 15 mins it is still blank .


I'm making a game where the user must solve a simple subtraction but the result must be a positive whole number. I managed to do everything but for some reason the answer is sometimes negative and I'm not sure how to fix it  import java.util.Random; import java.util.Scanner; public class Subtraction {   public static void main(String[] args) {     Random r = new Random();      final int MAX = 10;     // get two random numbers between 1 and MAX     int num1 = r.nextInt(MAX) - 1;     int num2 = r.nextInt(MAX) - 1;      int total = (num1 - num2);      // display a question     System.out.printf("What is your answer to %d - %d = ?%n", num1, num2);      // read in the result     Scanner stdin = new Scanner(System.in);     int ans = stdin.nextInt();     stdin.nextLine();      // give an reply     if (ans == total) {       System.out.println("You are correct!");     } else {       System.out.println("Sorry, wrong answer!");       System.out.printf("The answer is %d + %d = %d%n", num1, num2, (num1 - num2));     }    } }


Remove drivers intalled from Additional Drivers section

Ubuntu 11.04 was working fine with my Nvidia GT550M graphic card. It has got all shadows, effects etc. But yesterday i noticed the "additional drivers" icon in notification area and installed it. But now after login it says "your graphic card does not support unity, log in to classic gnome". how can i uninstall the driver and roll back to default one?


how to check if user exists on the SQL dataBase in android

I wrote a method(verifyUser) that checks if the user already exists in the database or not , but i get this error:     ( java.lang.NullPointerException: Attempt to invoke virtual method   'android.database.sqlite.SQLiteDatabase   com.example.testapp.DatatBaseHelper.getReadableDatabase()' on a null   object reference)   That's my ContentProvider Class:  public class TestProvider extends ContentProvider {      private DatatBaseHelper helper;     private SQLiteDatabase db;     public static final String LOG_TAG = TestProvider.class.getSimpleName();     private static final int test=1;     private static final int test_id=2;      private static final UriMatcher urim=new UriMatcher(UriMatcher.NO_MATCH);      static{         urim.addURI(Test.test.authority,Test.test.TABLE_NAME,test);         urim.addURI(Test.test.authority,Test.test.TABLE_NAME+"/#",test_id);     }     @Override     public boolean onCreate() {         helper=new DatatBaseHelper(getContext());         return false;     }      @Nullable     @Override     public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection, @Nullable String[] selectionArgs, @Nullable String sortOrder) {         int match=urim.match(uri);        db=helper.getReadableDatabase();          Cursor c;          switch(match){             case test:                 c=db.query(Test.test.TABLE_NAME,projection,selection,selectionArgs,null,null,sortOrder);                 break;              case test_id:                 selection= Test.test.ID+"=?";                 selectionArgs=new String[]{String.valueOf(ContentUris.parseId(uri))};                 c=db.query(Test.test.TABLE_NAME,projection,selection,selectionArgs,null,null,sortOrder);                  break;             default:                 throw new IllegalStateException("Cannot query form: " + uri);         }          return null;     }      @Nullable     @Override     public String getType(@NonNull Uri uri) {         return null;     }      @Nullable     @Override     public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {           db=helper.getWritableDatabase();          String email=values.getAsString(Test.test.EMAIL);              int match=urim.match(uri);          switch (match){             case test:           int   id=(int)(db.insert(Test.test.TABLE_NAME,null,values));                     uri= ContentUris.withAppendedId(uri, id);         }           return uri;     }      @Override     public int delete(@NonNull Uri uri, @Nullable String selection, @Nullable String[] selectionArgs) {         return 0;     }      @Override     public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection, @Nullable String[] selectionArgs) {         return 0;     }       public boolean verifyUser(String email){          SQLiteDatabase db=helper.getReadableDatabase();          Cursor c;          String pro[]={Test.test.ID};         String select=Test.test.EMAIL+"=?";         String args[]={email};          c=db.query(Test.test.TABLE_NAME,pro,select,args,null,null,null);          if(c.getCount()>0){             return true;         }          return false;     }   That's my datatbase class:  public class DatatBaseHelper extends SQLiteOpenHelper {      public static final  String DB_NAME="dress.db";     public static final int DB_VERSION=1;      public DatatBaseHelper(Context c){         super(c,DB_NAME,null,DB_VERSION);     }       private  String TABLE_CREATE= "CREATE TABLE " + test.TABLE_NAME+ "( "+   test. ID+" INTEGER PRIMARY KEY AUTOINCREMENT,"+ test.NAME+" TEXT NOT NULL,"+    test. EMAIL+" TEXT NOT NULL,"+ test.PASSWORD+ " TEXT NOT NULL);";            @Override         public void onCreate(SQLiteDatabase db) {     db.execSQL(TABLE_CREATE);         }          @Override         public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {          }           }


Glass cup + Water not rendering correctly, weird lines

I'm just starting to learn Blender and am following Blender Guru's donut tutorial. I just "filled" the glass cup with water and everything looks correct as far as I know but when I render it, the water doesn't look right and there are some weird horizontal lines going on. As I said, I'm very new and don't really know what to look for.


Facebook notifies others about my new added friend

Facebook is showing others my latest new added friends, saying something like "Aiwnas is now friends with X." Is it possible to stop Facebook from doing this? Or make it private for a customized list of my friends?


Hi guys I searched alot but not found any thing related to this. So if anyone tell me what's the reason for this.  I just purchased Google nexus 5 and upgraded from 4.4.2 to 4.4.4 and now waiting for 5.0 update on my device. But It has been over a month that I didn't received any updates and where others guys have received 5.0.1 as well. So anyone having same issue or something wrong with my device.  Thanks in advance


I am new to LaTeX. I have to add C code in my document, I looked for examles and found the following way to add it. But the problem is there is no proper color displying like comments and code is displaying in the same color. Could you please tell me how to fix it?  Here is an example based on C code display in eclipse.   \begin{lstlisting}  int abc = 3; //Variable for reference  \end{lstlisting}


Left/Right Alignment with Different Font Sizes in HTML

I am trying to have left and right alignment in my HTML. It works fine when the fonts are the same size, but they do not align when the fonts are different sizes.    .right {   float: right;   display: inline }  .left {   float: left;   font-size: 300%;   display: inline } Left Alignment  Right Alignment     I would like the two spans to be aligned by the bottom of the text. Can somebody please help me with this?  Thanks!


I'm reading  and I'm trying to understand the proof under "Degeneracy in One Dimension".  Here's what it says:     Considering a one-dimensional quantum system in a potential $V(x)$ with degenerate states $|\psi_1\rangle$ and $|\psi_2\rangle$ corresponding to the same energy eigenvalue $E$, writing the time-independent Schrödinger equation for the system:       $$-\frac{\hbar^2}{2m}\frac{ \partial^2\psi_1}{ \partial x^2} + V\psi_1 =E\psi_1$$       $$-\frac{\hbar^2}{2m}\frac{ \partial^2\psi_2}{ \partial x^2} + V\psi_2 =E\psi_2$$   Multiplying the first equation by $\psi_2$ and the second by $\psi_1$ and subtracting one from the other, we get:       $$\psi_1\frac{d^2}{d x^2}\psi_2-\psi_2\frac{d^2}{d x^2}\psi_1=0$$   Integrating both sides       $$\psi_1\frac{\partial \psi_2}{\partial x}-\psi_2\frac{\partial \psi_1}{\partial x}=constant$$   In case of well-defined and normalizable wave functions, the above constant vanishes, provided both the wave functions vanish at at least one point, and we find: $\psi_1(x)=c\psi_2(x)$ where $c$ is, in general, a complex constant. So, the two degenerate wave functions are not linearly independent. For bound state eigenfunctions, the wave function approaches zero in the limit $x\to\infty$ or $x\to-\infty$, so that the above constant is zero and we have no degeneracy.   Here are the parts I don't understand:   How does integrating $\psi_1\frac{d^2}{d x^2}\psi_2-\psi_2\frac{d^2}{d x^2}\psi_1=0$ yield $\psi_1\frac{\partial \psi_2}{\partial x}-\psi_2\frac{\partial \psi_1}{\partial x}=constant$.  Without having explicit formulas for $\psi_1(x)$ and $\psi_2(x)$, how do we just apparently pull them both out of the integral? I don't understand how the constant in the last equation vanishes just because $\psi_1$ and $\psi_2$ vanish at infinity. Even if it does vanish, how does that imply $\psi_1=c\psi_2$?


