I'm reading a online book titled Mathematical Statistics Old School which can be found .  In the section about the Dirichlet Distribution (which begins on page 63 if you would like to look) it says to let  $X_1, \ldots, X_K$ be independent random variables, where $X_k \sim Gamma(\alpha_k, 1)$.  Then the $K-1$ vector $\underline{Y}$ defined by  $$Y_k = \frac{X_k}{X_1 + \cdots + X_K} , k = 1,\ldots, K-1$$ has a Dirichlet distribution. So $\underline{Y} \sim Dirichlet(\alpha_1, \ldots, \alpha_K)$. It is noted that $Y_1 + \cdots +Y_K = 1$.   The text says the following two things, which I am having trouble understanding:        The marginals $Y_k \sim Beta(\alpha_k, 1- \alpha_k)$   If $X_k \sim Gamma(\alpha_k, \lambda)$, then the definition is the same.      For my first issue, I thought it would be that $$Y_k \sim Beta(\alpha_k, \sum_{i\neq k} \alpha_i)$$ because if $X_1 \sim Gamma(\alpha_1, \lambda)$ and $X_2 \sim Gamma(\alpha_2, \lambda)$ then $$\frac{X_1}{X_1 + X_2} \sim Beta(\alpha_1, \alpha_2).$$  I think clearing this issue up would help me see that if $X_k \sim Gamma(\alpha_k, \lambda)$, then the definition is the same.   EDIT Jan 24 '17: I'm not really sure how my question is a duplication of . But I am glad it was pointed out . As pointed out by Xi'an in the comments, my confusion is due to a typo in the text I am reading.   I think it would be more accurate to mark this question as answered instead of as duplicate.


Prove $a^{\frac{\phi(mn)}2} \equiv 1\pmod {mn}$

I want to show that given $\gcd(m,n)=1$ with $m,n \gt2$ and $\gcd(a, mn)=1$, then $a^{\frac{\phi(mn)}2} \equiv 1\pmod {mn}$, where $\phi(mn)$ is the Euler Totient function. My approach started using Euler's theorem, given $\gcd(a, n)= 1$ then $ a^{\phi(n)} \equiv 1\pmod {n}$. And since $(m,n)=1$ then: $$a^{\phi(mn)} \equiv 1\pmod {mn}$$ I just cannot seem to get the $\frac12$ factor to appear. What I tried doing was just raising both sides to the $\frac 12$ $$a^{\phi(mn)} \equiv 1\pmod {mn} \Rightarrow a^{\frac{\phi(mn)}2} \equiv 1^{\frac12}\pmod {mn} \equiv 1\pmod{mn}$$ But I somehow feel this is wrong. So another way I tried was again with Euler's theorem: $$a^{\phi(n)} \equiv 1\pmod {n} \Rightarrow (a^{\phi(m)})^{\phi(n)} \equiv 1\pmod {n} \Rightarrow a^{\phi(m)\phi(n)} \equiv 1\pmod {n} $$ $$a^{\phi(m)} \equiv 1\pmod {m} \Rightarrow (a^{\phi(n)})^{\phi(m)} \equiv 1\pmod {m} \Rightarrow a^{\phi(n)\phi(m)} \equiv 1\pmod {m} $$ Multiplying one by the other yields: $$a^{2\phi(m)\phi(n)} \equiv 1\pmod {mn} \Rightarrow a^{2\phi(mn)} \equiv 1\pmod {mn}$$ Or using the CRT: $$a^{\phi(m)\phi(n)} \equiv 1\pmod {mn} $$ From here I have no idea on where to go or what to try, I was thinking perhaps something related to Wilson's Theorem to make the $\frac12$ factor appear, but since m and n may not be prime, they are just coprime, I don't know if I can use that. Am I going in the right direction?


I noticed that I can't name my module prn, Cargo refuses to build and I get a rather confusing error message mod prn;  fn main() { }  error[E0583]: file not found for module `prn`  --> src\main.rs:6:1   | 6 | mod prn;   | ^^^^^^^^   |   = help: to create the module `prn`, create file "src\prn.rs"  The file src\prn.rs exists, and it is accessible to the compiler. Changing the name of the module to something/anything else addresses the issue. Why prn is not allowed? Are there any other similar keywords that are forbidden for module names? (I am using rustc 1.46.0-nightly)


Does anyone know where my Instance server is located? My organisation is located in Berlin, Europe.


Are water and vertical cracks normal for full height crawl space?

I am thinking about purchasing a home that is set on top of a crawl space (see image). The crawl space has the full height of a basement, windows and a door leading outside in the back. It has French Drains along the downhill base of the house and plastic lining covering a rock floor. I did see some water on top of the plastic in a few places. The foundation walls are footing and stem walls (I think). They appear nice but have some vertical cracks in several places upon closer inspection. The house was built in 2002. Is the water concerning given the French drains installed? Are the wall cracks normal for the crawl space foundation... should they concern me?


Cycles material node set-up for diffuse, specular, reflection/refraction, normal and illumination/emission map

I have 5 different images one each for diffuse, specular, reflection/refraction, normal and illumination/emission map. Can someone please help me to set-up cycles material node including all the 5 maps to get the best physical render as possible? A screenshot after setting up all the nodes would be much helpful.


Yesterday my Virtualbox guests were still running. Today I get the following error for all guests (windows or Linux).  Failed to open a session for the virtual machine win10.  The VM session was closed before any attempt to power it on.  Result Code: NS_ERROR_FAILURE (0x80004005) Component: SessionMachine Interface: ISession {7844aa05-b02e-4cdd-a04f-ade4a762e6b7}   I already tried to run sudo /sbin/vboxconfig, reinstalling from Software Manager, reinstalling following  and upgrading to 5.2.12 r122591 and 5.2.14 r123301. The result was always the same.  My current kernel version is 4.15.0-24-generic #26-Ubuntu SMP.  $ VBoxManage list extpacks Extension Packs: 1 Pack no. 0:   Oracle VM VirtualBox Extension Pack Version:      5.2.14 Revision:     123301 Edition:       Description:  USB 2.0 and USB 3.0 Host Controller, Host Webcam, VirtualBox RDP, PXE ROM, Disk Encryption, NVMe. VRDE Module:  VBoxVRDP Usable:       true


Does the following map from the circle to the projective space of $\mathbb{R}^2$ admit a continuous section?

Does the map $S^1\to P(\mathbb{R}^2)$ defined by $\vec{v} \mapsto \mathbb{R}\vec{v}$ admit a continuous section. Where:  $S^1:=\{ (x,y) \in \mathbb{R}^2 : x^2+y^2=1 \}$ denotes the circle,  $P(\mathbb{R}^2)$ denotes the projective space, and a section of a map $\pi:X\to Y$ is a map $\sigma : Y \to X$ such that $\pi \circ \sigma = id_Y$.   I believe that that it doesn't admit a continuous section, but I'm not sure since I haven't been able to prove or disprove.


How can Linux/Ubuntu be installed safely on ChromeBook?

Is installing Ubuntu on my Chromebook potentially dangerous to anything on my Chromebook? I got it as a gift, so I don't want to destroy anything that is important on the laptop. Also, which is better for being able to safely install Ubuntu: ChrUbuntu or Crouton? I'm using the Samsung Chromebook 3 (as described by the quick-start manual). Does that make any other differences as well?


What happens when I click: I do understand?

This is a followup to  which Anna answered with:     Only the audit failures themselves are considered when determining if a user should be blocked from reviewing for a while   I would like to know if there's any other mechanic behind any of the "I understand" buttons?  Or, phrased in stronger terms: Let's have a "I disagree with this audit" button to temporarily remove a post from the audit queue, put it back in review queues, and only after it got reviewed again with a confirmative result, add it back to the audit queue.  Or, maybe the "disagree" button could remove it and flag it for moderator review?  Or, that button could automatically create a corresponding meta post?  There are plenty of meta questions about "why did this audit fail". Some are legitimate, some are not. A button to signal disagreement with the audit could help and accelerate in the process or clarification.


Constructing confidence intervals for mean of means, using standard errors

Is it possible to construct confidence intervals for a mean of weighted means using standard errors?  I have 4 different weighted means ($p_t = \sum_{i=1}^{n} w_ip_i $ where $w_i$ is the respective weight) for $t = 1,2,3,4$ time periods, with $n = 16$: \begin{equation} \bar p_1 = 378.0494 \quad \bar p_2 = 349.1045 \quad \bar p_3 = 339.0127 \quad \bar p_4 = 338.8679 \end{equation} with corresponding standard errors: \begin{equation} s_1 = 43.668 \quad s_2 = 42.133 \quad s_3 = 40.465 \quad s_4 = 40.084  \end{equation} Calculating a moving average ($\hat P_m$) of these: \begin{equation} \hat P_m = 351.2586 \end{equation} Corresponding standard error: \begin{equation} s_{\hat p} = 9.246 \end{equation}


Why is the ##UserID## parameter not populated in Data Explorer anymore?

Environment I'm logging in using the OpenID from  and using Chrome 31.0.1650.57 m if that matters. Steps to reproduce: Log in to  and , for example, like: DECLARE @MyUserID INT = ##UserID:int##  SELECT TOP 1     Id AS [Post Link],     Score AS [Score],     CreationDate AS [Creation Date] FROM     Posts WHERE     OwnerUserId = @MyUserID AND     PostTypeId IN (2, 3) ORDER BY     CreationDate DESC  Then press the Run Query button and see if the UserID field is filled with your own user ID like shown in the below screenshot:  Question: Did something changed on the ##UserID## parameter (for example, that it's not supported anymore)?  If so, then there is an outdated  paragraph about it (What's the point of logging in). If not, it is a bug which is there about three days (I've been waiting since I noticed that you were going to do some changes to Data Explorer, but it remains there, hence my question).


