How we can prove that the logical result of $\{(p_i \vee $~ $p_{i+1}$$) $$: i \in  \mathbb{N} \}$ is effectively enumerable ?   Update: as one user requests, I add my method. I use truth table for check the result but I'm sure there is a flaw and other method must be used.

Dear Everyone on this Wonderful Sites:  I'm so glad to participate on this site and ask the first question that mentioned on the Contest some days ago. I ran into a question that wrote this set:   $\{(p_i \vee $~ $p_{i+1}$$) $$: i \in  \mathbb{N}  \}$   and ask this question, Which of the following is False:     -)  this is Satisfiable      --) this is Complete      ---) this is Decidable      ----) set of logical result of this set is effectively enumerable.   Solution of answer sheet is (2).   We try to solve it that without any detail is mentioned in the contest. one of our TA says, It is satisfiable because the TFTF... will satisfy it.  (We couldent get it) and it is decidable because propositional logic is decidable. We read some useful website for completeness (--) and for (----), but we get stuck in it until yet. any useful hint or idea for this question will be highly appreciated.


When should we use PCA over factor analysis? Aren't they essentially the same thing except that factor analysis is modeling observed variables as linear combinations of unobserved factors? Whereas PCA is modeling components as linear combinations of observed variables?

It seems that a number of the statistical packages that I use wrap these two concepts together. However, I'm wondering if there are different assumptions or data 'formalities' that must be true to use one over the other. A real example would be incredibly useful.


I have heard three theories for how space-time is shaped, flat, sphere-like, or saddle-like. Flat is the most likely, as all our measurements implies that space time has curvature close to 0.  Is it plausible for space-time to be shaped like some 3 or 4 dimensional analogue of a torus? A torus has an average curvature of 0. In fact, if you have something like a chess board, and glue the edges together, every square looks like the center, and it is flat around it. (again, I don't know how this generalizes to higher dimensions.)

General relativity says that spacetime is a Lorentzian 4-manifold $M$ whose metric satisfies Einstein's field equations.  I have two questions:   What topological restrictions do Einstein's equations put on the manifold?  For instance, the existence of a Lorentz metric implies some topological things, like the Euler characteristic vanishing. Are there any experiments being done or even any hypothetical experiments that can give information on the topology?  E.g. is there a group of graduate students out there trying to contract loops to discover the fundamental group of the universe?


In my code, i've run a Junit test and the two for loops come up as yellow saying 1 of 2 branches missed. and there's a null pointer exception on the code in the loops. i don't see what the issue is so could someone please help me out? (adding more cus mostly code)  @Test public void testTicTacToeBoard() {     TicTacToeBoard board = new TicTacToeBoard();     CellState[][] expectedBoard = {             {CellState.EMPTY, CellState.EMPTY,CellState.EMPTY},             {CellState.EMPTY,CellState.EMPTY,CellState.EMPTY},             {CellState.EMPTY,CellState.EMPTY,CellState.EMPTY}     };     assertEquals(PlayerID.PLAYER_ONE, board.turn);     assertTrue(array2Dequals(expectedBoard, board.board)); }  public enum PlayerID {     PLAYER_ONE, PLAYER_TWO }  public enum CellState {     EMPTY(" "),     PLAYER_ONE("X"),     PLAYER_TWO("O");      private final String icon;      CellState(String icon){         this.icon = icon;     }      @Override     public String toString(){         return this.icon;     } }  /**  * Represent the game board as a 2D array of CellState. We use enum object  * to ensure that only the three possible values are used.  */ CellState[][] board;  /**  * Represents whose turn it is to play the next time play(int,int) is  * called. We use an enum object PlayerID to ensure only the two possible  * values are used. We cannot use a CellState object as the value EMPTY is  * not a valid value for a player. Therefore we use another enum type.  */ PlayerID turn;  /**  * The constructor must initialise board to a 3x3 2D array fill with the  * value CellState.EMPTY. In addition the turn should be initialised to the  * first player to play, i.e. PlayerID.PLAYER_ONE.  */ public TicTacToeBoard() {     this.turn = PlayerID.PLAYER_ONE;     for(int i = 0; i < 3; i++) {         for(int j = 0; j < 3; j++) {             this.board[i][j] = CellState.EMPTY;         }     }            }

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


I've a shell script at  /home/abc/xyz/test.sh   I've a file at  /home/def/ghi/jkl/lmn/foo.txt   I'm running the scrip from /home as I've set my PATH variable to point to /home/abc/xyz/  I'm passing the relative path of foo.txt to my script like so test ./def/ghi/jkl/lmn/foo.txt  I want to capture the full path of foo.txt into a variable in my script, any pointers?  Tried  and  but in vain.

I want to transform /foo/bar/.. to /foo  Is there a bash command which does this?    Edit: in my practical case, the directory does exist.


I have a bibliography entry which shows up in my .bib file as      @article{Weber1885,     author = {Weber, H F},     journal = {Sitzungsberichte der Akademie der Wissenschaften zu Berlin},     pages = {809--815},     title = {{Das W\"{a}rmeleitungsverm\"{o}gen der tropfbaren Fl\"{u}ssigkeiten}},     year = {1885}     }   However when I compile this the entry shows the authors name as ----- instead of H F Weber (as shown in the picture). I have no idea what to do, however, it does seem to be linked to another article in my .bib file which is:    @article{Weber1880,   author = {Weber, H F},   journal = {Annalen der Physik und Chemie},   number = {5},   title = {{Untersuchungen \"{u}ber die W\"{a}rmeleitung in Fl\"{u}ssigkeiten}},   volume = {10},   year = {1880}   }   In the .bbl file the same reference shows up as:   \bibitem{Weber1885a}    ------, ``{Das W\"{a}rmeleitungsverm\"{o}gen der tropfbaren Fl\"{u}ssigkeiten},'' \emph{Sitzungsberichte der Akademie der Wissenschaften zu Berlin}, vol.~1, pp. 809--815, 1885.   Hence why I see the result I see in the bibliography... Has anyone come across this or have a solution?  Cheers

In my .bib file, I have two entries with exactly the same author names:  @article{Seshadrinathan2010A-Subjective-St,     Author = {K. Seshadrinathan and R. Soundararajan and A. C. Bovik and L. K. Cormack}, ....  @article{Seshadrinathan2009Study-of-Subjec,     Author = {K. Seshadrinathan and R. Soundararajan and A. C. Bovik and L. K. Cormack}, ....   When cited after each other, and typeset with the IEEEtran bibliography style, the .bbl file reads:  \bibitem{Seshadrinathan2010A-Subjective-St} K.~Seshadrinathan, R.~Soundararajan, A.~C. Bovik, and L.~K. Cormack, ``A   subjective study to evaluate video quality assessment algorithms,''   \emph{SPIE Proceedings Human Vision and Electronic Imaging}, 2010.  \bibitem{Seshadrinathan2009Study-of-Subjec} ------, ``Study of subjective and objective quality assessment of video,''   \emph{IEEE Transactions on Image Processing}, 2009.   As you can see, the author names have been replaced with ------. It looks like this in the final PDF:    Is this normal behavior?


I am studying 7th and I am having hard time with this problem. Need help. How to find the value of B in the following equation? A=B^e mod C Thanks in advance :-)

I have the following equation: $$ n \equiv M^k\mod(b) $$ where n, a, b are integers, and M is unknown. How do I solve this equation to find the M value? Those a and b are public keys of the RSA algorithm and n is the result of encryption. I need to find the encrypted message.


I have a file-geodatabase.  It is a road network of a city.   Now I want to export the data into a .txt file for map matching.  I have installed ArcGIS Desktop and not used that software before.  What should I do next?  open the data with ArcMap    txt format     I am completely new to GIS field!

How can I convert a shapefile (GIS) to text, or, how can I extract the information in a shapefile?


I have made a Chua's circuit that is nearly the same as the one in . I don't have an oscilloscope yet, so I connect a DC voltmeter at the place where probes of oscilloscopes should be connected to. From my understanding, the current in the circuit should be alternating current, since the "double scroll" pattern is symmetrical about zero (it is a nonlinear oscillator).   The DC voltmeter only measures the average voltage over a short time period, something like 0.1 seconds. So it should show zero reading if it is connected to an alternating current.  However, when I actually do the experiment, no matter how I adjust the value of R(see diagram), the reading of the voltmeter across C1 never gets to zero. I know that for some values of R, the p.d. across C1 is not alternating. But for the double scroll to appear, average p.d. should be zero.     However, for values of R less than 1000 Ohms, the p.d. across C1 is quite small (about 0.2V)  Does that indicate that there are something wrong in the circuit, or is my understanding above wrong?  Or are the information above insufficient to draw any conclusion?

Suppose I use a voltmeter instead of an oscilloscope in chua's circuit. Voltmeters only measure the average voltage over a short time period.   Questions (please consider both DC and AC voltmeter, because I don't know which one should be used...):   So does the voltmeter show a "coordinate" of the centroid of the double scroll attractor(or any other pattern formed)(since it is an "average") What voltmeter reading corresponds to the double scroll? If the double scroll is symmetric about the origin, should the voltmeter read zero? Will the voltmeter suddenly jump to zero or gradually declines to zero? Practically is there any other difference between voltmeter and oscilloscope?


Relating to :  Can you have multiple fire lashes, each enchanted differently (for example, +1 shock and +2 keen, choosing each time you summon a fire lash which type you want?

Can a  fire lash be made magical so that, for example, it's a +1 shock fire lash?  If so, can a pyrokineticist have multiple fire lashes, each of them different? (For example, can a pyrokineticist have a +1 shock fire lash and a +2 keen fire lash and choose which to use each time the fire lash ability's used?)


I was a final year PhD student (into the last quarter of year 4) in cancer research (passed my qualifying 2 yrs back) but was let go thereafter due to 'unsatisfactory progress' as my data is not sufficient for a PhD thesis. I have to admit here that I've gradually lost my enthusiasm in the project and kinda burnt up after year 3. I've completed all required modules with a decent GPA (4/5). My supervisor was lenient enough to recommend me to graduate with a MSc instead but am facing some 'cross-deparmental red tape' at the moment to say the least (no news of my MSc transfer after 2.5mths of appeal). I'm in the midst of preparing my CV for future job hunt but decided I should just state my current qualification as a 'BSc'. How should I address this 'failure/ 4-yr gap' in my CV?  I have no intention of applying for any academic research jobs but felt it's best that I stay in a relevant field (bio/pharma?). Any advise given would be greatly appreciated. Thank you!