Show that for an invertible matrix, the images of a set of vectors spanning the space also form a spanning set

Let $A$ be an invertible $n\times n$ matrix. Let $\mathcal C=\{\vec v_1,\ldots,\vec v_k\}$ be a set of vectors with $\def\span{\operatorname{span}}\span(\mathcal C)=\Bbb R^n$. Show that the set $\mathcal D=\{A\vec v_1,\ldots,A\vec v_k\}$ satisfies $\span(\mathcal D)=\Bbb R^n$.  The columns of an $n \times n$ invertible matrix are a basis for $\Bbb R^n$, so multiplying $A$ by $C$ wouldn't change the span. I'm just not sure how to "show" it.


Is showing pop up in front of main page good idea from seo perspective?

We are creating an e-commerce website where if a user lands without the city in the URL, we will open a pop up to ask the user city. As per current design, the city pop-up looks like:    Once user lands here, he has two choices:   Type his/her city and land to city-specific product page. Click on cross (top-right) on city popup and land to Pan-Country product page.   I was wondering if google would penalize us for showing pop up content in first fold view to the user.


Travelling backwards in time - is it possible?

Einstein predicted that gravity bends spacetime such that travelling through time is possible; but only forward in time. According to General Relativity we can travel in the future, but not backwards in past. Closed timelike curves are possible, i.e. we can travel in future and than come back to our origin.  Can we also travel backwards in time according to some physical theory? I have heard that antiparticles move backwards and not forward in time. Also I know about Tachyons (they have imaginary mass and travel backwards in time), but I think Tachyons are still not observed in experiments.    My question: Is there a physical theory that predicts also that particles can travel backwards in time? Or are such things still impossible due to natural laws?  Every answer would be greatly appreciated!


As in, do you have a .tex file from which you begin every document? This hypothetical file would contain most of the things you use in each document on a regular basis. For example, here's my "template".  \documentclass[10pt,letterpaper]{article}       % Basics \usepackage[utf8]{inputenc}                     % Inputs \usepackage[T1]{fontenc}                        % Inputs \usepackage[margin=1in]{geometry}               % 1 inch margins \usepackage[pdfauthor={author},                 % Begin PDF metadata             pdftitle={title},             pdfproducer={LaTeX with hyperref},             pdfcreator={pdflatex}]{hyperref}    % End PDF metadata \hypersetup{             colorlinks,                         % Begin setup of link colors             citecolor=black,             filecolor=black,             linkcolor=black,             urlcolor=black,                     % End setup             pdfpagemode=UseNone                 % Disables bookmarks sidebar auto appearing             }  \title{title} \author{author} \date{\today}  \begin{document} \maketitle Insert body here. \end{document}   I get the feeling that I'm missing some essential packages, but that's what I use to start out each document I make.


What are the normal subgroups of symmetric groups?

Let's for any cardinal $\alpha$ define $S_\alpha$ as the group of all permutations of a set of cardinality $\alpha$.  Is there some sort of classification of normal subgroups of $S_\alpha$?  For $\alpha < \aleph_0$ it is well known: they are $E$, $A_\alpha$ and itself (and also $C_2 \times C_2$ in the special case when $\alpha = 4$)  However, what is for $\alpha \geq \aleph_0$?   Here we have the following subgroups, that are obviously normal:  1)For any cardinal $\beta$, such that $\aleph_0 \leq \beta \leq \alpha$, we have the subgroup $S_\alpha^{\leq \beta}$ of all permutations with the cardinality of their support $\beta$ or less.  2)For any cardinal $\beta$, such that $\aleph_0 \leq \beta \leq \alpha$, we have the subgroup $S_\alpha^{< \beta}$ of all permutations with the cardinality of their support strictly less than $\beta$.  3)The subgroup $A_\alpha$ of all permutations, that are equal to a product of even number of transpositions  4)The trivial subgroup  My question is: is there anything else? And if there is, then what?


I want to access PC in LAN from other devices. I cannot use static ip for my PC. Is there a way to use hostname instead of dynamic ip to access PC so that even if ip changes i can access PC with its hostname? I am usin Linux.


How can I get the size of an array from a pointer in C?

I've allocated an "array" of mystruct of size n like this:  if (NULL == (p = calloc(sizeof(struct mystruct) * n,1))) {  /* handle error */ }   Later on, I only have access to p, and no longer have n. Is there a way to determine the length of the array given just the pointer p?  I figure it must be possible, since free(p) does just that. I know malloc() keeps track of how much memory it has allocated, and that's why it knows the length; perhaps there is a way to query for this information? Something like...  int length = askMallocLibraryHowMuchMemoryWasAlloced(p) / sizeof(mystruct)   I know I should just rework the code so that I know n, but I'd rather not if possible. Any ideas?


Electrodynamics textbooks that emphasize applications

Please recommend undergraduate-level textbooks on electrodynamics which emphasize practical applications and real life examples. Please describe the book's level and contents and its intended audience in as much detail as possible.   Please provide both applications from everyday life for curious students as well as engineering applications from a physics perspective.


Sum of alternate series $\sum_{n=0}^{\infty}\frac{(-1)^n}{(2n+1)} $

I have found an exercise in an exam; however, I don't know where to start.  Find the sum of the series:  $$\sum_{n=0}^{\infty}\dfrac{(-1)^n}{(2n+1)} $$  I just learned how to do it with polynomials in the numerator.


Stop Python input when a specific character is entered

I'm writing a Python program (on OS X/Linux) in which a user has to type some words in a while loop. This is the relevant part of it:  i = 0 array = [] while (i < 10):    array.append(raw_input("Prompt: "))    i = i + 1   However I'd like to stop the input as soon as the user types a SPACE, without the need to press ENTER.   I know I can't do this using raw_input, however I did not find any way to achieve what I'm trying to do. Basically I would like the user to be able to type one word after the other, using the SPACE button instead of ENTER to input the next word.  Do you have any idea? Thanks in advance.


There are 8 crew members, The leading member wants that only a crew of 5 people or more could open a safe he bought, To each member he gave equal amount of keys, and locked the safe with several locks.  What's the minimal number of locks he should put:   at least 5 crew members would be required to open the safe? Any team of 5 crew members could open the safe, but none of the 4 team crew members.   1,2 stands individually of course.


