I have accepted as postdoc researcher in a Swedish university. Three professors in the university are correspondent for this position. I have to travel to Sweden within 2 weeks and start my new job. However, I should make sure about some issue before leaving my homeland. They all are so quick in answering. However, I sent them a short e-mail but did not receive any reply from 10 days ago. I don't  know what I should do. Does such a behavior mean "No"? Or am I annoying them because of my e-mail?
As a grad student, I just find it tremendously frustrating when emails are ignored by faculty (both at my institution and at other places). Is this acceptable? I'd be content with a simple response with one line along the lines of "I have read this email and am busy right now, will respond in X days when I can write a more detailed email." I understand that, as a first year student in my field, I'm not really in a position to request anything of anyone, but it just seems like common decency.  Instead, I never hear back, as if my email has been jettisoned off into oblivion.
Chat arrangement question: Left or right? I'm building a small chat. Now I see but in other chats (whatsapp, facebook mobile chat, sms ...) that the arrangement is always the same:  Left: the chat partner. right: myself      Why is that? at least one element fixed by all the group $G$ is a p-group and $S$ is a set that $G$ acts on. p does not divide $|S|$. Why is there at least one element $a\in S$ such that $|O(a)|=1$, or in other words, $G_a=G$?  I tried to ask this question yesterday but did not word it right, so the one who helped me claim that this part is clearly true and I really do not understand why, and I couldn't get a straight answer for the past day.   Any of you are welcome to vote to delete this question (after some discussion with me about the problem I hope), but I just really want to know why it is "clearly true, because I still couldn't reason it right. Why is quadratic integer ring defined in that way? Quadratic integer ring $\mathcal{O}$ is defined by \begin{equation}    \mathcal{O}=\begin{cases}       \mathbb{Z}[\sqrt{D}] &amp; \text{if}\ D=2,3\ \pmod 4\\       \mathbb{Z}\left[\frac{1+\sqrt{D}}{2}\right]\  &amp; \text{if}\ D=1\pmod 4    \end{cases} \end{equation} where $D$ is square-free.   I understand $\mathbb{Z}\left[\frac{1+\sqrt{D}}{2}\right]$ is not closed under multiplication if $D=2,3\pmod 4$. But still, isn't it more natural to define $\mathcal{O}=\mathbb{Z}[\sqrt{D}]$ for all square-free $D$? (in that case, it really seems like 'quadratic integer') I wonder what is the motivation of this definition. Factoring $x^n + y^n$ over the integers Prove inequality $\sqrt{\frac{2a}{b+a}} + \sqrt{\frac{2b}{c+b}} + \sqrt{\frac{2c}{a+c}} \leq 3$ How best to determine if an argument is not sent to the JavaScript function I have now seen 2 methods for determining if an argument has been passed to a JavaScript function. I'm wondering if one method is better than the other or if one is just bad to use?   function Test(argument1, argument2) {       if (Test.arguments.length == 1) argument2 = 'blah';        alert(argument2);  }   Test('test');   Or   function Test(argument1, argument2) {       argument2 = argument2 || 'blah';        alert(argument2);  }   Test('test');   As far as I can tell, they both result in the same thing, but I've only used the first one before in production.  Another Option as mentioned by :  function Test(argument1, argument2) {     if(argument2 === null) {         argument2 = 'blah';     }      alert(argument2); }   As per Juan's comment, it would be better to change Tom's suggestion to:  function Test(argument1, argument2) {     if(argument2 === undefined) {         argument2 = 'blah';     }      alert(argument2); } How do I calculate spoke length? What do we mean by hyperparameters? Let $G$ be a group and $c\in G$. Define $*$ on $G$ by: $x*y=xdy$ for all $x,y\in G$, where $d$ is the inverse of $c$. Prove $(G,*)$ is a group. Let $G$ be a group and $c$ be a fixed element of $G$. Define a new operation $*$ on G by:   $$x*y=xdy$$   for all $x$ and $y$ in $G$, where $d$ is the inverse of $c$. Prove that $G$ is a group under the operation $*$.    If you want to check, this problem is in the book “A Course In Group Theory”, by John F. Humphreys (problem $3$, page $28$)   I know what are the axioms that $(G,*)$ must obey in order to be a group and I did show that all the axioms where obeyed except the inverse axiom.  