Circles partitioning the plane
N circles in the plane
See YouTube videos in Anaglyph mode How to see a YouTube video in  from a non-3D Android device? I am not able to enable Anaglyph mode from the YouTube application. In Europe usually you don't need to go through immigration to change planes (unless you are entering/exiting Schengen). Is it the case in the US as well? May I catch a connecting flight on one of the US airports if I don't have US visa? Editing question title creates whole new question and other question list problems HashSet vs. List performance It's clear that a search performance of the generic HashSet&lt;T&gt; class is higher than of the generic List&lt;T&gt; class. Just compare the hash-based key with the linear approach in the List&lt;T&gt; class.  However calculating a hash key may itself take some CPU cycles, so for a small amount of items the linear search can be a real alternative to the HashSet&lt;T&gt;.  My question: where is the break-even?  To simplify the scenario (and to be fair) let's assume that the List&lt;T&gt; class uses the element's Equals() method to identify an item. If $\Sigma \vdash \varphi$ then $\Sigma \vdash \forall x \varphi$. Why when $(\varphi \implies \forall x \varphi)$ is not true? In the book of first order logic I'm reading they say that if $(\varphi_1,...,\varphi_n)$ is a proof from a set of formulae $\Sigma$, then so is $(\varphi_1,...,\varphi_n,\forall x \varphi_j)$ for all $1\leq j \leq n$. They assume that as an axiom but it doesn't make sense to me. Why if $\varphi$ is true then so is $\forall x \varphi$? For example if $\varphi$ is $x=1$ that wouldn't mean that $\forall x : x=1$ , or would it?  Maybe what I don't understand is: why $(\Sigma \vdash \varphi \implies \Sigma \vdash \forall x \varphi)$ is true but $(\varphi \implies \forall x \varphi)$ is not true?  The book is this: Is Tolkien prejudiced against the East? In Tolkien's The Lord of the Rings series, there are generally two groups of Men. The good ones are coming from the West (Dúnedain, Men of the West), and the bad ones, the Easterlings, mostly fight under Morgoth and Sauron.  Why was this so? Appearing on the second page (under the section Digression: Size worries) of the following paper about the Yoneda Lemma:     It says that $a$ $priori$ $[\mathcal C^{op},Set](H_A,X))$ is a class. I don't understand why this is the case.  My understanding is that $a$ $priori$ each member of $[\mathcal C^{op},Set](H_A,X))$ is a class.  So it seems to me that $[\mathcal C^{op},Set](H_A,X))$ could be a collection of proper classes.  I've looked at this , but it hasn't helped me much.  Any help is appreciated -Thanks ARMA/GARCH estimation in sequence how many conditional sentence types are possible? I wonder how many conditional sentence types are possible. Basically, there are four main and two mixed types. By mixing tenses, it could be up to nine of them. Are the rest viable?  I came across the following examples in Full Spate Pre-Profficiency Primer:   After you have just sold alcohol to a young guy. If he is if under eighteen, you should not have sold him the alcohol. If he promised to bring the drinks, he will. If you will take a seat, the doctor will see you shortly. (Likely, the former will demonstrates politeness only.) I would be grateful if you would tell me a little about your friends. (The same politeness, but would instead.) If he will keep eating all those biscuits, he can not expect to stay as slim as he used to be.   I would be grateful if someone could shed more light on the topic. Visa for European countries for US passport holder I'm a US passport holder. What documents do I need when I fly from the U.S. to Germany?  Assume I'm going for a few weeks of vacation.  Obviously I need my passport.  What about a "visa"?  Anything else? Randomly populating procedural shape (or Image Texture) in Cycles Convert date to another timezone in JavaScript Converting a string to a tuple in python Call C++ library in C# I have a lot of libraries written in C++. I want to call these libraries from C#, however, I have met many problems. I want to know if there is a book or guideline to tell me how to do that. Does this answer your question? Notice remains open even after submitting feedback Weird line in my mirrored mesh was following a tutorial where I stumbled into this weird line in my mirrored mesh (sorry for the feet lol)      You can also download the blender file Use of 'const' for function parameters How far do you go with const?  Do you just make functions const when necessary or do you go the whole hog and use it everywhere?  For example, imagine a simple mutator that takes a single boolean parameter:  void SetValue(const bool b) { my_val_ = b; }   Is that const actually useful?  Personally I opt to use it extensively, including parameters, but in this case I wonder if it's worthwhile?  I was also surprised to learn that you can omit const from parameters in a function declaration but can include it in the function definition, e.g.:  .h file  void func(int n, long l);   .cpp file  void func(const int n, const long l)   Is there a reason for this? It seems a little unusual to me. Optimizing logical sector size for physical sector size 4096 HDD With many new hard drive disks the physical sector size is 4096. Would it be possible to make the system use a logical sector size of the same size, rather than the default logical sector size of 512?  Will it speed up bulk reads and writes? Where can it be configured? SD Card showing weird file names and files are lost I just plugged my SD Card to my PC after a long videography day, and I suddenly got this problem:    It is also not showing all the videos I took on my camera so what is the solution? Show that $R/I\otimes_R R/J\cong R/(I+J)$