Short story: man creates a computer simulation with crab-like beings, stops death after one sentient generation

I read this a few years ago online: a man creates some kind of simulated world using a quantum computer with creatures that end up evolving to look 'crab-like'. He's able to fast-forward the simulation; after fast-forwarding to where they're of human-level intelligence and grieving over their dead, he is emotionally unable to let them continue dying. That generation lives forever and (I believe) he stops them from being able to reproduce, so the population is entirely stagnant immortals. At some point he establishes contact with a crab-being, but only one.  Does anyone else remember reading it, what it was called, or what the website it was hosted on could have been?


Why does a factory reset keep the operating system updated?

I recently did a factory reset to my phone and to my surprise, the operating system remained to the last updated version (6.0.0) and not the version I had when I bought the phone (5.0.0).   Why does this happen? Doesn't a factory reset reset the operating system too?


Creating a leaf material that shows transparency from UV image (Blender Internal)

I've run into a complication when creating one of the trees for a location. I am not sure how to really ask this question without this picture:   As you can see I have a UV leaf texture that I want to apply to the rectangular generated leaves from the tree. When I put this into the texture tab it shows the leaf in the rendering, but keeps the white space that fills the rest of the rectangular shape.   Is there a way to eliminate this white space between the leaf and the edge of the rectangles to have it look like there are leaves on the tree?  Thank you for any help and suggestions.


N61JQ laptop random freeze, no bsod, heat related

I've had (and abused) for over 4 years: sandy gigs, pretty harsh drops, 2 failing hard drives, and it still runs fine EXCEPT for random freezing, no bsod; only way to get it moving is to keep the power button pressed or remove power. I've noticed that it is definitely heat related. Living in a big city the dust is a huge problem, I have to clean it out and replace the thermal paste every 2 months or so because the issue gets out of hand and the freezes become more and more frequent.   I've ruled out RAM and hard disk problems, so I figure it's either the CPU or GPU. Is there a way that I could rule out GPU? I've read that CPUs will start doing this if they have so many uptime hours, and this thing has definitely ran for hours on end almost every day for the past 4 years - but I could replace it and even perhaps upgrade it if I knew it was the cause of this problem.


I get a "Warning" after adding the line APT_AUTOGEN="yes" to /etc/default/rkhunter with gedit

The warning is the following: "(gedit:38572): Tepl-WARNING **: 09:45:20.468: GVfs metadata is not supported. Fallback to TeplMetadataManager. Either GVfs is not correctly installed or GVfs metadata are not supported on this platform. In the latter case, you should configure Tepl with --disable-gvfs-metadata."  What should I do? Is this normal?  This is what I was doing:  How should I proceed to properly install rkhunter?


What's the difference between $\equiv$ and $\leftrightarrow$ in a formal proof?

Some texts and online sources seem to imply that they're interchangeable, while others say that there is at least a small nuanced difference between the two.  For example, I've read that $ \equiv $ can be read as "can be replaced in a logical proof with...", yet I've also seen $ \leftrightarrow $ used in that same vein.  Edit: I'm trying to write my own textbook on this material as a way of forcing me to learn as much as possible before my final in 3 weeks. I'm trying to figure out a way to describe what $ \equiv $ means, while I've described $ \leftrightarrow $ as "If and only if"


Performing Wick Rotation to get Euclidean action of a scalar field $\Psi$

I'm working with the signature $(+,-,-,-)$ and with a Minkowski space-time Lagrangian  $$ \mathcal{L}_M ~=~ \Psi^\dagger\left(i\partial_0 + \frac{\nabla^2}{2m}\right)\Psi. $$ The Minkowski action is $$ S_M ~=~ \int dt d^3x \mathcal{L}_M. $$ I should obtain the Euclidean action by Wick rotation.  My question is about the way with that I should perform the Wick rotation. The topic is something has been already asked (). The problem is that the answer to the question is not satisfactory for me and for this special case.  Since the spacetime interval is defined by $ds^2 = dt^2 - d\vec{x}^2$, If I perform a Wick rotation (just rotating the time axis) I get a negative Euclidean interval.    What's the sense of that? What's the connection between physical actions calculated in two different signature? I can perform the rotation with different signs $t =\pm i\tau$. I know that, if there exist any poles, I must choose the correct sign in order to not cross them. But in this case, apparently I can choose both and I get always the same negative euclidean interval but different results.   If I choose $ t = i\tau $ I get  $$ S_M ~=~i\int_{+i\infty}^{-i\infty} d\tau d^3x \Psi^\dagger\left(i\frac{\partial}{\partial i\tau} + \frac{\nabla^2}{2m}\right)\Psi  ~=~ -i\int_{-i\infty}^{+i\infty}  d\tau d^3x \Psi^\dagger\left(\frac{\partial}{\partial \tau} + \frac{\nabla^2}{2m}\right)\Psi $$  If I choose $ t = -i\tau $ I get $$ S_M ~=~-i\int_{-i\infty}^{+i\infty} d\tau d^3x \Psi^\dagger\left(-i\frac{\partial}{\partial i\tau} + \frac{\nabla^2}{2m}\right)\Psi  ~=~ -i\int_{-i\infty}^{+i\infty}  d\tau d^3x \Psi^\dagger\left(-\frac{\partial}{\partial \tau} + \frac{\nabla^2}{2m}\right)\Psi $$  I think there is a slight difference that I don't understand   Is the Euclidean action defined by $S_M = i S_E$ or by $S_M = -iS_E$?


i Installed Ubuntu 17.10 alongside windows 10 But Windows 10 starts Automatically without showing OS Selection message

-> i installed ubuntu alongside windows10  -> both are installed in UEFI mode  -> but it automatically start windows10  -> i have separate partition Named as EFI  which contain      EFI\Boot\      EFI\Microsoft\Boot      EFI\ubuntu(some Files)       when i want to start UBUNTU at that time i have to press NOVO(Special Button On Lenovo Laptop for Go in Bios Or Select Boot option) button and select ubuntu   but it is not convenient way because novo button is pressed by only tiny pin   so anyone have any solution which is show me GRUB or bootselection at that time of starting my laptop   thanks in advance


Why Do My Objects Render Without Materials? [Ceramic]

So, I'm trying to make some ceramic (copied some nodes from online) objects for a practice project, but I can't get it to show up when Rendering. I tried to simplify, just apply it to a sphere, but I still can't get it to work.  I'm still pretty new so any help would be appreciated.


Condition for ({$n\alpha$},{$n\beta$}) being dense on [0,1]$\times$[0,1]

What is the condition for ({$n\alpha$},{$n\beta$}) being dense in [0,1]$\times$[0,1]? (Here {a} represents the fraction part of a). If the qustion changes to ({$n\alpha$},{$m\beta$}), then it is fairly easy: $\alpha$ and $\beta$ are irrationals. However, if the question is ({$n\alpha$},{$n\beta$}), it seems quite complex. For instance, if $\alpha$ and $\beta$ are both irrational but they are equal, then ({$n\alpha$},{$n\beta$}) lies on y=x, so it's not dense. I guess the condition is that $\alpha$ and $\beta$ are irrational while their division is also irrational. But I've got no idea about how to prove\disaprove my conjecture.


I have been working on this problem for about 2 hours and I can't seem to get it, here is exactly what the question reads. "Water is poured into the top of a conical tank at the constant rate of 1 cubic inch per second and flows out of an opening at the3 bottom at a rate of .5 cubic inches per second. The tank has a height of 4 inches, and a radius of 2 inches at the top. How fast is the water level changing when the water is 2 inches high?"


