I have owned a website for about 6 years and it has been a .net site because some squatter has had the other. Recently the domain expired and once its freed up i plan on purchasing it. Is there any real value in me changing the entire site to .com or is it just as good to make the .com domain redirect to the .net website to save any trouble of breaking links and stuff?


Which installed software packages use the most disk space on Debian?

Disk space on my root partition is running low, so I want to delete some applications from the system. How can I see which software packages use the most disk space? Is it possible to view that from aptitude?  I know about generic disk space analyzers like df or baobab, but I need solutions for installed applications.


Prove that all the roots of the equation $(1+z)^6+z^6=0$ are collinear.    $(1+z)^6+z^6=0$ $\frac{1+z}{z}=(-1)^{1/6}=e^{i\pi/6},e^{i3\pi/6},e^{i5\pi/6},e^{i7\pi/6},e^{i9\pi/6},e^{11i\pi/6}$,but i do not know how to solve further.


A problem on chinese remainder theorem (CSIR NET DEC 2015)

Which of the following intervals contains an integer satisfying following three congruences   $$x=2\pmod5\\ x=3\pmod7\\ x=4\pmod{11}$$   $a) [401,600] \\ b)[601, 800] \\ c)[801,1000] \\ d)[1001,1200]$   (CSIR NET 2015 Dec)  I tried this question and I got answer but it is not in the option. I applied Chinese remainder theorem.  $$x=2\pmod5\\ x=3\pmod7\\ x=4\pmod {11}$$  $$N_1=7\times11=77\\ N_2=5\times11=55\\ N_3=7\times5=35$$  $77x=1\pmod5\implies b_1=3\\ 55x=1\pmod7\implies b_2=6\\ 35x=1\pmod {11} \implies b_3=6$  then, $x=2\times77\times3+3\times55\times6+6\times35\times4=2292$  This answer is not in the option.  If my work is wrong please correct it.


Why does $\frac{d^2y}{dx^2}$ represent the second derivative?

I know the second derivative of y wrt x: $\frac{d^2y}{dx^2}$ means  $\frac{d}{dx}(\frac{dy}{dx})$, but is there a mathematical reason you square the $d$ in the numerator but the $x$ in the denominator?  I've wondered if it's because the $d$ in the denominator represents some arbitrary infinitely tiny amount, and the $d$ in the numerator is that same $d$, only squared to account for the second derivative.  Does that make sense, and/or am I missing something significant about derivatives?


Calculating projected area of polygons with field calculator in ArcMap?

I've got a polygon featurelayer in ArcMap 10.  The coordinate system of the featurelayer's featureclass is web mercator.  The dataframe of the map uses an equal-area projected coordinate system.  I've got a field on the featureclass called Acreage.   I'd like to calculate Acreage based on the polygon's re-projected area (into that of the dataframe's projection).  I don't want to create a new featureclass to do this.  Is there an easy way to do this in ArcMap 10?


Why are we allowed to ask only one question per 40 minutes? Shouldn't this time be reduced?  Also, when I was posting my second question on Computer Science.SE then this time limit was 40 minutes but when I head towards posting this question, here at meta, then it was showing 20 minutes limit. What is the logic behind this difference?


Should users be penalized for rejected suggested edits?

I have been paying more attention to the suggested edits pending approval area in my shiny new 10K tools, and I have noticed (just a few) very poor suggested edits.  Reputation is a rough measure of how much the community trusts you. Awarding people +2 reputation makes sense because of this. You're reputable because you suggested an edit that (at least two of) the community agrees with.   However, I think people should also be penalized for a rejected edit. Perhaps -1 reputation, or something more creative (like 5 rejected edits in a week results in -1 reputation).  In my opinion, the other side of reputation is not represented in the suggested edit process.  To me, this is similar to deciding an answer is useful (upvoting) and deciding an answer is not useful (downvoting).  Thoughts?


Problem      Let $A$, $B \in M_n(\mathbb{C}),$ $C=AB-BA$. If $CA=AC$, then $C$ is   not invertible.   To prove a matrix is not invertible, I only came up with $2$ ideas, one is to find a nonzero vector $v$ such that $Cv = 0$, and the other is to prove that $\det C = 0$. However, I have no idea how to use the condition $CA=AC$, so I don't know how to deal with $\det (AB-BA)$.  Is there any other criterion for invertibility of a matrix that is helpful to solve this problem?  I would like to prove $C$ is not invertible, rather than the stronger result that $C$ is nilpotent, so basically this is not a duplicate of another question.


Unable to append string arrays with SQL in operator dynamically. If more values are passed to the array dynamically, how to append it within operator in Oracle SQL query?       String[] rsIdArr = dObj.getRsId().split(",");     int length = rsIdArr.length;      for(int k=0; k<length; k++){         String appendArr[] = new String[k];          appendArr[k] =  "'"+rsIdArr[k]+"'" ;          if(ValidationUtil.isValid(dObj.getRsId())){              strQuery  = strQuery.append("AND TAppr.RS_ID IN " + appendArr[k] );          }      }   Expected result:        AND tappr.rs_id IN ('W0079', 'F002', 'P002159', 'D0701', ........)


I want to search only Google Maps tags and exclude "Android"  I wish to help out in answering googlemaps questions because I work with Google Maps in the Brazilian metro system.


In relation blender 2.79 and the archimesh tool shelf missing, which was answered in   The properties panel is disabled. For example when i add a column i cannot change top or base or add an arch. What do i need to do to enable it?  I posted a follow up there, apologies for that.


What's the best way to refactor a method that has too many (6+) parameters?

Occasionally I come across methods with an uncomfortable number of parameters.  More often than not, they seem to be constructors.  It seems like there ought to be a better way, but I can't see what it is.    return new Shniz(foo, bar, baz, quux, fred, wilma, barney, dino, donkey)   I've thought of using structs to represent the list of parameters, but that just seems to shift the problem from one place to another, and create another type in the process.  ShnizArgs args = new ShnizArgs(foo, bar, baz, quux, fred, wilma, barney, dino, donkey) return new Shniz(args);   So that doesn't seem like an improvement.  So what is the best approach?


How to setup login time limits (a.k.a. "parental controls") if you don't want to login with a Microsoft account?

When creating accounts on Windows 10, you get a choice between "Your family" and "Other users".  If you choose "Your family" you are forced to use a Microsoft account to sign in. There are various reasons why one wouldn't want to do that, such as too much sharing of private information with Microsoft, etc.  If you choose "Other users" you can create regular accounts just fine. However, if you need to setup time limits for some accounts, it is impossible to do so. It is a feature exclusive to "Your family". Not all time-restricted users I want to create are my family, and not everyone is okay with sharing their info with Microsoft.  So, is there a way to setup login time limits for the "Other users" type of accounts?


Help with the following words in a sentence

Hi should I say "I am declaring [a country] my children and I’s ordinarily resident country" or should I use another phrase for "my children and I's" ?  Thank you


The homework tag is now officially deprecated

Homework is no longer a tag on Stack Overflow.      Keeping this post for historical reference. --Shog9   The result of  concludes with the  tag needing to go away on Stack Overflow. As far as tag burninations go, this is quite large, with over 20,000 questions to examine. When the tag is removed, it will be blacklisted - banished to the outer realms and never spoken of again.  The need for preemptive cleanup  Before we put the torch to the thatch, it's worth taking a minute to review these questions manually. One of the reasons why the homework tag is now being discouraged is that it was so often used pejoratively - a way for someone to say, "this question looks  useless or lazily-written" rather than offering advice or... Cleaning it up. While the majority of the questions are decent enough, that still leaves hundreds that should've just been closed, and many more that could use some editing.   How can I help?   the following strategy:   View the tag ordered by votes, then go to the bottom (lowest voted). Deal with the "worst" 100-200 of these first.    If your page size is set to something sane, you'll want to click the last page number at the bottom there. View the closed questions in this tag, order by whatever you like (votes?) and deal with the worst.     Try to remove the worst of the worst, then we can remove the tag from the rest en masse.  So... I just need to edit out the tag on these then?  NO!   The vast majority of these questions will be re-tagged without anyone looking at them directly. We're looking specifically for questions that need some attention but will get lost in the noise when the tag is removed.   After you've given it the attention that it needs (whether that's editing, closing, or flagging), then remove the tag - but remember, you're re-tagging purely as a signal to others that this question is done. Only remove the tag once that question is as close to perfect as you can get it.  What should I look for?   Is this even a real question?  If you can't make sense out of the question, or it's simply a dump of an assignment with no context or additional detail, or an indecipherable mess vote to close it or flag it as "Not a Real Question". Does this only make sense if you know it's homework?  In some cases, an assignment is so contrived that it sounds completely insane unless you know that it is homework. If possible, edit these to clarify the purpose and intent, so that they can stand alone - but if that fails, vote to close as Not a Real Question. Was the tag inappropriately applied?  There are some very basic but still perfectly decent, on-topic questions that may have been closed once someone other than the OP made an edit to apply the  tag. If a closed question is basic, but on-topic and well-asked and was not closed as a duplicate, vote to re-open it.   Why do you hate students?!  We're not discouraging students from asking questions on Stack Overflow! However, the consensus is that everyone can benefit from answers that explain why not just how, and everyone should be encouraged to ask questions that are clear and complete (and list all requirements up-front, even if they're the nonsensical products of an out-of-touch professor or manager).  By getting rid of the "homework ghetto", we hope to make it clear that asking good questions and writing good, informative answers is something everyone should strive for. And if you feel the same way, we're all grateful for your assistance!


How to show (raise) all windows of an application?

I have an application using multiple windows. How can I quickly bring all the windows of that application to the foreground?   When I scroll through the applications with the scroll-wheel it only shows one window. When going to the next window, the last window is brought to the background again.  When I click on the application icon, I get a full-screen overview of all the windows. I have to select each window manually and move my mouse across half the screen several times.  My best solution so far is minimizing all windows (Ctrl+Super+D) and then show the windows of my application using the scroll-wheel.  Is there a better solution?


Recently I came across some documentation that stated that once sudo was successfully ran it stays unlocked for 5 minutes and can be reset through sudo -k. What I was wondering was how do I increase this 5 minute timer to say 10 minutes?


This proof looks extremely flawed, but I'm new to proofs so I'm not completely sure what is allowed and what isn't. Here it is:  Let $n$ be the largest positive integer. Then $n$ must be $\geq 1$. Multiplying both sides of the inequality gives $n^2\geq n$. But, because $n$ is the largest possible integer, we also have $n^2\leq n$, meaning $n^2=n$. Dividing both sides by $n$ gives us $n = 1$.  I'm guessing it has something to do with the $\geq$ sign at the beginning. After all, if $n$ is the largest possible integer, then $n > 1$. But there's also the fact that there is no largest integer. So if I just added "$2 > 1$" to the end of the proof, wouldn't that disprove $1$ being the largest integer?


I am trying (with no luck so far) to calculate the variance of future value of a portfolio. $E= \frac{(1+r)[(1+r)^{t}-1]}{r}$, $r$ is normally distributed random variable.  How to calculate $\text{Var}(E)$?


Is this equation $\nabla_a\sqrt{-g}=0$ correct?

Is the equation $$\nabla_a\sqrt{-g}=0$$ correct? Here $\nabla_a$ is the Levi-Civita connection, and $g$ is the determinant of metric $g_{ab}$. Apparently, we have $\nabla_ag_{bc}=0$, but I am not sure whether the up-mentioned equation is correct or not.