I am in the process of leaving my PhD programme in life sciences at a top university in the UK. A PhD is simply not for me and I find the work/life balance to be intolerable; in addition, my PhD so far has included an industrial placement at a Fortune 500 company that was very eye opening and enjoyable. I am looking to leave academia permanently and apply for graduate schemes.  My question is whether it is better to leave the fact that I quit a PhD off my CV, or to have the failed PhD / MPhil on there, or to mask it as '18 months of lab experience' or something similar. Is it possible to make the fact I left a PhD sound good?


if $m$ is an integer and $\gcd(m,3)=1$，prove that $m^7\equiv m \pmod {63} $. I try using Fermat's Little Theorem,but it doesn't work. Please help me.

Question:  Show that if $\gcd(a,3)=1$ then $a^7 \equiv a\pmod{63} $. Why is this assumption necessary?    Proof:  Since $\gcd(a,3)=1$ $\Leftrightarrow a\equiv 1\pmod 3$ $\Leftrightarrow a^7\equiv 1\pmod3\equiv a\pmod3$  Then using Fermat's Little Theorem:  If $a,p\in\mathbb N$ and $p$ is prime then $a^7\equiv a\pmod7$  $\Rightarrow 3 |a^7-a$ and $7 |a^7-a$  $\Leftrightarrow a^7-a=3k_1$ and $a^7-a=7k_2$  $\Rightarrow (a^7-a)^3=63(k_1)^2k_2$ $\Rightarrow (a^7-a)^3\pmod{63}\equiv 0$  Since $x^m\pmod n\equiv x\pmod n$  $\Rightarrow (a^7-a)^3\pmod{63}\equiv a^7-a\pmod{63}\equiv 0$  $\Leftrightarrow a^7\equiv a\pmod{63}$  The thing I am struggling with is that the question says that the only assumption necessary is that $\gcd(a,3)=1$. Surely there are two assumptions neccessary, since to use Fermat's Little Theorem (in this situation) we need $a\neq 0 \pmod7 \space\space\space(\gcd(a,7)=1)$. I am sure there is something obvious I'm missing -would be great if someone could check over what I have done and point out any mistakes :)


I've just upgraded my OS to Sierra and have turned on the "optimize storage" option for iCloud Drive. But strangely I now get a "your iCloud storage is full" message.    When I checked my local drive, it seems the total size of all folders inside wasn't the same as the iCloud Drive information. When I dive into iCloud preferences the Document size is insanely huge. How do I find out which ones are the large files?    [UPDATE]  I don't have any large files in my Documents folder. But it's strange:

I need help for this iCloud problem: I had no available space left, (of my 50GB plan) so, to keep using iCloud, I deleted some files. After that, instead fixing the problem, the system keep saying that "iCloud storage is full", or "there is no available space left on iCloud". I tried to deleted more files, also my iPhone backup of ~7GB, but iCloud seems not to detect I have done free space, and keep saying that there is no more storage. Has anyone had this issue? Does anyone know how to solve this? Thank you and sorry for my English mistakes because it's not my first language.


A friend found this bug, what is it?  Diamond Bar-ish, California.

I found the insect nside house near Shirdi, Maharashtra. I have captured the image


I've downloaded the tikzlibraryarrows.new.code.tex library from source forge and can use it in the following way:  \documentclass{article} \usepackage{tikz}  % for resizing arrow head \usetikzlibrary{arrows.new}  \begin{document} \begin{tikzpicture}  % collimated light \foreach \y in {2, 0, -2}   \draw[-stealth new, arrow head=2mm] (-10,\y) -- (-3,\y);   \end{tikzpicture} \end{document}   Only when I place the tikzlibraryarrows.new.code.tex file in the same directory as the rest of my source. I've read that you put these files in your "personal tree" and then use texhash. Where is this?  I've tried:  /usr/local/texlive/texmf-local/tex/latex/arrowsnew/tikzlibraryarrows.new.code.tex   and  /usr/local/texlive/2013/arrowsnew/tikzlibraryarrows.new.code.tex   followed by texhash but they still don't seem to be found, and I'm greeted with the following message:  (Press Enter to retry, or Control-D to exit) Please type another input file name:  ! Emergency stop. <argument> ...nput tikzlibrary\pgf@temp .code.tex                                                    \catcode `\@ =\csname tikz... l.8 \usetikzlibrary{arrows.new}

I have an non-root account on a shared server which has an old version of a package available to all users, and I want to use a newer one on my account. I cannot just use $TEXINPUTS, because latex finds the shared version first. How can I get latex to use my version?  I.e. how can I get latex to use the first of these two files:  /home/fgregg/share/texmf/tex/latex/pgf/basiclayer/pgf.sty /usr/share/texmf/tex/latex/pgf/pgf.sty


I was researching about  binary search of a number within a list and came across   Somewhere else I it was mentioned about going for even and odd numbered list separately. But is that language specific? The information is little confusing.  For Binary search , I know high-level I need to carry out following steps,   sort the list in ascending order     Check for middle item within a list  if thats the number we are done if not , if the number is  greater  than the middle number, get rid of lower half   if searched  number is lower than middle number , get rid of uppeer half    keep repeating until number is found   The list can be ascending or descending order and can be of float of int numbers. what's pythonic way of carrying out above pseudocode? I am using python 2.7.x on windows.  **  EDIT ** The mentioned discussion does not cover even and odd list (at least I couldn't see any I would like to request more clarifications on that such as, - If I need to treat even odd list differently - Is there a way in python that will take care of that

Is there a library function that performs binary search on a list/tuple and return the position of the item if found and 'False' (-1, None, etc.) if not?  I found the functions bisect_left/right in the , but they still return a position even if the item is not in the list. That's perfectly fine for their intended usage, but I just want to know if an item is in the list or not (don't want to insert anything).  I thought of using bisect_left and then checking if the item at that position is equal to what I'm searching, but that seems cumbersome (and I also need to do bounds checking if the number can be larger than the largest number in my list). If there is a nicer method I'd like to know about it.  Edit To clarify what I need this for: I'm aware that a dictionary would be very well suited for this, but I'm trying to keep the memory consumption as low as possible. My intended usage would be a sort of double-way look-up table. I have in the table a list of values and I need to be able to access the values based on their index. And also I want to be able to find the index of a particular value or None if the value is not in the list.  Using a dictionary for this would be the fastest way, but would (approximately) double the memory requirements.  I was asking this question thinking that I may have overlooked something in the Python libraries. It seems I'll have to write my own code, as Moe suggested.


I am asking this question after reading through most of the related/relevant question-answers and I believe my query is not a duplicate. Please highlight otherwise and my apologies if it is so.   My in-laws are in the UK now on a visitor visa that expires on 1 Nov 2017. They are having to leave the UK soon to attend a family emergency back in India (death of a close relative- follow up rituals take 13-15 days) and they want to be with the relative's family for an extended period in India. For this reason, I am planning to bring them back by Feb-Mar, by applying for another visitor visa. I am assuming this will be risk-free as I've heard of a certain unwritten rule of a 6 month cooling off period.  Now, my query is- is the 6-month cooling off period from the day the visitor visa expires?- in which case they can only apply for a visitor visa with a tentative travel date on or after 2 May 2018   (or)  Is the 6-month cooling off period from the time they leave UK? in which case they can apply for a visitor visa for a travel date that is 6 months from the date they leave UK, tentatively (if they leave mid-June 2017) early Jan 2018.  Thanks VK

I am a US citizen and have recently visted the UK  with simply a passport which allowed me to vist for 6months I have heard rumors that I am obligated to stay in the US for a Equal amount of time that I have visited the UK before I am able to return, but I am struggling tour no any proof of this obligation .. Am I missing somthing or is it simply not true


Niantic has just announced a new type of power cube called Circle K Power Cube to be released soon. What are the special features of Circle K Power Cube?

Both of these Power Cubes have the same description:     Enhanced Power Cube that provides large XM storage and automatically   recharges Scanner until exhausted.   My Questions:   Is there any difference between these two power cubes? How much Power is initially provided? Is the "automatically recharged" XM limited by time or by XM amount?


I'm new to Java Script  What is the exact difference between (== Vs ===, != Vs !==, etc) in JavaScript? Have read some articles and wanted to be more clear on this. Thanks in advance.

I'm using  to go through JavaScript, and it's returning many suggestions to replace == (two equals signs) with === (three equals signs) when doing things like comparing idSele_UNVEHtype.value.length == 0 inside of an if statement.  Is there a performance benefit to replacing == with ===?   Any performance improvement would be welcomed as many comparison operators exist.  If no type conversion takes place, would there be a performance gain over ==?


I am having problem to find a file has basic commands like rm, ls, cd, etc. I need the file path in Ubuntu to edit them. I checked on web but just found UNIX file locations (/usr/bin).  So, here it is what I mean,  # cd /usr/bin # ls -lh rm -r-xr-xr-x   1 root   bin   14K May  1  2007 rm # chmod 4555 rm # ls -lh rm -r-sr-xr-x   1 root   bin   14K May  1  2007 rm # chmod 2555 rm -r-xr-sr-x   1 root   bin   14K May  1  2007 rm   I want to change the privileges of rm. Inclusion of any suggestions or documentations are welcomed.

How to get the location of a program in Ubuntu? For example I have Oracle, how to get the folder racine (location) of Oracle?


Is there a way to have C++ like enumerated types like in Python? For example, in C++ I can do:  enum Foo {     bar,     foobar,     blah };   and use these as global constants. Is there a similar thing in Python?

I'm mainly a C# developer, but I'm currently working on a project in Python.  How can I represent the equivalent of an Enum in Python?


There's no option to disable Bluetooth permanently but under energy settings you can select to disable both Bluetooth and wifi when not in use. Does this mean that Bluetooth gets disabled automatically? I never use it and want to save power.

How can I deactivate Bluetooth on system startup?


I have this homework question. I looked at the man page for sort and I believe the answer is -o, --output=FILE Is that correct?  It is a Fedora server.  We're supposed to look on man pages, if there is no man page related to the subject than use an info page. If no info page exists either than use the internet.

Am I blind or is there no option like --in-place for sort?  In order to save results to the input file, sed uses -i (--in-place).  Redirecting the output of sort to the input file  sort < f > f   results in making it empty. If there is no --in-place option - maybe there is some trick how to do this in handy way?  (The only thing that cames to my mind:   sort < f > /tmp/f$$ ; cat /tmp/f$$ > f ; rm /tmp/f$$   Moving is not right choice, cause file permissions might be changed. That's why I overwrite with the contents of the temp file which I then remove.)


I want to select every column that its name does not contain Id  This is what I have tried:  Select * From Table_Name Where Column_Name Like '%Id%'   What is the solution?

Is there any RDBMS that implements something like SELECT * EXCEPT?  What I'm after is getting all of the fields except a specific TEXT/BLOB field, and I'd like to just select everything else.  Almost daily I complain to my coworkers that someone should implement this...  It's terribly annoying that it doesn't exist.  Edit: I understand everyone's concern for SELECT *.  I know the risks associated with SELECT *.  However, this, at least in my situation, would not be used for any Production level code, or even Development level code; strictly for debugging, when I need to see all of the values easily.  As I've stated in some of the comments, where I work is strictly a commandline shop, doing everything over ssh.  This makes it difficult to use any gui tools (external connections to the database aren't allowed), etc etc.  Thanks for the suggestions though.