Would time speed up on an object you're moving towards?

When we look at stars, we see light that is years old. This would mean that if aliens were to look at earth, they would see how the earth looked in the past.  My question is, if you were to move closer to an object so that you receive more photons in your eyes, would it look like the time sped up on the object? And the same if you were to move away from an object, would the time move slower?  Just a question that popped up in my head, thanks in advance!


Using Mods with the new Minecraft Launcher

I read the question "How to install mods for the new minecraft launcher" and got the modified directory to show up in the list and I can load mods for a 1.5.2 version from the launcher now. The problem I am having is that when Minecraft comes up everything is flipped. It is both upside down and in mirror image. If I load the same jar file using the old minecraft launcher it works just fine. (Mind you there is a lot of rearranging between these tries.)   Does anyone know what is causing this? Any help is appreciated. Thanks.


Need help to understand Maximum Likelihood Estimation for multivariate normal distribution?

In maximum likelihood estimation for the parameter, mean $\mu$ of multivariate normal distribution, I end up with the following result:  $\mu_{MLE} = \dfrac{1}{n}\sum_{i=1}^n x_i$  The way I understand the above equation is the following way below, but I am wondering if the above equation means the following equation:  $\mu_{MLE} = \begin{bmatrix}\mu_1\\\mu_2\\\vdots\\\mu_n\end{bmatrix} = \begin{bmatrix}\dfrac{1}{n}\sum_{i=1}^n x_1\\\dfrac{1}{n}\sum_{i=1}^n x_2\\\vdots\\\dfrac{1}{n}\sum_{i=1}^n x_i\end{bmatrix} = \begin{bmatrix}E(X_1)\\E(X_2)\\\vdots\\E(X_n)\end{bmatrix} = \begin{bmatrix}\bar{X_1} \\ \bar{X_2} \\ \vdots \\ \bar{X_n}\end{bmatrix}$   And also Maximum Likelhood Estimation for $\Sigma$, I have ended up with the following equation:  $\Sigma_{MLE} = \dfrac{1}{n}\sum_{i=1}^n(x_i-\mu)(x_i-\mu)^T = \begin{bmatrix}Var(\sigma_{11}) & Cov(\sigma_{12}) & \dots & Cov(\sigma_{1n}) \\ Cov(\sigma_{21}) & Var(\sigma_{22}) & \dots & Cov(\sigma_{2n}) \\ {}& \vdots&  \\ Cov(\sigma_{n1}) & Cov(\sigma_{n2}) & \dots & Var(\sigma_{nn})  \end{bmatrix}$  Somehow, I got the equation following some algebraic steps, but I can't see how this part, $\dfrac{1}{n}\sum_{i=1}^n(x_i-\mu)(x_i-\mu)^T$, works and produces the covariance matrix. Hope to hear some explanations.


Review queues in the dropdown menu have no indicator even when there are reviews

Earlier today (or at least ) the review queues had numbers showing up indicating how many reviews were pending in each. Those are now missing, and there's no indication of which queues have how many reviews:    (This screenshot was taken with all userscripts disabled.)  Some of these queues have reviews pending in them for me to act on, but no indicator is showing up at all. I clicked this menu because its icon was orange, and I visited all queues and there were two queues with one review each in them.  I could not tell from this dropdown which queues needed my attention though, and if it's trying to get my attention to the review queues, it really should tell me which of them actually need my attention.  Also from meta.se just now (icon orange):    (There's some earlier discussion of the review indicators being removed in , but this doesn't appear to describe a bug about the indicators going missing even when there's reviews.)


Function and its inverse in Discrete Mathematics

Prove that : if $L \subseteq M,$  then $f^{-1}(L) \subseteq f^{-1}(M)$.


Can you have both Attribute modifiers and displays on an item?

I'm making an adventure map where I have a Villager "merchant" that sells custom armour for the price of a custom currency (All of this works fine. In a previous arqade question (You can see it ) I had a problem with this but it works like a charm) I wanted to add another feature to this armour now that i have the villager working. Lone behold, I have yet another issue. I have tried fiddling around with tags and formatting. Nothing seems to be able to allow me to have a villager that sells a custom named item that also has it's own modified attributes. It seems I can only have the item to have a custom attribute (but no custom display) or a custom display (but no custom attributes) My current command displays a custom name and lore but has no attributes:  /summon villager ~ ~1 ~  { CustomName:"Lv.1 Gear Merchant" ,CustomNameVisible:1b ,NoAI:1b ,Invulnerable:1b ,Offers: { Recipes: [ { buy: { id:"minecraft:gold_nugget" ,tag: { display: { Name:"Gold Coin" ,Lore: [ "$1" ] } } ,Count:32 } ,sell: { id:"minecraft:leather_chestplate" ,tag: { display: { Name:"Shoddy Leather Jacket" ,Lore: [ "Lv.1" ] } } ,Count:1 } ,tag: { AttributeModifiers: [ { AttributeName:generic.maxHealth ,Amount:1 ,Operation:0 ,Name:Health+ ,UUIDLeast:999 ,UUIDMost:999 ,Slot:"chest" } ] } ,maxUses:9999999 } ] } }     Again in this draft I have no errors, it just doesn't seem to want to apply my attribute changes. I created another draft that seemed to result in the exact opposite. The command:  /summon villager ~ ~1 ~  { CustomName:"Lv.1 Gear Merchant" ,CustomNameVisible:1b ,NoAI:1b ,Invulnerable:1b ,Offers: { Recipes: [ { buy: { id:"minecraft:gold_nugget" ,tag: { display: { Name:"Gold Coin" ,Lore: [ "$1" ] } } ,Count:32 } ,sell: {id:"minecraft:leather_chestplate" ,tag: { AttributeModifiers: [ { AttributeName:generic.maxHealth ,Amount:1 ,Operation:0 ,Name:Health+ ,UUIDLeast:999 ,UUIDMost:999 ,Slot:"chest" } ] } ,display: { Name:"Shoddy Leather Jacket" ,Lore: [ "Lv.1" ] } ,Count:1 } ,maxUses:9999999 } ] } }     Now the health is working but the display is kaputz. This feels like a game of whack-a-mole that's making me pretty TRIGGERED. Anyways, I suck at commands and hopefully with the help of anyone who sees this, I can learn. Thanks.


Can not get correct sha256sum hash for Kubuntu 15.10 DVD

I have downloaded the .iso file for Kubuntu-15.10.iso from the official site. I successfully verified the correct sha256sum hash of  9e5eb424eabfd9b2d193d8c34eca7b48ad944b90c0de0bdcbb638563c14c4d2b   I am having trouble hashing the DVD though. When I used the burner xfburn I kept getting the hash   758061ca3be30128dca74e3f73b5dd6e76fb5047c0c4e0743f22786fb0a02dd0  /dev/cdrom   So I changed burners to K3B and it would give me the hash  d7559c90efece2b38021804cc34011eb2cb161fff2afe6894985083bd41232d5  /dev/cdrom   So I am unable to verify the correct DVD sha256sum hash. I have also used the burner that comes with my system which is Xubuntu 14.04. I also tried K3B burner which comes highly recommended online. I'm out of ideas.   Please help me get the correct hash...OR is the DVD's with the wrong hashes fine to burn? And its some bug in Xubuntu's DVD Rom system? Has anyone gottent the correct hashes for the DVD burned with this ISO?