Looking for a science fiction story collection about nanotechnology — included a story about anti-graffiti paint

I remember reading it while in middle school in English in the United States, so the latest it would have come out was 1998. I don't remember if it was all one author, or even the same universe. These are the stories I remember:   A man finds a way to create a medicine that prevents radiation poisoning (or possibly makes someone fireproof... it's a little confused in my head) and learns that part of the problem is finding a market for it. I vividly remember the inventor telling someone to not "let the doorknob ream you" as it slams shut. A bout of graffiti artists leads to the city buying anti-graffiti paint that dissolves any other paint put on top of it. After learning the futility of trying to paint over it, the protagonist consults with a friend and learns that the anti-graffiti paint will eat away at the paint above it at a steady rate, and will even eat successive layers of the anti-graffiti paint. he uses this property to engineer an animation involving a harlequin thumbing this nose at the officials even as they try to wash it away. Some guys (I want to say a gang) go to a clinic for an illegal nanotech transformation. The viewpoint character gets turned into a woman while a friend gets turned into a dog. After roaming about in their new forms, they return to find the clinic being raided, meaning there's no one to turn them back. I think I remember something bad happening to the one transformed into a dog where the transformation continued, erasing his human thought patterns. There was also a scene where the viewpoint character submitted to being sexually assaulted by his former friends as if it was simply to be expected given his form.   I don't remember if the first or the second story was the actual first story of the collection... I want to say that those are the order that they showed up as in the book.


Is there a way to install Ubuntu on usb pendrive as normal instalation (not live cd)?

I would like to use Ubuntu from a pendrive, but I read that it works like a live cd. I would like it to keep my files and new packages I install.  Is there a way to install Ubuntu on the pendrive as if it were in an HD?


Java Random class execution for printing a six digit number only

I want to generate a six-digit random number everytime. I am using public class Test {     static Random rand = new Random();           public static void main(String[] args) {          int rand_int1 = rand.nextInt(1000000);         System.out.println(rand_int1);  Will it print the six-digit number or it can print any number between 0 to 1000000. I executed and got a 6 digit number but just want to be sure Can it give 1 or 2 or 3 digit number also?


I'm an aspiring physicist who wants to self study some Quantum Physics. My thirst for knowledge is unquenchable and I can not wait 2 more years until I get my first quantum physics class in university, so I want to start with a self study. I am enrolled in a grammar school and the most gifted among the gifted (not my description, mind you, I hate coming off as cocky, sorry) are enrolled in a special 'project'. We are allowed to take 3 school hours a week off in order to work on a project, which can be about anything you want, from music to mathematics. On the 4th of April we have to present our projects. Last year an acquaintance of mine did it about university level mathematics, so I thought, why not do it about university level physics? It is now the 3rd of October so I have half a year. My question is, where can I conduct a self study of quantum physics? Starting from scratch? And is it possible for me to be able to use and understand the Schrödinger equation by April? What are good books, sites, etc. that can help me? My goal is to have a working knowledge of BASIC quantum physics and I would like to understand and be able to use the Schrödinger equation. Is this possible? What is needed for these goals?


Are there more general spaces than Euclidean spaces to have the Heine–Borel property?

From      A metric space (or topological vector space) is said to have the   Heine–Borel property if every closed and bounded subset is compact.   Any subset of a Euclidean space, including itself, has the Heine–Borel property. I was wondering if there are more general types of metric spaces, topological vector spaces, or whatever space where boundedness and closedness can make sense, such that they also have the Heine–Borel property?   Or does the Heine–Borel property characterize subsets of Euclidean spaces?  Thanks and regards!


Hi The model that I'm working with in blender isnt showing up in when I render my work

I'm making a short walk animation with a robot I modeled myself, but when I try to render out my work it doesn't show up. I have tried the following solutions  1 Camera icon is disabled in the outliner  2  Render layer not showing in the compositor  3   Render layer does not include scene layer or the objects are in a layer that is not renderable.  4 Scene layer not selected  5  Cycles camera visibility disabled in object settings  6  Cycles material disables visibility to the camera  7  Objects are not within the range set by the camera clipping  8  Using the wrong scene  9  Strips present in the VSE, and the sequencer box is enabled in the post process section  10  Cycles: Exposure setting in the film section set to 0  11  Depth of field not set properly making the whole scene blurry  12  Object blocking the camera view  13  An object has been set as the active camera.  14   There are no lights on the scene or they are on a different layer.     Objects have no faces.  15 The Solidify modifier takes over the object and is disabled in Viewport  16  Duplication type set to 'Group' and no group is selected.  17    Duplication issues (under the Object tab in the properties panel), e.g., duplication type is not 'None', and object has no children, or set to 'Group' and no group is selected.  I have checked all of these options, but none of them are the issue


Convergence of the series $\sum_{1}^\infty \left(1-n\sin(\frac{1}{n})\right)$

I have to study the convergence of the series $$\sum_{n=1}^\infty \left(1-n\sin\left(\frac{1}{n}\right)\right).$$ I know I should study the limit $$\lim_{n \to \infty}n^\alpha\left( 1-n\sin\left(\frac{1}{n}\right)\right).$$   But I have some troubles with this limit (and so the convergence of the series). Any ideas?


How to prove for $s<1,|a+b|^s\le|a|^s+|b|^s$

How to prove for $s<1$$$|a+b|^s\le|a|^s+|b|^s$$ I tried to prove $|a+b|\le (|a|^s+|b|^s)^{\frac{1}{s}}$, but $\frac{1}{s}$ may not be integer, so I do not know how to expand it if it is not integer.  Is it the right way to prove it by trying to expand it using binomial expansion? How to prove it?  Thanks!


Using repetitive word in a list separated by comma

Which one is correct 1 or 2? Please Explain why.  Such cluster offers a variety of advantages, such as reduced transport-, communication-, and transaction costs Such cluster offers a variety of advantages, such as reduced transport cost, communication cost, and transaction cost.


How can i use sizeof(pointer). So i get sizeof(array). Pointer is pointing to array

See the comment section in the code. There I explained what I want to understand and what I know.    How I can get 28 using ptr. sizeof(arr) is giving me 28. (length of array elements) * sizeof(int) But I can't figure out how to get this value using ptr. I want this thing so I can get an array length using this method. In function own here.    int main (void) {     int arr[7] = {5, 8, 10, 50, 55, 98, 354};     int result;      /* ------- From here ---------*/      int size = sizeof(arr) / sizeof(int);   // sizeof(arr) = 28, sizeof(int) = 4. So size = 28/4 = 7      result = anyFunction (arr);      return 0; }    int anyFunction (int array[])  {        int arraySize = sizeof(array) / sizeof(int);   // this line }     int *ptr = arr;  // Same as *ptr = &arr[0]  size = sizeof(ptr);  // 8 is the size of pointer.   size = sizeof(*ptr);  // size = 4.  4 is the size of arr[0]. Because its pointing to arr[0]. So its sizeof(arr[0]) or sizeof(5)


Will the site association bonus come after I already have the account?

I have an account with close to 100 reputation on .  -  When I get 200 reputation, will the site association bonus apply to already existing accounts (like my meta.se - this account),  or   Does it only apply to new communities joined thereafter?   And if I do get it on previous accounts, will I get +100 rep or enough to make my balance 100?


Consider the hyperbola $xy=1$ with $x>0$ and $y>0.$ The tangent line at any point on the hyperbola forms a right triangle with the coordinate axes. Show that the area of the triangle does not depend on the point chosen. To show this, do the following:      a) Choose a point on the hyperbola of your choice. Find the tangent line and then find the area of the right triangle described above.      b) Choose a different point of your choice. Find the tangent line and then find the area of the right triangle described above.      c) Now for the general case, choose the point at $x=a.$ Find the tangent line at $x=a$ and then find the area of the right triangle described above.   This is the work I have so far:    No method to find the area of a right triangle was given, so I just used 1/2*B*H.  But I get stuck when given $x=a$ for part C.  Any ideas?


Debugging errors of SAGA interpolation algorithms in QGIS Processing?

I encounter recurrent problems with the geoalgorithms that perform interpolations. No matter what technique I use I end with the following errors. As stated in the OGR tab QGIS 2.0 is unable to open a file in C drive. I have very little IT background so the message error is meaningless.   Is there anybody able to decrypt the message and solve the problem?      here this is the algorithm i used


How to execute a command in multiple Terminals by executing a command in only one?

I am going to have multiple machines that I am going to connect to via SSH so I am going to have multiple Terminal windows up, though what I want to do is to execute a command so that all the machines execute it, but currently what I will have to do is execute it in each individual Terminal window, is there any way that I can execute a command in one Terminal which will execute a specified command in all specified Terminal sessions for greater efficiency as I don't want to have to enter it into every individual Terminal window? I am going to be using gnome-terminal if that makes any difference.  I am running Ubuntu GNOME 15.10 with GNOME 3.18 and the other machines should be running the same.


I have been in the UK for the last 4 months (since April 2018). My husband is a dual citizen (British and Australian), and as an Australian citizen, I can stay for 6 months. The reason why I didn't originally enter on a spousal visa is because it takes 3 months, I have to apply from Australia, and I have to hand over my passport (so can't use it for 3 months). I had some family commitments which I needed to attend so was not in a position to apply until later this year (when I could remain in Australia for 3 months without travelling). Every time I enter the UK, I am grilled but I can show a return ticket to Australia, and that I do assignment/contract work remotely (I am not employed in the UK). The last time I entered, I received the following 'tag' stamp and am really nervous about my upcoming travels. I have two, possibly three, trips planned until I finally head home to Australia to apply for the spousal visa. Any advice on what this tag stamp means? Thanks!


Why am I allowed to sign up on a private beta site I never commited to?

According to Area51,  is still in private beta. But yet I just signed up on it  (already deleted the profile now) despite I didn't commit to the proposal or recieve any mail.  Why did this happen?