How can i style a sentences first word with only css

hello world
   Here, i want to styling first word "hello" without using any span or b tag or any JavaScript. just using style like h2:first-word{color:red}.   Is it possible? If possible how can i solve it?


When looking at the recent achievements drop downs, the icon for badges appears with the graphic for whatever site you're currently on, rather than the graphic for the site you've earned the badge for.  For instance, in this screenshot, I'm on the Science Fi & Fantasy site, and the badge in the drop-down is from Code Review.    On Code Review, this would be a simply bronze circle, but on SF&F it's this emblem.  Is this a bug, or is this working as intended?


What is "anycast" and how is it helpful?

I'd never heard of anycast until a few seconds ago when I read "".  The wikipedia "" article on it is quite formal and doesn't really evoke a mental picture of how it would be used.  Can someone explain in a few informal sentences what "anycast" is, how you configure it (just in a general sense), and what its benefits are (what does it make easier)?


Failed connection to Earth Engine servers

I'm trying to export a multi-layer image to drive on Earth Engine, but the task fails with the following error:     Error creating or submitting task. Failed to contact Earth Engine   servers. Please check your connection, firewall, or brows   and then the message cuts off.   I've tried getting around this by logging out and logging back in, restarting my computer, and even using separate Earth Engine accounts both on my home wifi and university VPN for internet, so I don't think it's specific to one Earth Engine account or internet situation. Also tried over two days now, so I don't think it's a temporary server problem either.  Repeatable code below; wondering if anyone can provide insight.  // Generate Region of Interest var ROI = ee.FeatureCollection('USDOS/LSIB/2013')   .filter(ee.Filter.eq('cc','GL'));  // Compile the data var dataset = ee.ImageCollection('MODIS/006/MOD13Q1')                   .filter(ee.Filter.date('2005-01-01', '2005-12-31'));  // Select the data you're interested in var ndvi = dataset.select('NDVI');  // Prep data for export // https://gis.stackexchange.com/a/254778/67264 var stackCollection = function(collection) {   var first = ee.Image(collection.first()).select([]);   var appendBands = function(image, previous) {       var dateString = ee.Date(image.get('system:time_start')).format('yyyy-MM-dd');       return ee.Image(previous).addBands(image.rename(dateString));   };   return ee.Image(collection.iterate(appendBands, first)); };  var ndvi_img = stackCollection(ndvi); print("NDVI Image", ndvi_img);  // Export the data // Export a cloud-optimized GeoTIFF. // See https://developers.google.com/earth-engine/exporting Export.image.toDrive({   image: ndvi_img,   description: 'MOD13Q1_NDVI',   scale: 250,   region: ROI,   fileFormat: 'GeoTIFF',   formatOptions: {     cloudOptimized: true   } });


I often have trouble estimating best image pixel size to large centimeter size, without causing much loss of quality.  Today is no different. A client wants a chosen image from shutterstock on his wall. (as wallpaper). The wall is 6680x1200mm  I can see on shutterstock the pixel size from the image. But how can I estimate if the pixel size is high enough for the size of the wall, without buying the image? Can I calculate what the minimum pixel format should be? If so, how can I do that?


Check if string array index is equal to string

So I'm trying to check a list of account names to see if the username entered by the operator is in the database or not. At the moment I have:  for(int i = 0; i < rowCount; i ++){             System.out.println("Stored in array:" + accounts[i+1]);             System.out.println("name entered:" + LoginPage.usrname);             if(accounts[i+1] == LoginPage.usrname){                 System.out.println("match");             }else{                 System.out.println("no match");             }         }   I tried messing around with things like indexOf string and can't get anything to work. I'm sure there's a simple solution, just having trouble finding one. I don't understand why I can't compare a String array index to a String variable, seems like ti should be cake.


Recently, I have installed ubuntu 13.04, and updated it. I want to install skype. I search in "ubuntu software center" but I did not find anything. Therefore, I search on internet. I found out some commands for skype installation. Then, I open the terminal and type the command. it request for password. The problem is that when i want to enter my password, my keyboard did not work and I can not type my password. How can I fix that?  Thanks


I would like the reference citation to appear like [1-4], rather than [1], [2], [3], [4].  Here is my MWE  \documentclass[a4paper,10pt]{book} \begin{document}   Some text  \bibliographystyle{unsrt}    \bibliography{refer}     \end{document}   How to solve this pooling of citations?


Series $\sum_0^{\infty} a_n$ and $\sum_0^{\infty} b_n$ are convergent series then so is $\sum_0^{\infty} c_k$ where $c_k= \sum_{l=0}^{k}a_lb_{k-l}$

Series $\sum\limits_0^{\infty} a_n$ and $\sum\limits_0^{\infty} b_n$ are convergent series then so is $\sum\limits_0^{\infty} c_k$ where  $c_k= \sum\limits_{l=0}^{k}a_lb_{k-l}$  Solution I tried:  I tried to prove this using a counterexample like $$a_n\frac{(-1)^n}{(n+1)^{\frac{1}{3}}}$$ and $$b_n=\frac{(-1)^n}{(n+2)^{\frac{2}{3}}}$$ then after that we get $$c_k=\frac{(-1)^{2n}}{(n+1)}$$  which is divergent,  but I contrardict this with an example, is there any way we can prove this divergent or convergent with proper definition?  Please help  Thank you


$G =(V,E)$ is $k$-connected ($k \geq 2$), prove that for every subset $S \subseteq V $, |S|=k there exists a cycle in $G$ that goes through all of $S$

I thought of starting from the Menger theorem which says that between every two vertices $u$ and $v$ there are $k$-edge disjoint graphs. So I think if I look at $G$ without the subset $S$ then I have $k$ paths from $S$ to $V-S$. I know for a fact that there has to be a cycle because $k \geq 2$ and between $u$ and $v$ there are at least two paths and they form a cycle. Now I was thinking about looking at $u\in S$ and $v\in V-S$. At this point I get stuck ...


Solving for the closed term solution of a third order recurrence relation with real constant coefficients

How would you solve for the closed term form of $a(n)$ given the general form of the third order linear homogenous recurrence relation with real constant coefficients.  $a(n)-P\,a(n-1)-Q\,a(n-2)-R\,a(n-3)=0$  with the initial terms of a1, a2, and a3  and given that the roots of the characteristic equations have   two repeated roots and a real root three repeated roots   (can you give answers for both cases please)  For second order recurrence relations I know that you can use generating functions to deduce a closed form because it is then expressed as a arithmetic series which can be converted into a closed form.  However in the case of the general term of the third order recurrence relations if I follow the same steps what I did with the second order recurrence relation, instead of getting a simple arithmetic series I seemed to get a second order recurrence relation inside the series.  What am I doing wrong?  or is there a different method of approach in this case?  When I search the web I get these results  S(n) = nAx1^n + Bx1^n + Cx2^n,for the case when there are two repeated roots  and  S(n) = n^2Ax^n + nBx^n + Cx^n, for the case when there are three repeated roots  I just don't know how to get to these results  Please help


Overland travel - Thai visa requires tickets in and out

I am an Indian citizen living in Singapore and will be travelling overland from Malaysia into Thailand and then onto Laos. The visa form (online) states that I should upload tickets showing that I enter and leave Thailand. How do I go about this? My options are:   Print a flight itinerary and say that I will be travelling over air. Don't upload any tickets and submit my visa for processing anyway.   EDIT: Rephrasing the question, can I apply for the visa with a flight itinerary and then go over land in the end or will there be problems if I do this?


Do I need a 32 bit version for my old PC?

I'm new to computers in general. I checked the system and it said 32 bit/pixels. I don't know if pixels is different than bit, but that's what it said. I want to know if there is either a 32 bit version or if I need a different OS. It currently has winXP as OS. It has 1.5 GB mem. Celeron d inside. It's a gateway. EDIT:I CHECKED THE DRIVES AND IT WAS MY DADS OLD PC. IT HAS UBUNTU ONE ON IT.  IF I MOVE A WINDOW IT SHAKES IT. KINDA LIT IMA KEEP IT.


How can i limit the character length in excerpt?

Possible Duplicate:          I have a question after reading this post (). I like this function(Search Term Without Plugin) very much but the character length is too long. What php code should i add to make the excerpt shorter? Would appreciate if someone can suggest it. Thank you!


Consider the following model for the populations of prey x ≥ 0 and predators y ≥ 0,

$$\dot{x} = x(1-\mu x-y), \quad \quad \dot{y} = y(-1+x-y)$$  where $\mu > 0$ is a constant. The number and type of equilibria depend on the value of μ; in fact there are three essentially different cases. Find the three corresponding ranges of μ and the number, type and stability of the equilibria in each case. (Ignore a borderline case with a zero eigenvalue, but look carefully at any other borderline cases.)  I've already worked out the following:  $$(x_0, y_0) = (0,0), \quad (0,-1), \quad (\frac{1}{\mu},0), \quad (\frac{2}{\mu +1},\frac{1-\mu}{\mu+1})$$  $\therefore$ If $\mu = -1$ or $\mu = 0$ then there exist only 3 equilibrium points. However, if $[\mu \in \mathbb{R} : \mu \ne 0, -1]$ then 4 equilibria exists.  Thus from here, assume $\mu \ne 0,-1$  Jacobian:  $$J = \begin{bmatrix} 1-2\mu x -y & -x\\y & -1+x-2y\end{bmatrix}$$  I've also worked out the Jacobian for $(\frac{1}{\mu},0)$ and found the polynomial for the EVal's to be $\frac{-b \pm \sqrt{b^2 - 4b}}{2}$ where $b = \frac{\mu -1}{\mu}$.  Now where do I go from here to complete the question? Also please do keep in mind that I'm studying Maths not Physics.  Many thanks.


Can I sell starting gear in Adventurers League play?

I'm starting a new AL game (as a player) and I have a question that's not addressed in the AL material.  According to Adventurers League Player's Guide (page 4)     When you create your D&D Adventurers League character for the current season, take starting equipment as determined by your class and background. You cannot roll for your starting wealth.   Meaning I can't start with whatever I want. However, I am playing a ranged-focused fighter, so the second gear option is of no use to me:   (a) a martial weapon and a shield or (b) two  martial weapons   Can I choose any two martial weapons and sell them for half price to use for purchasing other gear before play? And is there a restriction on how much gold I can get?  For example, two hand crossbows (martial ranged weapons) can net me 75 gp when sold, or two greatswords nets me 50 gp when sold.


I was using this:    To try and create numbered examples in my document.  However, when I load it and put the example exe in that link in one of the separate Tex files (Introduction.tex) I include in main.tex, I get:  ./Chapters/Introduction.tex:14: TeX capacity exceeded, sorry [parameter stack s ize=10000]. \gb@ifnextchar #1#2#3->                        \let \reserved@d =#1\def \reserved@a {#2}\def \reserv... l.14 ... and political news \cite{washington_post}                                                   .  More importantly, when ...   Which is not even referring to the exe example I inserted but a couple of blocks of tex above it.  For info, here is my full code before my document begins:  \documentclass{report} % [fontsize=11pt,border=5pt] % standalone for the tree \usepackage{forest} % This overrides warnings like http://tex.stackexchange.com/questions/52576/difference-between-bookmark-levels-greater-than-one-what-does-this-mean \usepackage{bookmark} \usepackage{amsmath} \usepackage{subcaption} \usepackage{standalone} \usepackage[round]{natbib} \usepackage[T1]{fontenc} \usepackage{lmodern} \usepackage[utf8]{inputenc} % This is for hyperlinks \usepackage{hyperref} \hypersetup{     colorlinks=true,     linkcolor=blue,     filecolor=magenta,           urlcolor=cyan, }  \urlstyle{same} % Not sure why I need to use this % \usepackage{graphicx} % \graphicspath{ {images/} } % \usepackage[pdftex]{graphicx} % fontsize=11pt,twoside]{scrartcl} % This is for numbered examples \usepackage{gb4e}   Would appreciate some help as I feel like my Latex is very messy here.