Is there any scientific literature investigating physical and psychological addiction to white flour made of wheat?  Some studies, like  talk about this subject but I'm not well informed and interested to know more by experts' voices.


How to reference a cell using a cell value?

I'm sure this is not as complicated as I'm trying to make it. What I'm trying to do is take a calculated cell value, add a letter to it, and reference it from another sheet.  So, if A1 is a value of 1, then I want the value of Sheet1!A1 If A1 is 92, I want the value of Sheet1!A92 If A1 is 0, I don't want anything. If A1 is blank, I don't want anything.


What would be a good solution for hooking up the satellite TV box (Dish network) in my room to be able to watch it on my PC and possibly record video from it?  Please share with me the best cards, cables, software, anything else needed to do this in the most efficient way?  I am looking at the WinTV-HVR from Hauppauge.  I am not sure, for performance, what would be the best to go with, PCI, PCI express, USB2.0?  Also on the Hauppauge website I saw this note: "WinTV-PVR products will not work in PC systems with 4GB or more of memory."  The new PC I am building will be 12-24gb of DDR3 RAM, does that mean their products will not work at all with my memory?  So confused now!


Why should we use ' instead of " for Strings in Javascript

If often heard that I should declare String in Javascript in ' (single quotation marks) instead of " (double quotation marks) like in Java or other languages.  Unfortunately did i never ask why to do that.  The "best" answer I got until now was      It's more performant   Is that true? And why?


I have a textarea to display the HTML content from the database. Here my code is:               <textarea name="cont" id="cont"></textarea> <textarea name="name" id="cont"></textarea>   When I try to load content dynamically, #name is working perfectly but the #cont shows an console error like:     Uncaught SyntaxError: Invalid or unexpected token   This is the content I am attempting to load in to the #cont
Coconut Oil

Extra Virgin / Premium
   Thanks for your answers


Show norm preserving property and determine Eigenvalues

Can someone of you give me a solution for this?     Let $N\in \mathbb N$.   a) We define the map $\mathfrak F:(\mathbb C^N, ||\cdot||_2)\to(\mathbb C^N, ||\cdot||_2)$ by $$(\mathfrak F(x))_k := \frac{1}{\sqrt N}\sum_{j=1}^Nx_je^{2\pi i\frac{(j-1)(k-1)}{N}} \quad \forall k\in \{1,...,N\}$$    Show that $\mathfrak F$ is norm-preserving, i.e. $$||(\mathfrak F(x))_k||_2 = ||x||_2 \quad \forall k\in \{1,...,N\}$$    b) For $n,m \in \{1,2,...,N\}$ we define the entries of $M\in \mathbb C^{N\times N}$ by $$M_{nm} :=  \begin{cases} \frac{N+1}{2}, \quad \quad n=m \\ \frac{1}{e^{2\pi i \frac{m-n}{N}}-1}, \,\,n \neq m \end{cases}$$   Show that $1, 2, 3, ..., N$ are the Eigenvalues of M.


Let $S$ be a subspace of an n-dimensional vector space $V$. Prove that $\operatorname{dim}(S)\leq\ n$.

Let $S$ be a subspace of an n-dimensional vector space $V$. Prove that $dim(S)\leq\ n$.  Let $B = \{v_1, v_2, v_3,...v_n\}$ be the basis set for vector space $V$.   Let $B_s = \{v_1, v_2, v_3,...v_n, v_{n+1}\}$ be the basis set for the subspace $S$.  Then $span(S) > V$ because $B_s$ has more vectors than $B$ and $span(S)$ can potentially reach a vector that is outside of the vector space $V$. But this cannot be the case because $S$ is a subset of $V$. Hence it must be the case that $B_s \leq\ B$ and therefore, $dim(S) \leq\ n$.  Note: If the proof is incorrect can you point out where I went wrong?


How to get my own SQLiteDatabase file in android app?

My android app need to use a existed SQLiteDatabase file(xxx.db), In eclipse project, In which project folder should I put this database file ? and How can I get the database in my code ?


most lightweight linux distribution for very old computer

I'm installing linux distributions on computers I find in the neighborhood's garbage area.  these computers are, hardware speaking, still working... nothing broken.., problem is: most of these computers are 8-15 years old.  some are netbooks, but most are laptops. a few towers as well.  the target functionality/usage of these computers differs, I give them as charity to people who can't afford a computer but still need access to internet and can't afford smartphone as well. (these people live in a third world country I visit every now and then... don't ask..)  sometimes they just function as live streaming TV for those who don't have TVs or that the only thing in TV is government's brainwash material.  these computers are too low on resources for ubuntu 16.04 (video lagging/delay in visual video compared to sound/video freezes, GUI get's slow and stuck etc.)  my question is: which linux distribution is the most lightweight and will be most potent to work with these kind of computers? doesn't it change by the target use of each computer (as I specified above)? Lubuntu? Xubuntu? Linux Lite?


Why didn't the Trace work in Goblet of Fire?

During Goblet of Fire, Voldemort lured Harry away from Hogwarts and into a Muggle cemetery. This was done during the Triwizard tournament to make Harry’s death look like an accident.  Harry was supposed to have a Trace on him, so why couldn’t the Ministry tell an underage wizard was performing magic (Expelliarmus) in a Muggle cemetery? Or (as the Trace seems to pick up ANY magic used near a young wizard/witch) magic used by the Death Eaters?


Looking for an understanding of Toroidal Moments

The  page is not so enlightening  Apparantly the Neutrino, if it is a Dirac particle, has a Toroidal Moment. Does this mean the Dirac neutrino would interact electromagnetically as well as weakly?


I am running this code on Python (both 2.7, 3.x):  >>> 1.1 + 2.2 3.3000000000000003 >>> 1.1 + 2.3 3.4   Could someone explain how does it work and what is happening?


If one of $n$ coins is fair, then find the probability that the total number of heads is even

A collection of $n$ coins is flipped. The outcomes are independent, and the $i$-th coin comes up heads with probability $\alpha_i, i=1, \dots, n$. Suppose that for some value of $j, 1 \leq j \leq n, \alpha_j=\frac{1}{2}$. Find the probability that the total number of heads to appear on the $n$ coins is an even number.   Now, I don't understand the importance of the statement "Suppose that for some value of $j, 1 \leq j \leq n, \alpha_j=\frac{1}{2}$"


What is the difference between DDR3 and GDDR5?

As I said, Before I begin, this is not a duplicate of , so idk why it has been marked as a duplicate this is an entirely different question. What im talking about is what is the difference between DDR3 and GDDR5? I have a desktop PC, and I am looking to upgrade the ram from 4GB to 8GB. But as I have discovered GDDR5, im not sure which one is better.  Can someone help me with the difference? (Ports are PCIe like all desktops)


I heard about story from, say 50 years ago, about a telephone grid gaining self-awareness (and probably ending the world). Similar in nature to the original Frankenstein's monster: take a thing, add electricity and get life. Naively applying Volta's animal electricity with a line of thought like: "Hey, there is an electricity in the grid, so it could get alive." But now I could not find any mention of it. Maybe it was even earlier and talking about a telegraph grid, not sure. Any ideas about the source or if it actually exists?


LG phone Internal storage with MicroSD card

How do I put an micro SD card on an LG phone as internal storage.


I'm interested in learning about some nice-looking table samples. Colors can make a huge difference, and just providing some color to headers, background, or borders can dramatically change presentation. Any samples you're proud to share?  (BTW here's a sample I like, but unfortunately, not TeX...)