This is a sample piece of code I am trying. I know that it is because of double precision/roundoff. But let me know exactly what is happening and how to overcome it.?  public class DoubleSample {      public static void main(String[] args) {         // TODO Auto-generated method stub         double price1 = 16.99;         double price2 = 12.99;         int multiplier =10000;          double price1updated = price1 * multiplier;         double price2updated = price2 * multiplier;          System.out.println("price1 "+price1updated);         System.out.println("price2 "+price2updated);     }  }   The output is   price1 169899.99999999997 price2 129900.0


Number of ways to arrange identical coins in a ring

I have $10$ identical coins that are to be placed at $10$ sites arranged in a ring. Assuming that the coins are placed at random, and by some chance only three coins turned out to be "up-faced". What are the number of possible ways such that none of these three "up-faced" coins are in adjacent sites?   What I tried is that there should be at least one "down-faced" coin in between two up-faced coins. Since, we have $7$ down-faced coins, all I have to find is number of ways to arrange these 7 coins such that there is at least one in between two "down-faced" coins. Note that the answer is $50$, but with my idea I get $38$. Any ideas?


Biblatex: incorrect name order for mutiple authors

I would like to cite the following @article{ott2015,     author =       "Ott, Dennis and de Vries, Mark",     title =        "Right Dislocation as Deletion",     journal =      "Natural Language and Linguistic Theory",     volume =       "34",     number =       "2",     pages =        "641-690",     year =         "2015",     DOI =          "http://dx.doi.org/10.1007/s11049-015-9307.7",     keywords =     "ott15" }  I use biber. But citing \cite{ott2015} gives me this:  Ott and de Vries 2015 References Ott, Dennis and Mark de Vries (2015). “Right Dislocation as Deletion”. In: Natural Language and Linguistic Theory 34.2, pp. 641–690. doi: . org/10.1007/s11049-015-9307.7.  Any author whose name is not the first is sorted as "Firstname Lastname" instead of "Lastname, Firstname", even though LaTeX clearly recognizes which one is the last name and which one is the first name. Help?


GRUB not appearing after reinstalling Ubuntu in dual boot

I had 17.0 Ubuntu installed along with Windows 7 as a dual boot.  Since apt-get wasn't installing anything I realized I had to update, so I did a fresh install to 18.04, erasing the previous version.    Everything works fine but now I can't boot back into Windows. GRUB isn't showing up. Any help?


Hide Total Size and Free Space on Network Drives

I would like to know if there is a way, preferably through Group Policy, that one can hide the total size listing and the free space listing on network drives.  We have an active directory environment that we map network drives to a MS Windows File Server.  We are afraid that users will become either unnecessarily concerned about the free space that is displayed or they will think that it is a free for all chewing up whatever space they want.  I do know about the use of quotas and how that will change the visual display, but we are not able to implement quotas within our organization due to various reasons.


How to handle questions where user asks for specific, less than optimal fix?

It happens from time to time that a question is asked where maybe the asker doesn't understand the scope of what they're asking about. They know what they want to do but perhaps they ask for directions about how to fix it in a less than ideal way.  I just came across  where a user wanted to replace %20 with spaces. The most basic, and in my opinion, correct way to ask this would probably be "how do I decode URL encoded strings?" and be tagged javascript. But whether it be shortsightedness or a misunderstanding of the big picture, the question focused on string manipulation. All but one answer used string manipulation and the question has, as of this posting, 4 close votes saying the question is a duplicate of a string manipulation question.  I feel this is off the mark. The question is slightly off as the correct answer is actually to take a different approach. People's response to the question (I'm specifically talking about the votes to close) also seem a little misguided because the original question asked for a particular approach that should probably not be used. In fact, the requested approach should probably be avoided.  How should we go about setting a question like this back on track? Or should we stick to the methods defined in the question even if the asker is obviously a little less than knowledgeable on the subject?


I am trying to center a div element on the page, but nothing seems to work. Currently the div grid structure "gallery" is pushed to the left , but I want to center it- does the flex property of its subelements have anything to do with it, and how can I best center it?    .album {   margin: 0;   overflow: hidden; }  .image {   display: inline-block;   margin-bottom: 8px;   margin-right: 8px;   text-decoration: none;   color: black;   cursor: pointer; }  .image:nth-of-type(2n) {   margin-right: 0; }  .image:hover img {   transform: scale(1.15); }  img {   border: none;   max-width: 100%;   height: auto;   display: block;   background: #ccc;   transition: transform .2s ease-in-out; }  .gallery {   margin-top: 1em;   background-color: #86b3d1;   display: flex;   flex-wrap: wrap; }  .main {   background-color: #86b3d1; }

Viewing the Collection for

{{ place_name }}

at {{ address }}

     {% for song, posts in posts_dict.items() %}
       <audio id="{{ song.song_uri[14:] }}" src="{{ song.song_preview }}"></audio>
     {% endfor %}
       <button class="add-button" >Add a song</button>


regular expression that matches on at least one alphabetic character

I'm not familiar with regular expressions and am not sure what I'm doing wrong.  reg=re.compile('[a-zA-z]+?') #regular expression checks for at least one alphabetic character  print(bool(reg.match('*ab*')))   I would like this to result in True. It doesn't matter where the alphabetic character occurs in the string.


Is using only HTTPS bad in a SEO perspective?

I would like to set up a new business site. I plan to direct www.example.com to example.com and only use that domain. My plan is also to only use HTTPS and not HTTP.   Does this affect the SEO for the site? E.g. do Google put lower or higher rank for sites that is only available via HTTPS?


A newcommand (for typesetting the symbol for parallel lines) not compiled

I copied the following command from a post on this web site.  \newcommand{\parallelsum}{\mathbin{\!/\mkern-5mu/\!}}   I have used it in other code and it has typeset the symbol for parallel lines nicely.  Why is it not compiled in this code?  (I try to use it in the last sentence.  I put a % in front of it so that the code will compile.)  \documentclass{amsart} \usepackage{amsmath} \usepackage{amsfonts}  \usepackage{tikz} \usetikzlibrary{calc,angles,positioning,intersections,quotes,decorations.markings,decorations.pathreplacing,backgrounds,patterns}   \usepackage{graphicx,tipa}% http://ctan.org/pkg/{graphicx,tipa} %This command typesets an arc symbol over letters. \newcommand{\arc}[1]{%   \setbox9=\hbox{#1}%   \ooalign{\resizebox{\wd9}{\height}{\texttoptiebar{\phantom{A}}}\cr#1}} %This command has LaTeX typeset the symbol for parallel lines. \newcommand{\parallelsum}{\mathbin{\!/\mkern-5mu/\!}}   \begin{document}  \noindent {\textbf{Proposition}} \vskip1.25mm {\em $\overline{AB}$ and $\overline{CD}$ are chords in a circle that do not intersect. They are parallel if, and only if, $\arc{AC} = \arc{BD}$.} \vskip0.2in  \noindent {\textbf{Demonstration}} \vskip1.25mm \noindent $\overline{AB}$ and $\overline{CD}$ are chords in a circle centered at $O$. $\arc{AC} = \arc{BD}$ if, and only if, ${\mathrm{m}}\angle{AOC} = {\mathrm{m}}\angle{BOD}$. \begin{equation*} {\mathrm{m}}\angle{ABC} = \frac{1}{2} \, {\mathrm{m}}\angle{AOC} \qquad \text{and} \qquad {\mathrm{m}}\angle{BCD} = \frac{1}{2} \, {\mathrm{m}}\angle{BOD} . \end{equation*} So, ${\mathrm{m}}\angle{AOC} = {\mathrm{m}}\angle{BOD}$ if, and only if, ${\mathrm{m}}\angle{ABC} = {\mathrm{m}}\angle{BCD}$. $\angle{ABC}$ and $\angle{BCD}$ are alternate interior angles. ${\mathrm{m}}\angle{ABC} = {\mathrm{m}}\angle{BCD}$ if, and only if,  %$\overline{AB} \parallelsum \overline{CD}$.  \end{document}


The second field in /etc/shadow shows "!*" for user "bin" , "uucp" and few other service accounts as well. Can anyome explain the reason for !*?

The second field in /etc/shadow shows "!" for user "bin" , "uucp" and few other service accounts as well. Can anyone explain the reason for "!" ?


This may be a dumb question for experts but i still want to ask as I don't want to throw away my old analog canon eos300. Has anyone attempted modding it from analog camera digital by adding CCD and electronics


Dirichlet's function expressed as $\lim_{m\to\infty} \lim_{n\to\infty} \cos^{2n}(m!\pi x)$

How can we see that Dirichlet's function   $$D(x):=\lim_{m\to\infty} \lim_{n\to\infty} \cos^{2n}(m!\pi x)= \begin{cases}         1 & x\in\mathbb Q\\         0 & x\notin\mathbb Q\\         \end{cases}$$


What is the difference between "I want" and "I do want"?

Reading some books and posts I noticed that there are some semantice differences between constructions described in the title of this post. Could someone help me to find out what are the real difference and in which situations are better to use appropriate constructions?  I would be very grateful to hear the correct answer.


How can we download a software from USB drive?

My laptop (Lenovo T440) doesn't run wifi while I'm using Ubuntu 18.04.2. I need to download few softwares, could anyone explain how I can download a software from USB drive in Ubuntu 18.04.2?  Kind regards


Python regular expression works in online tester, but not in program

I have a series of file names of the form "J9.0_Feature_ML_111.json". I need to retrieve the integer number after the J and before the "."  I can get it on Pythex.org using (?<=J)(\d+) but when I try and implement it in Python using   import re filename = 'J9.0_Feature_ML_111.json' num = re.match(r"(?<=J)(\d+)", filename).group()   I get a NoneType object returned. Is anyone able to help me with this please? I'm using Python 3.5.4. conda list doesn't give me a version of re so I assume it's part of the base package?


