Please settle an UNO debate with regards to Wild Draw 4.  The face card on top of the pile is a Blue 0.  Player 1 plays WD4 but does not change the color.  Player 2 plays WD4 changes the color to Blue.  Player 3 challenges player 2 on having Blue cards.  Who is being challenge player 1 or 2?
Need clarification on the Draw 4 rule. - Player 1 lays down a Draw 4 Card and says the color is Red. - Player 2 does not have a Red card but has a Draw 4 Card. Can Player 2 lay down his Draw 4 Card and have Player 3 draw 8 cards?
How to automatically generate a stacktrace when my program crashes I am working on Linux with the GCC compiler. When my C++ program crashes I would like it to automatically generate a stacktrace.  My program is being run by many different users and it also runs on Linux, Windows and Macintosh (all versions are compiled using gcc).  I would like my program to be able to generate a stack trace when it crashes and the next time the user runs it, it will ask them if it is ok to send the stack trace to me so I can track down the problem. I can handle the sending the info to me but I don't know how to generate the trace string. Any ideas? What are good advanced LaTeX books? I've been using LaTeX for about 3 months, and I'm hooked. My background is programming, so for the basic, google is sufficient. I did some research on amazon.com and found these two books with many positive feedback:    However, most of people said they are more like references than a real book. And if they really are, then I think I'd rather look up at CTAN. What I'm looking for is a book that can teach me how to program in LaTeX, for example:   Write my own package   Create animation  Create and using macro in LaTeX ....   I know there are many options around, however to pick the right one is not an easy task. Any advice or suggestion would be greatly appreciated. Thank you. difference fn(String... args) vs fn(String[] args) Whats this syntax useful for :       function(String... args)   Is this same as writing       function(String[] args)    with difference only while invoking this method or is there any other feature involved with it ? Why "be king", not "be a king"? I've heard people say "be king" (as in "I can't wait to be king") in movies and TV. Why don't they say "be a king"? Which is correct? Why does exclamation mark within double quotes cause a Bash error? Please look at these commands:  $ notify-send SYNC TIME! $ notify-send 'SYNC TIME!' $ notify-send "SYNC TIME!" bash: !": event not found $   The first two commands produce a notification bubble as expected. The third gives the error shown.  and  $ echo SYNC TIME! SYNC TIME! $ echo 'SYNC TIME!' SYNC TIME! $ echo "SYNC TIME!" bash: !": event not found $   Here as well, the echo works for first two commands but not in the third.  More problems here (although I was not planning on using this): both notify-send "SYNC!TIME" and echo "SYNC!TIME" give bash: !TIME": event not found.  But both notify-send and echo work with "SYNC! TIME"  Can someone please explain why the bash: !": event not found error appears? This is about that old chestnut, $\newcommand{\d}{\mathrm{d}} \int \sin^2 x\,\d x$.   OK, I know that ordinarily you're supposed to use the identity $\sin^2 x = (1 - \cos 2x)/2$ and integrating that is easy. But just for the heck of it, I tried using the $u$-$v$ substitution method (otherwise known as integration by parts).  $$ \int \sin^2 x\,\d x = \int \sin x \sin x\,\d x $$  We can say $u=\sin x$ and $\d u=\cos x\,\d x$ while $\d v = \sin x\,\d x$ and $v = -\cos x$. When we put it all together:   $$\int \sin^2 x\,\d x = u v - \int v\,\d u = -\sin x \cos x - \int -\cos^2 x\,\d x$$  and doing the same routine with $\cos^2 x$ we get $u = \cos x$, $\d u = -\sin x\,\d x$, $\d v = \cos x\,\d x $ and $v = -\sin x$, leading to:  $$\begin{align}   \int \sin^2 x\,\d x = uv - \int v\,\d u     &amp;= -\sin x \cos x - (-\cos x \sin x - \int -\sin^2 x\,\d x) \\     &amp;= -\sin x \cos x + \sin x \cos x - \int \sin^2 x\,\d x \end{align}$$  which eventually works out to  $$2\int \sin^2 x\,\d x = 0$$  So I wanted to get an idea why this didn't work. Maybe it's higher math and the why will be beyond me (I would think that might be the case), or maybe it's one of those proofs that looks absurdly simple when shown that I am just unaware of. Where can I see the source code of the Sun JDK? The book says:     Concentration. Some spells require you to maintain concentration in order to keep   their magic active. If you lose concentration, such a spell ends.   So what happens if, for example, you are already concentrating on a spell, and cast Witch Bolt without concentrating. Would you get the initial arc of blue energy, or would it not even go off?  I am asking if you can cast a spell that says concentration without concentrating for an immediate effect. This would be useful to avoid interrupting your existing concentration. In essence, if you are concentrating on thing A (doesn't have to be a spell since other things need concentration), can you cast a concentration spell getting an immediate effect without losing concentration on thing A?  Since the definition of concentration is to keep the spell active (meaning it is already active) I would think that you would get the initial effect (if it had one) without the need to concentrate on it. How to force the browser to reload cached CSS and JavaScript files I have noticed that some browsers (in particular, Firefox and ) are very zealous in using cached copies of .css and .js files, even between browser sessions. This leads to a problem when you update one of these files, but the user's browser keeps on using the cached copy. What is the most elegant way of forcing the user's browser to reload the file when it has changed? Ideally, the solution would not force the browser to reload the file on every visit to the page.  