How do you show that a Hilbert space is separable if and only if it has a countable dense subset?

I know that, by definition, a Hilbert space $\mathscr{H}$ is separable if there exists a countable subset $X$ such that $\operatorname{span}(X)$ is dense in $\mathscr{H}$.  I want to prove that $\mathscr{H}$ is separable if and only if there exists a countable and dense subset.  I know I have to try with combinations like "$p+iq$" with $p$ and $q$ rational, but I can't find the way.


I have just a normal bezier curve. And i have sub divide once. I want to extrude the sub divide vertex. Like the branch. But when i extrude the handle is remove and when i extruded from the handle it is extruded good way. I just want to make the branch type.


Changing colour of the close button in Windows 8

I'd like to change the colour of the red close button in the top right of each window (Windows 8 / 8.1). Presumably there's an RGB code / hex code somewhere in the registry that I could edit?


If $(a,b)=1$ and $a|c$ and $b|c$ then $ab|c$

I'm studying unique factorization domains and I was able to prove that in a UFD if $gcd(a,b)=1$ and $a|bc$ then $a|c$ with the help of the experts here  Now since I'm taking a number theory class too, I've learned this lemma: if $gcd(a,b)=1$ and $a|c$ and $b|c$ then $ab|c$. My question: Does this lemma hold in a UFD too?? If not can you explain why? It sounds natural to work but I don't know how to prove it....


Given that indexing is so important as your data set increases in size, can someone explain how indexing works at a database-agnostic level?  For information on queries to index a field, check out .


A way to see the original question/answer if it was edited on SE app

I often see edited question/answer while surfing around the SE sites on the app on my phone. Sometimes I wish to see the original post but on the app this seems impossible.  To do this now I have to open the question/answer in my browser which takes time and data  How can I do this? Can this feature be added to the SE app?


A continuous mapping is determined by its values on a dense set

Let f and g be continuous mappings of a metric space $X$ into a metric space $Y$ and let $E$ be a dense subset of $X$. Prove that $f(E)$ is dense in $f(X)$. If $g(p)=f(p)$ for all $p \in E$, prove that $g(p)=f(p)$ for all $p \in X$.


How to properly dual boot kubuntu and windows 10

Originally i was using only windows 10 on one of my computers ssds and yesterday i installed linux on my other ssd. After linux was successfully installed i was no longer able to boot into windows 10 from the other drive. It kept sending me to grub rescue, but i was able to boot into linux just fine. I tried many different commands in linux to try and fix the problem but no matter what i tried grub couldnt see windows. I am now restoring windows from a back up and would like to know what should i do to not encounter this problem again and easily switch between kubuntu and windows when ever i please?


Here is a problem I encountered some time back: Suppose $f$ is bounded for $a\leq x\leq b$ and for every pair of values $x_1$ and $x_2$ with $a\leq x_1\leq x_2 \leq b$, $f(\frac{1}{2}(x_1+x_2))\leq \frac{1}{2}(f(x_1)+f(x_2))$. Prove that $f$ is continuous for $a<x<b$.  I tried to solve it but I could not really come with anything...  Here's an attempt.The idea is not due to me but to a friend;  By the condition given, $f(\frac{2x+2\delta}{2})\leq \frac{1}{2}(f(x+2\delta)+f(x))$,i.e. $f(x+\delta)-f(x)\leq \frac{1}{2}f(x+2\delta)-f(x)$ and in this manner, $f(x+\delta)-f(x)\leq \frac{1}{2}f(x+2\delta)-f(x)\leq \frac{1}{2^2}(f(x+4\delta)-f(x))\leq$  $ \dots \dots \dots \dots $  $\frac{1}{2^n}(f(x+2^n\delta)-f(x))$ where $a<x+2^n\delta<b$  As $\delta\to 0$,$f(x+2^k\delta)\to f(x)$ for $k=1,2,\dots n$ i.e. $f$ is continuous in the interval $(a,b)$.  I tried posting this flawed attempt on Aops , but no one has suggested how to finish off the proof using what I used.I will be happy if someone could suggest something.Thanks!


How can I prove this relation between the elementary set theory and the elementary logic?

If you need to prove an equality like $A\Delta B=(B\setminus C)\cup[C\cap (B\Delta A)]$ we can first prove $p\underline{\lor} q\Longleftrightarrow (q\land\overline{r})\lor(q\underline{\lor}p)$ (with a truth table for example) and then use it whith $p=x\in A$, $q=x \in B$ and $r=x \in C$.  So, if we now that $p\underline{\lor} q\Longleftrightarrow (q\land\overline{r})\lor(q\underline{\lor}p)$ then we now that $A\Delta B=(B\setminus C)\cup[C\cap (B\Delta A)]$. But my question is. is true in general (with a general set equation) the reverse implication? that is  $A\Delta B=(B\setminus C)\cup[C\cap (B\Delta A)]$ implies $p\underline{\lor} q\Longleftrightarrow (q\land\overline{r})\lor(q\underline{\lor}p)$.


How can I recover data deleted during installation of Ubuntu?

i got a big trouble this is my first day with ubuntu.  while installing ubuntu the participation of the hard disk was deleted and it contains a big project ( i worked on that project about 5 months and i have no copy for it.). please help me. is there any way to return my project. bad starting with ubuntu :'(  tell me is there any way to return it. i search for programs to return files but they are only for windows. and that project for the 08 of October so i need it immediately.


I have a lamp project and I can't move my project in the file I'm supposed to move unless I do it from terminal as root, and then it doesn't let me open the project and change it, I have a lots of files I have to change and it's very time consuming to open them all from terminal each time I want to change them. How can I run my computer as root without the terminal?( I am new to ubuntu )


I am having trouble calculating the following improper integral: $$\displaystyle \int\limits_0^{\infty} \frac{\log^2(1 - e^{-x})x^5}{e^x - 1} \, dx $$  Can someone give me a way that I can calculate this?


Units used for distance calculations by distance matrix tool of QGIS

I can't seem to get the measure tool to match up with my distance matrix tool regardless of what measurements I use. There are conflicting answers on other posts about this question. Both of my layers are on WGS84


Seeking qml or sld file for QGIS + OpenStreetMap data?

I'm looking for a qml file (or equivalent e.g. sld) to allow me to use QGIS to take OpenStreetMap data and produce paper maps. I'm re-asking this question (it was asked once or twice over a couple of years by other people) because I'm really surprised not to easily find such a thing already (I looked hard).   I have found  - which are good, but only style basic data like roads (and do so simply). I've successfully followed the  for getting OSM data to work with. I've carried out some basic style editing successfully. I realise I could create my own styles for this purpose - but this seems like a very big job. I want a visually pleasing map taking into account most of the data available on OSM (i.e. not just streets, but tracks, paths, rivers, woods, lakes, buildings and so on). I'd have thought that there would be other people out there already doing the same... It seems odd to have to re-invent the wheel when both OSM and QGIS are open source / open data projects. I feel like maybe I've just missed the obvious repository of OSM qml files which resides out there on the internet somewhere if you know where to look.  Additional notes in response to query below...  Ideally I'm looking for a Mapnik style rendering of the OSM data, but any equivalent properly developed and complete style would be good.  At the moment the objective is to use this data to produce paper mapping, but simple use of the mapping as base data on which other geographic data can be displayed also requires a decent rendering. At work I use Ordnance Survey data completely styled to produce a full and very detailed UK map (the point being that I didn't have to design this styling, it came with the data). I realise that other tools exist for paper mapping, but the same issues tend to arise at one stage or another... I'm more or less successful in making the tool work for me in really basic terms, but to get to something visually useful I end up back with me either needing to re-invent a complete rendering style from scratch (beyond my skill), or encountering such a complex set of requirements for database setups or whatever that the process crashes and burns before I get anywhere useful. With a few more years of GIS experience I'll maybe be a database, CartoCSS (or whatever else) wizz... but until then I'm prevented from using the amazing resource that OSM provides by this one barrier.  Update (July 2015): Please note that I'm still looking for information on this, and given that I've just been informed that the question has had 2500 views in the last year clearly others are too.