I am trying to implement the following K-map with a table    AB C     00 01 11 10       ______________     0| 1  0  1  0     1| 0  1  1  0   I implemented it like this:   \begin{table}[htdp] \begin{center} \begin{tabular}{c|c|c|c|c|}  &00 & 01& 11& 10 \\ \hline 0&1&1&1&1\\ 1&0&0&0&0\\ \end{tabular} \end{center} \label{default} \end{table}   However on the top row I have vertical lines that I'd like to not see. I went with this approach because if i was to use a one row with the information so that I wouldn't have to worry about aligning the headings. So is there a way I can get the vertical lines not to appear in the heading row?


One MySQL Table keeps losing auto-increment after restart

We are trying to figure out why this one table keeps losing auto-increment value, thus giving an error message: Failed to read auto-increment value from storage engine.    The auto ID column has type BIGINT(20), and table has about 140K records. There are other tables that also use auto increment IDs and have more records (1M to 5M records).    It started a few month ago, that every time the service restarts, the same table loses the auto-increment, and we had to manually reset.  The MySQL server is of version 5.7, and is running on windows2012.  Where should we look into to fix it?  Or should we rebuild the table?  Thanks  Here is the create table;  CREATE TABLE `notification` (   `id` bigint(20) NOT NULL AUTO_INCREMENT,    `subject` varchar(400) NOT NULL,   `category` varchar(200) DEFAULT NULL,    `created_by` bigint(20) DEFAULT NULL,   `created_date` datetime NOT NULL,   `priority` int(11) NOT NULL DEFAULT '2',   `mime_type` varchar(45) DEFAULT NULL,    `attachment` varchar(500) DEFAULT NULL,    PRIMARY KEY (`id`)    FULLTEXT KEY `ix_notification_subject` (`subject`) ) ENGINE=InnoDB AUTO_INCREMENT=141570 DEFAULT CHARSET=utf8;


Why SharePoint 2016 is not referring images from 16 hive folder?

We migrated the SharePoint 2013 solutions to 2016. But all images are deployed in 16 hive folder.In 15 hive folder images are not there but SharePoint site still referring the 15 hive folder path.  If i give the url   ImageUrl="**/_layouts/16**/images/icon.png? its not referring this path images are not displaying. If i give ImageUrl="**/_layouts/15/**images/icon.png? it was working and all images are displaying.   Why is this happening? which path should we refer? 16 hive folder or 15 hive folder?


Calendar.app extremely slow in El Capitan. Rebuild cache? Other solution?

After updating to El Capitan, my friend found her  runs extremely slowly. Clicking the button to move to the next week's display results in spinning beach ball (). Beach ball spins for something like half a minute. Makes the app practically unusable for someone booking appointments while the customer waits.  The same calendars shared over iCloud run nearly instantaneously on an iPad Calendar app (iOS 9.0.2). So the problem seems to be Mac-only.   All other apps run well. Only Calendar is beach-ball-spinning slow.  Calendar.app was already annoyingly slow in Mountain Lion & Yosemite, but is much worse in El Capitan. This computer has been upgraded through the years across these OSes.  Perhaps crud has accumulated in the Mac's local files for these calendars. Is there some way to rebuild or replace the Mac's cache of these calendars and get fresh copies from iCloud?  Any other workarounds or solutions?


Is there a BASIC compiler for Ubuntu which will run a program written in 1984 for the TRS-80 computer?

I'm copying a BASIC program from a book written in 1984 and want a compiler to run it on in Ubuntu. I'm not a coder so I don't have the skills to modify the code to  a different version of BASIC than the version used in the book.


Postfix acting as spam server. Looks like it's part of a botnet, spam messages being sent to customers

Let me first start out by saying I am no mail guru. If you need more info to help me just let me know.   This week the mail server has been having all sorts of strange issues. It has been duplicating emails last week it wouldn't even let me connect to imap with thunderbird until postfix was restarted. I never did determine why this was. At any rate a few nights ago I was searching around in the mail log trying to search for an answer as to why this might be causing these issues. With no real leads I simply began looking for anomalies. Doing this I stumbled upon thousands of email messages that are being routed through the mail system. So far as I can tell my main.cf file is correct and postfix should not be acting as an open relay. I do not understand how mail is being sent through the system. Does anyone know how this is possible?   The spam messages seem to be coming from hundreds of different domains that from all over the world. Most of them seem point to CentOS servers running apache, mail, and ssh. The only thing that's set up on them is the apache test page that comes with CentOS. The mails that are being sent through our system are mostly being sent to cornerstone-valuation.com (little website with a submit email form that does not have a captcha) although there are some being sent from [CUSTOMER EMAIL] to a disposable email service(10minutemail.com) and the rest from [REDACTED]@cfm-valuation.com. This leads me to think these machines are actually part of a botnet and that our machine is as well.   From there things get even more wild. The IP’s that is sending spam though our system to [REDACTED]@cornerstone-valuation.com and drdrb.net are also sending spam many of our customers using our system. Maybe all of them I’m not sure. This means the people doing this have access to all of our customer email accounts which are located in /var/vmail/vmail1 (which can’t even be viewed unless root) and have distributed this information all across the internet. Does anyone here know how the spammer got this information?  Here are examples of log files and a huge list of domains that probably point at a bonnet of CentOS servers. Just follow the link below.    Edit: Another issue is that A lot of the messages that are being kicked back at the server, are not originating from the server in the first place.  They are coming from outside servers that are using [OUR MAIL DOMAIN] in the EHLO statements.


Table that is always at the top of the page

I have created a command to generate a table with 7 arguments since I need to repeat it many times with different content. The problem I have is that when I create the table using this command, it is always placed at the top of the page. I have loaded the floats package, I have added H in the table header, I have also tried with !H but it returns an error ... I cannot find the cause of this Latex behavior regarding the position of a table with respect to the page. I add the definition code of the command: \newcommand{\PTgen}[7]{ \begin{table}[htbp]     \extrarowheight = -0.5ex     \renewcommand{\tabcolsep}{6pt}     \renewcommand{\arraystretch}{3}     \renewcommand {\tabcolsep}{3pt}     \renewcommand{\arrayrulewidth}{3pt}     \centering     \begin{tabular}{ c |  c | c }         $ #1 $ &$  #2 $ & \\ \hline         $ #3 $ & $ #4 $ & \cellcolor[gray]{0.9} $ #5 $ \\ \hline         & \cellcolor[gray]{0.9} $ #6 $ & \cellcolor[gray]{0.9} $ #7 $ \\     \end{tabular} \end{table}  }  Invoking the command: \PTgen{1} {2} {3} {4} {5} {6} {7}  I would appreciate any suggestions that help me solve the problem.


Relation of $det(AA^T)$ and $det(A^TA)$ with Range and Nullspaces of a Matrix

While I was studying for my exam, I found this question about range and nullspaces of a matrix, which seemed easy at the first glance, but I couldn't find a way to prove it. Could you please take a look at it?  Let $A\in R^{mxn}$  Prove that:   i) If $R(A) = R^m \implies det(AA^T)\neq0.$   ii)If $N(A)=\{0\} \implies det(A^TA)\neq0$


I am going to be cooking for someone who, because of Crohn's disease, is unable to eat pretty much anything from the allium family (ie. onions, garlic, shallots, chives, scallions and leeks; this includes garlic and onion powder), as well as spicy food (so that excludes chilis and piquant spices). I have seen  but because the suggestions there are pretty much other alliums, it is not very helpful for my purposes.  Because onions tends to be in a lot of things (if nothing else, as half of a mirepoix, which tends to appear in many recipes, and is also the base of stocks, which makes things complicated -- I am not 100% sure if the two degrees of separation from onion to stock to whatever the stock is used for is enough to make it "safe", and unfortunately I won't have time to make an onion-less stock), I am not really sure what I can use instead.  I realize that it might be hard to substitute onions and garlic with other similar tasting ingredients without using other alliums, so instead, I am looking for suggestions to replace onions and garlic with things that will still let me cook flavourful food (that doesn't necessarily need to taste the same as it would with alliums, though).   For example, I was thinking about roasting a chicken and making a couscous dressing, but the chicken would sit on mirepoix (can I replace the onions in it with something else?) which would be used as a base for the sauce as well; and my couscous dressing recipe uses shallots (as well as sage, thyme, oregano and pine nuts). General suggestions would be useful as well, though.  Any suggestions would be greatly appreciated!


Are there cheat codes for Grand Theft Auto San Andreas on the iPhone?

Is it possible to enter cheat codes on Grand Theft Auto San Andreas for iOS?  I want to buy the game for my iPhone 4, but I'd still like to have the ability to enter cheat codes.


Why were these characters not hurt after their jump?

In Game of Thrones s05e10      Sansa Stark and Theon Greyjoy (Reek) jump off the wall of Winterfell to escape Ramsay Bolton.    In the scene the wall looked rather high and even though the ground was covered by snow, I just can not believe they would have survived that jump. Even if  survival is possible, they should have had a couple broken bones, especially their legs.  So how did they make that jump and were able to keep traveling after it?


I have asked this before on two different forums, but there seems to be different opinions on this, so I'll just ask again. Can you duck through a door? Or can you only duck into a room?  She heard someone in the hallway and ducked through the nearest door.


By a combinatorial argument, prove for $r \le n$ and $r \le m$,   $${n+m \choose r} = { m\choose 0}{n \choose r} + {m \choose 1} {n \choose r-1}+\cdots+{m \choose r}{n \choose 0}$$  Besides knowing that ${m \choose 0}=1$ and ${m \choose 1}=m$, I am completely at a loss. Can someone please advise?


