Unicode character range not being consumed by Regex
C# Regular Expressions with \Uxxxxxxxx characters in the pattern
Ruby on Rails on IIS? What is the difference between "var=${var:-word}" and "var=${var:=word}"? Preserve search engine rankings while shifting to new domain name Finding centrelines from polygons in QGIS? I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file. Where $\phi(n)$ is the Euler phi function, how do you find all $n$ such that $\phi(n)|n$? Can a single sentence be used to distinguish between isomorphic classes of finite structures? The answer seems to be yes, judging from the following exercise I found in the book Mathematical Logic by H.D. Ebbinghaus, J. Flum, and W. Thomas:     Let $S$ be a finite symbol set and let $\mathfrak{U}$ be a finite $S$-structure. Show that there is an $S$-sentence $\varphi _{\mathfrak{U}}$ the models of which are precisely the $S$-structures isomorphic to $\mathfrak{U}$.   I think I have an idea of how to solve this exercise, but I seem to be unable to materialize it. Thanks. Prove $f(S \cup T) = f(S) \cup f(T)$ $f(S \cup T) = f(S) \cup f(T)$  $f(S)$ encompasses all $x$ that is in $S$ $f(T)$ encompasses all $x$ that is in $T$  Thus the domain being the same, both the LHS and RHS map to the same $y$, since the function $f$ is the same for both.  Can you post the solution? Can newsletters take into account a user's favorite tags on that site? Stack Overflow is huge and varied. Wouldn't it be great if I could just subscribe to a newsletter with a list of my favorite tags? If I love dealing with , I think it would make sense for my version of the newsletter to focus more on Android questions.  Or, if I sign up for the  newsletter, but don't own a Mac, it would be nice if I my newsletter would focus on the part of the site I do follow (i.e., iOS).  So I would like to suggest that the newsletters for each site (optionally) take into account the user's favorited and ignored tags for that site.  I know that you can receive emails about specific filters, but I don't think that's a good solution for users who already receive the newsletter. Most of the questions it highlights cover topics that I have no interest in. It would be much better if I could filter out all the noise and get down to my likely favorites. Creating a query that uses criteria from two tables? How to validate phone numbers using regex I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant. Use of “f ” instead of “s” in historic, printed English documents I was at a museum in London yesterday, and one of the items on exhibit is a document from the eighteenth century. It uses the letter f a lot where s should be used—for example, in Majefty.     Did the letter f once have the same sound as s today, or were some of those words actually spoken with an f ? How to rate philosophy essays? I might end up teaching philosophy in Finnish lukio/gymnasium. I will not get an opportunity to practice teaching it - I do get to practice teaching mathematics a fair deal, though. (The situation is somewhat unfortunate.) I have taken subject studies in philosophy at university. They amount to around 60 credits (ECTS).  Suppose I give the students an exam, which asks them to write an essay or two. After that my task is to grade the exams in a fair way and comment them in such a way that the students can learn from the feedback.  -  Suppose the task was to write an essay on the problem of universals - nominalism and realism, say. Let us say 6 points is the perfect score for this task.  I would expect the students to define nominalism and realism (2 points, maybe?) and explain the problem (2 points). Remaining two points for taking some stance and arguing for it - realism is more reasonable because so and so. Partial credits for demonstrating only partial understanding.  -  Am I missing some important aspects of philosophical thinking? Should I emphasize the different parts of an answer in a different way? I suspect my perspective is influenced by fairly extensive mathematics education - is there something particular I should watch out for? Linear algebra skew symmetric Test of whole distribution for two samples Let $f$ be differentiable at $x=a$.   Prove that if $x_n \to a^+$ and $y_n \to a^-$ then:  $$\lim_{n\to \infty} \frac{f(x_n)-f(y_n)}{x_n-y_n}=f'(a).$$  Every option that I think about seems to my very trivial, so I believe that I am doing something wrong.  Both numerator and denominator approach zero as $n\to\infty$ as the case of the formal definition of derivative, but it isn't guaranteed that the limits are equal (“$\frac{0}{0}$”).   Any direction? Windows 8.1 missing font files after restart Some days ago I rebooted my windows 8.1 system. After the reboot all my system texts were very cryptic - showing only some strange symbols. After some investigation I discovered that my c:\windows\fonts folder was nearly empty. So I copied the font files from another windows 8.1 installation to the nearly empty folder. As soon as I had copied the files the system texts were readable again.  But after another reboot the problem occured again - the systems font folder was empty again. Does anyone know why windows deletes my font files during a restart? Approaches to Sand on a Conveyor Belt What punctuation should follow after a list introduced by a colon? The whole department: John, Jeff, Jean, and the accountant [?] were thrown into jail. Fastest way to try all passwords Suppose you have a computer with a password of length $k$ in an alphabet of $n$ letters.  You can write an arbitrarly long word and the computer will try all the subwords of $k$ consecutive letters. What is the smallest word that contains all combinations of $k$ letters as subword? (i.e. the fastest way to hack the computer :) )  The smallest word that contains $n^k$ subwords of size $k$ has length $k-1+n^k$ and based on some easy cases, we would like to prove that it is in fact possible to find a word of such length that contains all possible passwords. The problem can be translated into a problem in graph theory, by taking as vertices all words of length $k$.  We tried $k=2$, where you can prove the conjecture by induction. For $n=2$ and small $k$ it also works. Combining  with allowframebreaks in beamer