Went to do some reviewing on SO and one of the "first answers" that came up to review had no username showing and incorrect number of votes (0 instead of 11).    It was also not the user's first answer (81k rep), and was posted over a fortnight ago.    Review presented to me:          The answer as viewed in the question:          Not moaning, just reportin' in case something is out of align that needs fixin'!


I am using this sed command to extract a json value for a key, say MyKey..  sedPattern='s/^.*"myKey":"\([^"]*\)".*$/\1/'   For a json string like,  {"myKey" : 1, "yourKey": 2}   It returns what i need,  1   But what does \1 action in the above sed command mean?


Which of the Physics textbooks would you recommend I read this quarter (Analytical Mechanics)?

My Analytical Mechanics class this quarter has one required textbook:   "Classical Dynamics of Particles and Systems" by Thornton & Marion   and three recommended readings:   "Mechanics" by Landau and Lifshitz "Classical Mechanics" by Goldstein "Modern Analytical Mechanics" by Pellegrini & Cooper   Due to time constraints, I won't be able to read all of them, so I am wondering if any of you are familiar with these books and would be able to make suggestions as to which I should read this quarter.  These books seem to cover the same topics, though perhaps from different perspectives and cover different aspects of those topics.  Or would you suggest that I stick to the required book, and refer to the recommended books when I get confused?  It seems my professor uses a lot of the same notation and terminology from Landau's book during his lectures, so that book is probably also a "required" to some degree.


How does random forest generate the random forest

I am not an expert of random forest but I clearly understand that the key issue with random forest is the (random) tree generation. Can you explain me how the trees are generated? (i.e. What is the used distribution for tree generation?)  Thanks in advance !


how to start with ruby and install it? Which is better windows or VM?

I have Windows 8 OS running on my machine and i also have Linux Ubuntu Virtual machine. I want to install ruby and work with it and I heard that windows doesn't support all ruby gems and Linux will be better for ruby. so do you think I should install ruby on windows or on my Virtual machine? which will be better? And help me with installing ruby on it. Also I want to know if there is any IDE as in eclipse for java better than a command prompt?


How can I find the version number of an installed package via dpkg?

I use the dpkg -l command to find out what version of a package I have installed. For example:  dpkg -l network-manager   returns the information on the package:  Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name                      Version                   Description +++-=========================-=========================-================================================================== ii  network-manager           0.8.3~git.20101118t223039 network management framework daemon   As you can see, it returns 0.8.3~git.20101118t223039 which is wrong because it truncates the version (I've picked a long one for the purpose of this question). The way I've solved this in the past is to pass a stupidly long COLUMNS argument to make it expand:  COLUMNS=200 dpkg -l network-manager   which gives me the entire version number, but also a bunch of junk:  Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name                                         Version                                      Description +++-============================================-============================================-======================================================================================================== ii  network-manager                              0.8.3~git.20101118t223039.d60a988-0ubuntu1   network management framework daemon   Now I can see the full version number, which is 0.8.3~git.20101118t223039.d60a988-0ubuntu1.  I get the feeling that this is not the proper way to find the version number of an installed package. This never really was a problem in the past, but with the tacking on of "ubuntu" in the versions and the proliferation of PPAs these strings are getting longer and longer. Is there an easier way?


How to install Popcorn Time using installer from their official site?

How do you install Popcorntime Beta on Linux? The Beta Version is a tar.xz file that is downloaded that does not auto install when clicked on like the Windows and Mac versions do. Installing programs in Linux is Not easy for the average non advanced user if it is not a self installing file or is not available via the Ubuntu Software Center.


Is it possible to use "negative sound waves" to "cancel out" a sound to create silence?

I saw youtube videos that claimed to do this, although I'm quite certain the videos just excluded sound and lied.  However, I am wondering if the physics of this is actually possible - to create a completely negative sound wave that cancels the sound out to a flat line i.e. complete silence.  p.s. I am not referring to white noise, which prevents the sound from being heard by overriding it with a different sound (white noise). Rather, I am referring to making a sound be completely silent by generating the inverse, opposite, or "negative" sound wave.


Why do some statistics symbols have a "squared", e.g. Variance $\sigma^2$, "R squared" $R^2$ or heritability $H^2$

I sometimes encounter symbols in statistics whose symbol carries a "squared". In other areas, like for example mechanics, you give the quantity you are interested in a normal letter and then define your formulas so that you can rearrange them until the quantity you are interested in stands as a normal letter at the left-hand side of the formula. An example is the position $x$ after moving for a time $t$ and a velocity $v$:  $$x = vt$$  However in statistics, sometimes squared quantities are on the left-hand side, because that's what's used for further interpretation of results:   The variance $\sigma^2_X$ of a random variable $X$ with expectation value $E[X]=µ$:  $$\sigma^2_X = E[(X-µ)^2] $$  Here, a squared entity stands on the left-hand side of the formula. The Coefficient of determination $R^2$, which is even only called "R squared" all  the time  by statisticians. Why do you not give him a "normal" letter if it's  used so often? The heritability is a measure which is employed in genetics when the amount of variation which comes from the environment vs. the amount of variation which comes from genetics shall be put in a ratio. A quantitative trait $P$ (e.g. growth height) is modelled like this in dependence of genotype effect $G$ and environment effect $E$ (all random variables):  $$P = G + E$$  Broad-sense Heritability $H^2$ is defined $H^2 = \operatorname{Var}(G)/\operatorname{Var}(P)$   No-one is ever interested in $H$, only $H^2$.   What is the sense of this convention? What does it tell to statisticians? Or are there several unrelated causes?