If $a_{n+1}/a_n\to\ell$ show $a_n^{1/n}\to\ell$

Suppose we have a sequence $(a_n)$ such that $a_n\neq0$ and $$\lim\dfrac{a_{n+1}}{a_n}=\ell$$ Show that $$\lim a_n^{1/n}=\ell.$$   I have a proof sketch, but it needs an extra assumption: By the definition of convergence $\forall\varepsilon>0\exists N\forall n>N,\ \ell-\varepsilon<\dfrac{a_{n+1}}{a_n}<\ell+\varepsilon$. Here is where I have to assume that eventually $a_n>0$ to conclude (by induction) that eventually $$(\ell-\varepsilon)^na_0<a_n<(\ell+\varepsilon)^na_0\\\therefore(\ell-\varepsilon)a_0^{1/n}<a_n^{1/n}<(\ell+\varepsilon)a_0^{1/n}\\\therefore \ell-\varepsilon\leq\lim a_n^{1/n}\leq\ell+\varepsilon\\\therefore\lim a_n^{1/n}=\ell$$ But I haven't yet figured out how to prove this without the extra assumption.


I am new to LaTeX. I got a problem with an eps files. When I use   \usepackage{graphicx} \usepackage{epstopdf}  \begin{document} \begin{center} \includegraphics[scale=0.8]{mjo.pdf} \end{center}  \end{document}   I got LaTeX Error:   unknown graphics extension.eps se the latex manual...   Can you help me to resolve this issue?


uninstall ubuntu 14 and reinstall window 8.1

I have tried to uninstall and reload windows but I can't. I have tried everything in other posts and nothing seems to work.  Even tried to just clean partition and then reinstall got the grub rescue screen. Even tried to do that didn't work. I have now reinstalled so can you give me step by step instructions on how to do it please.  UPDATE  I have discovered that Windows 8.1 computers do not come with recovery discs.  They have the software on a virtual drive on the HDD.  When you get the machine you are supposed to do a back up of it on either several DVD's or on a 16GB USB drive.  The product code is part of the Bios of the machine.  So when you install Ubuntu on a Windows 8 machine you need to partition FIRST!  The installer will not do it automatically for you.  Something I have found out to my cost as I now have to pay for a recovery disc from Acer.  :(


Can I go to Poland from Ukraine with the Netherlands (schengen, Multi, type C) visa from Ukraine for the first time?

I have multivisa issued by the Netherlands, type C. I have never entered any country using this visa. I am Ukrainian and would like to travel from Ukraine to Poland, maybe visit some other countries. However, I may not visit the Netherlands during my trip. I don't want to make any reservations for a hotel in the Netherlands, buy tickets etc, to confuse the officers that I go to the Netherlands as my final point.  There is an assumption in Ukraine (maybe, it is a myth), that you have to go to the country the visa was issued by, when traveling for the first time using this visa, or, at least visit this country during the trip. I have no biometrical passport, so no visa-free rules currently apply. Will there be any problems?


Is there something wrong with my method logic?

here is the code that calls a method if input is yes and says invalid selection if input is anything else.  private static void continueyn()     {         String option;         Scanner input = new Scanner(System.in);         System.out.println("Continue using program? type in yes or no");         option = input.nextLine();         if (option == "yes" || option == "Yes" || option == "YES" || option == "Y" || option == "y")         {             printmenu();             menusystem();         }         else         {             System.out.println("Invalid answer");         }      }   However, whenever i type yes,y,fdjs,f fisj, bascically anything, it says "invalid selection".  I am trying to make a menu system that continues after using the method but i dont know how to make it the right way so that is why i am using this function and putting it under every switch case method.


I am a programmer and sorry if this sounds stupid.  If I have to specify the same value for both the right and the left property of something, I usually refer it as the SIDE property. Is there a similar generic word to use for a value for both the top and the bottom property?   Examples:   "The rectangle has 3 pixels left and 3 pixels right margin" = "The rectangle has 3 pixels side margin." "The image is 40 pixels high and 40 pixels wide" = "The image size is 40 pixels."


I want GEdit to show all paragraphs in right-to-left view. I know that it renders paragraphs starting with rtl characters correctly. But I need paragraphs starting with ltr characters also shown as rtl.  Something like vim -F or set: rl command in Vim.n


Examples of Cohen-Macaulay integral domains

Question 1 Could you find a non Cohen-Macaulay ring $A$ without zero divisors.  I would like $A$ to be as simple as possible. For instance, I want $A$ to be finitely generated alegbra over $\mathbb{C}$.  Comment I found plenty of examples of non Cohen-Macaulay rings in wiki and from other sources. But those rings are not integral domains.  Question 2 A projective curve is called ACM if it's homogeneous coordinate ring is Cohen-Macaulay. It would be great if one give me an example of non ACM curve in $\mathbb{P}^3$.


How many monospace characters fit horizontally and vertically in an element?

I'm trying to find out how many monospace characters fit in an element (e.g. div), knowing the size and the font-size.  For instance I expected the result being:  {    x: Math.floor(divWidth / fontSize)  , y: Math.floor(divHeight / lineHeight) }   But it seems that they are not right: for a font size 50px and width: 100px, the expected answer would be 2, but it is 3:    div {     font-family: monospace;     background: black;     color: lightgreen;     font-weight: bold;     width: 100px;     height: 100px;     font-size: 50px; } <div> 123 123 </div>     For the example above the answer should be:  {    x: 3 // 3 chars horizontally  , y: 1 // 1 char vertically }   How to compute these values automatically?  var $div = $("div"); var divSize = {     w: $div.width()   , h: $div.height() }; var fontSize = parseInt($div.css("font-size"));


Evaluate $\iint dy\,dx;\frac{\pi}{4}\leq\theta \leq\frac{3\pi}{4};0\leq r\leq2$

I need to evaluate  $\displaystyle\iint \color{red}{dydx}\;\;\;,\frac{\pi}{4}\leq\theta \leq\frac{3\pi}{4}\;\;\;\;,0\leq r\leq2$  $\color{blue}{\text{without using polar coordinates}}$.  My attempt:  $$\int_{x=-2}^{x=0}\int_{y=-x}^{\sqrt{4-x^2}}dydx+\int_{x=0}^{x=2}\int_{y=x}^{y=\sqrt{4-x^2}}dydx$$     Is the correct?


Why does BTRFS seem to have comically large allocations for metadata?

I've recently discovered the marvel of a modern filesystem, btrfs. After playing with it for a few hours, I decided to dive straight in and converted my entire /home partition using the btrfs-convert tool. After that process was completed, I was left with a perfectly functional filesystem, except for the strange fact that it seemed to have nearly 80 gigabytes of metadata (for a 420 gb block device), and it seemed to have allocated off 123 gigabytes (30% of the entire device) for metadata.  root@asmodeus:/home/robbie# btrfs fi df /home Data, single: total=249.50GiB, used=210.80GiB System, single: total=32.00MiB, used=24.00KiB Metadata, single: total=123.00GiB, used=79.69GiB   I then realized that I have forgotten the last step in the filesystem conversion process, a defragmentation. I initiated the defrag with btrfs fi defrag -v -c -r -f /home (The article on converting ext3 to btrfs only said to use the recursion flag, but I decided it couldn't hurt to throw some compression in the mix and flush the changed to disk right away, and be verbose because that's how I roll) and that has been running for a good hour now. At first I was going to leave asking the question until after the defrag had finished, but I noticed that while the amount of metadata was slowly going down, my disk usage was actually going up.  root@asmodeus:/home/robbie# btrfs fi df /home Data, single: total=249.50GiB, used=223.15GiB System, single: total=32.00MiB, used=24.00KiB Metadata, single: total=123.00GiB, used=65.48GiB   I noticed that the amount of data has gone up by about the same amount that the metadata has gone down. I could see this being a temporary artefact of adding the compression, and perhaps after the defrag has completed all will be well, but I'd still like to know what is up with the ludicrous allocation for metadata? Am I able to reduce it?  Progress report: After running for many hours, this is what the usage looks like  robbie@asmodeus:~$ btrfs fi df /home Data, single: total=249.50GiB, used=230.50GiB System, single: total=32.00MiB, used=24.00KiB Metadata, single: total=123.00GiB, used=12.23GiB   The metadata usage has reduced by nearly 60 gigabytes (wow), and the data usage has increased by 32 gigabytes (It appears to be less, I moved some 12 gigabytes of media files to an external disk). In terms of disk usage, things look better, but the question remains why is so much space allocated? Now that I've reduced the amount of metadata that needs to be stored, may I reallocate some of the metadata space as data space?


Efficiency about i++ & ++i in for loop(Java)

I found the information to know ++i is more efficient, so I wrote a piece of code.  long iStartTime = System.nanoTime(); for (int i = 0; i < times; i++) { } long iEndTime = System.nanoTime(); System.out.println("i++: " + (iEndTime - iStartTime));  long startTimeI = System.nanoTime(); for (int i = 0; i < times; ++i) { } long endTimeI = System.nanoTime(); System.out.println("++i: " + (endTimeI - startTimeI));   when times is 100:  i++: 3911 ++i: 3632   when times is 999999:  i++: 4242438 ++i: 3434235   but when times is 1000:  i++: 11734 ++i: 32406   Why this happend?


I want to mob-proof the main island in the End and I'd like to use carpets for it, as they are cheap (for me, I have a massive sheep farm) and also look nicer in my eyes than most slabs. Can Endermen spawn on carpets?


String: Y|ZXIET|V| |N|100|Y||ZXIET|ZXIET|Nl Need to get first ZXIET.  I've tried this (?<=Y\|)(.*)(?=\|). It gets it right for the first Y\|, but it takes the last | character, instead of the first one.


Stock Sold at Loss, Will buying a Put Option Cause a Wash Sale?

I sold 250 shares of a stock at a loss of (-1,000).  2 weeks later bought a single put contract (100 shares) n the same stock.  If I sell the put option for profit a few days later, is this a partial wash sale?  If so, how do I calculate it? (IRS)


public class PassByReference {     int oneTozero (int arg[]) {     } }   I've never seen a variable declared this way. Can someone explain? Thanks


How to put a Div Element at the center using margin property in css

I want to Have a Text Box at the center. I tried with the code below. But it is not putting it at the center. Image of output can also be found below. Please help me by pointing errors in my code.  <html>  <head>  <style>  #form {     margin-top:40%;     margin-left:40%; }  </style>   </head>  <body>  <div id="form">      <form method = "post" action = "test.htm" >     UserName: <input type="text" name = "username" />        </form> </div>  </body>  </html>   My output from the above code is:


How did the cardiovascular system evolve?