I have the following example from :  "Your dog gets some kind of reward when they bark. Otherwise, they wouldn't do it."  Should it actually be:  "Your dog gets some kind of reward when it barks. Otherwise, it wouldn't do it."  If the first example is actually correct, can you please tell me why. I thought when talking about a single thing, you should always say "it" as opposed to "they".

As I know,  (not only "it"). Also, if a person's gender is unknown, . Is it possible to use "they" when we talk about a specific animal and in what context?


Jakob Nielsen in "Eyetracking Web Usability," recommends against placing text on top of images or textured background in advertisements because only 35% of people will look at it.  Is there any other research addressing how text on images or patterned background affects the usability or readability of that text or site?

What are your thoughts on writing your text in images?  I'm not saying throughout the whole website... But in certain key locations like image carousels. And I'm not talking about the special cases where you have font types that browsers can't render. I'm talking about text that uses standard fonts and is not too big (3/4 bullets).  Should I embed the text in the images that compose the carousel? Or should I apply the text to the images as "real text" HTML?  What are the advantages/ disadvantages of using text in an image?


import java.util.Scanner;  public class Michal {     public static void main(String[] args) {         reply();      }     public static void reply() {         Scanner input=new Scanner(System.in);         String name=input.nextLine();           if(name=="john"){               System.out.println("bear!");         }else if(name=="mary")         {              System.out.println("lovely lady!");         }else{             System.out.println("I don't know that person.");         }         System.out.println(name);         input.close();     }  }   I consider myself still a beginner to Java ,so please don't be harsh in your answers. I was trying to create a program that returns an answer every time it gets a certain input , however it seems to return "I don't know that person" all the time.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Evaluate $L=\lim_{n\rightarrow\infty}\sqrt[{n+1}]{(n+1)!}-\sqrt[n]{n!}$   How I approached it and where I get stuck:  $$\lim_{n\rightarrow\infty}\sqrt[{n+1}]{(n+1)!}-\sqrt[n]{n!}=\lim_{n\rightarrow\infty}\frac{\sqrt[n]{n!}}nn(\frac{\sqrt[{n+1}]{(n+1)!}}{\sqrt[n]{n!}}-1)$$  Now:  $$\lim_{n\rightarrow\infty}\frac{\sqrt[n]{n!}}n=\lim_{n\rightarrow\infty}\sqrt[n]{\frac{n!}{n^n}}=\lim_{n\rightarrow\infty}e^{\frac1n\sum_{k=1}^n\ln(\frac kn)}=e^{\int_0^1\ln(x)dx}=e^{-1}=\frac1e$$  So $L=\lim_{n\to\infty}\frac 1e\times n(\frac{\sqrt[{n+1}]{(n+1)!}}{\sqrt[n]{n!}}-1)$. Now this is where I get stuck. What should I do?

I want to prove the following limit:  $$\lim_{n \to \infty} \sqrt[n+1\;] {(n+1)!} - \sqrt[n] {(n)!} = \frac{1}{e}.$$  I searched the forum & found the link here:  .  But still, there is no way out of the problem. So, please solve it.


There is a plethora of other examples of blatant mistreatment which I'll gladly share with anyone who cares enough to listen.  Should I use the plural instead?  There are a plethora of other examples of blatant mistreatment which I'll gladly share with anyone who cares enough to listen.

A simple question that has sparked some debate, and I couldn't find a concrete answer anywhere. There seems to be two camps: The word plethora indicates plural, so therefore it should be "There are a plethora"; and the other camp says that there is only one plethora (which contains multiple), so it should be "There is a plethora".  I've seen many examples of both. Is there a consensus, or is it just one of those things that can go either way?


So I had a test today, and one of the questions was:   "Give an example of a set, S contained in $R^3$ that is closed under scalar multiplication but isn't closed under addition"  And I was just wondering -- is there a systematic way to go about this rather than search for examples? Perhaps some sort of algebraic way to create such a set that satisfies these conditions without any further thought?

Could anyone provide an example of a nonempty subset $U$ of $R^2$ such that $U$ is closed under scalar multiplication, but $U$ is not a subspace of $R^2$


Obviously, a perpetuum mobile isn't possible by any law in physics, because energy can't be "created" or "destroyed", only transformed. This said, I've had an idea for a perpetuum mobile and can't seem to find my mistake (I'm actually very close to building and trying it).  Here's the plan:  Take a piece of wood and attach its upper end to a screw so it can swing like a pendulum. Then, attach a magnetic metal at the lower end of the wood. Now, place two magnets at each side of the pendulum, so that at the maximum amplitude, the metal will barely touch the magnets and will swing back, due to its weight. Now, in my head, if you give the pendulum a little impulse, it will swing up in one direction and get attracted by the magnet just a tiny bit. Thus, on the "way back", it will have a slightly higher amplitude. So it swings to the other side, closer to the magnet, which will pull the pendulum a bit more upwards, thus increasing the amplitude furthermore. This could theoretically go on and the pendulum will never stop, it will actually gain more momentum at the start.  So the conditions are:   The Metal must be heavy enough so it doesn't stick to the magnets The Metal must be magnetic enough so that we gain amplitude instead of losing it each swing   And that's basically it. I am aware that the construction couldn't work, but struggle to find where I made my mistake. Anyways, if it does work and you guys build it before I do: I want 50% of all profits and want you to name it Perpenduluum Mobile :D

I know that this machine does not work, via thermodynamics. I am asking for an analysis in terms of mechanics and magnetism.  Anyway, so here is the machine:   (source: )    The magnet (the red ball) pull the ball up the ramp, and then it drops the ball through the hole, which then rolls down, and go ups the ramp again. Thermodynamics shows that this can not work.  From a mechanics and magnetism perspective, what happens when you do this, and why can't it happen?  I have a source saying that it would work if it were frictionless and we didn't try to extract energy from it (), so in a certain sense, it is very close to possible (they didn't provide a full analysis though.)  Another Image:


I need a command for an if condition to know if 'file_name' is an hard link (not symlink). Thanks

I'm creating a shell script that would take a filename/path to a file and determine if the file is a symbolic link or a hard link.   The only thing is, I don't know how to see if they are a hard link. I created 2 files, one a hard link and one a symbolic link, to use as a test file. But how would I determine if a file is a hard link or symbolic within a shell script?   Also, how would I find the destination partition of a symbolic link? So let's say I have a file that links to a different partition, how would I find the path to that original file?


I want to use git for my visual studio project , when I googled I found these two tools which integrate in Visual studio.    and   I want to know which is better to use.

As a long-time  user (and hater) I was discussing switching to  with a colleague; he suggested using  instead. Since, apparently, it can be used as peer-to-peer without a central server (we are a 3-developer team).   I have not been able to find anything about tools that integrate Git with Visual Studio, though - does such a thing exist?   What are the technologies available for using Git with Visual Studio? And what do I need to know about how they differ before I begin?


Is it possible to write a macro, that takes the rest of the current group as an argument?  Usecase  I want to write a macro that can be used as  \section{\TODO Introduction $of$ \textsc{The Topic}}   such that \TODO is passed Introduction of the topic as its first argument. The \textsc and $of$ is there in order to clarify, that I need support for general latex constructs, not only for plain-text sequences.  Why not \TODO{Intro...}?  Normally I'd be the first to advocate justusing \TODO{Intro...} instead, but this reduces the readability of software-provided document outlines. E.g. in TeXStudio:

I want to define a macro that behaves like \ttfamily, i.e. it should read everything until } (or \endgroup?) as a parameter.  I.e. this  {\mynewmacro lorem ipsum  dolores }   should be equivalent to this  \mymacro{lorem ipsum  dolores }   Is this possible?


I would like to use single domain for multiple countries web site. So, instead of using second level domain for each country like:  us.mysite.com  uk.mysite.com  fr.mysite.com  de.mysite.com   I would like to use same top level domain mysite.com but for each IP connected from US it will return US content, for IP connected from GB - GB content and so forth. Same for scan robots, google, bing etc.  What are advantages and disadvantages of using that way, especially for SEO?  Appreciate any response! Thank you!

Is it better to have separate country specific domains (which costs more money) or sub domains which define the country, for better SEO?  e.g.   example.com example.com.au example.co.uk   vs   example.com au.example.com uk.example.com   Assumption: The search engine web master tools, each sub domain are associated to a country. Example au.example.com is associated to the country Australia.  Update #1  I understand that both methods do work, especially when i utilize the assumption, listed above. The question is about: Which method is better? Is there such a small SEO difference between them? Is the first method way way way better than the second with getting better SEO results?  Update #2  A number of folks have suggested that the following is a good/better approach:   example.com/ example.com/au example.com/uk      By adding a country specific ISO   code to the end of the url/the first   folder of the domain can be recognised   as the country.   But a number of SEO mates have suggested that this is a valuable waste of folder level space. Er.. how can I explain. OK, it's been suggested by some SEO experts that if the number of levels or folders in the domain exceeds 5 then the page drops dramatically in importance. Basically, you don't want to make it deep. As such, adding the country as the first level can be considered a waste, especially when it can be handled by the domain OR sub domain - hence the question :)


I have a  that collects WordPress tags with specific description.   I'm looking for a hook name that fires when user edits a WordPress tag or creates a new tag in admin so I can delete my transient and create a new one from updated tags.

So, i have a function in my template file functions.php which cache a search form that contain a custom taxonomie terms. I want to flush cache (or delete one cache group) when I add/delete/edit terms of a specific taxonomie.  Is it possible? maybe with do_action, but for which hook? thx


This question is in relation to the specific case where $\sqrt{3} \gt \sqrt{2}$. Can we generalize this result and prove that  $\sqrt{x+1} \gt \sqrt{x}$ if $x \gt 1$. Can we also prove the more general case that $\sqrt{y} \gt \sqrt{x}$ if $0 \lt x \lt y$

In terms of Inequalities, we have covered till AM-GM inequality and Cauchy-Schwarz Inequality in class. I was thinking about applying AM-GM inequality but not sure if its right.


I made a mistake and used uninitialized local variable in a function and happened to find a single line of "cout" could change the uninitialized value. To simplify, I show the problem as follow.  #include <stdio.h>  void foo(void){   int i;   printf("%d\n", i);   i = 777; } int main(void){   foo();   //cout << "hello!" << endl;   foo();   return 0; }   The line I comment out will change the output from (unknown#;777) to (unknown#;hello!;0). Could someone help explain?  Thanks.