Biblatex: authoryear style with full date instead of year only

I'm trying to use the authoryear-icomp style with full date (if available) instead of year only. With this MWE:  \documentclass[paper=a4,12pt,oneside,ngerman]{article}  \let\mkccitation\mkcitation  \usepackage[ backend=biber, style=authoryear-icomp, maxbibnames=2,            % maximale Namen, die im Literaturverzeichnis angezeigt werden maxcitenames=2,            % maximale Namen, die im Text angezeigt werden, ab 3 wird u.a. nach den ersten Autor angezeigt idemtracker=constrict, ibidtracker=constrict, pagetracker=true, ibidpage=true, isbn=false, alldates=comp, dateabbrev=true, sortcites=true, mergedate=compact, datelabel=comp, block=space, mincrossrefs=6 ]{biblatex}  \usepackage{filecontents} \begin{filecontents}{jobname.bib}         @book{book1,     author = {{Some Author}},     date = {2013},     title = {{Some Title}},     url = {http://www.someurl.com},     address = {Somewhere},     urldate = {2015-08-19},     publisher = {{Any Publisher}},     institution = {{Any Institution}} }    @misc{misc1,     author = {{Some Author}},     date = {2013-06-09},     title = {{Some Other Title}},     url = {http://www.anyurl.net},     urldate = {2015-05-31} }    @misc{misc2,     author = {{Some Author}},     date = {2013-06-09},     title = {{Not The Same Title}},     url = {http://www.anyurl.net},     urldate = {2015-05-21} }    @misc{misc3,     author = {{Some Author}},     date = {2013-01-03},     title = {{Any Title}} }    @misc{misc4,     author = {{Some Author}},     date = {2014-01-01},     title = {{Anything}} } \end{filecontents} \bibliography{jobname}  \usepackage[ngerman]{babel} \DefineBibliographyStrings{ngerman}{url={Online}} \DefineBibliographyStrings{ngerman}{urlseen = {zuletzt gepr\"uft am}}  \AtEveryBibitem{ \DeclareFieldFormat{url}{\bibstring{url}\addcolon\space\url{#1}} }    %%% \renewbibmacro*{cite:labelyear+extrayear}{%     \iffieldundef{labelyear}     {}     {%         \printtext[bibhyperref]{\printdatelabel\printfield{extrayear}}%      }% }  %\AtEveryBibitem{\iffieldundef{day}{}{\clearfield{extrayear}}{}} %\AtEveryCitekey{\iffieldundef{day}{}{\clearfield{extrayear}}{}}   \begin{document}     \selectlanguage{ngerman}      \parencite{book1}     \parencite{misc1}     \parencite{misc2}     \parencite{misc3}     \parencite{misc4}      \printbibliography[title=References]  \end{document}   which gives the following output at the time:   it is at least close to what I need. But I would like to get rid of all unnecessary extrayear labels. When using      \AtEveryBibitem{\iffieldundef{day}{}{\clearfield{extrayear}}{}}     \AtEveryCitekey{\iffieldundef{day}{}{\clearfield{extrayear}}{}}   The output reads:    I would like the labels to look like: (Some Author 2013) (Some Author 9. Juni 2013a) (Some Author 9. Juni 2013b) (Some Author 3. Jan. 2013) (Some Author 1. Jan. 2014)  Is there any way to achieve the desired labeling?


What is postselection in quantum computing?

A quantum computer can efficiently solve problems lying in the complexity class . I have seen a claim the one can (potentially, because we don't know whether BQP is a proper subset or equal to PP) increase the efficiency of a quantum computer by applying postselection and that the class of efficiently solvable problems becomes now postBQP = .  What does postselection mean here?


Suggested textbooks for statistical physics

I intend to get into some serious study of Statistical Physics. I was hoping if you could tell me the best books in that field? I've heard Reif and Pathria are great. But for now, I can only afford one book. Any suggestions bw the two, or some other book idk of?


How to remove an element from a fixed array USING ONLY for loops and additional arrays

Without using arraylists, arraycopy, or any other imported method, but simply just using for loops and an additional array, how does one remove the first occurrence of a certain element?  this is my code so far:   public class remover { public static void main(String[] args) {      //initial array     int[] oldArray = {1,2,3,4};      //value to remove is 3       //define the new array with smaller size     int[] newArray = new int[oldArray.length];      //cycle through array     for(int i=0;i < oldArray.length;i++)      {         if(oldArray[i] == 3) {             for(int k=0; k<i; k++) {                 newArray[i] = oldArray[i];             }             for(int m=i; m<oldArray.length; m++) {                 newArray[m] = oldArray[m];             }           }      }   for(int i=0; i<oldArray.length; i++) { System.out.println(oldArray[i]); } } }


Meta restrictions even if other accounts have enough rep?

Why, even if you have a lot of reputation on one site, can you not participate in meta on another you have just joined? Should you be able to partcipate straight away? After all, I assume that the feature is just to stop spam users, but you're obviously not a spam account if you have tens, hundreds or even thousands of reputation points? Is it something worth changing, or is it to make sure the users get a feel for a site before starting discussion?


The cache is getting at full level so fast

Please, the memory and the cache are getting to the full level quite quickly under my linux mint 9 - isadora system. I used Ubuntu and Debian before, and it was not causing this issue at all. At the current time i typing the following command frequently to empty the cache "echo 3 > /proc/sys/vm/drop_caches".   Please any way around this? or do you know what's going wrong? | I am only programming on this machine; no graphics, no games nothing.  Thanks in advance for your help!


Let $f : G → G_1$ be a surjective homomorphism (also called epimorphism) from $G$ to another group $G_1$. Prove that $f(Z(G)) \subseteq Z(G_1)$.

I am working on a school assignment and have been stuck on this question for some time.   Let $f : G \rightarrow G_1$ be a surjective homomorphism (also called epimorphism) from $G$ to another group $G_1$. Prove that $f(Z(G)) \subseteq Z(G_1)$  I know we start by assuming we have an element in $f(Z(G))$ then showing it is also in $Z(G_1)$. Also, $Z(G)$ is the center of $G$, so $Z(G)$ is all the elements of $G$ that commute with all elements in $G$. But how do we know that if we map the elements of $Z(G)$ to $G_1$, then their image will also commute with all the elements in $G_1$? Does it have something to do with using commutativity with the homomorphism? i.e. $f(gz) = f(g)f(z) = f(zg) = f(z)f(g)$.


Renaming hundreds of files at once for proper sorting

I have a ton of files, all named stuff like 1.jpg, 2.jpg, 3.jpg, and so on up to 1439.jpg, however, I have a problem with one of my projects and alphabetizing. It will usually go in the order 1.jpg, 10.jpg, 11.jpg and so on.  What I need is some way to name the files so they are in the format such as 00001.jpg all the way up to 01439.jpg.  How would I be able to do this quickly and efficiently?


What is the correct pronunciation of the word "route"?

I have always used both "root" as in route 66 and "rooter" as in the networking device. The latter has gotten me funny looks often, however I could not bring myself to accept the inconsistency. Today I heard "rowt"  used for a path of movement by a radio presenter. Which is correct?


$f(g(x))=g(f(x))$ implies $f(c)=g(c)$ for some $c$

Let $f$ and $g$ be continuous functions and map from $[0,1]$ to $[0,1]$. Also let $f(g(x)) = g(f(x))$ . Prove that there exists $c$ from $[0,1]$ such that $f(c)=g(c)$.   I will try with contradiction. Let $h(x) = f(x) - g(x) > 0$ for all $x$ from $[0,1]$. Since $f(x)$ maps from $[0,1]$ to $[0,1]$ and is greater then $g$ for all $x$ from $[0,1]$ then this implies that $g(x)$ is not an element of $[0,1]$ for all $x$ from $[0,1]$. This is a contradiction, so there exists $c$ from $[0,1]$ such that $f(c)=g(c)$. Problem here is that I never used fact that  $f(g(x)) = g(f(x))$ which bothers me. Is proof correct or there is hole somewhere?


Sage question: Define the polynomial ring $\Bbb Q[c][x]$.Find the $c$ values where $x^2 + x + c + 1$ has a double root. Sage code I have used.  K.<c>=QQ['c']  R.<x>=K[]  f=x^2+x+c+1  f   How do I find the code for the $c$ values where $x^2 + x + c + 1$ has a double root. Also, can you give some examples so that I can construct some programming code in sage?


I know that the square root of $9$ is $3$  But somebody told me that   If $x^2= 9$ we get the solution as $x=\pm3$  I am confused when do we have $\sqrt{9}=\pm3$ and only $3$?  Please help.