What’s the purpose of prototype?
Use of 'prototype' vs. 'this' in JavaScript?
How many physical degrees of freedom does the $\mathrm{SU(N)}$ Yang-Mills theory have? The $\mathrm{U(1)}$ QED case has two physical degrees of freedom, which is easy to understand because the free electromagnetic field must be transverse to the direction of propagation. But what are the physical degrees of freedom the $\mathrm{SU(N)}$ Yang-Mills theory?   I believe that the $\mathrm{SU(N)}$ Y.M. theory has four degrees of freedom, and it is easy to see that by gauge fixing (such as the Lorentz condition or the Coulomb condition) that we can always remove one redundant degree of freedom. But then we still haven't completely fixed the redundant degrees of freedom. Thus my question is:     How many physical degrees and how many are redundant degrees of freedom does the Y.M. theory have?    I would be interested to understand how we can determine this mathematically, and also to understand what the physical intuition behind this is? This is the announcement post of the Stack Exchange Data Explorer. Its answers were meant to iron out the initial glitches 6 to 8 years ago.  If you have found a bug or need support  today with any of SEDEs features, please ask a new question and tag it with   What does it do? Allows you to run arbitrary SQL queries on the data dumps, and share those queries with your friends. Technical details It is hosted on the Stack Exchange infrastructure , the database is hosted on the same SQL Server version all other sites are hosted on. You can use most of the TSQL commands, even create temporary objects (but not User Defined Functions). The controls used are jQuery based, the grid is  . All query results are cached, so sharing a link to a query will not result in the server going in to a tailspin. The query edit control is a slightly modified  control, I also am considering bespin cause the inter iframe communication is nasty complicated. It gives up nice syntax highlighting for queries. Parameters There is support for parameterized queries, to get it to work name your params like ##this##. For example have a . Query name and description A query can have a name and description, to name it lead with a comment, to describe it continue commenting, for example: -- This is my query name  -- This is my description -- I can span multiple lines  SELECT 1  Anonymous users can initially name a query, but can not change the names of any existing queries. Tutorial There's a  which helps you getting started in writing your own SQL queries. Logging in You can use your openid provider to log in, at the moment once logged in we will track the list of queries you execute (giving you basic history support) Also if there are any params named UserId they will be populated automatically if your EmailHash matches the one on the site being queried. Magic columns If you alias an id column with as [Post Link] it will automatically create a link in the result set to the parent site. Similarly if you alias an id column with as [User Link] it will display a link to the user page. select top 10 * from Posts will show you how tags are done. (Magic columns for images is planned) example (most controversial posts:  ) So what are you waiting for, check it out at  Any feedback would be greatly appreciated. I hope to have the login section working fairly soon and allow voting on the best queries and commenting. Featured Queries At the moment, admins have permission to feature interesting queries on this page , I am looking for better ways to manage the huge query list that is building up. In H. P. Lovecraft's The Case of Charles Dexter Ward, Dr. Willett      Enters Joseph Curwen's dungeon and resurrects a dead person identified as No. 118 by reciting the incantation of the Ascending Node over his salts.   Dr. Willett is told by      The resurrected Joseph Curwen, impersonating Charles Dexter Ward, who he secretly murdered,   that   " 'twas Number 118, and I conceive you would have shook had you looked it up in my list in t'other room."  No. 118 himself gives Dr. Willett a note asking the doctor to      kill Joseph Curwen.   It soon becomes clear that No. 118 is opposed to the nefarious dealings that have been transpiring and desirous of being an ally of Dr. Willett.  Who is No. 118?  Earlier in the story,      The grave of Ezra Weeden, a primary instigator in Joseph Curwen's initial downfall and the romantic rival of Curwen, is robbed. There doesn't seem to be any other mention of Weeden in the 20th century occurrences, so without a further connection the passage seems superfluous.   The shared goals of these two people seem to indicate that No. 118 may, in fact, have been that person, but the      Note given by No. 118 to Dr. Willett in eighth century Latin seems to indicate someone much older than Ezra Weeden.   It also occurred to me that No. 118 could be      The recently murdered Charles Dexter Ward himself. Ward's reference to killing Dr. Allen (who is actually an alias of Curwen) and dissolving his body with acid and No. 118's mention of doing the same to Curwen seem to support the idea, but that still doesn't explain the archaic note. Ward is described as writing in a somewhat modern style, at least as opposed to Curwen. It also doesn't explain why Curwen would want to murder Ward if he was going to resurrect him later anyway. Generalized mean value theorem I know and understand the mean value theorem. But at the moment I don't have the intuition to understand the generalized mean value theorem     If $f$ and $g$ are continuous on the closed interval $[a,b]$ and differentiable on the open interval $(a,b)$, then there exists a point $c\in(a,b)$ where$$[f(b)-f(a)]g'(c)=[g(b)-g(a)]f'(c).$$If $g'$ is never zero on $(a,b)$, then the conclusion can be stated as$$\frac{f'(c)}{g'(c)}=\frac{f(b)-f(a)}{g(b)-g(a)}.$$   What is the intuition? And how can you prove this (generally) ? Easiest process for me to apply textures, created externally, to my models For the first time I'm working with an artist who is going to be creating the textures for the models I create in Blender.  Up till now I had been building the models and the texturing them myself using pre-built textures from websites.  My question is: What is the easiest process for me to apply the textures our artist creates to my model?  Should I give the artist the UV Map from my model, or should I just get textures from the artist and fit them to the UV Map?  