What are all the common undefined behaviours that a C++ programmer should know about?  Say, like:  a[i] = i++;


My baby is 2 weeks old and cries a lot sudden, his grandma think it's because of tummy as he get pain in tummy and have they have started to give him drops of Liquorice extract water on a room temperature (which IMO is strange), how to know what is going on with my baby? As I hate grandma experiments on her.

my 4 week old daughter will not stop crying. We've tried everything from sucking, both on pacifiers and fingers to breastfeeding, white noise, movement, diaper is clean she doesn't seem to have a fever.   We've tried everything we can read about and think of.  We are both a little bit ill, the common cold and the baby may have gotten it and be upset but we are just at the end of our nerves when nothing helps our poor little one!   Does anyone know anything we can do to help?


Since   $ G =( \prod_{1}^{\infty} \mathbb{Z} )\times  \mathbb{Z}  \times \mathbb{Z}  \cong (\prod_{1}^{\infty} \mathbb{Z}) \times \mathbb{Z}  $,   by taking quotients we get  $\mathbb{Z \times Z} \cong G/ \prod_{1}^{\infty} \mathbb{Z} \cong \mathbb{Z}$.  Therefore   $\mathbb{Z} \cong \mathbb{Z \times Z}$.  But $\mathbb{Z}$ is indecomposable!  What's wrong with above proof?

Let $G$, $H$, and $K$ be abelian groups. Assume $G \oplus H \cong G \oplus K$. If each are finitely generated, then the structure theorem easily gives us that $H \cong K$. However, there are counterexamples in the general case, namely $H=\mathbb{Z}$, $K=\mathbb{Z} \oplus \mathbb{Z}$, and $G=\bigoplus_{i=1}^\infty\mathbb{Z}$.   I am wondering what goes wrong with the following argument:   Form the split short exact sequence  $$0 \to G \xrightarrow{i} G \oplus H \xrightarrow{\pi} H \to 0$$  where $i$ and $\pi$ are the inclusion and projection, respectively. Then don't we immediately get from the first isomorphism theorem that $H \cong (G \oplus H)/G$, which would contradict the counterexample above?   If we run this for the counterexample given, we get the sequence   $$0 \to \bigoplus_{i=1}^\infty\mathbb{Z} \to \bigoplus_{i=1}^\infty\mathbb{Z} \to \mathbb{Z} \to 0$$  which seems to still be short exact, even though here $G \cong G \oplus H$. But of course here we can see directly that $(G \oplus H)/G \cong G/G$, which is trivial. So what went wrong?   It seems to me to be something along these lines: In this case, the kernel of the projection is not the same as the original group, it is just, say, $0 \oplus \mathbb{Z} \oplus \mathbb{Z} \oplus \dots$, i.e. nontrivial from the second coordinate on, which just happens to be isomorphic to the original group. So if we form the other short exact sequence with $K$ in place of $H$, then the difference seems to be that we have two different projection maps with different (but isomorphic) kernels.   But I'm not really sure how to explain this in the general case, if my reasoning is correct to begin with.   Thanks in advance for any help!


I'm in my second year studying physics, and ever since I took LinAlg, I've been noticing LinAlg-related concepts pop up all over the place, but it has never been presented directly as matrices, bases, etc.   For instance, I want to understand what an eigenstate- or frequency has to do with matrix eigenvalues. I want to know why we use sin and cos in Fourier analysis (it's a basis, but for which vector space, etc.). I find LinAlg elegant and compact, and I want to know what formal classical mechanics, special relativity, analytical mechanics, QM and EM (and statistical mechanics if possible) looks like using LinAlg to accomplish general and rigid derivations of the concepts involved.   Tensor notation might also be acceptable, even though I have no experience with it yet.   Any suggestions for textbooks/texts that might help?  EDIT: I don't see how this is a question about how QM relates to/uses LinAlg? There is one textbook reference in the answers for that other question, and it only refers to one chapter.

A week ago I  people on this site what mathematical background was needed for understanding Quantum Physics, and most of you mentioned Linear Algebra, so I decided to conduct a self-study of Linear Algebra. Of course, I'm just 1 week in, but I have some questions.    How is this going to be applicable to quantum physics? I have learned about matrices (addition, subtraction, multiplication and inversion) and about how to solve multiple equations with 3 unknowns using matrices, and now I am starting to learn about vectors. I am just 1 week in, so this is probably not even the tip of the iceberg, but I want to know how this is going to help me.  Also, say I master Linear Algebra in general in half a year (I'm in high school but I'm extremely fast with maths), what other 'types' of math would I need to self-study before being able to understand rudimentary quantum physics mathematically?


Below code compiles as-is but fails when commenting out the \input statement. Why, and how to fix this?  \documentclass{article}  \usepackage{booktabs}  \begin{filecontents*}{mwe-bottomrule} abc \\ \end{filecontents*}  \begin{document}  \begin{tabular}{l}     abc \\     %\input{mwe-bottomrule}     \bottomrule \end{tabular}  \end{document}  Replacing \\ with \tabularnewline has no effect. Latest TeXlive on macOS.

Since updating to the 2020 Fall release (MikTeX on Windows but also tested with TeXLive), I can no longer compile files where tables are imported from an external file using \input and followed by \hline (or \bottomrule). Things work perfectly with older releases. Note that it works if the last \\ is outside the file to be imported, but this is not a feasible option if the tables are created automatically from other softwares. Here is a MWE:  \begin{document}  \begin{table}   \caption{Table in text}   \begin{tabular}{lcc}     a & 1 & 2\\     b & 1 & 2\\     \hline   \end{tabular} \end{table}  \begin{table}   \caption{Table in other file 1}   \begin{tabular}{lcc}     \input{table1}     \hline   \end{tabular} \end{table}  \begin{table}   \caption{Table in other file 2}   \begin{tabular}{lcc}     \input{table2}\\     \hline   \end{tabular} \end{table}  \end{document}  with external files: table1.tex:     a & 1 & 2\\     b & 1 & 2\\  table2.tex:     a & 1 & 2\\     b & 1 & 2  Here is the log when it fails: This is pdfTeX, Version 3.14159265-2.6-1.40.21 (MiKTeX 20.10) entering extended mode (MWE.tex LaTeX2e <2020-10-01> patch level 1 L3 programming layer <2020-10-05> xparse <2020-03-03> ("C:\Program Files\MiKTeX\tex/latex/base\article.cls" Document Class: article 2020/04/10 v1.4m Standard LaTeX document class ("C:\Program Files\MiKTeX\tex/latex/base\size10.clo")) ("C:\Program Files\MiKTeX\tex/latex/l3backend\l3backend-pdftex.def") (MWE.aux) (table1.tex) ! Misplaced \noalign. \hline ->\noalign                    {\ifnum 0=`}\fi \hrule \@height \arrayrulewidth \futurelet... l.18     \hline                 ! You can't use `\hrule' here except with leaders. \hline ->\noalign {\ifnum 0=`}\fi \hrule                                           \@height \arrayrulewidth \futurelet... l.18     \hline                 ! Missing number, treated as zero. <to be read again>                     \futurelet  l.18     \hline                 ! Illegal unit of measure (pt inserted). <to be read again>                     \futurelet  l.18     \hline                 (table2.tex) [1{C:/Users/Gouel/AppData/Local/MiKTeX/pdftex/config/pdftex.map}] (MWE.aux) ) (see the transcript file for additional information)<C:/Program Files/MiKTeX/fo nts/type1/public/amsfonts/cm/cmr10.pfb> Output written on MWE.pdf (1 page, 14750 bytes). Transcript written on MWE.log.  With an older release under Linux, it works perfectly: This is pdfTeX, Version 3.14159265-2.6-1.40.20 (TeX Live 2019/Debian) (preloaded format=pdflatex)  restricted \write18 enabled. entering extended mode (./MWE.tex LaTeX2e <2020-02-02> patch level 2 L3 programming layer <2020-02-14> (/usr/share/texlive/texmf-dist/tex/latex/base/article.cls Document Class: article 2019/12/20 v1.4l Standard LaTeX document class (/usr/share/texlive/texmf-dist/tex/latex/base/size10.clo)) (/usr/share/texlive/texmf-dist/tex/latex/l3backend/l3backend-pdfmode.def) (./MWE.aux) (./table1.tex) (./table2.tex) [1{/var/lib/texmf/fonts/map/pdftex/up dmap/pdftex.map}] (./MWE.aux) )</usr/share/texlive/texmf-dist/fonts/type1/publi c/amsfonts/cm/cmr10.pfb> Output written on MWE.pdf (1 page, 13788 bytes). Transcript written on MWE.log.


I'm making a blog page and I want everything on the page be centered. It's just 1 column, I'm not going to introduce any extra columns, at least not soon. To center everything on the page I wrap everything into a div of center-block class. That works great, until I set max-width:28em on the article's text, which makes it render a little off center and more to the left.  Here are examples. Check on "Full page" mode.  Without max-width:28em: centering works great, but the article text is too wide.    <link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent porta nulla in tellus condimentum eleifend. Suspendisse purus lectus, fermentum et magna nec, egestas pretium est. Vestibulum ultrices leo nibh, quis aliquam nisl aliquam vitae. Vivamus nec fringilla ex, hendrerit dictum lorem. Suspendisse condimentum ut lectus ultrices sodales. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Aenean faucibus purus at malesuada consequat. Donec urna risus, imperdiet id dapibus sit amet, scelerisque ut leo. Donec arcu turpis, congue at elit et, dignissim congue lorem. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Quisque eget malesuada tellus. Duis quis dignissim tortor. Pellentesque ac imperdiet justo, at tempor nisl. Duis sed justo nisi.

     With max-width:28em: centering is broken but article's text is of good width.    .article {     max-width: 28em; } <link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent porta nulla in tellus condimentum eleifend. Suspendisse purus lectus, fermentum et magna nec, egestas pretium est. Vestibulum ultrices leo nibh, quis aliquam nisl aliquam vitae. Vivamus nec fringilla ex, hendrerit dictum lorem. Suspendisse condimentum ut lectus ultrices sodales. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Aenean faucibus purus at malesuada consequat. Donec urna risus, imperdiet id dapibus sit amet, scelerisque ut leo. Donec arcu turpis, congue at elit et, dignissim congue lorem. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Quisque eget malesuada tellus. Duis quis dignissim tortor. Pellentesque ac imperdiet justo, at tempor nisl. Duis sed justo nisi.

