tr not replacing apostrophe
How to make tr aware of non-ascii(unicode) characters?
Does the equivalence $$\neg\neg (P \rightarrow Q) \leftrightarrow (\neg\neg P \rightarrow \neg\neg Q)$$ hold in propositional intuitionistic logic? In propositional classical logic the equivalence holds obviously since $P \leftrightarrow \neg\neg P$. However, the similar-looking implication $\neg\neg (P \vee Q) \rightarrow (\neg\neg P \vee \neg\neg Q)$ is . The validity of the backward implication comes up in  as well. The number of different ways to choose $k$ out of $n$ unique items The number of different ways to choose $k$ out of $n$ unique items:   Without repetition and without order-significance: $\binom{n}{k}=\frac{n!}{k!(n-k)!}$ Without repetition and with order-significance: $\binom{n}{k}\times k!=\frac{n!}{(n-k)!}$ With repetition and with order-significance: $n^k$ With repetition and without order-significance: $?$   Thank you! Symbol for “such that” (not in set) How to set up beamer to grey out past items but hide future items? I know about beamer's  feature \setbeamercovered{invisible} and \setbeamercovered{transparent} to hide or grey out upcoming item's . But is there some way to have past items greyed (transparent) and future items hidden (invisible), so that only the current item is black/highlighted? And the best would be if on or 1 slide after the last all the item's could be visible highlighted. Something like this:   [grey] past 1 [grey] past 2 current [hidden] future 1 [hidden] future 2 [hidden] future 3   Is there any easy way of doing this? While studying rotational mechanics, I came across a section where it mentioned that angular momentum may not necessarily be parallel to angular velocity. My thoughts were as follows:  Angular momentum ($L$) has the relation $L=I\omega$ where $\omega$ is angular velocity and $I$ is the moment of inertia, so following this relation, it seems they should be in the same direction. Why are they not? still frame camera solve I've found a number of how-tos for solving video but I'm just looking to put an element in a photo and can't seem to find a how-to for that.  Is it possible in blender to do a camera solve with a still image?  Thanks. Is there any way to accept only numeric values in a JTextField? Why can't I say “She died from drinking 18 cans of Coca-Cola”? Instead, the correct sentence would be “She died of drinking 18 cans of Coca-Cola”. Why does that happen? Sorting Directory.GetFiles() System.IO.Directory.GetFiles() returns a string[].  What is the default sort order for the returned values?  I'm assuming by name, but if so how much does the current culture effect it?  Can you change it to something like creation date?   Update: MSDN points out that the sort order is not guaranteed for .Net 3.5, but the 2.0 version of the page doesn't say anything at all and neither page will help you sort by things like creation or modification time.  That information is lost once you have the array (it contains only strings).  I could build a comparer that would check for each file it gets, but that means accessing the file system repeatedly when presumably the .GetFiles() method already does this.  Seems very inefficient. I'm looking for some way to run a batch file (.bat) without anything visible to the user (no window, no taskbar name, .etc..).  I don't want to use some program to do that, I'm looking for something cleaner. I've found  that uses VBScript, but I don't really like using VBS, either. Obtaining client IP address in WCF 3.0 Using the Fitch system, how do I prove $((p \implies q) \implies p)\implies p$? I started with the hypotheses $(p \implies q) \implies p$ and $\sim p$. However, from these hypotheses I did not get the desired contradiction to solve the question.  Thanks sb45 Compiler error C3493: 'func' cannot be implicitly captured because no default capture mode has been specified How to identify predatory publishers/journals What are the best strategies for assessing if a journal is a &quot;vanity&quot; or &quot;predatory&quot; journal that should be avoided (both for publishing in and reviewing for)? For example, how would one go about determining if a journal/publisher belongs on ? How do i prove invertibility of this linear transformation Let $T$ be a linear transformation from a vector space $V$  over reals into $V$ such that $T-T^2=I$. Show that $T$ is invertible It would be easier to ask for a user's password only once during registration.  The problem: The user could make a mistake while typing the password once because of hiding letters.  The solution: The user could have a toggle button for showing or hiding the password.    Working example with . This approach could be used on the registration or login page.   Are there any benefits to asking a user's password twice during registration vs just not masking the password? Why would you ask twice?  P.S. :        Users make more errors when they can't see what they're typing while filling in a form. They therefore feel less confident. This double degradation of the user experience means that people are more likely to give up and never log in to your site at all, leading to lost business. (Or, in the case of intranets, increased support calls.)   The more uncertain users feel about typing passwords, the more likely they are to (a) employ overly simple passwords and/or (b) copy-paste passwords from a file on their computer. Both behaviors lead to a true loss of security.      Update: I created a . So you may use it if you want to.    Update 2: .  Update 3: Internet Explorer 10 added a toggle password visibility icon. It looks like this:    Update 4: Article about .  Update 5: Example with . Number of non decreasing sequences of length $M$ How many non decreasing sequences are there of length $M$, provided the number in the sequences are allowed from $1,2,3,...,N$? if $x+2y+z=4$ and $x,y,z$ are real number. then find maximum value of $xy+yz+zx$  putting $x+z=4-2z$ in $y(x+z)+zx = y(4-2z)+zx = 4y-2yz+zx$  i wan,t be able to  go further,could some help me with this Academic dishonest: Possession of unauthorized materials during an exam that you didn't even know existed So unfortunately during an exam, I had the misfortune of using an eraser (with cover) that was not mine and had a small amount of words inside it unknown to me. I did not know this was the case, as I don't have a habit of unraveling erasers or looking at them closely?  However, now I face the problem in trying to defend myself against the accusation of me cheating.  I'm specifically concerned on my university's blank statement of "possession of unauthorized materials during an exam" is considered academic dishonesty. Seems like student conduct has all the power in trying to prove academic dishonesty, despite none of my test containing any of what to me is  unreadable, small notes. ctrl + a doesn't work in browsers The combination for select all (Ctrl+A) doesn't work in a browser (either if we speak about firefox or chromium). It doesn't work if I try to clik in to the adress bar nor if I try to use it to select what I've written in google search bar at google.com. When I press Ctrl+A it simply takes the cursor before the first letter.  This doesn't happen when I use a text editor software like Libre Office. There the shortcut does what's supposed to do, selecting all the text.  What could be the problem?