Conditional probability (two coins)
If two coins are flipped and one gets head, what is the probability that both get head?
Canned reasons for up/down vote (w/ example of how it would work) I'm annoyed by down voters that don't explain why they down voted a question or an answer. Although, at the same time, I understand that they . I think there is a middle ground, though, where the voter can remain anonymous, while the poster can get aggregated feedback on ways to improve the post.  Rather than having to imagine what it might be like, the current stackoverflow engine can emulate this rather effectively with the use of comments and the up-voting of those comments (essentially saying "I agree"). So I thought I would give it a try. The only difference is that in this testing post, you will always see the list of "canned responses" where as in the complete version, it will most likely be hidden in a popup (e.g. when you hover over the score of an answer/question). To try it out, simply up or down vote this question (or one of its answers), and press the up arrow next to the comment which best describes why are voting that way. For example, if you hate this idea, give this a down vote, and then press the up arrow near -1: I don't like this idea.  In addition to retaining anonymity, this will also save time for the voter so that they don't need to write out the comment. This wouldn't be required, obviously, and there could be a default option selected don't leave a reason. In addition, there could be a custom option which allows you type exactly why you are down-voting this way. Depending on the final implementation, this could either simply be converted to a comment automatically prefixed with -1:  or +1:; or, to retain anonymity, it would be added to this same list that shows the canned responses and how many users have voted that way.  Here are some ideas for the canned responses:  Question:   +1: Well formatted and thought out question. -1: It doesn't seem like enough time was spent trying to solve this issue on your own. -1: I don't like this idea. (Could be especially useful on meta.stackoverflow.com feature-request.) -1: No prior research/work. (Idea from .) -1: Poor question. Please see . -1: Doesn't contain code. (This would be useful on stackoverflow.com. Idea from )   Answer:   +1: Concise. +1: Insightful. +1: Worked for me. -1: It's wrong. -1: Confusing. -1: Encouraging bad behavior (e.g. answering a question that shouldn't have been asked; see ).   I made this a community-wiki since there will probably be testing of up/down votes. Several of these canned responses have been taken from . This same idea was also . Most MTP () devices show up in Windows File Explorer under their device name or a GUID, but they don't have a drive letter assigned.  How can I access the files on such devices from the command line? Using either cmd.exe or PowerShell. Question:     I want to scale a tikzcd diagram, but it doesn't seem to be working. It always compiles in a small scale. How does one scale a tikzcd diagram to, say, large scale?   Attempt:   I tried to set the option scale but it doesn't do anyhting.   \documentclass{article}  \usepackage{tikz} \usepackage{tizk-cd}  \begin{document} \begin{tikzcd}[scale=2.7em]  X \arrow{d}[swap]{\mathcal Q} \arrow{r}{f}  &amp;Z \\   Y \arrow{ru}[swap]{\bar f} &amp;{} \end{tikzcd} \end{document}    I've also read the manual  but I don't understand how to use the command /tikz/commutative diagrams/ row step=\langle size \rangle or its variances. I believe I'm using the latest version of tikz-cd and pgf files.   Note: I'm not interested in tikzpicture or similar environments, I'm working with tikzcd. TL:DR Smart guides aren't accurate - even though the snap, (end up causing more problems in the long run) is there a way to fix it?  Maybe there are some settings that I'm missing (need to be changed)    I use my smart guides all the time (and am overall pleased with them). I do have my issues with it, as explained here:  A lot of times, when I'm trying to make a bunch of triangles like this:    Done by making a triangle, cloning, flipping, rotating etc. Repeat until full  (Perfect) Snapping using Smart Guides    Ends up looking likebetween the triangles (Outline Mode)    Now I personally (with a strong attention to detail) will notice that there is something off after making just 1 or 2 triangles (Even before outline mode... strokes look oh so slightly thicker/off)   And then I check in outline mode... and sure enough:    Notice the line spaces (and this is in outline mode, so if I didn't notice it before, now it's sitting right in front of my nose)  The way I (seemingly) "fixed" the first image was by adding in a thick stroke outline so that masks out the difference, however, in a lot of my cases I don't want to have a stroke at all (and then you really notice the problems). How can I break on an unhandled exception in ASP.NET? Series of binomial coefficients: $\sum\limits_{n=k}^{\infty}{\binom nk}x^n=\frac{x^k}{(1-x)^{k+1}}$ Any hint to prove this? I tried with properties of binomial coefficient but I can't get anything. $$\sum_{n=k}^{\infty}{{n}\choose{k}}x^n=\dfrac{x^k}{(1-x)^{k+1}}$$ With markdown, you can use some dashes for headings. For example, this: Hello ---- this is some other text  renders as this: Hello this is some other text This is fine and works well. When I want to quote that text is when the problem arises, since this Markdown: &gt; Hello &gt; ---- &gt; this is some other text  When written down shows well in the preview but not when posted:  Hello this is some other text   As an example, see an screenshot of the preview:    and a screenshot of the posted content, where the ---- becomes a &lt;hr&gt;:  Note a similar bug I also reported: . Is the question mark misused in affirmative sentences? I'm using OSX 10.9. I'm trying to set up Internet Sharing to connect my Android to my Mac directly over Wi-Fi. Every tutorial I've come across (including ) mentions checking a box for "AirPort" in a "To computers using" list. However, the option is simply not available on my machine:    I have a few related questions:   Why isn't the AirPort option available? Is there anything I can do to make it available? If there isn't, how can I work around it to finish setting up Internet Sharing so I can connect my Android and my Mac directly over Wi-Fi? Possible to perform cross-database queries with PostgreSQL? Inertial forces and centre of mass Is inertial force always attached to the centre of mass of the object? Why? What rules cause this to happen?  