How can I horizontally center a
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Foo foo


I have a Google Spreadsheet with a list of emails. I want to build a routine that send email automatically to those email addresses. I also want to attach a PDF to this email. The PDF file is located in my Google Drive.  When running the following script, I'm getting the following error:     TypeError: Cannot find function getAs in object FileIterator. (line   21, file "Code")   I'm new to Google Spreadsheets, please can you help me out?  This is the code:  // This constant is written in column C for rows for which an email // has been sent successfully. var EMAIL_SENT = "EMAIL_SENT";  function sendEmails2() {   var sheet = SpreadsheetApp.getActiveSheet();   var startRow = 2;  // First row of data to process   var numRows = 1;   // Number of rows to process   // Fetch the range of cells A2:B3   var dataRange = sheet.getRange(startRow, 1, numRows, 2)   // Fetch values for each row in the Range.   var data = dataRange.getValues();   for (var i = 0; i < data.length; ++i) {     var row = data[i];     var emailAddress = row[0];  // First column     var message = row[1];       // Second column     var emailSent = row[2];     // Third column     if (emailSent != EMAIL_SENT) {  // Prevents sending duplicates       var subject = "Sending emails from a Spreadsheet";       var file = DriveApp.getFilesByName('test123.pdf')       MailApp.sendEmail(emailAddress, subject, message, {      attachments: [file.getAs(MimeType.PDF)],      name: 'Automatic Emailer Script'  });       sheet.getRange(startRow + i, 3).setValue(EMAIL_SENT);       // Make sure the cell is updated right away in case the script is interrupted       SpreadsheetApp.flush();     }   } }

I want to send a PDF attachment located on Google Drive from a Sheet.   Code I'm using is:  function sendEmails() {   var sheet = SpreadsheetApp.getActiveSheet();   var startRow = 2;  // First row of data to process   var numRows = 8;   // Number of rows to process   // Fetch the range of cells A2:B3   var dataRange = sheet.getRange(startRow, 1, numRows, 2)   // Fetch values for each row in the Range.   var file = DriveApp.getFilesByName('ScriptCarPass.pdf')   var data = dataRange.getValues();   for (i in data) {      var row = data[i];     var emailAddress = row[0];  // First column     var message = row[1];       // Second column     var subject = "Sending emails from a Spreadsheet";     MailApp.sendEmail(emailAddress, subject, message, {attachments: file});   } }   Everything works fine except the attachment - i.e. if I run without the attachment it works fine.  I keep getting error Invalid argument: inlineImages  I've also tried with:   attachments: [file.getAs(MimeType.PDF)]   but that gives error that .getAs isn't recognised.


I was reading an  over on Law.SE, and it made me wonder about how the IRS calculates tax on barter transactions.  Lets say that I do a job in January, and get paid for my work with 20 goats and when I received the payment, goats were worth about $100 each.  Later that year, in October, I do another job of about the same value, but this time I get paid with 5 goats.  The goat market has gone absolutely crazy and they are now worth about $400 a head.  In December, the goat bubble officially popped, and they're down to $20 each.  I didn't earn any goats in December, but this market downturn might be important.  So, for the year, my taxable income was 25 goats.  How would I, or more importantly, how would the IRS allow me to calculate taxes on my earnings?  Would I have to prove the market value of the goat when I received payment?  Can I claim that I only earned 25 * $20 since that's what the goats are worth now?  Note:  Assume that this small income is taxable as if I just made $50k/year.  I realize that with such a small earning taxes wouldn't normally be due and I'd be living in poverty with my goats, but that's not a part of my question.

Can someone help me elucidate the definition of "income" from a tax perspective? More specifically, if Joe is paid for his work in avocados instead of dollars, then would Joe be exempt from paying any income tax for the year? Or would the value of avocados earned for the year be translated into dollars which would then be considered Joe's annual income? If so, what guidelines would one use to make this translation? (Make the assumption that Joe does not sell the avocados (for dollars) at a later date and either eats them or trades them for other real property)  What if he was paid in gold instead of avocados?


I would like to know how to connect with friends on Minecraft without everyone using the same WiFi Network?

I've had this problem a lot lately because me and my friend would like to play a map together, but the thing is we can't use LAN. She lives in California and I live 700 miles away, so we are definitely not connected to the same wifi. If you could please answer this it would be a lot of help to me because I have been searching this for a while and nothing that works have come up so far. Thanks


Windows 10 update kb3081436 added dynamic wallpaper changes on login/lock screen. The photos are really awesome.    Does exist some script to take those photos and uses them as Ubuntu wallpaper

Can anyone help me out with how to make Bing Picture to my Desktop Wallpaper?    So it works by downloading the highest quality of todays picture. Then storing it ex in the Picture folder of your account. After that automatically changing the picture itself.  It should continue the same everyday without hassle in the background.  Probably something I have to add in the Startup Applications. Any differences between Ubuntu versions?    -Do I have to write a script?  This would be appreciated by many others too! Thank You in Advance :)


Yesterday I was watching discovery channel, on a program they said that 'if two pieces of the same type of metal touch in space, they will be permanently stuck to each other.' Is it true..? If yes... then how is it so? Why is it not possible on Earth?

It is my understanding that metals are a crystal lattice of ions, held together by delocalized electrons, which move freely through the lattice (and conduct electricity, heat, etc.).   If two pieces of the same metal are touched together, why don't they bond?   It seems to me the delocalized electrons would move from one metal to the other, and extend the bond, holding the two pieces together. If the electrons don't move freely from one piece to the other, why would this not happen when a current is applied (through the two pieces)?


I torrented a bunch of movies last week, but there was one within the group that didn't have a name. I did not think much of it as it was downloading, since I was torrenting a few obscure titles. When I went to open it earlier this afternoon, it would not play on any program on my laptop. It was saved as an MPEG file, so I downloaded a codec from the Microsoft store to play it, and still, no dice. I googled the title it provided - movie 65923 - to try and see what movie it even was, and it said that it was probably malware and I should get rid of it. However, when I go to delete it, a message comes up saying another program has opened the file, so I should close that program and try again. I closed every program on my laptop and still, no success. I even did the Windows key + R + %temp% trick, deleted everything there, and nothing changed. What can I do? I appreciate your help :)

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


I want to ask about Linq. Can I discard change to database using Linq? For example, I've submit data to database, but I haven't use db.SubmitChanges(); syntax. Well, this is going to be hard to explain, so let's take a look for the example.  //the Code for insert the data to database db.myTable.InsertOnSubmit(insert);   So, if I want to submit to database, I have to use :  db.SubmitChanges();   But, what I want to do is to discard or cancel my insert data, so when I use db.SubmitChanges(); the data will not go to the database.  I'm so sorry if this is so confusing, I'm still beginner.

On Linq to SQL's DataContext I am able to call SubmitChanges() to submit all changes.  What I want is to somehow reject all changes in the datacontext and rollback all changes (preferable without going to the database).  Is this possible?


Is there any (fast) algorithm that produces irreducible polynomials over $\mathbb{F}_2$?  EDIT: I look up for a irreducible polynomial generator, that is different from decider algorithm for irreducibility.  EDIT2: By Input $n \in \mathbb{N}$ to the algorithm $A$ we expect $n$ irreducible polynomials over $\mathbb{F}_2$. I need that $A$ always returns same result by a specific input $n$ (I don't want random irr. polynomials generator).

Is there any criterion (theorem or algorithm) to find out a given polynomial $f(x)$ is irreducible over the field $\mathbb{F}_2$?


I am starting to learn PHP and encounter the issue below:  function dechex_helper($dec){     $hex = dechex($dec);     if($hex == 0){         return '00';     }     return $hex; }  function webColors($red, $green, $blue){     return '#'.dechex_helper($red).dechex_helper($green).dechex_helper($blue); }  echo 'webColors(255, 0, 0)'.': '.webColors(255, 0, 0).'
'; echo 'webColors(0, 0, 255)'.': '.webColors(0, 0, 255).'
'; echo 'webColors(255, 0, 191)'.': '.webColors(255, 0, 191).'
'; echo 'webColors(0, 0, 0)'.': '.webColors(0, 0, 0).'
';   Result:  webColors(255, 0, 0): #000000 webColors(0, 0, 255): #000000 webColors(255, 0, 191): #000000 webColors(0, 0, 0): #000000   but if I change the line:  if($hex == 0){   To:  if($hex === '0'){   The result will be correct:  webColors(255, 0, 0): #ff0000 webColors(0, 0, 255): #0000ff webColors(255, 0, 191): #ff00bf webColors(0, 0, 0): #000000   Can someone explain what happens with it?

What is the difference between == and ===?  How exactly does the loosely == comparison work? How exactly does the strict === comparison work?  What would be some useful examples?


Of course I can set headers when issuing requests programmatically, i.e. for Ajax calls.  But is there a way to let the browser do its thing and access the request headers for resources in a document, similar to timing information provided by the ?  I'd like to know the complete set of headers the browser used when requesting the document and its resources.

How do I access a page's HTTP response headers via JavaScript?  Related to , which was modified to ask about accessing two specific HTTP headers.     Related:


The first benefit of PAM says  When you take the Attack action and attack with only a glaive, halberd, quarterstaff, or spear, you can use a bonus action to make a melee attack with the opposite end of the weapon.  Can I only make this extra attack after the first attack action? And if so, can I make another attack in between the first attack action, and then bonus action attack or could I do it in reverse so I use my BA first, then the non-polearm attack, and then the polearm attack.

The first benefit of the  feat says (PHB, p. 168):  When you take the Attack action and attack with only a glaive, halberd, quarterstaff, or spear, you can use a bonus action to make a melee attack with the opposite end of the weapon.  Does this additional attack clearly occur after the attack with the main weapon? Or is there a time to use it between the attack being "declared" and resolving the main attack? Background/motivation: I would like to attempt the following:  Announce I am attacking Bandit Keith; Use the bonus action to attack with my halberd's shaft, with a Tripping Attack maneuver; Assuming success on the attack / STR check, attack with the halberd blade at advantage;  While that appears to fit how the flow of a fight works in my head, the word take appears a bit ambiguous to me if I wish to argue from RAW. If an action is taken, does this mean it must be completely resolved?


I'm implementing a filtering option on my website where users can post and upvote images. The filtering options are: trending (by default) and new.  The URLs are like this:     example.com/tags/sunset/ ← Trending images (ALL images with more than 5 upvotes) example.com/tags/sunset/?sort=new ← New images (ALL images ordered by descending date)   I'm using canonical URLs in order to avoid duplicate content. For example the two URLs above will have the same canonical URL (URL with trending content):  example.com/tags/sunset/   However I'm having a problem with the pagination canonical URLs.   There are 10 images per pages.   Let's say the sunset tag have 25 images (1,2,3 pages):  example.com/tags/sunset/?sort=new&page=3   but only 15 are trending (1,2 pages):  example.com/tags/sunset/?page=2   The canonical URL for the URL filtered with new content (all image) will be:   example.com/tags/sunset/&page=3   However this URL will return an error 404 because there are not 3 pages of trending content for the tag sunset.  What can I do to avoid this issue?

How should one use rel="canonical" in sortable paginated lists?  An unsorted list of products is not the same as the same list sorted, nor are lists sorted in different ways equivalent. For example, compare:   http://www.example.com/desktops?sort=p.price&order=ASC&limit=5&page=2 with http://www.example.com/desktops?sort=p.price&order=DESC&limit=5&page=2   These are two very different pages, but they have the same canonical URL. Surely this is incorrect?