How to decouple reference to python object

I create the following list of list containing False:  array=[[False] * 3] * 5   How can I change only value value?  array[1][0]='change only this'   Currently the result is   [['change only this', False, False],  ['change only this', False, False],  ['change only this', False, False],  ['change only this', False, False],  ['change only this', False, False]]   which is not desired. I understand each column is one single object [False] * 3]. How can I decouple them from each other. Do I need to make them immutable somehow?


How to inform new users to tag user name when replying

Some new users ask questions and I sometimes reply in the comments. Also, some other users also comment on questions.   We will just comment and close the URL of the question, and if the OP comments again, we don't get the notification because he didn't tag any usernames. This way there are a lot of chances that they may miss help.  How can we avoid this? Can the system make it mandatory to add tags in the comments?


What is the difference between the two Police Stations?

The police station public works project just became available in my town.  There are two of them - modern and classic.    What are the differences / similarities between the two, and are there things exclusive to either that the other one doesn't offer?


Hard inequality $ (xy+yz+zx)\left(\frac{1}{(x+y)^2}+\frac{1}{(y+z)^2}+\frac{1}{(z+x)^2}\right)\ge\frac{9}{4} $

I need to prove or disprove the following inequality: $$ (xy+yz+zx)\left(\frac{1}{(x+y)^2}+\frac{1}{(y+z)^2}+\frac{1}{(z+x)^2}\right)\ge\frac{9}{4} $$ For $x,y,z \in \mathbb R^+$. I found no counter examples, so I think it should be true. I tried Cauchy-Schwarz, but I didn't get anything useful. Is it possible to prove this inequality without using brute force methods like Bunching and Schur?  This inequality was in the Iran MO in 1996.


Interstellar war using transfer booths, novella length

Serialization, likely Omni, possibly Analog, likely early 1980s.  Space war, Earth and unknown aliens. Both use interstellar transporter booths. Small versions, large enough for cameras and similar, are shot to nearby stars. When they arrive they turn on, connect to Earth, and start sending back data. If the system proves interesting, they transfer in parts and use them to build a larger booth, and then use that to make a larger one, and then...  I recall two bits:  The protagonist is part of a group that goes through booths when they enter new systems. A booth has collided with a planet that seems to have an atmosphere and he's the guy that has to go through. When he arrives he realizes it's a trap, and as a very brief encounter with an alien, who's arm he crushes before transporting out.  The second is the end of the portion I read, which I guess was the first half/third of the whole. A new booth arrives in a system where the enemy has also just arrived, and a race breaks out between the two to get their largest booths in-system. However, a General is arguing this is the only chance to attempt peace talks. And that's the last page.


Can a question that is on hold be reopened?

Can a question which is on hold be reopened? I've edited the post, will it be opened again?   My post is here:  It is under hold now. What should I do?


How does mass of the exchange particles affect the range of a force?

I read an article asserting that nuclear force is a short range force because of gluon's mass, and EM force is a long range force because photons massless.  I also want to know, why quantum confinement is a consequence gluon's mass?


Circle-Rectangle collision detection (intersection)

How can I tell whether a circle and a rectangle intersect in 2D Euclidean space? (i.e. classic 2D geometry)


I'm trying to get away from windows and wanted to install Ubuntu Studio on my custom built gaming computer. It ran Windows 10 perfectly, but I removed the HDD and installed a SSD, but when attempting to boot iso from USB via 3.0 slot from Gigabyte motherboard bios, I'm getting this error.  reboot and select proper boot device or insert boot media in selected boot device and press a key  I've seen a lot of steps from other sites about this, but relating to booting windows 8/10.   Has anyone come across a solution?  Motherboard is UEFI, Secure boot is disabled, and I placed in legacy mode. Still getting this issue. Thank you.


Convergence in Distribution and Ordered Statistics

Let $X_1, X_2, \ldots$ be iid from Exp$(\theta)$ with density function $f(x) = \frac{1}{\theta}e^{-\frac{x}{\theta}}$. Find the limiting distribution of $M_n = Y_1 - \theta\ln(n)$ and $T_n = nY_n$, where $Y_1$ and $Y_n$ represent the first and last order statistics (among $n$ observations) respectively. Answer: The CDF of $X$ is: \begin{eqnarray*} F_X(x) & = & P(X\leq x) \\ & = & \int\limits_0^x \frac{1}{\theta}e^{-\frac{t}{\theta}} dt \\ & = & \frac{1}{\theta}\cdot\frac{-\theta}{1}e^{-\frac{t}{\theta}}\Big|_0^x \\ & = & 1 - e^{-\frac{x}{\theta}}. \end{eqnarray*} or $P(X \geq x) = e^{-\frac{x}{\theta}}.$ Then since $Y_1 = \min\{X_1, X_2, X_3, \ldots, X_n\}$: \begin{eqnarray*} P(Y_1 \geq x) & = & P(\min\{X_1, X_2, X_3, \ldots, X_n\} \geq x) \\ & = & P(X_1 \geq x, \ldots, X_n\geq x) \\ & = & P(X_1\geq x)\cdot P(X_n\geq x) \\ & = & (e^{-\frac{x}{\theta}})^n \\ & = & e^{-\frac{xn}{\theta}}. \end{eqnarray*} So the CDF of $Y_1$ is: $$F_{Y_1}(x) = P(Y_1 \leq x) = 1 - e^{-\frac{xn}{\theta}}$$ Thus, the CDF of $M_n$ is: \begin{eqnarray*} F_{M_n}(x) & = & P(M_n\leq x) \\ & = & P(Y_1 - \theta\ln(n) \leq x) \\ & = & P(Y_1 \leq x + \theta\ln(x)) \\ & =  & 1 - e^{-\frac{n}{\theta}(x + \theta\ln(n)}.  \end{eqnarray*} I do not know how to compute the limiting distribution because I am unsure how to evaluate $\lim\limits_{n\to\infty} F_{M_n}(x)$. Have I completed the mathematics correctly? I did not attempt $T_n$ portion yet because I believe $M_n$ part is incorrect.


How do I uninstall Ubuntu 16.04 running alongside Windows 7 (preferably without using a cd)?

I was trying to install Ubuntu 16.04 on my flash drive, but it installed on the computer (at a public library) that I was using (although the computer still runs Windows 7). The librarians asked me to uninstall it because the Ubuntu purple boot menu pops up every time somebody starts the computer. How do I uninstall Ubuntu (preferably without a cd). This question is not a duplicate because I am asking for instructions when Windows is still on the computer, and I specified that I would rather not use a cd.


how to change the os ubuntu 14.04 to windows completely?

when i try to install windows 8.1 o.s to my laptop.it shows that the required cannot be selected showing something like drive 0 cannot be installed.i my Ubuntu o.s is in u.e.f.i mode.and the entire o.s is in a single partition which is under the owner of root..i cannot unmount the drive.


What is the difference between pseudoscience and non-science?

Within the scope of the problem of demarcation there seems to be an implicit distinction between pseudoscience and non-science. Trying to make explicit what such distinction might be, I wonder: Does the difference between pseudoscience and non-science amount simply to the fact that the former "pretends to be scientific" whereas the latter does not? --- What does it really mean for some theory "to pretend to be scientific"?  (And, could it be that theories we might consider pseudoscientific at present time, would turn in future into scientific ones (just as it happens from time to time with non-scientific theories that evolve into scientific ones?))


My current python version is python 2.7 (python --version), However, I've accidentally removed python2.7 from /usr/lib/ so I cannot do anything and I see this error:  Could not find platform independent libraries <prefix> Could not find platform dependent libraries <exec_prefix> Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>] ImportError: No module named site   Any suggestion?


What's difference between su username and sudo login username command?

I can't notice any differences except welcome message in second case. Also different files in etc/pam.d/ are responsible for different types of login


How do I import multiple OBJ files into blender using python?

So far I have the code:  scene = bpy.context.scene import_avHat1 = bpy.ops.import_scene.obj(filepath=avatarHat_1) import_avHat2 = bpy.ops.import_scene.obj(filepath=avatarHat_2) import_avHat3 = bpy.ops.import_scene.obj(filepath=avatarHat_3) hats = bpy.context.selected_objects[:]  for obj in hats:     # print the name of the current obj     print (obj.name)     bpy.context.view_layer.objects.active = obj   obj_camera = bpy.context.scene.camera scene.render.image_settings.file_format = 'PNG' scene.render.filepath = "~/mark/renderOutput.png" bpy.ops.render.render(write_still = 1)   It only renders the first hat and I get no errors importing the others. What should I do? This occurs in blender 2.8.


My oscilloscope has 100 MHz -3dB bandwidth. -3dB is 0.707 units (sqrt(2) / 2). What does this mean, why 70.7% attenuation? Is there any particular reason for this attenuation level?


Is there a limit for the bonus experience % that you can get?  Say you equip   Cain's Laurel, socketed with a Star ruby +25% 2 other Cain's set items                 +30% hellfire ring                            +35%   This will give you 90% bonus experience, is there a limit?


Parameter estimation problem: maximum likelihood

Suppose I have some observations $x_{1}, x_{2}, \dots, x_{n}$. I also have a probability density function with one unknown parameter $\theta$. I would like to find such $\theta$, which would give the highest probability of observing the data points I have. How do I solve such problem?


PGFPlots: Sometimes minor ticks don't show

See code below: xtick={-0.8,0,...,3.2} does not show minor x ticks, but, for example, xtick={0,0.5,...,3.5} does.   I'm confused, what's going on?  \documentclass[border=0pt]{standalone} \usepackage{pgfplots}  \begin{document}  \begin{tikzpicture}   \begin{axis}[       smooth,       axis lines=middle,       axis line style = {very thick},       xmin=-0.8,       xmax=3.2,       ymin=-1.5,       ymax=1.5,       xtick={-0.8,0,...,3.2}, %minor tick DO NOT show       % xtick = {-0.8,0,0.8,1.6,2.4,3.2}, %minor do tick show                 % xtick = {0,1,...,3}, %minor tick do show       % xtick = {0,0.5,...,3.5}, %minor do tick show       minor tick num=1,       grid=both,       ]     \addplot+[samples=100]{cos(deg(x))};   \end{axis} \end{tikzpicture}  \end{document}


Use induction and elimination rules of propositional logic to prove

I was asked to prove p -> q |- ¬p or q by nature induction   $p \rightarrow q$         premise p                        assume q                        $\rightarrow e,1$ $¬ p \rightarrow ¬ q$ ¬p                       assume ¬p or q                   or-i, 3-5   is it correct?


