how to validate email
How to validate an email address in JavaScript
How many regenerations does the Doctor have after The Time of the Doctor? How to make a standalone document with one equation? Changing background color to transparent in GeoServer? How to set the background color to transparent. I want use style which describe in *.sld file for all my photo with tif format. How to do that? I am using the book documentclass and have a list of figures. After  I noticed that there is a blank line to separate figures that are in different chapters, but not if they are within the same chapter. Since I changed the numbering of my figures to be {1, 2, 3, etc.} instead of {2.1, 2.2, 3.1, etc.} this looks silly and I'd rather have a blank line between each figure, no matter what.  How do I do that?  Similar: Prime factorizations of consecutive numbers, can they both contains powers of greater than or equal to $1000$? Reverting back to Unity (Unity 7) How to convert Strings to and from UTF8 byte arrays in Java In Java, I have a String and I want to encode it as a byte array (in UTF8, or some other encoding). Alternately, I have a byte array (in some known encoding) and I want to convert it into a Java String. How do I do these conversions? How to cite own unpublished work in text and reference? Are the known exoplanets representative of the population of exoplanets? An  states that most of the 715 newly announced exoplanets orbit very close to their host stars.   Do the theories predict that this is a representative sample and that most planets are very close to their host stars? Or is it just that our current detection techniques are predisposed to finding only those planets close to their stars (because the sensors look for dimming of the host star for example)? $f(x)=x/1$ is not injective? I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general relativity there is this one illustration, which is being used over and over (image from Wikipedia):    I always thought that general relativity gives another way how you can describe gravity. However for this illustration to work, there needs to be another force, pulling the object down (referring to a direction in the attached image). If I put two non-moving objects in the image, what force will pull them together?  So where is my understanding incorrect? Or is general relativity not about explaining gravity and just describes how heavy objects bends spacetime (in that case the analogy is being used not correctly in my opinion)?    UPDATE Thank you for the answers and comments. Namely the XKCD comics is a spot on. I understand that the analogy with bent sheet of fabric pretty bad, but it seems that it can be fixed if you don't bent the fabric, but just distort the drawn grid.   Would you be so kind and answer the second part of the question as well - whether general relativity is explaining gravitational force. To me it seems that it is not (bending of spacetime simply can not affect two non-moving objects). However most of the time it is being presented that it does. Can [sic] be used to highlight a punctuational error?    In the sentence below, the bracketed sic would obviously denote that the punctuation preceding it was an error &mdash; that is, a semicolon should supplant the comma. Has anybody ever seen this usage, and would you support it?     The sun is high, [sic] put on some sunblock. What's in a name: hyperparameters So in a normal distribution, we have two parameters: mean $\mu$ and variance $\sigma^2$. In the book Pattern Recognition and Machine Learning, there suddenly appears a hyperparameter $\lambda$ in the  regularization terms of the error function.  What are hyperparameters? Why are they named as such? And how are they intuitively different from parameters in general? Fix SD card that cannot be formatted I recently started an account on , and went to add an answer to a question which was protected. I have enough rep on other sites that I have the "Association Bonus", so I was confused as to why I wasn't being allowed to answer the question.     This question is protected to prevent "thanks!", "me too!", or spam answers by new users. To answer it, you must have earned at least 10 reputation on this site.   After re-reading the message and reviewing , I realized that the bonus didn't count as points earned toward that site.  This is a really minor issue, but I think it's worth fixing (not sure if bug or feature).  I believe that users who have enough rep to receive the association bonus should generally already know not to post "thanks!" and "me too!" style answers, so if the message is accurate, users who receive the association bonus should be able to answer protected questions.  