I have a problem. I have found the HTML code for the downwards arrow, &darr; (↓)  Cool. Now I need to use it in CSS like so:  nav a:hover {content:"&darr";}   That obviously won't work since &darr; is an HTML symbol. There seems to be less info about these "escaped unicode" symbols that are used in css. There are other symbols like \2020 that I found but no arrows. What are the arrow codes?

How do you use the CSS content property to add HTML entities?  Using something like this just prints &nbsp; to the screen instead of the non-breaking space:  .breadcrumbs a:before {     content: '&nbsp;'; }


I want to do something like this:  user@myserver$echo -en "\rSome text to overwrite same line command is on"   The problem is I end up with this:  Some text to overwrite same line command is onuser@myserver$   If I do echo -e only then I get this:  Some text to overwrite same line command is on  user@myserver$   Which is okay except it causes the console to scroll.  I don't want it to scroll because my console window with tmux is only one line high.  I've tried padding the right hand side of the string with spaces but that doesn't work correctly.

How can certain programs set background and font colors, write characters to the same location on screen (e.g. to the third row, fifth column) more than once?  Some examples are the progress bar displayed by curl google.com > a, some installation screens and nearly any text editor.


I've got some customer_comments split out into multiple rows due to database design, and for a report I need to combine the comments from each unique id into one row. I previously tried something working with this  trick but I can't recall it and must not have saved it. I can't seem to get it to work in this case either, only seems to work on a single row.  The data looks like this:  id  row_num  customer_code comments ----------------------------------- 1   1        Dilbert        Hard 1   2        Dilbert        Worker 2   1        Wally          Lazy   My results need to look like this:  id  customer_code comments ------------------------------ 1   Dilbert        Hard Worker 2   Wally          Lazy   So for each row_num there's really only one row of results; the comments should be combined in the order of row_num. The above linked SELECT trick works to get all the values for a specific query as one row, but I can't figure out how to make it work as part of a SELECT statement that spits all these rows out.   My query has to go through the whole table on its own and output these rows. I'm not combining them into multiple columns, one for each row, so PIVOT doesn't seem applicable.


Let's say we have a massless body connected to 2 strings. Now lets pull the body with a force $F$. As the body is massless tension in both strings will be equal. Let that be $T$. Now we know that $$F-2T=Ma$$ But as $M=0$, we get $F=2T$. Now although the forces are equal the body still has an non zero acceleration $a$. How can this be possible, even theoretically?

Do massless particles have a meaning in Newtonian mechanics? Do they have a physical interpretation? Because we don't have an equation of motion for massless particles, we don't have a gravitational potential. We could have electric potential but then we lack the equation of motion. I don't see how they can be a physical object, but I would love to hear from you about this.


I have some data that is described by $n$, quartiles (+ additional quantile point) and the mean.  Is it possible to rebuild or model this distribution from these statistics?  As the median and the mean are not the same, there is at least some skew, but otherwise, I would assume the data to be normal like.  Edit:  This was marked as a duplicate, but in the other questions I found while searching, none of them included the information regarding the mean as a data point to recreate the distribution.  Because of that additional parameter, I wondered if it made the estimation possible.  In short, the affect of having the mean was not apparent from the other answers related to the question.

I am interested in predicting a normal distribution, but not sure if this is possible.   I do not have information on the mean or standard deviation. However, I know the range of values, let's say from 0 to 10, and I know the sample size, let's say 1000, and I also know that value 8.1 is the 50th highest value.  Is it possible in any way from this information to infer more about what the distribution looks like?


I am playing minecraft 1.15.2 single player and want to invite some people to play with me there. However every time they try to connect, they get as far as joining and seeing only the sky or an empty minecraft world.  I have setup a hamachi network and for the duration of this I have disabled the firewall of my Antivirus (Eset) which allowed us to get to this point. I even get the chat message that he had joined the game but then after a short while he gets the message that he has timed out.  I have no idea what else to try since we have tried to find a solution for this for quite some time now. I don't know if there is anything better I should try or not or if I have to change something on my side or not.

My friend had hosted a Minecraft server before and brought it back up today with my help. He and anyone in his LAN can connect. However we have had a few people try to connect, including me, and when we try to connect it gives the message:  Failed to connect to the server Connection timed out: connect  What does this exactly mean? How do we fix this?


Recently, while I was installing windows 7, I tried to re-partition my 750 gb hdd. There were following partitions inside my HDD:   Swap  Ubuntu Backtrack System reserved for Windows 7 Windows 7   I tried to remove old windows 7's reserved partition (which is 100 mb). And my laptop suddenly stuck and there was no way to continue installation process but restart.   When I restarted my laptop, BIOS was detecting HDD as device but nothing else. Just black screen.   I rejected hdd from my laptop and tested on another pc.   I tried to fix this problem using bunch of software such as: Gparted (which stuck during loading process, and alerted message "... kernel panic ...") , Mini XP (doesn't see any hdd device), Windows 7 (alse didn't see any hdd device).  What do you suggest? Thx in advance for your time.

After moving to SSD I deleted the System Partition (100MB) from my previous drive, causing mass destruction.  I tried to delete the System Partition which windows 7 creates (on my previous disc as I moved to SSD) and when I tried to extend the main partition size to include the new Unallocated Space it asked me if I wanted to convert the disc to Dynamic.  I simply pressed yes and the partition simply disappeared into unallocated space. All of my family pictures / videos lost.  After reading an article on Microsoft they said to recreate the partition with the same exact size, so I tried to do that but it didn't work. I did not format the drive at all when I created partitions.  How can I possibly recover the partitions?  Thanks!


I want to replace the first string with the next  FindText[1]=/Folder 1/01. SubFolder/Demo(Object)  ReplaceText[1]=/Folder 1/01. SubFolder/02. SubFolder/Demo(Object)   I have tried this option with "|" but doesn't work.   >>sed -i 's|FindText[1]=/Folder 1/01. SubFolder/Demo(Object)|ReplaceText[1]=/Folder 1/01. SubFolder/02. SubFolder/Demo(Object)|g' filename.txt   The square brackets in the find expression doesn't seem to be found.

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


I created a low poly tree, and it's what I see in the editor:    But, in my 3D game engine (Godot Engine), this is how the tree looks:    (On the left, this is an icosphere created with Blender).  I don't know what part I missed, or what I done wrong for having this result with the 3D engine.  I started with a simple cube, cutting it and extruded it for this result, and I created manually near all the faces (except for the trunk). Then I exported the object in the Wavefront format (.obj).  Is my method wrong? Need I to recreate the whole object? How can I fix it?

While rendering a mesh with smooth shading on, I get a dark region/shadow on certain faces. The effect is more evident when smooth shading is applied to a mesh containing ngons, with the ngons turning black when rendered.   The blackening effect is visible in the viewport too.  How can I solve this problem?


If I have a machine learning question, I am able to post it in any of Cross Validated, Data Science SE, or AI SE. Does it make sense to have so many different places to post the same type of content rather than some consolidated place to post machine learning questions? Why should I pick one over another? All I'm able to infer from  that CV is aimed for more theoretical problems and Data Science is for more applied questions.    Where does that leave the AI SE?  What incentive is there to ever post in the AI SE over one of the other two, given that the other two have larger communities and are more likely to get a response back?  Also, since SE discourages cross-posting, how can I get my question to have the attention of both communities?

There seems to be more than a few computer science/programming Stack Exchange networks (is that the correct term?). Stack Overflow, being the first, has by far the most users, questions, and answers.  What is the reasoning for creating the others, and are there clear guidelines for which kinds of questions should be posted? I can see a large amount of potential overflow, many cases of people not getting a good answer to their question, because the person who has the answer isn't browsing that particular network at the moment.  I understand that they were probably created for organizational purposes, but wouldn't it almost make more sense to just have them as categories under Stack Overflow, keep them separated but still connected, instead of making people have to create multiple 'account's, one for each network?  I am sure there was a very good reason to break them up, but as someone that is new to SE, it can be somewhat intimidating to decide which one to post in to ensure you get a good answer. For example, if I am a computer science student, my first instinct might to be to post in the computer science network, until I see that it literally has 1% of the users as the Stack Overflow network, which still seems to be for programming/computer science related questions.  So my second instinct would then to be to post it into the Stack Overflow site on the basis that I have a significantly higher chance of my question being seen and getting a good answer. Then I notice that there is also a 'programmers' network, and I don't even begin to know where that fits in. I, and I am assuming most people, will probably just post on Stack Overflow to be safe.  My question is, other than the short little description blurb of each one, is there a clear cut set of guidelines which what each network is intended for, what kinds of questions should go to each one, and is anything being done to encourage people to post in these newer, smaller (more specialized?) networks as opposed to just posting in big daddy Stack Overflow?  Now again, this is for computer science/programming/"why isn't this code doing what I want?" related questions, I am not saying that if I had a question about Linux or WordPress or something I would have the same confusion.


When I play MTG, sometimes I can't kill creature which entered the battlefield under opponent's control right away. To give example  entered the battlefield but I could not kill him instant speed even when I had both mana and spell. But at other occasions (if I remember correctly) I could kill a creature which entered the game before it could activate its ability (not ability activated "When entered" but something like use mana to deal damage so similar to Lurrus). Should not I be able to react instant speed on Lurrus and since his ability is casting from graveyard which is not instant speed he should not even be able to react with it on my instant removal?

The two following rulings for  apply:  You must follow the normal timing permissions and restrictions of the spell you cast from your graveyard.   Once you begin to cast the spell, losing control of Lurrus won’t affect the spell. You can finish casting it as normal.  By the second quoted rule, I see if I don't respond to Lurrus being cast and entering, and my opponent chooses to cast a permanent from their graveyard, even if I then kill Lurrus, the chosen permanent will still be cast. So my question is if my opponent casts Lurrus and it enters the battlefield, can I immediately kill it before my opponent gets priority to cast a permanent from their graveyard.


Is there any way to check that, web page is loaded 100 percent in javascript?   100 percent means all the images,files,scripts,styles everything that a web page contains.

I want to write an application that detects when a page is loaded in the browser, then I should be able to insert content on top of the loaded web page? Anybody with an idea on how to do that?  Please note that I should be able to do this in any browser (Firefox/IE).  What language should I use to help me do this?  How do I detect this from an external application?  How should I integrate this with the browser?