Can't install 3rd party software after 16.04

I just finished a clean install of 16.04 after some hardware changes, and I'm reconstructing system. Having trouble getting software center to install any 3rd party software, google chrome and teamviewer so far, I bet Skype will hang too. I checked all the obvious settings. I don't want to have to look up and add repositories one by one, I never had to do that before upgrade, and I try to minimize terminal use. What's the fix? Thanks!


Why would I want to disable Copy-On-Write while creating QEMU Images?

The  recommends that images have Copy-On-Write disabled on the directory when using btfs.  I do see that it would be a good idea if you had a lot of file read/writes.   question explores this idea.  I know that VMWare will grow into different files and will write snapshots out which could be problematic when using Copy-On-Write.  For QEMU the file is left open for the VMs existance so there is a potential problem in the write after the VM is shutdown, but I would see slow I/O after a VM is shutdown not being an issue.  What pitfalls would I be avoiding by performing this step for QEMU.    Additionally: I have assumed that the image is raw for this question.  Is there a possible stability issue as qcow2 already has copy-on write.


I have a multi step custom made form in Drupal 8.2.x.  Some of the user input from the form needs to be shown on a separate block.  The following code worked fine for users that are logged in:  $tempstore = \Drupal::service('user.private_tempstore')->get('mymodule_name'); $tempstore->set('my_variable_name', $some_data);   But it doesn't work for anonymous users on my site.  Is there a tempstore for anonymous users that works site wide that I just haven't discovered yet?


Is there a difference between malloc() and creating a variable and then using the & operator?

In C, is there a difference between  struct Foo foo; struct Foo* fooPtr = &foo;   and  struct Foo* fooPtr = (struct Foo*) malloc(sizeof(struct Foo));


I have an Ubuntu VM (running in VMWare Fusion) and I can no longer update my apps - software updater tells me I must update from 15.10  When I try to Upgrade the machine does nothing - I never see any upgrade happen and I seem to be stuck on 15.10


Now, before you flag this question as blatantly off-topic, I claim to have a scientific basis for this(!): not some drug or remote control, but parasitic infection. While reading about , I found this:  Parasites that induce behavioral changes in their hosts often exploit the regulation of social behavior in the brain...For example, Toxoplasma gondii attaches to the hypothalamus rather than target a specific cellular pathway; this broad targeting leads to a widespread increase in host dopamine levels, which may in turn account for the loss of aversion to cat odor...This rise in dopamine levels induces a loss of aversion to cat odor in the rats, increasing the risk of predation by cats, T. gondii’s definitive host.  Now, if a parasite can prevent mice from being afraid of cats, how hard would it be for another parasite to prevent humans from caring about each other's life(!)? Can a parasite develop some method by which it can alter behavior of humans in such a way that they just start killing each other for no reason? How easy/hard would it be for a parasite to do so? Note: although it is just a curiosity question about whether it is possible or not, giving some description of neural pathways which stimulate social behavior in humans and how they are regulated would be much more appreciated.


How do I find at least the closest penetrating point with SAT?

For more accurate simulations, I want to find the closest point of another polygon to one polygon's center when they collide. Is this possible with the SAT algorithm? Is it a good strategy at all for semi-accurate physics simulations (more accurate than the normal between the 2 polygons' centers)?


in browser if i click on back button or backspace how it will going to redirect to login page

I am working on online exam page if the user click on start exam button there are three process have to done    disable button click on back button in browser it will going to redirect to login page    In the section, I have completed 1. But how to achieve point 2? Does this require C#, JavaScript, jQuery or ASP.NET?  Could this work? Response.Redirect() or Server.Redirect()


How do I add codecs for  MP3 url streams ? I am running ubuntu 12.04 with the standard firefox from 12.04


Failed to load module “canberra-gtk-module” .... but already installed

Gtk-Message: Failed to load module "canberra-gtk-module"   but I already have the libcanberra-gtk-module  and libcanberra-gtk3-module installed. (i.e. I tried , but it is already installed.)  This happens for instance, when I run ipython --pylab  I'm running Ubuntu 13.04 - raring.


Why can't I post a detailed question and link to jsfiddle without including code?

Apparently I can't post a question which refers to an earlier question, links to a couple of separate jsfiddle scenarios, and is illustrated, without adding code.   Error is "you can't link to jsfiddle without adding code".  So I've added a pointless bit of code.  I can understand the point is to stop people posting brief answers which link to jsfiddle, with no context.  But in  the code is a distraction.   Shouldn't questions which link to jsfiddle be excused the code requirement (especially if theyshow their effort in other ways)?


Script to move all files in a dir (and subs) to a new folder based on extension

I had to recover a micro-sd card using photorec. I'm left with a dir that contains lots of other dirs which also include multiple file extensions. I would like to move each file to a new dir based on the file extension:  *.jpg moved to dir /SortedDir/jpg  *.gif moved to dir /SortedDir/gif  Also needing to take into account raw files with no extension or *.<'blank>  I have done this successfully in a batch on Windows:  @Echo OFF  Set "Folder=C:\MessyDir" Set "DestDir=C:\SortedDir"  FOR /R "%Folder%" %%# in ("*") DO (     If not exist "%DestDir%\%%~x#" (MKDIR "%DestDir%\%%~x#")     Echo [+] Moving: "%%~nx#"     Move "%%#" "%DestDir%\%%~x#\" 1>NUL )  Pause&Exit   Looking for a linux script version.  Thanks!!


Constant $g$ acceleration from astronaut's frame of reference

When a spaceship is experiencing a constant acceleration of $10m/s^2$, the astronauts will be moving at nearly the speed of light after about a year in the earth's reference frame. This means the spaceship's energy will start to diverge as a function of the speed $v$ so there will be a huge amount of energy necessary to increase the speed of the ship any further. This way, the speed of light can never be crossed.  All of this is clear to me, but all of this is also formulated in earth's reference frame. But from the astronaut's reference frame: the spaceship is simply accelerating at $10m/s^2$ and so the force on the spaceship is constant. Then why would we need huge amounts of energy to accelerate the spaceship?  For example, I read somewhere that the amount of energy that would be needed to accelerate a large spaceship to half the speed of light is more than 2000 times the current world annual energy consumption. How does this make sense in the astronaut's (non-inertial) frame?


Please, how i can change date format in php  from something like 2012-12-14 08:40:26  to format number like 28124629523


Prove the identity $\sum_{k=0}^n \binom{n}{k}=2^n.$ using combinatorial proof.


Linked account +100 rep bonus also applied to account with 200

Not sure if it is a bug or not, but it feels like a bug to me. When I got to 200 rep on SO the other day I got +100 rep to all my accounts including SO. So my rep jumped up to 300 on SO.  Considering there are others on SO with rep between 200 and 300 I think it is possible that the +100 was supposed to apply only to the linked accounts, not to the account with 200+.


How can I make a new account when I am question banned?

I have an account on Seasoned Advice, but it has been question banned. I would like to create an additional account so I can continue to ask questions. How can I do this?


How to join a line with a pattern with the next line with sed?

I can't find this case in the board, so I'm asking the question.  This is input file:  module   x(a,b,c)   module   y(d,e,f,   g,h,i)   module   z(j,k,l)   And output file should be:  module x(a,b,c)   module y(d,e,f,   g,h,i)   module z(j,k,l)


Ubuntu 18.04 can't resume after hibernate

Hibernate worked correctly when I had been using Ubuntu 17.04. After upgrade to 17.10 I couldn't resume because of black screen after resume ().   After upgrade to 18.04 if I try to start my computer after hibernation it boots as if there was no hibernation done.


Why undefined referenced to mMutex in my singleton class

I have implemented a Meyer's singleton pattern. And I try to do some stuff testing it in a multithreading environment. Here is how I implemented the class in C++.  #include<thread> #include<mutex> class singleton { public:   static singleton& instance() {     std::lock_guard<std::mutex> lck(mtx);     static singleton *my = new singleton;     return *my;   } private:   static std::mutex mtx;   singleton() {}   ~singleton() {}   singleton(const singleton &) {}   singleton& operator=(const singleton &) {} };   But when I compile this with g++ -std=c++11 singleton.cpp -o singleton -lpthread, it says   /tmp/ccfEBnmN.o: In function `singleton::instance()': singleton.cpp(.text._ZN11singleton12instanceEv[_ZN11singelton12instanceEv]+0x10): undefined reference to `singleton::mtx' collect2: error: ld returned 1 exit status   I understand this might be some problem in design, since without initializing the first singleton instance how could we get the mtx. If in this case, my question comes to how to implement a thread safe singleton class based on my code? How do we initialized the mtx in my singleton class?  I know there is a traditional way to create a singleton pattern by maintaining a static pointer points to the singleton class. But indeed that is not "so" thread safe. Even applying the double check mechanism in the instance() method.


C++ Undefined reference to 'LinkedList::append(int)'

I'm trying to write a linked list with a generic object based on this guide: . When I put the declarations and implimentations in the same file it works, but I'm having trouble separating the code into source and header files.  For reference I'm using code::blocks. I've tried readding the linked_list.cpp file, I've tried adding the directory it's in to the search directories under build options -> Search Directories -> Linker, and i've tried compiling it in gcc and g++ from command line manually and they've all given me the same error. I've obviously done something wrong when I tried to separate out the header file from the source file, I just can't figure out what. Relevant snippets from my code below.   main.cpp:  int main() {     LinkedList<int> *list = new LinkedList<int>();     list->append(1);     list->append(13);     list->append(32);     list->displayListValues();     return 0; }   linked_list.h  #ifndef LINKED_LIST_H #define LINKED_LIST_H  using namespace std;  template <class T> struct node {     T data;     node *next;     node *prev; };  template <class T> class LinkedList { private:     node<T> *head, *tail; public:     LinkedList<T>();     bool isEmpty();     void displayListValues();     void append(T value); }; #endif   linked_list.cpp  template <class T> void LinkedList<T>::append(T value) {     node<T> *new_node = new node<T>;     new_node->data = value;      if (head == NULL) {         head = new_node;         tail = new_node;         new_node = NULL;     } else {         new_node->prev = tail;         tail->next = new_node;         tail = new_node;         new_node = NULL;     } };


Does "make offline" option in Google Maps works with applications that utilize Google Maps?

In newer Google Maps I can make area available offline.  Do other applications that rely on Google Maps (utilize Google Maps Android API) use offline maps?


What happens when you flag a post or comment?

Does your reputation get compromised when the flag is declined?  Do you get notified when your flag has been reviewed?


The other houses’ mascots make sense. Lions represent bravery, snakes represent cunning, and eagles have a refined quality about them. But what exactly does a badger symbolize? Hufflepuffs are known for their patience, hard work, and loyalty.


Why double-headed arrows when the direction of node is specified?

I am quite puzzled when drawing the connection of nodes.  \usepackage{xcolor} \definecolor{darkblue}{HTML}{1F4E79} \definecolor{salmon}{HTML}{FF9C6B} \tikzstyle{cell} = [rectangle, minimum width=1cm, minimum height=0.5cm,text centered, draw=black, fill=salmon] \tikzstyle{state} = [rectangle, minimum width=1cm, minimum height=0.5cm,text centered, draw=black, fill=darkblue] \tikzstyle{arrow} = [thick,->,>=stealth]  \begin{tikzpicture}[thick,scale=0.8, every node/.style={scale=0.8},node distance=1.5cm]     \node (0) [state] {\textcolor{white}{feature extraction}};     \node (1) [cell, below of=0] {invertBotConE2\_f48\_k1\_b4\_noskip};     \node (2) [cell, below of=1] {invertBotConE2\_f16\_k3\_b4\_noskip};     \draw [arrow] (0) -- (1);     \draw [arrow] (1) -- (2);     \draw  (0.east)  [arrow]  edge [out=0, in=0, out looseness=4, in looseness=4]  (2.north); \end{tikzpicture}   0,2 are my nodes. When east is specified, it creates an arrow on node 0. If removed, it disappears. What if I would like to put 0.south as the start of the edge?