How has evolution created our blood, lungs and the heart?  We can't exist without blood, which transports the oxygen to all areas of our body. However, the blood needs a lung, which gives it the oxygen to transport. The blood also needs something which lets it flow through the whole body, which are our veins. And in order to allow the blood to flow through our veins, an organ is needed to pump the blood, which is our heart. We also need a brain which controls all that, and the brain in turn needs the blood in order to function right.  Evolution makes very slow steps....."it just doesn't jump". So, How did evolution manage to create all that?


Need help installing wifi driver for TP-Link tl-wn821n v6

I have a TP-Link tl-wn821n v6 and there is no driver for the 18.04 version of Ubuntu. The latest one that I found is .  I don't know much about Linux in general... I would really appreciate it if you could help me out.  This is the bottom part of what popped up after "make":  /home/johnk/Downloads/TP-Link_Driver_Linux_series8_beta/rtl8192EU_WiFi_linux_v5.2.19.1_25633.20171222_COEX20171113-0047/include/osdep_service_linux.h:299:8: error: ‘_timer {aka struct timer_list}’ has no member named ‘data’   ptimer->data = (unsigned long)cntx;         ^~ /home/johnk/Downloads/TP-Link_Driver_Linux_series8_beta/rtl8192EU_WiFi_linux_v5.2.19.1_25633.20171222_COEX20171113-0047/include/osdep_service_linux.h:300:2: error: implicit declaration of function ‘init_timer’; did you mean ‘_init_timer’? [-Werror=implicit-function-declaration]   init_timer(ptimer);   ^~~~~~~~~~   _init_timer cc1: some warnings being treated as errors scripts/Makefile.build:332: recipe for target '/home/johnk/Downloads/TP-Link_Driver_Linux_series8_beta/rtl8192EU_WiFi_linux_v5.2.19.1_25633.20171222_COEX20171113-0047/core/rtw_cmd.o' failed make[2]: *** [/home/johnk/Downloads/TP-Link_Driver_Linux_series8_beta/rtl8192EU_WiFi_linux_v5.2.19.1_25633.20171jjjjjjjj   lsusb list:  Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 005: ID 2357:0107   Bus 003 Device 002: ID 1532:0214 Razer USA, Ltd  Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 005: ID 054c:0ba0 Sony Corp.  Bus 001 Device 004: ID 12d1:14dc Huawei Technologies Co., Ltd.  Bus 001 Device 003: ID 046d:c08b Logitech, Inc.  Bus 001 Device 002: ID 0951:16a4 Kingston Technology  Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


What is the idiom, proverb for "Little problems often become big problems if no one takes the initiative to correct them"  Which means in an example that If the employees don’t bother to report a malfunctioning machine or a slip-and-fall hazard, serious injuries could occur – injuries that could have been preventable. Ignoring any hazard can be detrimental to one's business and the safety of their employees.


What are disadvantages of using the lasso for variable selection for regression?

From what I know, using lasso for variable selection handles the problem of correlated inputs. Also, since it is equivalent to Least Angle Regression, it is not slow computationally. However, many people (for example people I know doing bio-statistics) still seem to favour stepwise or stagewise variable selection. Are there any practical disadvantages of using the lasso that makes it unfavourable?


I have some information against each company we deal with.  For e.g. number of employees, business volume, average salary, etc. Which technique can I use to rank each company against the others? Thanks!


What if the parents of a Muggle-born witch or wizard refuse to let them attend Hogwarts?

In the Harry Potter universe, young wizards and witches are sometimes born to Muggle parents. In this case, someone from the wizarding world visits them to offer the child their place at Hogwarts.   Anyway, attendance at Hogwarts isn't mandatory because parents can home school their children, but is this true for all children, or only those whose parents can teach them magic?  Would a Muggle-born wizard or witch be left to their own devices, not taught magic or integrated in the wizarding community, basically be left to live as a Muggle?   The only example I know of is Harry (the Dursleys didn't want him to go, but they were intimidated into letting him) but then again he is Harry Potter and there is no other way (even for Dumbledore in-universe) than to make an exception for him.   Do we know what the general rule would be for muggle born wizards and witches, or do we have any clues?


Proving $L$ is the splitting field of $f(x) = \min_Q(ζ_7)$

Given the extension $L = Q(ζ_7)$ of $Q$ where $ζ_7 = e^{2πi/7}$,  I had a small difficulty in first proving $L$ is the splitting field of $f(x) = x^6 + x^5 + x^4 + x^3 + x^2 + x + 1$ over $Q$ and that $f(x) = min_Q(ζ_7)$ before showing a further result here   So, for this, I know the six roots of $f(x)$ are $\zeta_{7},\zeta_{7}^{2},\zeta_{7}^{3},\zeta_{7}^{4},\zeta_{7}^{5}$ and $\zeta_{7}^{6}$ so $L = Q(ζ_7)$ is the splitting field of $f(x)$ over $Q$ but how to show $f(x)$ is irreducible over $Q$? I must be missing something simple here.


Command to add column to all tables in a schema

Could you please give the command to add a column to all the tables if the table doesn't contain that column in a schema?  e.g. The schema schema1 contains 50 tables in which 20 tables contain a column named colTest.   I need to add the column colTest to the remaining 30 tables.


New global preferences: keyboard shortcuts and sticky topbar

Following a global preference for , as of now, the preferences for enabling keyboard shortcuts and disabling the fixed topbar are network-wide* as well.  If you had either checked off on any site in the network, that setting has been preserved and applied to the whole network for your account already. Future changes will also apply to all* Q&A sites.  Find them in their usual spot as previously on the  pages.    * With the exception of , which will support the fixed topbar after the .


Is it possible to use superscript/subscript in comments?

EDIT: this question is not covered  as this does not refer to subscript or superscript  QUESTION:  How do I use subscript or superscript in comments?  <sup> and </sup> don't work.  I see the chemists using latex in comments ?  Maybe that's the only way?


How can I block people from my Minecraft world?

Every time I open my world to LAN, people join and start destroying stuff. I want to ban them, but every time I ask someone for help they can't ban them.


Touchscreen on HP Envy x360 is not working with 18.04

When I tried Ubuntu 18.04 LTS on my HP envy x360, the touchscreen of the laptop is not working. How can I fix it?


InstalledPackage Failure When Deploying to Sandbox

I'm a bit of a force.com IDE newbie - still learning. I'm trying to migrate a simple custom object (no fields) from one sandbox to another and I'm running into this error:  # Deploy Results:    File Name:    package.xml    Full Name:  package.xml    Action:  NO ACTION    Result:  FAILED    Problem: Cannot deploy InstalledPackage in Package Manifest with any other types!   Any help would be greatly appreciated.  Thanks!


Why I can't scan the Whatsapp QR from my inbuilt whatsapp scanner?

My whatsapps apps has upgraded to version 2.12.94 and now i am no longer able to scan the web QR code from my whatsapp app inbuilt scanner.   The code is displayed from the web whatsapps but while using the mobile whatsapp to scan the code, the mobile(HTC M8 Android 5.0.1) and PC is not being paired.  Thanks to provide for a solution.


How to swap mouse buttons AND touchpad taps INDEPENDENTLY?

I alternate between left-handed and right-handed mouse on even/odd days for reasons not relevant here. I use for such thing a widget in Kubuntu 12.04  When it is left-handed day, my mouse understand wells that the primary button should be secondary and vice versa. The problem is that on those days the touchpad thinks "Hey, today one tap means secondary button" and it becomes nearly useless.  This happens because in the touchpad configuration settings of Kubuntu 12.04 you can assign left vs right mouse button to the action "Tapping with one finger", and not the primary vs secundary button. Therefore, on left-handed days one tap on the touchpad means "secondary".  Sure you linux experts can tell me a way to swap both mouse buttons and the meaning of touchpad taps INDEPENDENTLY and by konsole, so that I can run a script on even/odd days and forget about this nasty thing.


Explanation about the address of a pointer

I am just learning the concept of pointers in c++. From what I have studied I understand that & is used for finding memory address of a variable. I want to ask if there is also memory address of a pointer. Take a look at my code below  #include <iostream>  using namespace std;  int main() {  int fish=5; int *fishpointer=&fish;  cout << fishpointer << endl; cout << &fishpointer << endl;  return 0; }   The above code on run print the following  0x7fff64cc1f14 0x7fff64cc1f18   Each time I run it the both the address changes, but the second address is I think 4 more in value than first. Why that is so? I understand that first address is of variable fish, but not able to understand about second address. Is it just garbage value?


Why does Google not consider dot in usernames of Gmail addresses?

E.g.: If your Gmail ID is abc.xyz@gmail.com, it considers this the same as abcxyz@gmail.com.  Why is this so?


Can I install a ROM made for a different device?

I own a MicroMax A100. I want to install the latest version of a different ROM (Samsung or Nexus).  Is it possible? If so, can you tell me how?  If not, can I install a ROM made for a different device, but from the same manufacturer? For example, could I install a ROM for the MicroMax A110, which is the successor of A100?


What is the recommended way to upgrade: full reinstall or over current system?

I have previously upgraded from 16.10 to 17.04 but it didn't go well at all.  I used deja-dup to restore my settings and this resulted in a messed up connection manager, the inability to change the wallpaper anymore, and random app crashes.  What is the recommended way to upgrade Ubuntu? And if reinstalling from scratch, what is the point of the deja-dup backup if it can't be restored without creating issues? How else do you migrate your settings?


Search in all tables for a field with given value or name

Is there a pure sql solution to search in all tables for a specific field with a given value or name. In pseudocode the query im looking for would be  SELECT * FROM * WHERE field = "value"   or  SELECT tablename, field FROM *   I already know how I could use the mysql  to search for all tables with the column, but I'm unsure if (and how) I could combine this inside a query (or stored procedure).