Using Windows server 2016 instances.  I want the instance to run a local command before it terminates.  I can have a script run when windows is shutting down.  I would like the script to check if the instance itself is in the terminating state and if so run some clean up stuff.  Not sure from the docs, is there a way to check if the local instance is being terminated from the instance itself?   This returns InstanceStatuses:  aws ec2 describe-instance-status --include-all-instances --instance-ids i-123123123   Which looks like:  {     "InstanceStatuses": [         {             "AvailabilityZone": "us-west-2a",             "InstanceId": "i-123123123",             "InstanceState": {                 "Code": 16,                 "Name": "running"             },             "InstanceStatus": {                 "Details": [                     {                         "Name": "reachability",                         "Status": "passed"                     }                 ],                 "Status": "ok"             },             "SystemStatus": {                 "Details": [                     {                         "Name": "reachability",                         "Status": "passed"                     }                 ],                 "Status": "ok"             }         }     ] }   What does the state looks like when the instance is "terminating"? Not already terminated but pending termination? How can I check if an instance is in the pending termination state?


Saying that there is a running process named a.  Is it possible to list all of the lib files that a needs, including static link files and dynamic link files (.a, .so)?

I want to find out the list of dynamic libraries a binary loads when run (With their full paths). I am using CentOS 6.0. How to do this?


I'm trying to merge these two lines that appear periodically in a text file.  travel_ by_night_and_day   I have tried:  sed '/_\nby/_by/s' input.txt > output.txt   but, it doesn't do anything.  Do I have to escape something?  It's a text file created in ubuntu 12.04  Any suggestions?

I've noticed that, if I add \n to a pattern for substituting using sed, it does not match. Example:  $ cat > alpha.txt This is a test Please do not be alarmed  $ sed -i'.original' 's/a test\nPlease do not/not a test\nBe/' alpha.txt  $ diff alpha.txt{,.original}  $ # No differences printed out   How can I get this to work?


The anti-commutation relation between the components of a fermion field $\psi$ is given by $$[\psi _\alpha(x),\psi_\beta^\dagger(y)]_+=\delta_{\alpha\beta}\delta^{(3)}(\textbf{x}-\textbf{y}).$$    In case of two different and independent fermion fields, should I impose commutation or anticommutation between them?  If we continue to use anticommutation, how should the RHS change for two different fermion fields $\psi^1$ and $\psi^2$? $$[\psi^1 _\alpha(x),\psi_\beta^{2\dagger}(y)]_+=?$$ $$[\psi^1 _\alpha(x),\psi_\beta^2(y)]_+=?$$ $$[\psi^{1\dagger} _\alpha(x),\psi_\beta^{2\dagger}(y)]_+=?$$

My question is straightforward:  Do fermionic operators associated to different species commute or anticommute? Even if these operators have different quantum numbers? How can one prove this fact in a general QFT?


Image Source:  The pin no 6 of the optocoupler IC is connected to the base of the NPN transistor. Should I keep it open? Or grounded? Does it anything to do with improving the performance of the optocoupler?

I'm thinking about using  optocoupler - it has a separate lead for base of phototransistor. How do I use it? I suppose I can't leave it floating?


Here's the story, I have windows 7 on my Pc and I just installed Ubuntu 14.04, here's how I've done it:   Went in Windows and made some unallocated space in order to install ubuntu there. Installed ubuntu there using the something else method ( I have made a ext4 partition for ubuntu and a swap partition ). Everythings done I restart.   Problem is, now that I have installed it I can't access it.When my pc boots up it directly boots in windows and also in it's boot options there is none that could boot me into Ubuntu.  I've seen some solutions using boot-repair and such but they don't seem to work anymore in 14.04.   So how can I make it to Dual-Boot both Windows and Ubuntu ?  Update  Due to the fact that I have installed ubuntu from an USB I tried the following lines:  sudo grub-install /dev/sdX sudo update-grub   I used sd4 ( the place where I installed Ubuntu ) instead of sdX.Sadly after the first line it gave me the follwing error : "Failed to get the canonical path of '/cow' "    I have tried the possible duplicate solution and here's what I get.  ubuntu@ubuntu:~$ sudo mount /dev/sd4 /mnt mount: special device /dev/sd4 does not exist ubuntu@ubuntu:~$ sudo mount /dev/sda4 /mnt ubuntu@ubuntu:~$ sudo mount /dev/sda4 /mnt/boot ubuntu@ubuntu:~$ sudo grub-install --root-directory=/mnt /dev/sda4 Installing for i386-pc platform. grub-install: warning: File system `ext2' doesn't support embedding. grub-install: warning: Embedding is not possible.  GRUB can only be installed in     this setup by using blocklists.  However, blocklists are UNRELIABLE and their use is discouraged.. grub-install: error: will not proceed with blocklists. ubuntu@ubuntu:~$ sudo grub-install --root-directory=/mnt /dev/sda4 Installing for i386-pc platform. grub-install: warning: File system `ext2' doesn't support embedding. grub-install: warning: Embedding is not possible.  GRUB can only be installed in this setup by using blocklists.  However, blocklists are UNRELIABLE and their use is discouraged.. grub-install: error: will not proceed with blocklists. ubuntu@ubuntu:~$ sudo grub-install /dev/sda4 Installing for i386-pc platform. grub-install: error: failed to get canonical path of `/cow'. ubuntu@ubuntu:~$    Sda4 is a Ext4 partition however so I don't understand why it sais Ext2.

I installed Ubuntu on a Dell XPS 13 laptop that had Windows 10 preinstalled on it. I installed it from a USB flash drive on a partition. When I boot my computer I can only boot into Windows 10 and Ubuntu is nowhere to be seen.  If I boot into my USB then I can see that Ubuntu is installed, but I can't get to it from the BIOS boot menu.


Let $f_1$ and $f_2$ be bounded functions on $[a, b]$. Prove that $$L(f_1) + L(f_2) \leq L(f_1 + f_2)$$  For this question specifically, I know that I am supposed to show that the   $$\sup L(f_1,p) + \sup L(f_2,p) \leq \sup L(f_1+f_2, p)$$  But I get confused when considering the sup of these three functions since the partition is any arbitrary partition.   I have also thought about trying to show $$\inf f_1 + \inf f_2 \leq \inf (f_1+f_2)$$ first in every interval, but I got stuck in terms of how to prove the above statement.  New to real analysis, would appreciate any insights.

Let $f_1 , f_2: I\mapsto \mathbb{R}$ bounded functions. Show that $L(f_1)+L(f_2)\leq L(f_1+f_2)$ where $L(F)$ is the supremum of the lower sums of the Riemann integral.  I tried to by contradicction $L(f_1)+L(f_2)> L(f_1+f_2)$ and isoleting $L(f_1)> L(f_1+f_2)-L(f_2)$ and usig the definition of sup.  I also tried to use $\sup(A)+\sup(B)=\sup(A+B)$ but it din't work.  Thanks.


I have 100 shares of stock X which I am very long-term bullish on, and lately I've been considering selling those 100 shares and buying a LEAP for as far out as possible instead. The furthest I can buy expires in January 2020.  But I'm not positive that if the stock went up $100 between now and January 2020, that I would make the same amount as I would just owning my 100 shares.  How can I calculate it to be sure? I know the option greeks but don't they change over time? Or is it that once you've bought one, they stay the same for the duration of ownership? Do I need to pull out some Black-Scholes for this?  For instance, if I own 100 shares and the stock moves up $100, I gain $10,000 (100 x 100). But if I owned a single LEAP, would I have gained $10,000? I suppose it depends on the delta....see, here's where I get stuck. I don't know.

I don't really know how to anticipate the changes in an option's price.  If I have an call set to expire the following Friday at $10 above the current share price, I know in the absence of other changes it loses value with each day that passes getting closer to its expiration. (Talking about American options.) But it gains value as the share price gets closer to the strike price.  So, if two days pass but the stock goes up $3, would the option have gained value or lost value? Is there any way to calculate this?


I am trying to install Jasmin Gateway on Ubuntu Server 16.04 LTS, but I have the error below:  root@ds234:/home# sudo apt-get install python-jasmin                          Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  python-jasmin : Depends: rabbitmq-server but it is not going to be installed E: Unable to correct problems, you have held broken packages.   I tried to install rabbitmq-server:  root@ds234:/home/prodadmin# sudo apt-get install rabbitmq-server -y Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  rabbitmq-server : Depends: locales-all E: Unable to correct problems, you have held broken packages.   I tried to run the commands below to fix the broken packages but did not install:  sudo dpkg --configure -a sudo apt-get install -f sudo apt remove

After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


I also got  (which was previously closed as fixed), with a very long error message that had lots of red text overlapping other areas on the page. This error message was observed after typing an incorrect password once, and then a correct password. Some strings have been replaced by [stringX] for privacy, and a space has been added after each protocol to avoid autolinking. I was attempting to log in with my Stack Exchange account that I was already logged into on most other Stack Exchange  sites. The return_to parameter does not have the same protocol (HTTP vs HTTPS) as the "actual URL" and the latter also has a whole lot more in parameter information.  Unable to log in with your OpenID provider: The openid.return_to parameter (http:// area51.stackexchange.com/users/authenticate/?[string1]) does not match the actual URL (https:// area51.stackexchange.com/users/authenticate/?[string1]&openid.claimed_id=https%3A%2F%2Fopenid.stackexchange.com%2Fuser%2F[string2]&openid.identity=https%3A%2F%2Fopenid.stackexchange.com%2Fuser%2F[string2]&openid.sig=[string3]&openid.signed=claimed_id%2Cidentity%2Cassoc_handle%2Cop_endpoint%2Creturn_to%2Cresponse_nonce%2Cns.alias3%2Calias3.mode%2Calias3.type.alias1%2Calias3.value.alias1%2Calias3.type.alias2%2Calias3.value.alias2&openid.assoc_handle=[string4]&openid.op_endpoint=https%3A%2F%2Fopenid.stackexchange.com%2Fopenid%2Fprovider&openid.return_to=http%3A%2F%2Farea51.stackexchange.com%2Fusers%2Fauthenticate%2F[string5]%26dnoa.userSuppliedIdentifier%3Dhttps%253A%252F%252Fopenid.stackexchange.com%252Fuser%252F[string2]&openid.response_nonce=[string6]&openid.mode=id_res&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.ns.alias3=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.alias3.mode=fetch_response&openid.alias3.type.alias1=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.alias3.value.alias1=[string7]&openid.alias3.type.alias2=http%3A%2F%2Faxschema.org%2FnamePerson&openid.alias3.value.alias2=[string8]) the request was made with.