I implemented a recommender using tensorflow, based on e-commerce data. This recommender is predicting the next item a user will buy. I will judge the performance of my fitted model, by getting the next estimate of the model and comparing, if the user did actually buy this item (compare  with k == 1).  My precision is around 20% (meaning in 20% of the cases the user did actually buy the product the system recommended). Our shop has about 150 Products and my evaluation is based only on properties of the user, not his/her purchase history.   In this case, is 20% good? Are there other, similar systems I can compare to? What would be a good precision for, e.g. 100.000 products?


Why do some people write the indefinite article "a" before vowels?

According to the rule, the article "a" is for consonants and the article "an" is for vowels. Nevertheless, I have seen it frequently that many use the article "a" with both vowels and consonants. For example, they say "this is a expensive car" not "this is an expensive car" as it should be. Is there a reason for that?


Always a have problem when I install any version of ubuntu, but in this opportunity I can't solve the issue. My wifi connection down after 1 or 2 minutes in Ubuntu 17.04, it's so unstable, I already tried with:  apt install firmware-b43-installer   I have read so many articles in internet about the issue and nothing solve the problem, only change the time of issue ie the wifi get down in 2 minutes or in 10 minutes or in 1 more day but always get down, I do not know what doing. These are the tech features of my notebook when I execute these commands:     lspci -nn   Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8821AE 802.11ac PCIe Wireless Network Adapter [10ec:8821]   and      lspci -knn | grep Net -A2   Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8821AE 802.11ac PCIe Wireless Network Adapter [10ec:8821]  Subsystem: Lenovo RTL8821AE 802.11ac PCIe Wireless Network Adapter [17aa:a814] Kernel driver in use: rtl8821ae Kernel modules: rtl8821ae   This is my kernel info:     uname -mrs   Linux 4.10.0-20-generic x86_64   My notebook is a Lenovo 310-14IKB. I am not what more doing


write a simple shell program to show a loader in TUI

I am thinking of writing a simple shell program that will show an output in the console about the percentage work completed. something like thiss:-  2%==>   which will increase the arrow with respect to the work done. I donot want to print the loader every time in a new line. what should be my approach?' *I often see this thing is used in wget and similar commands   TIA


Can "said someone" appear at the beginning of the sentence?

The film debuted at No. 2 in both France and Italy, generating the year's third-best box office return on an opening weekend in Italy. Said Roberto Proia, distribution chief of the film's Italian distributor Moviemax, about its surprisingly warm reception, "Almost two years after his death, Ledger has a huge fanbase which, along with the rest of the stellar cast, certainly contributed hugely. [...] We also found out that teenagers massively love Gilliam, and we did not expect this. He really has rock star status." ()   The structure of this sentence strikes me as unusual. Can you say something like     Said John, "I didn't like the movie."   Can "said" appear at the beginning of the sentence like this?


How to draw a branch name to the console?

Is it possible to display the name of the branch in this place?    How is this done in git bash for windows?


Justifying an early equation from *Introduction to Statistical Learning*

I'm self-studying Introduction to Statistical Learning. Page 19 of the book states the following:     Consider a given estimate $\hat{f}$ and a set of predictors $X$, which yields the prediction $\hat{Y} = \hat{f}(X)$. Assume for a moment that both $\hat{f}$ and $X$ are fixed. Then, it is easy to show that      $$ E(Y-\hat{Y})^2 = E[f(X) + \epsilon - \hat{f}(X)]^2 = [f(X) = \hat{f}(X)]^2 + Var(\epsilon)$$   Question: How exactly is the step from $E[f(X) + \epsilon - \hat{f}(X)]^2$ to $[f(X) = \hat{f}(X)]^2 + Var(\epsilon)$ justified?


Probability of at least 3-of-a-kind in a 7-card poker hand

This problem asks to explain why the method used is overcounting or undercounting cards in a 7-card poker hand that contains at least two 3-of-a-kind (3-of-a-kind means three cards of the same rank) and calculate the correct probability.For example, this would be a valid hand: ace of hearts, ace of diamonds, ace of spaces, 7 of clubs, 7 of spades, 7 of hearts and queen of clubs. (Note that a hand consisting of all 4 aces and three of the 7s is also valid.). The $P_1(E)$ answer is given and basically we have to refute it. My answer is that the correct answer is $P_2(E)$ but cannot really grasp why the first one is wrong and if it is overcounting or undercounting cards. $P_1(E) = \frac{{13\choose 2}{4\choose 3}{4\choose 3}{46\choose 1}}{{52\choose 7}}$ or $P_2(E) = \frac{{13\choose 1}{4\choose 3}{12\choose 1}{4\choose 3}{46\choose 1}}{{52\choose 7}}$ . Any explanations on this would be really helpful.


CentOS server refusing all connections except for ssh telnet and http

For some reason my CentOS VPS refuses all connections except for HTTP, SSH and Telnet. Whenever I try to connect to a port such as 25 (SMTP) or even a random port such as 225 I get a connection refused error :S netstat -ap shows that the server is listening and iptables is turned off.  However I can interface with the same ports on the server through telnet...  # iptables -L Chain INPUT (policy ACCEPT) target     prot opt source               destination           Chain FORWARD (policy ACCEPT) target     prot opt source               destination           Chain OUTPUT (policy ACCEPT) target     prot opt source               destination      # netstat -an | fgrep LISTEN tcp        0      0 0.0.0.0:25                  0.0.0.0:*                   LISTEN       tcp        0      0 0.0.0.0:225                 0.0.0.0:*                   LISTEN       tcp        0      0 :::22                       :::*                        LISTEN       tcp        0      0 :::80                       :::*                        LISTEN       unix  2      [ ACC ]     STREAM     LISTENING     169786017 /tmp/.font-unix/fs7100 unix  2      [ ACC ]     STREAM     LISTENING     169786045 /var/run/saslauthd/mux   This is the error message i'm getting from my php script. My PHP script works fine with every other SMTP server I've come across Warning: fsockopen() [function.fsockopen]: unable to connect to :25 (Connection refused)


Mystery status bar icon (handset plus wifi signal indicator)

As the title says, does anyone know what this icon means? Just upgraded to a Samsung galaxy s10, but it's not an icon I've seen before. It sits between the wifi and cell signal strength icons.   Edit/Answer: To summarise the answer found in the above link, this icon indicates that "wifi calling" is enabled. I've noticed that the icon will appear and disappear depending on how close you are to your router, presumably because the wifi calling feature requires a good signal.


Neural net: Cost goes down but performance on train isnt!

So, While building a simpel neural net (MLP) for recognizing digits, I ordered my function to print me both the mean cost overall off the train dataset and %currect answers, also over the train dataset (even though the function doing this is called val()). the cost kept going down for an hour and a half, but the %currect answers stayed the same as the beginning.  the wierd thing is that while the cosr is constantly going down, the train accurasy do not change AT ALL from the very beggining.   Any ideas why this is happening?   Here is the , if needed.


Possible paradox with black holes and time dilation

I am by no means an expert in the realm of physics. I do from time to time, try to understand the concepts of modern physics and their applications.  I came across  video that I am currently watching, and in the beginning it explains what would happen to someone if they crossed over the event horizon of a black hole.  From my understanding, the time dilation is so great near a black hole, that if you were to cross over the event horizon someone viewing you from further away would never actually see you cross and you would appear frozen forever at the edge of the event horizon due to this time dilation near great mass.  If this is true, in the sense that the entire existence of the universe outside the black hole would unfold while you were stuck at the edge of the event horizon due to time dilation (Please fact check me here, I would love to know if time does actually stop for you if you cross the event horizon of a black hole), wouldn't it be true that you would actually spend no time at all inside the black hole due to hawking radiation and it's effect on the evaporation of black holes?  What I mean by this is that, apparently from what I've read, a black hole will evaporate and cease to exist at the end of some finite period of time in the universe due to it giving off hawking radiation. If this is true, and if the fact that you appear to be forever frozen at the event horizon due to time dilation is also true, wouldn't it seem from the perspective of the person crossing the event horizon that the black hole ceases to exist?  I am very intrigued by this possible paradox that I was questioning and I would love to know more about it's ramifications, if there are any, from many of you whom are more advanced that I.  Thank you in advance.


apt-get update for a particular repository

Consider a situation like this: I am going to install Ubuntu on an UEFI system (dual boot with Windows) where I need to install boot-repair. When I run sudo apt-get update it will update cache for all   the repos. I need to update only a particular ppa (yannubuntu/boot- repair) to install boot-repair. Many times I had to update all the repos when I think updating a single ppa is enough. Questions  Is there any problem/harm if I update only one repo? Can it affect the software installation in any way? If the answer is No then how could I update a particular repo?


UK visa hotel booking and contact information

It seems like that this question has been asked for visas to other countries, but I am not sure if it applies juts the same for a UK short-term visit visa.  I want to visit UK for 2 weeks and the visa asks for the "details of where you’ll be staying during your visit".   In the application, I need to provide the address and phone number of where I'll be staying. Is the normal approach to this (assuming I plan on staying in hotels or hostels and have no family members there) to just book a refundable hotel reservation?   Also, if I plan on visiting several different cities in UK (ie. London, Manchester, Edinburgh), should I just put the first place I am staying at on the application? I can then attach an itinerary of the trip with the address and phone number of a hotel booked in each city for the duration I am there.


I'm quite new to Linux so could do with a little help.  If there a way to make this work for all subdirectory contents rather than just the current directory?  for f in *\ *; do mv "$f" "${f// /_}"; done


What does it mean that $\frac{d}{dx}\sin(x)=\cos(x)$?

I have recently read that      $$\frac{d}{dx}\sin(x)=\cos(x)$$   But,unfortunately I have not been able to make out what it exactly means that the rate of change of $\sin(x)$ is $\cos(x)$?  What does it simply mean that rate of change of $\sin(x)$ is $\cos(x)$?  I am a beginner in this branch of mathematics.  Any help is welcome.


I recently asked a question about . There  told me about the “blow off” feature. Now, I am curious about how the whole system works.   So, can anyone tell me about how a lockable front suspension works, together with features like “remote-lock” and “blow-off”.


I have a 38mm apple watch and I put in on power reserve and no matter what I do it wont get out of it.

I have held the side button, I have held both buttons down. Each for 6 seconds or even to a minute nothing is working. Please help!


Seconds in Windows 10 clock - the answer may have changed

Update: I was looking under wrong key. It's not Computer\HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Explorer, it's Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer. I was missing the "Software" part.  This is a possible duplicate of   .  However, as of 3/16/2020, the latest update to Windows 10 does not have "Advanced" under Computer\HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Explorer.     What is the solution now? Should we add the Advanced key?


How can I upgrade lubuntu 14.04 to 15.04?

Will I lose my configurations or it's simple to do?


Is there any possibility of semi-automated text execution in selenium?

