Python create all possible combinations from a integer
How to get all possible combinations of a list’s elements?
Why my U.S. B1 Visa got refused under 214 (b)? Google Spreadsheets: IF not working I have problems with my IF command in Google Sheets. If gives #ERROR! all the time. See this simple test:    Not even if I put in the number directly and avoid references:    Am I using the IF wrong? Or what could such a problem be? This example is from a new document. What does size of a directory mean in output of 'ls -l' command? What does size of a directory mean in output of ls -l command? I'm a Georgian national holding a multiple entry Schengen visa.  Last summer I was traveling to Hungary, spent a few days there, then flew to the UK. The Hungarian border official did NOT stamp my passport on exiting the Schengen area. I had to enter it again a few days later and the German border guards were confused by what had happened. Finally they let me enter.  Now I have one more entry stamp into Schengen than exit stamp and run into problems EVERY time at a Schengen border.  Is there a way to fix this? How to handle relative urls correctly with a nginx reverse proxy How to iterate through the name of files in a folder Assume I have many TeX files. For the sake of simplicity, also asssume they are in a single folder or directory.  I want to input all files from within my main LaTeX document. Actually I can create a list of those files using C# in advance.  To enrich my view about LaTeX or TeX, could you tell me whether or not this job can be done only by using pure TeX or LaTeX? I have a datetime column in MySQL.   How can I convert it to the display as mm/dd/yy H:M (AM/PM) using PHP? Margin on child element moves parent element Is there any information in canon to indicate that Dumbledore knew that the Marauders were Animagi? Is there any information in canon (or from JKR) to indicate that Dumbledore knew that three of the Marauders were Animagi?  I can't recall anything, but Harry seems to be firmly convinced that Dumbledore knows "everything that goes on around here," and that assessment seems to be accurate during Harry's years. Image of concave mirror when object is farther than the focal point I have a set of concave/convex mirrors/lenses, and I have drawn out all of the ray tracing diagrams for each possible combination and type of image each optical element can produce. When I look at the ray tracing diagrams then reproduce the situation in the real world with myself as the &quot;object&quot;, all the scenarios make sense to me except one: when I as the object stand beyond the focal point of a concave mirror.  The image ends up as &quot;real&quot; and appears to be in front of the mirror. Now I understand that in the situation above, I as the object would stand at 6m and this would result in the image appearing at 12m. So if I placed a wall or screen at the 12m mark, the image would form on that surface (just like a movie theater screen).... at least I think I interpreted that correctly. But I still see myself when I look in the mirror?! If the image is supposed to form and come into focus behind me, what in the world am I seeing when looking at the surface of the mirror? I still see myself, just inverted. The surface of the concave mirror still has a reflection on it. It doesn't look quite like a normal flat mirror, in that the image doesn't really look like it's &quot;inside&quot; the mirror, more like it's right on the surface of it. It's really frustrating because every other possible arrangement of optical elements makes total sense to me, except this one. Any suggestions on how to think about it? Thank you for your time! In the Breusch-Godfrey test we use a model  $$ e_t = \varepsilon_t + \beta_1 \varepsilon_{t-1} + \dots+ \beta_p \varepsilon_{t-p}. $$  If we reject the null hypotesis of no serial auotocorrelation of the error, it means that the residuals follow an auto-regressive model of order ($p$).  If I want to avoid this problem, I must add a certain number of lags of the response variable $y$ as regressors in the original model. However, in some cases this method is not useful.   Are there other options to consider? What is "it" in the following sentence: It is clear that Bob likes doughnuts I am very confused. Unless I am mistaken, I know "it" has to be a noun of some sort, but I am unable to figure out what noun "it" is referring to.   What is "it" in the following sentence:      It is clear that Bob likes doughnuts.   Heres another couple of examples:     It is impossible to fly. Always allow commenting on posts I have previously commented, irrespective of current rep Proving that $-a=(-1)\cdot a$ As the title reveals, I want to prove (based on the axioms of field) that $$-a=(-1)\cdot a$$ I've been trying for a while now, but couldn't think of a way to do it and it got me thinking that maybe its does not require a proof, but it doesn't feel right. Any ideas? I want to generate sprite-sheets for an isometric projection of various 3d assets purchased from the Unity3D asset store. I'd preferably also render the normal maps. I am a programmer, but new to 3D modeling software (Blender, etc.)  I found two tools for this;  and , but neither supports enough formats to be worth their cost.  There must be an efficient way of isometrically rendering various animations of a 3d assets in Blender&mdash;but I don't know how. How can I do this? Is there a possibility of using REST Assured library for testing SOAP webservices? I have a bunch of Test Suites in SOAP UI and I need to check if there is possibility of using REST Assured. Can anyone suggest if this is possible? Many thanks for any comments. How to decide whether to replace or repair? External hard drive very slow to load after dropping it and can't be repaired with Disk Utility Today as I was using my WD HDD, it fell off my corner. After I fixed the thing, I plugged it into the Mac and it loads the HDD but it's very very very very slow. It also does not work sometimes. The entire laptop just hangs  Tried running Disk Utility First Aid but it won't work.  It says some error and hangs  Can someone advise me on what I can do in this case? When does a dual of a compound proposition equal itself? So I am studying computer science and right now I am stuck on a problem.  When does s∗ = s, where s is a compound proposition?  So far the only thing I can come up with is:  s* = s when the compound proposition is composed only of the same           propositions. (ex. p ∧ p = p ∨ p)  The book defines duality as:  The dual of a compound proposition that contains only the logical operators ∨, ∧, and ¬ is the compound proposition obtained by replacing each ∨ by ∧, each ∧ by ∨, each T by F, and each F by T. The dual of s is denoted by s∗. (Discrete Mathematics and its Applications, Rosen, 7e)  Any help would be great, this is a tricky one. Modelling a spiral around a sphere I'm trying to figure out the best way to model the sphere-spiral here:    Is it possible to make this shape directly? Or do you have to make it as a cylinder and wrap it to a sphere?