I recentely tried to log-in / sign-up for  using my SE account (which works on ,  and sign-up here) but it showed me an OpenID related error. (See below)  I could reproduce this error across multiple days and browser refreshes and using my other OpenID provider.  Error message (shown in red, obfuscated my e-mail address):  Unable to log in with your OpenID provider:  The openid.return_to parameter (http://area51.stackexchange.com/users/authenticate/?s=bd394805-cf55-4e8e-ad73-21485a09a989&dnoa.userSuppliedIdentifier=https%3A%2F%2Fopenid.stackexchange.com%2Fuser%2F642b1038-5c91-40d4-83ab-eb92db46c3d1) does not match the actual URL (https://area51.stackexchange.com/users/authenticate/?s=bd394805-cf55-4e8e-ad73-21485a09a989&dnoa.userSuppliedIdentifier=https%3A%2F%2Fopenid.stackexchange.com%2Fuser%2F642b1038-5c91-40d4-83ab-eb92db46c3d1&openid.claimed_id=https%3A%2F%2Fopenid.stackexchange.com%2Fuser%2F642b1038-5c91-40d4-83ab-eb92db46c3d1&openid.identity=https%3A%2F%2Fopenid.stackexchange.com%2Fuser%2F642b1038-5c91-40d4-83ab-eb92db46c3d1&openid.sig=4emyzuA31ChHU0LabPGJXldbN8GeKN%2FFBJXJy69yD10%3D&openid.signed=claimed_id%2Cidentity%2Cassoc_handle%2Cop_endpoint%2Creturn_to%2Cresponse_nonce%2Cns.alias3%2Calias3.mode%2Calias3.type.alias1%2Calias3.value.alias1%2Calias3.type.alias2%2Calias3.value.alias2&openid.assoc_handle=hrQL%21IAAAAGzBtFeNGBLU2o04XSWr7ISRAbO-B2tZCK3L61IzAsuQQQAAAAEdoTN6rf9fqaP1oekJGXGXJeB8fNSVuByptp5yx1VpQbAzQwF6HJzh6a0DwedydNJ-wwpJQoN5dOLEFmndZt-L&openid.op_endpoint=https%3A%2F%2Fopenid.stackexchange.com%2Fopenid%2Fprovider&openid.return_to=http%3A%2F%2Farea51.stackexchange.com%2Fusers%2Fauthenticate%2F%3Fs%3Dbd394805-cf55-4e8e-ad73-21485a09a989%26dnoa.userSuppliedIdentifier%3Dhttps%253A%252F%252Fopenid.stackexchange.com%252Fuser%252F642b1038-5c91-40d4-83ab-eb92db46c3d1&openid.response_nonce=2015-06-12T12%3A30%3A42Z7tADDeYZ&openid.mode=id_res&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.ns.alias3=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.alias3.mode=fetch_response&openid.alias3.type.alias1=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.alias3.value.alias1=mycorrectaddress%40web.de&openid.alias3.type.alias2=http%3A%2F%2Faxschema.org%2FnamePerson&openid.alias3.value.alias2=SOJPM) the request was made with.    As noted in the comments I'm not the only one, so I'd guess it may be not something I can fix. So will this be fixed?  Repro steps (using SE OpenID):   Get an Stackexchange OpenID account (like I have) (optional?) Add other OpenID providers and check they're working (StartSSL in my case) Please note: "You" don't have an "account" for the Area 51 subpage yet and still need to do the initial sign-in. Go to the Area 51 SE page Hit "Log-in" in the top-bar Hit the "log-in using stackexchange" button Enter your e-mail and password and submit Get the above error   Repro steps (using other OpenID)   Perform as above (until step 4), but this time step 2 is mandatory Hit "more OpenID options" Provide your OpenID link XXX.provider.com (works on crypto, server fault, ...) Authenticate against your provider Receive a variation of the above error (can be included if needed)


I always struggle with the time concept when it comes to general relativity. In the recent discovery the gravitational waves have been detected by the "displacement" of the mirrors and the difference that occurred between the "lengths" of the two arms. Which seems to me that it only dealt with the spatial parameters to see the ripples.  My question is that, we have seen that chirp from the spatial point of view, but what was the effect of the passage of such a "space-time" wave on our clocks? I mean, if we saw the distortion of the space, what change could we see in time?

Two questions.  It is said that time can only go slower in gravity fields and if you move faster.  I have heard that when a gravitational wave pass earth then the space/time vibrate and time change for an instance.  But a wave is often with a top and a valley.  They have now atomic clocks that might be able to detect time variations, placed in satellites around the sun and "quantum entangled". "Using Atomic Clocks to Detect Gravitational Waves"   So what if we could compare time ticks between clocks in space at "absolute frame of reference" where time has its maximum universal speed as time in deep space between Galaxy Filaments.  Will we only detect that time ticks slower for an instance when the gravational wave pass?  1. Or will we detect that time tick slower AND faster than normal time also, as compared to zero gravity time and no movement time in "absolute frame of reference"?  2. Can time go let's say 10 times faster by theory/mathematics, by a extreme theoretical gravitational wave, than time in "absolute frame of reference time"?


I'm struggling to recall this word. If I recall correctly, it's of French origin. My search has so far been fruitless.   The nearest equivalent I came up with was the idiom  but that is obviously English and not a single word.     pull strings / wires   (a) to use one's influence or authority, usually in secret, in order to bring about a desired result.   (b) to gain or attempt to gain one's objectives by means of influential friends, associates, etc.:      He had his uncle pull strings to get him a promotion.

I’m looking for a word I’m struggling to remember that refers to a job or role which is inconsequential and usually created in order to install someone in a company, not based on their merit.  An example would be creating a vague new role for a friend’s son. The word I’m looking for refers to the actual job itself - it’s a noun that would replace the ‘job’ (e.g “they put so and so’s cousin in a ____”).   I believe the word may not be a strictly formal or technical word but I don’t think it was slang.


I have been working on a project for my college course for a couple of months. When I went to submit it the other day the source code has gone missing. It was a WPF C# application. Because all of the work was done on my memory stick I have no backup of it.  I tried running a recovery tool but it was unable to find anything.  What I have is the following:   The contents of the bin > Debug folder including an up to date compiled version of the application (an exe file) The .sln file for the project.   I really need the source code for this as without it I might end up failing the project. Is there any way to get it with what I have?

I wrote a C# application for a client a couple of years ago, but I no longer have the source code.  All I have is the EXE that I deployed on the client's PC.  Is there a way I can generate C# source code from the EXE?


Let $\mathbb{D}= \{ z \in \mathbb{C} : |z| <1\}$.   Which of the following are correct?      1) There exists a holomorphic function $f: \mathbb{D} \to \mathbb{D}$ s.t $f(0)=0$ and $f'(0)=2$.      2) There exists a holomorphic function $f: \mathbb{D} \to \mathbb{D}$ s.t $f(\frac{3}{4})=\frac{3}{4}$ and $f'(\frac{2}{3})=\frac{3}{4}$.      3) There exists a holomorphic function $f: \mathbb{D} \to \mathbb{D}$ s.t $f(\frac{3}{4})=\frac{-3}{4}$ and $f'(\frac{3}{4})=\frac{-3}{4}$.      4) There exists a holomorphic function $f: \mathbb{D} \to \mathbb{D}$ s.t $f(\frac{1}{2})=\frac{-1}{2}$ and $f'(\frac{1}{4})=1$.   1) is not true by Schwarz lemma. How to comment on 2),3) and 4)?  I think 3) is also true as $|f'(\frac{3}{4})| \leq \dfrac{1-|f(\frac{3}{4})|^2}{1-|\frac{3}{4}|^2}$ holds.

Let $\mathbb{D}=\{ z\in\mathbb{C}:|z|<1\}$. Which of the following are correct?   There exist a holomorphic function $f:\mathbb{D}\rightarrow\mathbb{D}$ with $f(0)=0$ and $f'(0)=2$ There exist a holomorphic function $f:\mathbb{D}\rightarrow\mathbb{D}$ with $f(3/4)=3/4$ and $f'(2/3)=3/4$ There exist a holomorphic function $f:\mathbb{D}\rightarrow\mathbb{D}$ with $f(3/4)=-3/4$ and $f'(3/4)=-3/4$ There exist a holomorphic function $f:\mathbb{D}\rightarrow\mathbb{D}$ with $f(1/2)=-1/2$ and $f'(1/4)=1.$   Option one is not true by Schwartz-lemma. But i don't know how to think about other options. I  don't know which theorem or result gives condition of existence of this type of holomorphic function. Please help me to solve this problem. If possible please solve this problem. Thanks in advance.


I've tried MacLaurin expansion of the integrand, which resulted in   $x^2/4 - x^4/16 + x^6/96 + O(x^7)$   When integrated from $0$ to $\infty$ it obviously explodes, but the defined result is ~ $1645$. I've also tried using hyperbolic functions, but it was useless. Does anyone know how to solve this?  Thank you

I need to compute the improper integral $$ \int_{-\infty}^{\infty}\frac{x^{2}}{\cosh\left(x\right)}\,{\rm d}x $$ using contour integration and possibly principal values.  Trying to approach this as I would normally approach evaluating an improper integral using contour integration doesn't work here, and doesn't really give me any clues as to how I should do it. This normal approach is namely evaluating the contour integral $$ \oint_{C}{\frac{z^2}{\cosh\left(z\right)}\mathrm{d}z} $$ using a semicircle in the upper-half plane centered at the origin, but the semicircular part of this contour integral does not vanish since $\cosh\left(z\right)$ has period $2\pi\mathrm{i}$ and there are infinitely-many poles of the integrand along the imaginary axis given by $-\pi\mathrm{i}/2 + 2n\pi\mathrm{i}$ and $\pi\mathrm{i}/2 + 2n\pi\mathrm{i}$ for $n \in \mathbb{Z}$. The residues of the integrand at these simple poles are $-\frac{1}{4}\mathrm{i}\pi^{2}\left(1 - 4n\right)^{2}$ and $\frac{1}{4}\mathrm{i}\left(4\pi n + \pi\right)^{2}$, so that even when we add up all of the poles, we have the sum $4\pi^{2}\mathrm{i}\sum_{n = 0}^{\infty}\,n$, which clearly diverges.  Any hints would be greatly appreciated.


$ e^\pi$ and $\pi^e $  Which one is greater, How do I proceed without a calculator, I do not have any idea how to solve ,   using AM GM concept

How can I  compare (without calculator or similar device) the values of $\pi^e$ and $e^\pi$ ?


I was trying to set up a virtual machine of Android 5.0 and it didn't work out that well. I got the ISO and Virtual Box. I created a virtual machine in VB and I selected the ISO and powered on the VM in Virtual Box. It loads and then it reboots. The Android OS just keeps loading and rebooting all the time. Please note I was able to run all the previous Android versions successfully on a VM with no errors.  How can I get Android 5.0 to work in a Virtual Box VM?

I came across a how-to guide for running Android 1.7 in a virtual machine (VirtualBox), but 1.7 is old. I haven't been able to find a Android 2.2 or 2.3 image anywhere, does anyone have any ideas on how to virtualize newer Android OS's? Preferably a free virtualization solution like VirtualBox.  Here is the link about virtualizing 1.7:    They send you to here to download Android disk images:    But I can't find anything newer than 1.7, anyone have any ideas?