Can one semi-automate the test execution, say there are certain things that we can`t do using selenium like captcha issue, so is it possible to start the script, perform some task manually and automate others, in the same session or any other approach that solves the same problem.   Example scenario   Login. (Selenium) Captcha. (Take control and solve it yourself, in the same session)  Perform some task. (Selenium) Logout. (Selenium)


Can't get References to work in TeXnicCentre

First question, and an account made specifically for it. I'm having trouble getting citations to work from my bib file. I've spent the last several hours trying to get it to work, and as far as I can tell - I'm doing everything correctly! However, it is still not working. Even with the simplest files, I can't get teXnicCentre to read the citations inside my bib file, and cite them as expected. For a minimum working example, I have a tex file:  \documentclass[% oneside ,bibliography=totoc ]{scrbook}  \usepackage{amsmath}% \usepackage{amsfonts}% \usepackage{amssymb}% \usepackage[natbib=true]{biblatex}  \addbibresource{reflist.bib}  \begin{document} Creating a computerized model of the system then becomes part of the process to achieve deeper understanding of the phenomena, alongside observations and analytic theory \citep{Narita2004}. \printbibliography \end{document}   where the context in reflist.bib is a single citation:  @article{Narita2004, author = {Narita, Y. and Glassmeier, K.-H. and Sch{\"{a}}fer, S. and Motschmann, U. and Fr{\"{a}}nz, M. and Dandouras, I. and Forna{\c{c}}on, K.-H. and Georgescu, E. and Korth, a. and R{\`{e}}me, H. and Richter, I.}, doi = {10.5194/angeo-22-2315-2004}, issn = {1432-0576}, journal = {Annales Geophysicae}, keywords = {electromagnetics,inter-,physics,planetary bow shocks,planetary physics,space plasma,tions which are unstable,to different types of,wave propagation,waves and instabilities,waves at vari-}, pages = {2315--2323}, title = {{Alfv{\'{e}}n waves in the foreshock propagating upstream in the plasma rest frame: statistics from Cluster observations}}, volume = {22}, year = {2004} }   The .bib citation was generated by Mendeley (the database software I'm using), and although it looks messy it should still work as expected (to my knowledge). I'm trying to use the natbib commands in biblatex because I like the use of their /citep{} and /citet{} functions.  Any help? This has taken up far too much of my time already!  PS: When I run the files in TXC, all the aux, bbl, etc. files are generated. The .bbl file is blank (so no citations were sourced). In the .blg file, it states:  This is BibTeX, Version 0.99dThe top-level auxiliary file: example.aux I found no \citation commands---while reading file example.aux I found no \bibdata command---while reading file example.aux I found no \bibstyle command---while reading file example.aux (There were 3 error messages)   Yet, in the .aux file:  \relax  \providecommand*\new@tpo@label[2]{} \abx@aux@sortscheme{nty} \abx@aux@refcontext{nty/global/} \abx@aux@cite{Narita2004} \abx@aux@segm{0}{0}{Narita2004} \@writefile{toc}{\boolfalse {citerequest}\boolfalse {citetracker}\boolfalse {pagetracker}\boolfalse {backtracker}\relax } \@writefile{lof}{\boolfalse {citerequest}\boolfalse {citetracker}\boolfalse {pagetracker}\boolfalse {backtracker}\relax } \@writefile{lot}{\boolfalse {citerequest}\boolfalse {citetracker}\boolfalse {pagetracker}\boolfalse {backtracker}\relax }   I can see my citation key sitting in there, meaning that it actually has recognized that I've cited something... and for some reason it hasn't been picked up with it goes through the .bib file.   All files are in the same directory.


Why does local fn=$(...) mask the $? status code

Two function definitions, the only difference is that the first combines the local storage keyword with the assignment, while the second separates them:  function foo {     local fn=$(mktemp -p /path/does/not/exist 2>/dev/null)     echo $? }  function bar {     local fn     fn=$(mktemp -p /path/does/not/exist 2>/dev/null)     echo $? }  foo bar   This echoes "0" then "1". I expect it to echo "1" then "1". It seems like the value of $? is the result of the assignment to local, rather than the result of the command substitution.  Why does bash 4.2.46(1)-release behave this way?


Is there any pair of 128-bit strings M and K such that AES$_K$(M) = M?  If yes, how do I go about (efficiently) finding such a pair?


How can I extract EXIF information from an image and display it?

I would like to build a function that inserts a JPG in a xelatex file and automatically caption it with information extracted from the JPG's EXIF data, such as exposure time, etc. How can I do that?


"not good" vs "not very good" - which is more negative?

Which of these two phrases has more negative undertone?      "The interview I had was not very good"    or      "The interview I had was not good"


I had a business trip with some free time in the evening, so I took my photo gear with me, but on the last moment, decided to leave my film camera at home because I did not want to ruin the film with X-ray scans in airports. I wasn't going to stay long enough to buy, shoot and develop a film during my stay, which seems to be the best way of avoiding X-ray scans.  I want to be better prepared next time, so what would the best practice to travel with undeveloped film?


I'm new to ubuntu or linux at all. I'm trying to install the drivers for my GTX 550 Ti from nvidia's official website. I'm downloading the drivers for linux 64 bit (What i'm using). I'm choosing geforge and 500 series. After download I start the run file and then gedit starts. After that program takes a while on downloading stuff it stops working or says some numbers is not valid. and something about editing texts.  The point is I don't know how or why i cannot install the drivers so please help!  Sorry for my bad english...


Every bijective conformal transformation of $\mathbb{C} \to \mathbb{C}$ is of the form $f(z)=az+b$.

Show that every bijective conformal transformation of $\mathbb{C} \to \mathbb{C}$ is of the form $f(z)=az+b$.  I find it difficult to start because it does not specify $f$ to be analytic, which would have made the question a lot easier.   Is it true that bijective conformal mappings are necessarily analytic with nonzero derivatives?


Bounded operator that does not attain its norm

What is a bounded operator on a Hilbert space that does not attain its norm? An example in $L^2$ or $l^2$ would be preferred.  All of the simple examples I have looked at (the identity operator, the shift operator) attain their respective norms.


Could anyone help me with an example of a pair of generating elements for the group $\mathrm{PSL}(2,q)$?  Here $\mathrm{PSL}(2,q)$ denotes the group of $2\times 2$ matrices with determinant $1$ and whose entries are elements of a finite field of order $q$ (alternatively, the quotient group of $\mathrm{SL}(2,q)$ by its center).  Many thanks!


Uniform continuity of $f(x)=x + \frac{x}{x+1}$ using definition

I need to prove that the following function is uniformly continuous on the interval  $[0,\infty)$ : $$f(x)=x + \frac{x}{x+1}$$  I want to prove it by defenition, any help?


Bash script not working on Automator but working from terminal

I have this bash script that works perfectly on terminal  #!/bin/bash  for f in "$@"; do    DIRNAME="$(dirname "$f")"    filename=$(basename "$f")   name="${filename%.*}"   extension="${filename##*.}"    /usr/local/bin/ffmpeg -i "$f" -filter_complex 'scale=1920:1080, pad=2134:1200:107:60' "$DIRNAME"/OUTPUT_"$name"."$extension"   /usr/local/bin/ffmpeg -i OUTPUT_"$name"."$extension" -vf 'scale=1920:1080' FINAL_"$name"."$extension"   done   I am trying to create a service for finder that accept movie files and process them using this script. The service is setup to pass input to stdin. When I select movies on finder and run that service, nothing happens. Like I said, the script works perfectly from terminal.    Any clues?    This question appears to similar to  but applying the answer (full path to ffmpeg) did not solve my problem.


Insert a TeX file created with knitr into a main TeX file

I want to insert a knitr output file (created in RStudio as .rnw file, then I compiled, it creates the .tex file) into my main .tex file. But I got an error, how we can do this?  Knitter Tex file:  \documentclass{article}\usepackage[]{graphicx}\usepackage[]{color} %% maxwidth is the original width if it is less than linewidth %% otherwise use linewidth (to make sure the graphics do not exceed the margin) \makeatletter \def\maxwidth{ %   \ifdim\Gin@nat@width>\linewidth     \linewidth   \else     \Gin@nat@width   \fi } \makeatother  \definecolor{fgcolor}{rgb}{0.345, 0.345, 0.345} \newcommand{\hlnum}[1]{\textcolor[rgb]{0.686,0.059,0.569}{#1}}% \newcommand{\hlstr}[1]{\textcolor[rgb]{0.192,0.494,0.8}{#1}}% \newcommand{\hlcom}[1]{\textcolor[rgb]{0.678,0.584,0.686}{\textit{#1}}}% \newcommand{\hlopt}[1]{\textcolor[rgb]{0,0,0}{#1}}% \newcommand{\hlstd}[1]{\textcolor[rgb]{0.345,0.345,0.345}{#1}}% \newcommand{\hlkwa}[1]{\textcolor[rgb]{0.161,0.373,0.58}{\textbf{#1}}}% \newcommand{\hlkwb}[1]{\textcolor[rgb]{0.69,0.353,0.396}{#1}}% \newcommand{\hlkwc}[1]{\textcolor[rgb]{0.333,0.667,0.333}{#1}}% \newcommand{\hlkwd}[1]{\textcolor[rgb]{0.737,0.353,0.396}{\textbf{#1}}}%  \usepackage{framed} \makeatletter \newenvironment{kframe}{%  \def\at@end@of@kframe{}%  \ifinner\ifhmode%   \def\at@end@of@kframe{\end{minipage}}%   \begin{minipage}{\columnwidth}%  \fi\fi%  \def\FrameCommand##1{\hskip\@totalleftmargin \hskip-\fboxsep  \colorbox{shadecolor}{##1}\hskip-\fboxsep      % There is no \\@totalrightmargin, so:      \hskip-\linewidth \hskip-\@totalleftmargin \hskip\columnwidth}%  \MakeFramed {\advance\hsize-\width    \@totalleftmargin\z@ \linewidth\hsize    \@setminipage}}%  {\par\unskip\endMakeFramed%  \at@end@of@kframe} \makeatother  \definecolor{shadecolor}{rgb}{.97, .97, .97} \definecolor{messagecolor}{rgb}{0, 0, 0} \definecolor{warningcolor}{rgb}{1, 0, 1} \definecolor{errorcolor}{rgb}{1, 0, 0} \newenvironment{knitrout}{}{} % an empty environment to be redefined in TeX  \usepackage{alltt} \IfFileExists{upquote.sty}{\usepackage{upquote}}{}  \begin{document}  The log returns are calculated from the theoritical distrbutions. Then we consider the autocorraltion of the entire series.   \begin{knitrout} \definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor} \includegraphics[width=\maxwidth]{figure/acf}   \end{knitrout}   The lag 1 significnat autocorrelation -0.5053 found.   \end{document}     Main TeX file:  % edited by JG on 31/10/13 to 6/11/13 \documentclass[12pt,a4paper]{article}  \usepackage{amssymb} \usepackage{amsfonts} \usepackage{multirow}  \usepackage{lscape} \usepackage{graphicx} \usepackage{hyperref} \usepackage{lettrine} \usepackage{setspace} \usepackage[authoryear]{natbib} \usepackage{caption} \usepackage{subcaption}  \doublespacing % page layout \addtolength{\topmargin}{-20mm} \addtolength{\textheight}{35mm} \setlength{\textwidth}{150mm} \setlength{\oddsidemargin}{8mm} \hyphenation{Shew-hart}  \begin{document}  \title{Applying quality improvement techniques to analyze the asymmetric behavior in stock returns}  \section{ACF}  \input{ThirdPaper_Autocorrelation} % name of the knitter file                          \end{document}


I'm right-clicking the minecraft.jar file and going under the Properties tab and there is no checkbox that allows the file to be executable.   Neither the Open With nor command options are working either. Any ideas?