See the  below of the leaned bike in a corner.    The force $m\frac{v^2}{r}$ pointing to the right is the centrifugal force (inertial force - because it's a rotating reference frame, therefore a non-inertial reference frame). It is attached to the centre of gravity of the bike.  I'm thinking that inertial force is attached to the centre of mass because of the fact that it should simply avoid creating a torque on the object. That's intuitive, but there must be a general rule that allows us to conclude that. Is hyperref really the best way to add metadata to a TeX file? So I know one of hyperref's features is that it can add metadata to you PDFs. This is a nice feature and if you're putting stuff online, it's good to include metadata.  But is the hyperref package really the best way to do it? I mean, if you're using hyperref anyway, that's fine. But if you don't want hyperrefs in your document, it seems weird to include the package, and then turn off pretty much all its functionality. And given that hyperref is a shorthand for "package conflict nightmare", is seems insane that you should have to deal with it just for the sake of some metadata.  So I have two questions.   Is there a good reason that hyperref includes this functionality which is apparently unrelated to its primary purpose? Is there a better (smaller, less conflicty, easier...) option to include metadata in my PDFs? Renewing an unused B1/B2 US visa I have a valid 5 years B1/B2 visa that was issued about 4 years ago.  I never used it as I intended to travel to work in a specific project that was cancelled.  Now, There is a similar project scheduled next year. So, I have to renew the visa as it will expire before the project's start date.  Can I renew the visa although it wasn't used (I never traveled to US) ? I installed the latest pgAdmin 4 (v2.1) but I found out that (), for the moment, the only way to establish a connection through an SSH tunneling is using another outside process, an  says:  I setup a tunnel as follows: ssh -f dpage(at)hostname(dot)enterprisedb(dot)com -L 5999: hostname.enterprisedb.com:5432 -N  (...) I was running on Mac, but the same procedure should work on Linux. On Windows, there's a tunnelling app in Putty iirc, but I don't know how to use it offhand.  I have found a simple . The connection is established but it seems, when I try to connect through pgAdmin it fails or is refused (using 127.0.0.1:3306 or 127.0.0.1:5432 as the tunnel's destination). Why? Does changing your Compute Device, change all computes of Blender? So, I have recently moved from using Blender, on my family's Nettop PC, to my personal, gaming PC. And with this move, came to option to use CUDA instead of CPU.  Which leaves the question, if I move to CUDA, does that change all computing, for like physics baking, or only for rendering?  Just a nooby question that I wanted to know, and yes, I know you can specify GPU rendering separately. Many people (at least in Germany) think that Italians add olive oil to the boiling water for spaghetti. However, Italians tend to tell the opposite (from my experience).  So, can you please state objective reasons for or against adding olive oil to the boiling water for spaghetti? Why there isn't a feature that lets any user on SO to request other user to answer their question? When I browse through other questions to find my answer, sometimes I'll find answers similar to what I'm looking for, and though they don't exactly answer my question, the author might be able to do so. Could we have a feature on SO that will let me request that another user answer my question, in case I find someone who could potentially answer my question? Can I get a \widebar without using the mathabx package? One can use \bar to put a bar over a letter in math mode, but often the bar isn't wide enough. An alternative is \overline, but this isn't an accent, so it doesn't take into account the skew of the letter. In the following example, the bar extends too far to the left:    Now the mathabx package offers a \widebar accent, but this has several drawbacks:   mathabx changes a lot of other things, The \widebar sits slightly higher than \bar and \overline, In previewers (checked with kpdf and acroread), the \widebar appears fuzzy, which \bar and \overline don't.   So my question is: How can I put a wide bar over a letter in math mode without the above drawbacks? Are cardinal numbers well defined? Or could we have something like $\aleph_{1/2}$? From what I understood, cardinal numbers are defined as:  $\aleph_0$ = the cardinality of $\mathbb{N}$ $\aleph_{n+1}$ = is the least cardinal number greater than $\aleph_n$  The continuum hypothesis states that the cardinality of $\mathbb{R}$ is  $\aleph_1$. I more or less understand this cannot be proven (does not follow from ZFC).  However, can it be proven dat there in fact is a 'least cardinal number' greater than $\aleph_0$?  Is it possible that there are sets with cardinality $\aleph_{1/2}$, $\aleph_{1/3}$, et cetera, so to speak?  Or expressed differently: is it possible that for every set A with cardinality CA > $\aleph_0$, there exists another set B with cardinality CB where CA > CB > $\aleph_0$? find spectrum matrix A Let $A = \left[ \begin{array}{*{20}{c}} 0&amp;b&amp;0&amp;0&amp;0&amp;0\\ c&amp;0&amp;b&amp;0&amp;0&amp;0\\ 0&amp;c&amp;0&amp;b&amp;0&amp;0\\ 0&amp;0&amp;c&amp;0&amp;b&amp;0\\ 0&amp;0&amp;0&amp;c&amp;0&amp;b\\ 0&amp;0&amp;0&amp;0&amp;c&amp;0 \end{array} \right]_{n \times n}$.  Why does matrix $A$ have spectrum $\sigma (A) = \left\{ 2\sqrt {bc} \cos \left(\frac{\pi k}{n + 1}\right):k = 1,2,\ldots,n \right\}$?