If there's another reason to keep users from answering protected questions, such as  claim that:     For protected questions, you are expected to have experience on the target site itself. Experience at other sites is not enough.   then the message should be updated to reflect this.  Option 1:  make protected questions open to anyone who has >10 rep on that site and update the message to read:     This question is protected to prevent "thanks!", "me too!", or spam answers by new users. To answer it, you must have at least 10 reputation on this site.   Option 2:  leave protected questions the way they are, but update the message to read:     This question is protected to prevent "thanks!", "me too!", or spam answers by new users. To answer it, you must have earned at least 10 reputation on this site to show that you have experience on this topic; experience on other StackExchange sites is not enough.   Option 3:  Answer with your own suggestions/improvements to these ideas. I have a quick question. Looking at the next GIF that I made, what is the quickier way you can come up with to delete the excess material that goes beyond the wall? It is basically the attachment of the handrail to the wall what is giving me this "problem".    My solution would be using the boolean modifier with a cube or something, so obviously I know how to do it. But I'm looking for the best solution, i.e., does Blender let me select the excess material in any way? For example, is there a quick way to intersect those planes? I read about intersecting planes in Blender and seems like a difficult task (not worth it in this case). So I discarded that solution.  Thanks. Cannot get to a new line by hitting Enter I am using a Mac machine.  I asked a question, and then, someone answered it.    I clicked "Edit" to add a comment, and I would like to press Enter to go to a new line, but doing so submitted my comment and ended the edit instead. Here is my proof, I would appreciate it if someone could critique it for me:  To prove this statement true, we must proof that the two conditional statements ("If $\mathcal{P}(A)⊆ \mathcal{P}(B)$, then $A⊆B$," and, If $A⊆B$, then $\mathcal{P}(A)⊆ \mathcal{P}(B)$) are true.    Contrapositive of the first statement: If $A \nsubseteq B$, then $\mathcal{P}(A) \nsubseteq \mathcal{P}(B)$  If $A \nsubseteq B$, then there must be some element in $A$, call it $x$, that is not in $B$: $x \in A$, and $x \notin B$. Since $x \in A$, then $\{x\} \in \mathcal{P}(A)$; moreover, since $x \notin B$, then $\{x\} \notin \mathcal{P}(B)$, which proves that, if $A \nsubseteq B$, then $\mathcal{P}(A) \nsubseteq \mathcal{P}(B)$. By proving the contrapositive true, the original proposition must be true.    To prove the second statement true, I would implement nearly the same argument, so that isn't necessary to write. So, does this proof seem correct? Also, was the contrapositive necessary? Or is there another way to prove the initial statement? I recently purged Libreoffice because it was buggy.  I then reinstalled the latest version from apt and now it's missing the symbols above the equation editor.  Here is the current Texmaths equation editor:   There used to be shortcuts for latex including frac{}{} and various set theory operations, as well as the binomial distribution on the top of the window.  What happened to them and how do I get them back? I just figured that they were in some package and installed all packages useing sudo apt install libreoffice*, but this didn't help after I refreshed the program.  EDIT 0: I'm using Kubuntu 19.04  sarah@LesserArk:~$ sudo apt-cache policy libreoffice-texmaths libreoffice-writer texlive libreoffice-texmaths:   Installed: 0.43-2   Candidate: 0.43-2   Version table:  *** 0.43-2 500         500 http://us.archive.ubuntu.com/ubuntu disco/universe amd64 Packages         500 http://us.archive.ubuntu.com/ubuntu disco/universe i386 Packages         100 /var/lib/dpkg/status libreoffice-writer:   Installed: 1:6.2.2-0ubuntu2   Candidate: 1:6.2.2-0ubuntu2   Version table:  *** 1:6.2.2-0ubuntu2 500         500 http://us.archive.ubuntu.com/ubuntu disco/main amd64 Packages         100 /var/lib/dpkg/status texlive:   Installed: 2018.20190227-1   Candidate: 2018.20190227-1   Version table:  *** 2018.20190227-1 500         500 http://us.archive.ubuntu.com/ubuntu disco/universe amd64 Packages         500 http://us.archive.ubuntu.com/ubuntu disco/universe i386 Packages         100 /var/lib/dpkg/status Nsolve gives solutions with a small complex part which can't be eliminated by chop command