Question about Big O notation for asymptotic behavior in convergent power series

Examples of such use of Big O notation can be found for instance on Wolfram Alpha . More details on the .  The idea, as I understand it, is that the term between parenthesis in Big O bounds the rest of the series asymptotically (as $x$ goes to $0$ or $\infty$) giving and elegant way of writing the series (if you don't like "+ ..." or "etc") while also providing an error approximation. Taking the example of $e^x$:  $$ e^x=1+x+\frac{x^2}{2!}+\frac{x^3}{3!}+\frac{x^4}{4!}+O(x^5) $$  When we write $O(x^5)$ we mean that all the rest of the terms (like $\frac{x^6}{6!}+\frac{(x^7)}{7!}+\frac{x^8}{8!}+\cdots+\frac{x^y}{y!}$) are bounded by $x^5$ as $x$ goes to $0$. Giving a more concrete example if we take $e^{2.42}$ then this is more or less $1 + 2.42 + (\frac12)(2.42)^2 + (\frac16)(2.42)^3 + (\frac{1}{24})(2.42)^4$ and the error between the approximation and the actual value is no larger than $2.42^5$.  The question is how do we know this?  Certainly $x^5$ bounds, as $x$ goes to $0$, each term individually ($Cx^n=O(x^5)$ as $\lim_{x\to\infty}$ as long as $n>5, C$ constant) but how do we prove the sum of all the individual terms is bounded? We have to show that:  $$ O(x^5)=\frac{x^6}{6!}+\frac{x^7}{7!}+\frac{x^8}{8!}+\frac{x^9}{9!}+\frac{x^{10}}{10!}+\frac{x^{11}}{11!}+...),x\rightarrow 0 $$  Falling back on the previous example, maybe the infinite sum will actually be slightly larger than $2.42^5$. How do we prove this is actually not the case? While I have used the example of $e^x$, feel free to give a more general proof, and not one for this particular function only.  Your help with this issue will be greatly appreciated.  Thank you for taking the time to read this and have a good day.  Note: I wrongly asked this on Math Overflow and copied it here. I'm not sure whether the other question gets transferred or if I made the right choice in reasking here.


How to fill out form W4 when I'm earning $1600 extra income per month?

August 22 was my last day at a job that paid $76,000 / yr. Afterward, that job is supposed to pay me $400 / wk for consulting for $1,600 / month. At the new job (which I started on Aug 26) I'm making $80,000 / yr.  On the  I filled out, there was a section for "additional amount, if any, you want withheld from each paycheck". I'm thinking I could use this section to withhold taxes on the consulting money I'm getting for as long as I'm getting it. It's just not clear to me how much I need to withhold.  Any ideas?  Thanks!


Let $f$ be Lebesgue integrable on $\mathbb{R}$. Show that  $ \sum_{n=1}^{\infty} f(x+n) $ converges almost everywhere.   I was thinking that maybe the finite sum could be compared to a simple function and maybe this could lead somewhere, but i've doubt this since I don't know what the level sets look like for the $f(i)'s$. The result seems a  bit obvious but I don't have a good idea.  Any helpful hints or help would be great


How to decrease the utilization of my SSD drive as much as possible?

I have a PC with a    250GB SSD & 500GB SATA HD.    I will have Linux root (/) in the SSD disk after the installation.    I want to minimize ssd utilization as much as possible. Therefore, I will put the /home and SWAP on the SATA disk. Is there anything else that I should put on SATA hard disk to decrease the utilization of SSD?


Closest points between two line segments. If infinite, choose "closest to centers".

Let $x, y, z, a, b, c, d$ be vectors, and $t,s$ be scalars.  Let line segments be $y = a + bt, \ t \in [0,1]; \ \ z = c + ds, \ s \in [0,1]$.  The distance $d(z(s), y(t)) = \sqrt{(z(s)- y(t))\bullet (z(s) - y(t))}$.  How do I minimize the distance and output two points one for each segment.  If there are an infinite number of solutions, make a "nice-looking" line between the segments, such that if they are paralell and form the sides of a rectangle, then the line is just the line that splits the rectangle.  Then choose the output points to be the ends of this beautiful line.  Algorithm?  How do I solve this?  Calculus?


If my mom Grandmother was Spaniard, does that make my mom 25 percent Spaniard? What percent does that make me?


Is there anything political in Lord Of Rings

I am not deeply interested in Science Fiction, I probably just know popular movies, books. Thus this will be the only question which I will ask in this site most probably please don't misunderstand me I am really curious about this.   In the map of Middle Earth which I saw, mordor in east . And good guys are in west part of the map. And also phrases like "man-of-west" are repeated many times in the movie. In third movie I remember there were elephants and persian like man were riding them again like bad guys.     Again please don't misunderstand me I am asking this question as a guy who doesn't in any religion and I am proud of my culture but I can't count myself very very nationalist. I am part of east culture and feeling a little bad about these facts. Am I mistaken in my observations or did Tolkien really meant what I am feeling? Anyways love you guys all.


Character encoding in location field in iOS App

My location is Malmö, Sweden - but the iOS App location field can't interpret foreign language characters.  This is no major issue, but it would be nice to have it solved before release to App Store.


Draw two symmetrical pseudo root nodes for binary tree using tikz

I need to draw a binary tree (in fact the Stern-Brocot tree) with two pseudo nodes as parents to the root, as seen in the first picture.  At the moment I'm using tikz to draw it but the two pseudo nodes are all the way on the left. (See second picture) How can I align them or is there another completely different, better aproach?  The code I'm using: \begin{figure}     \centering         \begin{tikzpicture}             \tikzset{                 level 1/.style={level distance=15mm,sibling distance=65mm},                 level 2/.style={level distance=15mm,sibling distance=30mm},                 level 3/.style={level distance=15mm,sibling distance=15mm},                 level 4/.style={level distance=15mm,sibling distance=10mm},             }             \node {$\frac{1}{1}$}             child[grow=up, left] {node {$\frac{0}{1}$} edge from parent[dashed]}              child[grow=up, right] {node {$\frac{1}{0}$} edge from parent[dashed]}              child {node {$\frac{1}{2}$}                 child {node {$\frac{1}{3}$}                     child {node {$\frac{1}{4}$}}                     child {node {$\frac{2}{5}$}}                 }                 child {node {$\frac{2}{3}$}                     child {node {$\frac{3}{5}$}}                     child {node {$\frac{3}{4}$}}                 }             }             child {node {$\frac{2}{1}$}                 child {node {$\frac{3}{2}$}                     child {node {$\frac{4}{3}$}}                     child {node {$\frac{5}{3}$}}                 }                 child {node {$\frac{3}{1}$}                     child {node {$\frac{5}{2}$}}                     child {node {$\frac{4}{1}$}}                 }             };         \end{tikzpicture}     \caption{...} \end{figure}


Quadratic extensions in characteristic $2$

I recently saw in class that the degree $2$ extensions of a field of characteristic $\neq 2$ are given by square roots of non-squares in the base field.   I wonder what happens in the case of characteristic $2$ fields. For finite fields of characteristic $2$, it's clear what's going on, but what about others like $(\mathbb{Z}/2\mathbb{Z})(X)$?


How to print HTML content on click of a button, but not the page?

I want to print some HTML content, when the user clicks on a button. Once the user clicks on that button, the print dialog of the browser will open, but it will not print the webpage. Instead, it will print the some other HTML content which is not displayed on the page.  While asking this question, there are few solutions coming into my mind. But I am not sure whether those are good ideas or something better can be done. One of those solutions are: I can keep this HTML content in a div and make it display: to print, but display: none to screen. All other elements on the webpage can be made to display: none for print and display: for the screen. And then call to print.  Any better idea?


Interested in Neuroscience programs but lack research experience & grades

About me:   I'm in my last year of undergraduate studies majoring in cognitive science at a very prestigious university.  I'm very interested in going to graduate school for neuroscience.   My concerns:   I lack research experience. I recently just learned about how wonderful neuroscience is so I have a very late start compared to my already-competent peers. I did apply to RA positions but was rejected to all of them. I will be graduating in one semester so I do not have enough time to build up my research experience. After graduating, what can I do to be more competent - research experience wise?  I have a mediocre GPA (3.077). I did not take any courses like chemistry, or physics. Many programs make these a requirement. I also did poorly in my math classes - as it is not my strength. But I did very well in psychology, cognitive neuroscience, biology psychology, philosophy, and sociology. Since I only have one semester left, I don't have enough time to take classes that programs want. Will GRE subject tests be able to compensate? Is there any hope for someone in a situation like mine? I feel very lost and hopeful, to be honest. Any words of advice would be helpful.   My current plans:   Self-learn R, Matlab, Python, HTML, CSS, and Javascript. Take on the habit of reading papers related to the field, in order to build knowledge.  Will apply to many RA positions.


Explicitly finding the sum of $\arctan(1/(n^2+n+1))$

This is from a GRE prep book, so I know the solution and process but I thought it was an interesting question: Explicitly evaluate $$\sum_{n=1}^{m}\arctan\left({\frac{1}{{n^2+n+1}}}\right).$$


How to run program on Unix server and then close SSH?

I need to run a long operation in MATLAB on a remote Unix server. But I know I won't be able to stay logged in via SSH the whole time. I am root/admin if that helps.  How can I do this without losing my work?   What I'm currently doing is opening MATLAB and then doing something like the following:  t=cputime; x=A\b; time=cputime-t; save('workspace.mat')   While this is running (x=A\b is the operation taking all the time) I close my SSH shell which was running MATLAB, and the operation doesn't continue to run. So I don't get the results.   How can I accomplish running this even when I logout of SSH midway? Thanks.


Weird wireframe display on viewport when in camera (or certain angle maybe)  It happens with a certain camera, but it is not like this in perspective view, and I do not think this is overlapping vertices.  May I know what might solve this? I need to show this to my school's presentation and I want my wireframe in my OpenGL render to look clean.


Quantum Field Theory without LSZ, how is it possible?

Most modern texts spend some time deriving the  that connects S matrix elements to time ordered field correlation functions. It seems essential, and really helps clear up what you are calculating. Yet some earlier texts and even some modern texts (e.g.  by R. Klauber) seem to skip right past this, working everything out in the "interaction" picture. It seems there must be something going wrong with this latter procedure, but I am not quite able to put it together.


Why are american call options more valuable than european options ONLY if the underlying asset pays cash flows?

While studying for the CFA, I ran into the following statement in my study materials: "American style calls are only more valuable than European style calls IF the underlying asset pays cash flows, such as dividends or interest".   Lets imagine a stock call option. Even if the underlying is a no-dividend-paying stock, its price is still going to fluctuate, so that there is a higher chance that the American call could be exercised above the strike price than the european, since there is simply a higher chance that S is going to be higher than X on any given day during the period until expiration than ONLY on the day of expiration.   Could someone help me understand this? I realize there is a simmilar question in the forum, but it is not identical. Thank you.


