I'm trying to find questions that I can answer. So I reviewed advanced search help page, and I found answers:0 which helps me avoid questions that already have answers and locked:false to avoid locked questions.  What I would like to do is limit questions to those that have one of the tags in a list. For example, if I search for [python] [php], then I only get questions that have both tags. How do I get those that have either one?
How do I search for questions with specific tags?       For more information about searching, see &quot;&quot; in the .
Java Equivalent to Python Dictionaries Take most recent (or concatenate) edit comments when editing during grace period Recently, I edited  to update a link to a better resource. I clicked "Save" without entering a description of the edit (edit #1).  Then I realised that the question was asked by a new user who may not be able to easily identify the change that was made. So I edited it again, this time only to add a detailed edit description (edit #2).  Since edit #2 was made during the grace period (within 5 minutes of edit #1), the system has merged them into a single edit, but only the edit comment from edit #1 was recorded in the revision history, whereas edit #2's comment was simply discarded/ignored.  I'd suggest that either the most recent (non-default) edit comment is taken or that the comments are concatenated to provide a more useful edit history Why is $l^\infty$ not separable? mv : not found when executed from script that modifies PATH variable I have this in my script. But is returning an error. If I execute the command in the console works fine  ./script.sh[16]: mv: not found [No such file or directory]   I want move some files what starts in T353 from one folder to another. REMOTE_PATH is /tmp/ and PATH is my working directory  cd $REMOTE_PATH mv T353* $PATH #this is the line 16   If I make mv /tmp/T353* . works fine. Focus existing terminal with `Ctrl-Alt-T` shortcut I tend to use the terminal a lot,  So I wondering if there is a way I can make Ctrl+Alt+T focus the existing terminal if there is one, otherwise create a new terminal? Symmetric Inequality in $\mathbb{R}$ Using separation of variables to solve the wave equation I'm trying to teach myself separation of variables and have been following some notes for the wave equation, but there's one part which really confuses me and I'm not exactly sure how it makes the step.  For the wave equation   $$u_{tt} - c^2 u_{xx} = 0$$   with length $l$ and fixed ends, $u(0,t)=u(l,t)=0$ we seek a solution in the form $$u(x,t)=v(x)q(t)$$  and substituting this into the equation gives $$\frac{1}{q(t)}\frac{d^2 q}{dt^2}=c^2 \frac{1}{v(x)}\frac{d^2 v}{dx^2}=-\omega ^2$$   and I understand all of this so far. But when solving the equation  $$q''+\omega ^2 q = 0$$ the general solution is $$q(t)=A \cos(\omega t +\alpha)$$ where $A$ and $\alpha$ are constants - which is the part which I'm not exactly sure on how it gets to.   Could someone explain this step to me? Thanks! I am trying to solve this exercise from Jech's book on set theory:  Ex. 3.6: There is a well ordering of the class of all finite sequences of ordinals such that for each $\alpha$, the set of all finite sequences in $\omega_{\alpha}$ is an initial segment and its order-type is $\omega_{\alpha}$. Definition: If $W$ is a well ordered set and $u \in W$, then the set $\{ x \in W \mid  x &lt; u \}$ is an initial segment in W  Any help? Sensitivity to initial conditions and topological transitivity Heathrow change in terminal flight UK Border control check? I am traveling from NYC to Mumbai via London. Assume my connecting flight belongs to different terminal. If I have to change terminal at Heathrow, do I need to go through UK Border control ? Is it possible to call the base method from a prototype method in JavaScript if it's been overridden?  MyClass = function(name){     this.name = name;     this.do = function() {         //do somthing      } };  MyClass.prototype.do = function() {       if (this.name === 'something') {         //do something new     } else {         //CALL BASE METHOD     } }; What is "#!' in a script file? $cat shebang.sed  #! /bin/sed -f s/red/xxx/ s/BLUE/1234/  $./shebang.sed rgb lower (#1): "xxx green blue" UPPER (#2): "RED GREEN 1234"  $sed -f shebang.sed rgb lower (#1): "xxx green blue" UPPER (#2): "RED GREEN 1234"   I may guess what #! is doing. However, I don't say I know it. what is "#!"? We have more than one content management system (eCommerce) running on our site and we want to know would it be wise to separate these systems and run on their own server for better performance, easier to manage and better for security, but our concern is the SEO impact.  Is it better to run site.com/this-is-our-other-platform/ or this-is-our-other-platform.site.com? Why exactly do sometimes universal covers, and sometimes central extensions feature in the application of a symmetry group to quantum physics? There seem to be two different things one must consider when representing a symmetry group in quantum mechanics:   The universal cover: For instance, when representing the rotation group $\mathrm{SO}(3)$, it turns out that one must allow also $\mathrm{SU}(2)$ representations, since the negative sign a "$2\pi$ rotation" induces in $\mathrm{SU}(2)$ is an overall phase that doesn't change the physics. Equivalently, all representations of the Lie algebra are what we seek. ($\mathfrak{so}(3) = \mathfrak{su}(2)$, but although every representation of the algebra is one of the universal cover, not every representation of the algebra is one of $\mathrm{SO}(3)$.) Central extensions: In conformal field theory, one has classically the  of infinitesimal conformal transformations. From the universal cover treatment one is used to in most other cases, one would expect nothing changes in the quantum case, since we are already seeking only representation of an algebra. Nevertheless, in the quantization process, a  appears, which is often interpreted to arise as an "ordering constant" for the now no longer commuting fields, and we have to consider the  instead.   The question is: What is going on here? Is there a way to explain both the appearence of universal covers and central extensions in a unified way? iCloud storage always full What antivirus programs are available? What antivirus programs are available for Ubuntu?  We previously used Symantec Endpoint Protection but it does not work in Ubuntu. I can easily find files with given string in name:  me@comp:/usr/local/hydra/hydra-7.4.2$ find -D stat -name "*hack*" ./hack881663129.txt ./hack881663129_7.txt ./hack881663129_5.txt ./hack881663129_4.txt ./hack881663129_4_7.txt ./hack881663129_6.txt ./hack881663129_1_6.txt ./hack881663129_8.txt   How can I also print file details, like size, date of creation etc.? Does applying the Collatz conjecture algorithm to negative integers always result in sequences ending with $-1$ and then repeating themselves an infinite number of times? It is so for the first several seed values.  After hours of thinking and research, I don't know how to answer the question. How to code around known MMa special-case failures? Deleting multiple elements from a list