Prove that no integer in the sequence $11,111,1111....... $ is a perfect square.

My problem is well described in title. I know that it can be proved as follow:  Since every number in the sequence is of the form $4x+3$ and perfect square does not exist in such form so none  is a perfect square.  But I need to prove in a different way, a way different from modular arithmatic. Any ideas??


How to remove Windows and partition on dual boot system

If I have a copy of the latest Ubuntu installer on DVD can I run it from within Ubuntu or simply boot from it and then be given the option to remove windows and the partition so I have just Ubuntu on my drive with no separate partition?  I'm trying to get rid of windows and the partition.  I'm currently running a dual boot, Ubuntu/windows system.


How long were the bullet holes present in the glass from the non-inverted perspective?

In the first half of Tenet, there is a scene where The Protagonist and Neil break into Freeport and find a glass wall with bullet holes (could only find a good photo with Christopher Nolan in it):  In the next scene, we find out that these bullet holes were caused by an inverted armed man entering the room (exiting the room from their perspective) and reverse-shooting the glass, which removes the bullet holes from the future-facing perspective. This all makes sense, but raises a question: how long were the bullet holes there in the first place? Were they in place as soon as the glass was installed, possibly years ago? Or even back when the glass was manufactured?


Given a real function $g$ satisfying certain conditions, can we construct a convex $h$ with $h \le g$?

The following is Exercise 8 from Chapter 3 of Rudin's Real and Complex Analysis (not a homework problem, just for fun).     Let $g$ be a positive function on $(0, 1)$ such that $g(x) \to \infty$ as $x \to 0$. Does there exist a convex function $h$ on $(0, 1)$ such that $h \le g$ and $h(x) \to \infty$ as $x \to 0$?   This seems true, but I can't show it. All I've been able to do is to reduce the problem to $g$ being a monotone step function or a strictly monotone piecewise-linear function but this doesn't seem to get me anywhere. I'm not sure how to use the property of $g$ to construct the explicit $h$.


Meaning of Files/Folders With a Red/Gray X on Them

There are some files and folders that have a red X on them. What are those? What does that red X represent?


What type of path in shebang is more preferable?

In scripts, first line should specify the path to interpreter. But on different servers Linux, Unix, or BSD this path could be different.  What is more preferable?  #!/usr/bin/env bash    or  #!/bin/bash


Install self compiled software to /usr or /usr/local?

Generally speaking, should self installation by compiling source be stored in /usr or /usr/local (specified to --prefix)?   When to install to /usr and when to /usr/local?  E.g.   I often  run checkinstall to create a deb file after compilation of source distribution, and checkinstall installs the software by calling dpkg. isn't this the same as installing software from OS repositories? After install, both can be managed by dpkg. What differences are between them? I am running Ubuntu 14.04. I don't use emacs from its repository.   I installed  my emacs by compling from source and checkinstall, the default location is /usr/local. e.g. /usr/local/bin/emacsand /usr/local/share/emacs/24.4/.  I installed . The default install location is /usr e.g. /usr/share/emacs/. I don't find a way to specify --prefix for ESS. I run make install directly.  So in my emacs, I can't find S mode offered by ESS.  Shall I reinstall emacs with ./configure --prefix=/usr?   Thanks!


Why and why would/wouldn't a company split their stock?

When Apple was in the high $600 or so range, it split 6 times and made it more affordable to purchase more shares for less, even though the value was technically the same. I see companies like Google are extremely high per share and am wondering why or why not they would or wouldn't split their stock right now.


How to prove reflexivity, symmetry and transitivity for the following relation?

I would like to know how to prove reflexivity, symmetry and transitivity for $\sim$ according to the following definition:     Suppose $\sim$ is defined on the set of the integers as follows : $a\sim b$ iff $ab ≤ a|b|$   Please help me. Thanks!


$$\sum_{r=0}^{k-1}4^r$$ Hi, I was wondering whether anyone could explain how to work this out. I know the end result is $\frac{4^k-1}{3}$, but I don't know why or how to get there.  Thank you :D


Typing at symbol (shift+2) displays double quote (") and Typing at symbol (shift+') attherate (@) in ubuntu 16.04

I am working with ubuntu16.04. While working with terminal i had seen that my keyboard keys typing different signs. For example   Typing at symbol (shift+2) displays double quote (")  Typing at symbol (shift+') atTheRate (@)  Typing at symbol (shift+3) Euro (£)   .  I restarted my system but still it's showing same.


Training set target categories' distribution

In a book I'm reading I've come across the following quote:     Accuracy on the test set is a good performance measure only when there is a relatively uniform distribution of target categories in the training set.   If the real world categories are distributed 10% A and 90% B, then should the training categories also be 10% A and 90% B, or should they be 50% A and 50% B?


$\lim_{n \to \infty}a_n=\sqrt{2+\sqrt{2+\sqrt{2}+\sqrt{2...}}}$   I am trying to find the limit using the Monotone convergence theorem   But first I am trying to find an explicit presentation of $a_n$.  is the only presentation of it is a sequence $$\sum_{n=1}^{\infty}2^\frac{1}{2n}$$ ?


Camera perspective in viewport is different to in render

I want my image to look like image 1, but when I render, the result is image 2. Why is the viewport different to the rendered output?


What is this algebraic structure called like?

Is there a name for an object $L$ that has an additive structure and a (not necessarily total) order such that for all $a,b,c \in $ L we have  $a+b = b+a$ $a+(b+c)= (a+b)+c $ $a+b \leq a+c \Leftrightarrow b \leq c$


i have the following LINQ statement, I need to write inside, the if clause, I did the following but obviously its an error,im asking how can I implement something like this in LINQ?  var devices = (from c in db.MasterDatas                join m in db.TurbineDevices on                c.turbine_id equals m.turbine_ip                join t in db.v_vpn_gateway_info                on m.turbine_ip equals t.turbine_id                where m.turbine_ip == id                                   select new TurbineDvce                {                   if(t.vpn_gateway==m.device_ip)                       {Comments =vpn_gateway                             }else                     Comments = m.comments,                    Description = m.description,                    DeviceIP = m.device_ip,                    DeviceType = m.device_type,                    FirmwareVersion = m.firmware_version,                    Model = m.model,                    Password = m.psw,                    Phone = m.tel_number,                    Producer = m.producer,                    PublicIP = m.public_ip,                    TurbineId = m.turbine_ip,                    Username = m.username                });


Got boards tomorrow and I was going through some past years paper and one question stumped me. The leader counted _______ the cooperation of his colleagues. On/Upon both sound equally correct but I am not sure.  Could someone please tell me the correct answer and also explain when 'on' is used and when 'upon' is.


I wonder how to build a 1-1 correspondence between [0,1] and [0,1). My professor offers an example such that 1 in the first set corresponds to 1/2 in the second set, and 1/2 in the first set corresponds to 1/4 in the second. I don't quite understand it. Does it mean every element in the first set corresponds to its half value in the second set? wouldn't that make some elements left out in the second set? Does it still count as 1-1 correspondence? Does it connect to Schroder-Bernstein theorem?


$$\lim_{n\to\infty}\sqrt n(\sqrt[n]x-1)$$ I have never previously encountered functional sequences, so I am a newbie in this matter. I know that intuitively, $x^{1/n}\to1$ and that $\infty\cdot0=1$. As a result, the limit should be 1. However, can this reasoning be considered correct and rigorous enough? I'm pretty sure that if I write this in my first year bachelor exam, my answer will be considered incorrect.   What is the more formal way of doing this? (I think that the squeeze theorem should work, but can't choose suitable bounds). Thanks in advance.


I recently came across an article printed in our school magazine, which read, "I studied that a year ago". But, doesn't "I studied that a year back" sound better?  What's your say?


Coarsest topology such that addition and multiplication are continuous

I asked this question earlier    Now for a follow-up question. I want to know what's the coarsest topology such that addition and multiplication $\sigma(x,y) = xy$ are continuous. The preimage of the addition map is a diagonal line, while the preimage of multiplication map are two curves ($y = \frac{1}{x})$. How do I find the coarsest topology such that these map are continuous?


Considering the fault of any experimental evidence from LHC for supporting the supersymmetry idea until now, can we say that it is dead? Generally the people who are working on this subject say that MSSM probably is dead but we have some new extensions of it such as NMSSM. This argument seems weird a bit. Sometimes I feel that it is a vain try to keep an idea live because they have invested their scientific life on it. On the other side, I have to confess that the supersymmetry is a beautiful idea. But it seems that the nature does not like it and we have to accept it. Other related question is, if the supersymmetry fails, can we say that the superstring fails too?


Where is it appropriate to post about a new Linux software utility that I want some feedback about?

I have a new Linux utility that I'd like to get a small handful of folks to try out...   It would be appropriate for the readers on ServerFault.   But, I don't think it meets the guidelines for posting on that site.  Where would it be appropriate to post this?