$a,b,c$ are distinct real numbers that $$(a^2)(1-b+c)+(b^2)(1-c+a)+(c^2)(1-a+b)=ab+bc+ca.$$ Prove $$\frac{1}{(a-b)^2}+\frac{1}{(b-c)^2}+\frac{1}{(c-a)^2}=1.$$ I have tried two different approaches to this problem but am stuck.  First I started by expanding the bottom of each fraction. $\frac{1}{(a^2)-2ab+(b^2)}+\frac{1}{(b^2)-2bc+(c^2)}+\frac{1}{(c^2)-2ac+(a^2)}=1$  I also tried to expand $(a^2)(1-b+c)+(b^2)(1-c-a)+(c^2)(1-a+b)=ab+bc+ca$   $(a^2)-(a^2)b+(a^2)c+(b^2)-(b^2)c-(b^2)a+(c^2)-(c^2)a+(c^2)b=ab+bc+ca$ $(a^2)-(a^2)b+(a^2)c+(b^2)-(b^2)c-(b^2)a+(c^2)-(c^2)a+(c^2)b-ab-bc-ca=0$ Then I added one to both sides $(a^2)-(a^2)b+(a^2)c+(b^2)-(b^2)c-(b^2)a+(c^2)-(c^2)a+(c^2)b-ab-bc-ca+1=0+1$ Help will be appreciated.


Annoying "JQMIGRATE: Migrate is..." in console after update to WordPress 4.5

Why is there a constant notice,  JQMIGRATE: Migrate is installed, version 1.4.0  that points to load-scripts.php in my console when I updated my theme to WordPress 4.5, and how can it be removed? It's not an error, but it's always present in my console, and I really don't see what's the point of it. Should I update something, or make some changes to my code? Maybe I have a bit of OCD, but usually when I inspect the site, I like to see errors and real notices that point to an issue in my console... EDIT WordPress 5.5 removed jQuery Migrate script, as a preparation step for updating jQuery to the latest version in 5.6. So the notice should be gone.


$f:[0,1] \to \mathbb R$ is a continuously differentiable function, and $f(\frac{1}{2})=0$. I'm trying to show $$( \int_0^1{f(x)} \, dx)^2 \le \frac{1}{4} \int_0^1 (f'(x))^2  \, dx $$ I tried using the mean value theorem but got nowhere.  Are there any hints? Thank you!


Analysis (tree diagram) of "She hugged and kissed her mother"

I was wondering how linguists analyze sentences like "She hugged and kissed her mother" or "Will you have that with or without syrup?" or "Four and five are the square roots of sixteen and twenty-five, respectively"?  My previous understanding was that all sentences can be , with each word being part of the "argument" of exactly one other word.  So in the sentence "Will you have that with syrup", will have is the verb that the entire sentence hangs from, with you being the subject, that the object, and with syrup a prepositional phrase in which syrup depends on with. (Please correct me if my understanding is incorrect.) But how would you ever draw a tree for "with or without syrup"? Specifically, whose child is syrup?  My first thought was that with or without forms a sort of super-preposition. But then what about "She rescued and provided shelter for the cat", in which the cat is simultaneously the object of a verb and a prepositional phrase?


Can I travel to Australia with my UN traveling document?

I have a refugee travel document (UN Passport) issued to me by Greece.  I would like to travel to Australia or Canada.  Do I need a visa for this travel?


Terminal shows malformed entry 48 in list file

When i try to update or install any software using the terminal for Ubuntu 18.4 it shows the following:  jean@jean-Latitude-E5550:~$ sudo apt install update [sudo] password for jean:  E: Malformed entry 48 in list file /etc/apt/sources.list (Component) E: The list of sources could not be read. E: Malformed entry 48 in list file /etc/apt/sources.list (Component) E: The list of sources could not be read. jean@jean-Latitude-E5550:~$    And also it shows in color everything, so help me guys, please help me????


Suppose you have:  A-B-C   Now your build/test fails. The fix should be merged in A.  My current work-flow is like this:  $ git commit -m "fixA"  A-B-C-fixA  $ git rebase -i A~1   And squash fixA in A, result in:   A'-B-C   Is there a command to do something like:  A-B-C + (index with fix for A)  $ git commit -supperdupper A    Result:  A'-B-C


I have a valid Schengen visa in my Vietnamese passport. Can I use a Schengen Visa (Tourism) to visit Mexico ?


I'm trying to remember the name of a historical figure whose name has since entered the lexicon. He confused the order of words to say things like it's all nuff and stonsense for example. - I think he was a member of the clergy or a Don.


Update Errors on Ubuntu- I get this message

W:Failed to fetch http://ppa.launchpad.net/shakaran/ppa/ubuntu/dists/precise/main/source/Sources  404  Not Found W:Failed to fetch http://ppa.launchpad.net/shakaran/ppa/ubuntu/dists/precise/main/binary-i386/Packages  404  Not Found E:Some index files failed to download. They have been ignored, or old ones used instead.


Department of Telelcom (India) just blocked some sites in India.  But, only Government-based ISPs block access those sites. Other ISPs still have these sites working. One of those sites is Github and I want to use Github.  How can I apply proxy settings so they work for git sessions to Github in a Terminal?  (Note: I saw this  for doing this in Linux but I guess OS X is little different from Ubuntu?)


Name of rubber "sandwich" between PCB and LCD?

In taking apart my moribund wall thermostat I found a conductive rubber-ish connector between the PCB and LCD panel. It's cool stuff!  What's it called?


Average of all data vs. average of group averages

Assume I operate a chain of 20 hot dog stands. I am asked to figure out the average % of customers who buy a hot dog after visiting a stand.  Method 1: Divide total number of hot dogs sold by all 20 stands by the total number of people who visited one of my stands.  Method 2: Follow process for method 1 for each individual stand. Then take the average of the 20 individual averages.  Are there any inherent benefits/drawbacks of method 1 vs. method 2? Any implicit assumptions in either approach?


To show that Fermat number $F_{5}$ is divisible by $641$.

How can I show that  $F_{5}=2^{2^5}+1$ is divisible by $641$.


I am trying to understand the following JavaFX example. I do not understand why it is not necessary to create an object (at "openButton.setOnAction", at "handle", at "openFile") - because "openFile" is not a static method ?!  Thanks.  public final class FileChooserSample extends Application {  private Desktop desktop = Desktop.getDesktop();  @Override public void start(final Stage stage) {     stage.setTitle("File Chooser Sample");      final FileChooser fileChooser = new FileChooser();      final Button openButton = new Button("Open a Picture...");     final Button openMultipleButton = new Button("Open Pictures...");      openButton.setOnAction(         new EventHandler<ActionEvent>() {             @Override             public void handle(final ActionEvent e) {                 File file = fileChooser.showOpenDialog(stage);                 if (file != null) {                     openFile(file);                 }             }         });      openMultipleButton.setOnAction(         new EventHandler<ActionEvent>() {             @Override             public void handle(final ActionEvent e) {                 List<File> list =                     fileChooser.showOpenMultipleDialog(stage);                 if (list != null) {                     for (File file : list) {                         openFile(file);                     }                 }             }         });       final GridPane inputGridPane = new GridPane();      GridPane.setConstraints(openButton, 0, 0);     GridPane.setConstraints(openMultipleButton, 1, 0);     inputGridPane.setHgap(6);     inputGridPane.setVgap(6);     inputGridPane.getChildren().addAll(openButton, openMultipleButton);      final Pane rootGroup = new VBox(12);     rootGroup.getChildren().addAll(inputGridPane);     rootGroup.setPadding(new Insets(12, 12, 12, 12));      stage.setScene(new Scene(rootGroup));     stage.show(); }  public static void main(String[] args) {     Application.launch(args); }  private void openFile(File file) {     try {         desktop.open(file);     } catch (IOException ex) {         Logger.getLogger(             FileChooserSample.class.getName()).log(                 Level.SEVERE, null, ex             );     } }   }


What is x-nautilus-desktop:/// and why do I have it?

I have a new bookmark in my nautilus I didn't make.    It links to my desktop.  What is it and where did it came from?  Am I giving desktop access to someone?


I have about 80 windows splits currently open, but I can't figure out why they wont close. I tried Googling. I read the documentation, but the little corner grabbers don't seem to work.


I am a pretty new contributor so forgive me if this is some common phenomenon. I was writing an answer a few minutes ago on MathSE, but when I opened my profile to check on my reputation, there was a weird increase in my reputation (from 481 to 531) with no indication in my reputation summary (no new upvotes or downvotes). Also, when I checked on my account section from other sites, I found that my reputation was still 481. Is this a bug or something else?


How can I change my Ubuntu version from LTS to the latest non-LTS release?

I just installed Ubuntu Desktop and got everything setup, but I realized this is the LTS version. Is there any way to change to the latest version to ensure I get all the latest updates instead of staying on LTS or is this not possible without a re-installation?


How could i embed an unmanaged dll? (C#)

In my project I reference a managed dll, that references other unmanaged dlls. I would like to know how I can embed these unmanaged dlls instead of putting them in the application's directory. I can not embed them as I would with a regular managed dll since they can not be added as a reference in my project. Thanks


Keep original array after JavaScript function

I'm sure there is an easy answer for this, though I only really have experience with PHP. Why does the "pizza" array change when I pass it to my function as "my_pizza" and only make changes to "my_pizza"? How do I keep my original array I pass to the function outside of the function? Once the function is finished running, the pizza array should have not changed. I noticed if I change my string variable (pie) it will stay the same after the function runs, unlike the array.  In short, I want the first set of results to be identical to the second.  var pizza = []; pizza.push('crust'); pizza.push('ham');  var pie = "apple"  function bake_goods(my_pizza, my_pie){     console.log(my_pizza);     console.log(my_pie);      delete my_pizza['1'];     my_pie = "peach";      console.log(my_pizza);     console.log(my_pie); }  //first run  bake_goods(pizza, pie); //console logs //['crust','ham'] //apple  //['crust'] //peach  //second run  bake_goods(pizza, pie); //console logs //['crust'] //apple  //['crust'] //peach


Use induction and Newton's binomial formula to show that $\binom{n}{0}+\binom{n}{1}+\cdot+\binom{n}{n}=2^n, \forall n\in \mathbb N$

Use induction and Newton's binomial formula to show that:  $ i)$ $ \binom{n}{0}+\binom{n}{1}+\cdots+\binom{n}{n}=2^n, \forall n\in \mathbb N$  $ ii)$ $\binom{n}{0}-\binom{n}{1}+\binom{n}{3}-\cdots+(-1)^n\binom{n}{n}=0, \forall n\in \mathbb N$  $ iii)$ $\binom{n}{1}+2\binom{n}{2}+3\binom{n}{3}+\cdots+n\binom{n}{n}=n(2^{n-1}), \forall n\in \mathbb N$  $ iv)$ $1\cdot 2\binom{n}{2}+2\cdot 3\binom{n}{3}+\cdots+(n-1)\cdot n\binom{n}{n}=n(n-1)2^{n-2}, \forall n\in \mathbb N$  I really don't know how I can start with this.


How to show that $\mathrm{mgf}$ $M(s)$ and $\mathrm{pgf}$ $P(s)$ are related?

Let $X$ be an integer-valued $rv$ with $\mathrm{pgf}$ $P(s)$ (probability generating functions) and suppose that $\mathrm{mgf}$ $M(s)$ (moment generating functions) exist for $s∈(-s_0,s_0),s_0>0$. How can we proof that $M(s)$ and $P(s)$ are related??