I have found  and  suggestion to be useful. It turns out there is a term for this: auto-versioning. I have posted a new answer below which is a combination of my original solution and John's suggestion. Another idea that was suggested by SCdF would be to append a bogus query string to the file. (Some Python code, to automatically use the timestamp as a bogus query string, was .) However, there is some discussion as to whether or not the browser would cache a file with a query string. (Remember, we want the browser to cache the file and use it on future visits. We only want it to fetch the file again when it has changed.) How to Install Virtualbox on Windows 10 host? Writing letters of recommendation for more than one student to the same department Suppose multiple students have asked me for letters of recommendation to the same graduate department in the US. Am I expected to explicitly compare the students to one another? Am I supposed to do this in both letters (assuming they haven't been submitted yet)? Do I need to explicitly state a preference for one over the other, or can I just get away with listing relative strengths and weaknesses (for instance, "X is stronger academically, but Y has more research experience and is a stronger programmer")? Is it possible to exit the airport without going through the customs? Submitting ACM Conference papers to ArXiv I'm a little confused. The  states:     ACM authors hold the right to post copies of their own peer-reviewed accepted ACM works on any non-commercial repository or aggregation that does not duplicate ACM tables of contents, i.e., whose patterns of links do not substantially duplicate an ACM-copyrighted volume or issue. Non-commercial repositories are here understood as repositories owned by non-profit organizations that do not charge a fee for accessing deposited articles and that do not sell advertising or otherwise profit from serving articles.   However, the  site states:     Can I publish the published version of my publication on arXiv?       No. An ACM author cannot grant arXiv.org or any other publisher rights to distribute their works that have been published by ACM.   SHERPA/Romeo shows ACM as being a "Green Publisher", which would support the case that I can upload to ArXiv.   states that I can upload pre- or postprints under certain circumstances, but does not explicitly mention Arxiv, positively or negatively.  So, what is it? Can I submit a paper I published with an ACM Conference (ACM WiSec, if that makes a difference) to ArXiv or not? As I understand it, ArXiv is a non-profit, so it would fit the terms of the publishing policy. Or is this related to the rights you have to grant ArXiv upon submission?  If I can only publish a specific version of the paper, which one? I have a sheet in which I first apply a filter to a certain column to show "Unique records only". Now I have a column which contains, for e.g., values like:  Applepie Applesauce Crabapple Banana Mango   What I need is the count of all visible cells containing the word "Apple". Note that this should exclude the hidden (filtered out) cells. Now I have found out a formula:  `=SUMPRODUCT(SUBTOTAL(3,OFFSET(Sheet1!A:A,ROW(Sheet1!A:A)-MIN(ROW(Sheet1!A:A)),,1))*(Sheet1!A:A="&lt;Text to search&gt;"))`   However the problem with this one is this formula searches for the entire text. NOT just a part of it. How do I modify this formula to return count of cells containing "Apple" i.e. for this example it should return 3 as the result. This is a problem from Rudin's Functional Analysis:  Show that there is a sequence of functions $\{ f_n \}$ in $X$ (the vector space of all complex functions) such that $f_n \to 0$ pointwise, but if any sequence $\{ \gamma_n \}$ tends to $\infty$, $\gamma_n f_n \not\to 0$.  The hint says to use the fact that the collections of all complex sequences converging to $0$ has the same cardinality as $[0,1]$. Honestly, this confused me more than it helped me.  My main issue is through the method of showing existence: I am not sure if I should attempt to construct an explicit sequence $f_n$, or if I need to appeal to other nonconstructive means such as Zorn's Lemma, etc. I have been trying to construct clever choices of sequences for a good bit now, but it always seems like I will be able to find a sequence that diverges slowly enough to allow that $\gamma_n f_n \to 0$.   Thanks! Linux command line. Move all files and directories in directory, except some files and directories I have a folder A which has files and directories, I want to move all those files and directories to another folder B, except file, file2, directory, and directory2.  How can this be done? PHP considers null is equal to zero How did this person gain possession of the Infinity Stones? What does `:-` mean in a shell script I saw this in the end of an awesome shell script but I can't understand the login here because I think it's being short-handed for a longer command.  spark ${@:-`cat`}   This apears at the end of . Any ideas?  + Marks for some one who extends it into a full segment of code, even if its slower (Better for explanation) Why are integer literals with leading zeroes interpreted strangely?