Basically I have no idea how this process works in a professional environment. Where is the right place to register/enqueue scripts & styles I accidentally discovered () that a closing square bracket within an optional argument delimited by [ ] can cause problems.  Here is example code illustrating the issue:  \documentclass{article}   \begin{document}  \tableofcontents  \section[Square brackets ([ and ])]{Square brackets: [ and ]} % bad: the TOC now has "Square brackets ([ and", and the actual title is a mere ")".  Some text.  \section[{Square brackets ([ and ])}]{Square brackets: [ and ]} % good (works as originally intended)  Some text.  \end{document}   The text to be used as the optional (as well as the non-optional) argument contains a ], and this character is not supposed to function as the optional argument terminator but as a matching square bracket/parenthesis. Perhaps this is as it should be, but the question is how to best circumvent any potential problems. Enclosing this in a group works, but I don't know whether doing this has other side effects (perhaps not here in the case of \section but hopefully someone else has a better example of where grouping could lead to a problem). There is no (obvious) way other than writing [{ }] because [ and ] are not normally escaped. That [ and ] are normal characters and bear syntactic function (as optional argument delimiters) creates this potentially problematic situation.  Is simply enclosing the entire optional argument in a group ({ }) a good solution? Are there other/better ways? Where did the name "Stack Exchange" come from? I get Stack Overflow (which I'm guessing was the first site?) and Super User, Code Review, and the other sibling site names make sense to me.  But I've never heard of a stack exchange before.  Is a stack exchange a real thing, or is this site's name a combination of Stack Overflow and an exchange of ideas? Is $(\mathbb{R}^2, lexicographic) \cong (\mathbb{R}, discrete)\times (\mathbb{R}, usual)$? I have the following question:  Is $(\mathbb{R}^2, lexicographic) \cong (\mathbb{R}, discrete)\times (\mathbb{R}, usual)$?  Note: the symbol $\cong$ denotes a homeomorphism between topological spaces  What I think:  I think that in fact there is a homeomorphism between those spaces, because is possible to express the lexicographic order as union of vertical lines with open extremes, I mean this is a basis for the lexicographic order. If I consider the Identical function I have the homeomorphism. Am I right? If A is a finite set and B is an infinite set, then B\A is an infinite set Prove: If $A$ is a finite set and $B$ is an infinite set, then $B \setminus A$ is an infinite set.   I've tried proving the contrapositive, that if $B \setminus A$ is a finite set then $A$ is infinite or $B$ is finite, but I don't think this is the way to go. I am having a problem running the CDC change capture job against some of my test databases.  The error message I'm getting is the following:     Executed as user: NT AUTHORITY\NETWORK SERVICE. Cannot execute as the database principal because the principal "dbo" does not exist, this type of principal cannot be impersonated, or you do not have permission. [SQLSTATE 42000] (Error 15517).   How can I fix this? Following , I would like to know what exactly it means for a tag to be marked as blocked (formerly blacklisted) on a Stack Exchange site.  Does it mean I can't use that tag on my question? What are the reasons for blocking a tag? Who can block tags? Why am I being prompted to remove a tag from a question I'm editing? Leave bash script running on remote terminal while not logged in? I have a bash script that takes several hours to run.  While it's running, I would like to do other things, which may involve logging out or disconnecting from the internet (my script runs network tests on various computers).  I understand that there is a command that would allow me to run my tests from a remote terminal and logout of the terminal while it runs.  Does anyone know what this command is? What changed in the Hot Questions sidebar algorithm? I've recently noticed that the hot questions list is now different almost every time I look at it. It used to be static - I.e. I could browse around for half an hour and the items on it would be minimally changed.  Was the algorithm changed? In what way? Target='_blank' to show in new window, NOT new tab, possible? How Deep Are Bender's Insides? Bender often pulls large objects from his torso cupboard, but how deep or how much empty space is he capable of storing? Can he bend space around the perimeters of the frame of his torso's door? If that is the case, does it also bend time? I suppose he might bend in more ways than one... Can a wizard choose where to place their soul piece when creating a horcrux? In PCA, when the number of dimensions $d$ is greater than (or even equal to) the number of samples $N$, why is it that you will have at most $N-1$ non-zero eigenvectors? In other words, the rank of the covariance matrix amongst the $d\ge N$ dimensions is $N-1$.  Example: Your samples are vectorized images, which are of dimension $d = 640\times480 = 307\,200$, but you only have $N=10$ images. In C, is it possible to forward the invocation of a variadic function? As in,  int my_printf(char *fmt, ...) {     fprintf(stderr, "Calling printf with fmt %s", fmt);     return SOMEHOW_INVOKE_LIBC_PRINTF; }   Forwarding the invocation in the manner above obviously isn't strictly necessary in this case (since you could log invocations in other ways, or use vfprintf), but the codebase I'm working on requires the wrapper to do some actual work, and doesn't have (and can't have added) a helper function akin to vfprintf.  [Update: there seems to be some confusion based on the answers that have been supplied so far. To phrase the question another way: in general, can you wrap some arbitrary variadic function without modifying that function's definition.] mod [= remainder] operation (and relation), name and meaning I am trying to write the Euclidean algorithm in the following way:  $A = \lfloor A \div B \rfloor \times B + (\text{remainder of}) \: A \div B $   Now is there any symbol I can use  to say "remainder of A $\div$ B"? I know that in the C programming language there is the operator % for modulus; is that a valid symbol in maths? Can I write A % B? Or is there some other way?