My problem is that, whenever I try to verify what would the inverse be for some element $x$, I get an equation where the $x$ is cancelled in both sides.  Can please someone guide me?  Thank you!  (P.S.: This is NOT a homework assignment, I’m studying Group Theory by this book and got problems solving this question) Let $a,b$ be positive integers such that $a\mid b^2 , b^2\mid a^3 , a^3\mid b^4 \ldots$ so on , then $a=b$? Let $a,b$ be positive integers such that $a\mid b^2 , b^2\mid a^3 , a^3\mid b^4 \ldots$ that is $a^{2n-1}\mid b^{2n} ; b^{2n}\mid a^{2n+1} , \forall n \in \mathbb Z^+$ , then is it true that $a=b$ ? If router is off for a few days, do you have an ip address as far as ISP is concerned? I have an ISP which assigns IP addresses dynamically. If I go out and turn my router off I am always assigned a new one once I turn it back on. Does that mean that...  1) my previous IP goes elsewhere when my router is turned off?  2) i dont actually have an IP address if my router is off for a day or more? I tried this in mysql:  mysql&gt; alter table region drop column country_id;   And got this:  ERROR 1025 (HY000): Error on rename of './product/#sql-14ae_81' to './product/region' (errno: 150)   Any ideas? Foreign key stuff? Polynomial contrasts for regression How can I type special symbols on my Android device like ☺ or ♥ as a regular character? Terms for collections of animals As I watched the murder of crows sitting on the line above my house this evening, I got wondering where all of the collective nouns for animals (pod of whales, gaggle of geese, pride of lions) came from and why we need so many.    If sheep can be a flock, why can't whales, geese, lions, and crows? I have some simple python code that searches files for a string e.g. path=c:\path, where the c:\path part may vary. The current code is:  def find_path(i_file):     lines = open(i_file).readlines()     for line in lines:         if line.startswith("Path="):             return # what to do here in order to get line content after "Path=" ?   What is a simple way to get the text after Path=? Accessing an array out of bounds gives no error, why? Why use a certain measure of forecast error (e.g. MAD) as opposed to another (e.g. MSE)? MAD = Mean Absolute Deviation MSE = Mean Squared Error  I've seen suggestions from various places that MSE is used despite some undesirable qualities (e.g. , which states on p8 "It is commonly believed that MAD is a better criterion than MSE. However, mathematically MSE is more convenient than MAD.")  Is there more to it than that? Is there a paper that thoroughly analyzes the situations in which various methods of measuring forecast error are more/less appropriate? My google searches haven't revealed anything.   A similar question to this was asked at , and the user was asked to post on stats.stackexchange.com, but I don't think they ever did. Why doesn't the Doctor go back to Gallifrey before the Time War? According to , it’s just the Time War that is time locked. So why does Eccelston's Doctor tell Rose:     My whole planet is gone. My people, my family, all gone. Don't you think I want to go back and save them?   Why hasn't he ever gone back to before the war?   All the other Doctors basically see Gallifrey as gone from them, and when you say the Doctor cannot go back on his own timeline, there will have been plenty of time periods he could go to; maybe to a time before they could regenerate, or maybe when Time Lords were using Tardises — as in "The Doctor's Wife" she says to Matt Smith:     I was already a museum piece when I stole you How can I script the settings made by gnome-tweak-tool? I like to be able to configure things from the command line, so that when I reinstall the OS I can just run a script and get my preferred configuration back.  Since "upgrading" to Ubuntu 17.10, I found I had to use gnome-tweak-tool to get some settings the way I want them.  Once I find a setting in the gnome-tweak-tool GUI, how can I figure out its scriptable translation?  For example the following gsettings lines match the relevant entries in the gnome-tweak-tool screen shot below...  gsettings set org.gnome.desktop.wm.preferences titlebar-font "Tahoma Bold 8" gsettings set org.gnome.desktop.interface font-name "Tahoma 8" gsettings set org.gnome.desktop.interface document-font-name "Tahoma 8" gsettings set org.gnome.desktop.interface monospace-font-name "FixedSC 10"    ...but how could anyone guess that? And how would I, for example, figure out where to get the corresponding settings for hinting and antialiasing?