RAID level confusion (MegaCli vs megasasctl output)

I'm utterly new to working with LSI MegaRAID controllers and I'm confused as to what RAID level I am actually running. My server is equipped with 4 disks, 4TB each and I would like to have them running in RAID-10. Searching around for some hints I've found  and followed the  in one of the answers.  Now, what confuses me is the output of megacli and megasasctl:   # megacli -LDInfo -Lall -aALL | grep RAID RAID Level          : Primary-1, Secondary-0, RAID Level Qualifier-0   According to the  this should mean I am currently running RAID-1. However according to this I am running RAID-10:   # megasasctl a0       LSI MegaRAID SAS 9260-4i encl:1 ldrv:1  batt:FAULT, module missing, pack missing, charge failed a0d0      7451GiB RAID 10  2x2  optimal a0e252s0   3726GiB  a0d0  online   a0e252s1   3726GiB  a0d0  online   a0e252s2   3726GiB  a0d0  online   a0e252s3   3726GiB  a0d0  online     My confusion on this probably couldn't be worse.What am I missing here and which output is the one to be believed?   EDIT (in reply to CharlesH's request)  The output is as follows:  # megacli -LDInfo -Lall -aall   Adapter 0 -- Virtual Drive Information: Virtual Drive: 0 (Target Id: 0) Name                : RAID Level          : Primary-1, Secondary-0, RAID Level Qualifier-0 Size                : 7.276 TB Sector Size         : 512 Is VD emulated      : Yes Mirror Data         : 7.276 TB State               : Optimal Strip Size          : 256 KB Number Of Drives per span:2 Span Depth          : 2 Default Cache Policy: WriteBack, ReadAhead, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteThrough, ReadAhead, Direct, No Write Cache if Bad BBU Default Access Policy: Read/Write Current Access Policy: Read/Write Disk Cache Policy   : Disk's Default Encryption Type     : None Bad Blocks Exist: No Is VD Cached: No    Exit Code: 0x00


I believe I understand what a function and relation are, but what is a mapping? At first I thought the term was synonyms with relation, but after looking it up, I’m thinking it could be more or less the same thing as a function.  Does a “mapping” or “map” imply a relationship with one output value per input?


Is there any shortcut/easy way to switch this system proxy settings?

Sometimes I need to send my traffic to a proxy, sometimes I don't.  Currently, I have to go to the settings every time to click it.  Is there any simple way for me to switch this? For instance, use a shell command to do this.


Why is placing the tag name in the question title bad?

I often see edits which remove tags like "C#", "SQL", etc. from question titles. Why are tags in titles considered bad practice?  It doesn't make things unclear; it doesn't confuse anybody. But, most importantly, this enables search engines to find relevant posts much easier, especially if some concept or technology is present in different languages.


Ubuntu 14.04 to 16.04 upgrade got interrupted due to power failure. Now when I try to upgrade again I am getting the following message:  "Not all upgrades can be installed, run a partial upgrade"    What should I do to upgrade to 16.04?


Evaluate $\int_0^{\infty}\frac{\ln x}{1+e^x}dx$ using Frullani Identity

Wolfram Alpha said that $$\int_0^{\infty}\frac{\ln x}{1+e^x}dx = -\frac{\ln^22}{2}.$$ I have attempted to multiply top and bottom by $e^{-x}$ and then use the geometric series on $\frac{1}{1+e^{-x}}$, but that eventually led to me having to deal with expressions involving $\eta’(1)$. My alternative attempt was to use the fact that $\ln x=\int_0^{\infty}\frac{e^{-t}-e^{-tx}}{t}dt.$ $$\int_0^{\infty}\frac{\ln x}{1+e^x}dx$$$$ = \int_0^{\infty}\int_0^{\infty}\frac{e^{-t}-e^{-tx}}{t(1+e^x)}dtdx$$ I am confident there is a way to go from here involving symmetry or some manipulations that lead to the answer. Any help or hint for going from my double integral step would be appreciated.


Here on Meta, I was able to edit , without it going to a review queue, even though I only have 268 rep here.  However, on Spanish SE Beta, I have 800 rep and my edits go to the review queue.  What's the difference?


Answering the oldest correct answer or the best

Consider  on Mathematics. It was first answered by  and then better explained by . both answers are correct but the second one better addressed corner cases to explain what I was not able to grasp from the first answer.  As a general rule, is it better to mark the original answer as correct or the one that helped me more?


I somehow managed to get wireframe looked like this:  How to change it back to default wireframe view? Edit: here is the sample file.


What is the added value of the -T option in GNU cp and mv?

Why do some GNU Coreutils commands have the -T/--no-target-directory option? It seems like everything that it does can be achieved using the semantics of the . (self dot) in a traditional Unix directory hierarchy.   Considering:  cp -rT /this/source dir   The -T option prevents the copy from creating a dir/source subdirectory. Rather /this/source is identified with dir and the contents are mapped between the trees accordingly. So for instance /this/source/foo.c goes to dir/foo.c and so on, rather than to dir/source/foo.c.  But this can be easily accomplished without the -T option using:  cp -r /this/source/. dir  # Probably worked fine since dawn of Unix?   Semantically, the trailing dot component is copied as a child of dir, but of course that "child" already exists (so doesn't have to be created) and is actually dir itself, so the effect is that /this/path is identified with dir.  It works fine if the current directory is the target:  cp -r /this/tree/node/. . # node's children go to current dir   Is there something you can do only with -T that can rationalize its existence? (Besides support for operating systems that don't implement the dot directory, a rationale not mentioned in the documentation.)  Does the above dot trick not solve the same race conditions that are mentioned in the GNU Info documentation about -T?


Show that every number is the limit of a sequence of irrational numbers

I am not even sure where to start with this one. I understand for something to be a limit then that means if we have a sequence $\{a_n\}$ of irrational numbers then for any number $a$ in the reals, the $|a_n - a| < \epsilon$ for $\epsilon > 0$. But how would you show that any number fulfils this statement?


In how many ways can the Letters of the Alphabet be permuted such that it does not contain CAR,DOG,PUN,BYTE

Im using the principle on inclusion and exclusion to solve this  There are 4 cases C1,C2,C3 ,C4 respectively   So taking the case where CAR DOG and BYTE comes together  n(C1^C2^C4)=20!   But in my book its given as 19!. This is my explanation Taking CAR,DOG AND BYTE together total 10 letters so (26-10)!=16!  These letters are considered as one word so (16+1)!=17!  But there will be 3 inter arrangements among them so (17+3)!=20!   Where am i doing wrong?   EDIT: You need to find 26!-N(C1UC2UC3UC4) For this i need to calculate each permutations involving the words so my question is regarding a particular case


Do phrases "Yes, it did not." and "No, it did not." have different meanings?

Let say the question is:     So this ended up not working?   What is the proper way to say, this indeed not work?  These two seem fine to me:     Yes, it did not.   or     No, it did not.   Are they both right? Or does one of them have different meaning. Is there any difference between the two phrases?


If $A$ and $B$ are operators on $V$ and $AB=I$, must $BA=I$?

Let $V$ be a vector space and $A,B\in\mathcal L(V)$, the set of linear operators on $V$. Suppose $AB=I$. Must $BA=I$? In other words, do left and right inverses coincide? If not, do conditions of finite-dimensionality of $V$ or boundedness of $A$ and $B$ change anything?  I am asking because I know that for a group, the existence of left inverses or right inverses alone guarantees existence of the other, with both coinciding. But the set of operators with, say, left inverses, doesn't automatically form a group, so I am not sure whether this applies. But I can't think of any example of square matrices with different left and right inverses.


What Integral Measures When we calculate integral of Functions from $[a,b]$ to $\mathbb{C}$?

As we know, the integral of function $f:[a,b]\to \mathbb{C}$ is defined $$ \int\limits_a^bf(t)\,\mathrm{d}t=\int\limits_a^b\operatorname{Re}[f(t)]\,\mathrm{d}t\,+\,i \int\limits_a^b\operatorname{Im}[f(t)]\,\mathrm{d}t$$ But, I am curious to know how we defined this integral in this way? Why? As integral of any function $g:[a,b]\to \mathbb{R}$ measures area. But I also want to know what the integral of $f$  measures?


Let $R$ be a commutative ring with $1$. We call $R$ a local ring when $R$ has exactly one maximal ideal $m$. Let $I \subset R$ be a proper ideal of $R$, i.e. $I \neq R$.     Question: Is $I$ contained in $m$?   Approach: I think this is true. If $I$ is a proper ideal of $R$, then $I$ does not contain any units of $R$ (otherwise we would have $I=R$, contradiction!). But this is the only thing I can think of.  Could you please help me solving my question? Thank you!


How do I set up Minecraft Cross Play in Same House / Same Wifi?

I have been trying to set up Minecraft so that my kids can play it on our home wifi across multiple devices. I am so confused.. too many versions of Minecraft  I own:   Minecraft Java Edition (Windows 10) Minecraft: Xbox Edition Minecraft for Windows 10 (through the Windows Store) I also have a Nintendo Switch   with this combination of computers/Xbox/Nintendo Switch can someone tell me step by step how to get 2 or 3 players in my house playing in the same Minecraft World (without spending any more money?)  thanks.. yes I have googled this to death. I have also watched many many unhelpful youtube videos.. and I am a minecraft noobie.. thanks


Good introductory textbook for group theory

I am beginning to learn group theory (specifically finite groups) and I’m wondering which textbooks can help me.  So any suggestions for introductory texts?


Does the principle of conservation of momentum really imply Newton's third law? ("Classical Mechanics" by John Taylor)

I am reading "Classical Mechanics" by John Taylor.    There is the following problem in this book:       In Section 1.5 we proved that Newton's third law implies the conservation of momentum. Prove the converse, that if the law of conservation of momentum applies to every possible group of particles, then the interparticle forces must obey the third law. [Hint: However many particles your system contains, you can focus your attention on just two of them. (Call them $1$ and $2$.) The law of conservation of momentum says that if there are no external forces on this pair of particles, then their total momentum must be constant. Use this to prove that $F_{12} = -F_{21}$.]     It is true that $F_{12} = -F_{21}$ holds when there are no external forces on this pair of particles.   Then, can we say the following statement?     $F_{12} = -F_{21}$ holds when there exist external forces on this pair of particles.


Linux Distro: Lubuntu 19.04  My system is working fine but I just get distracted when I update my packages because of this error which I don't know how to fix. I've been finding some related topics and I tried their solution but still fail to fix the error.  sudo apt update Hit:1 http://repo.steampowered.com/steam precise InRelease Hit:2 http://packages.microsoft.com/repos/vscode stable InRelease               Ign:3 http://dl.google.com/linux/chrome/deb stable InRelease                    Hit:4 http://dl.google.com/linux/chrome/deb stable Release                      Hit:5 http://archive.ubuntu.com/ubuntu disco InRelease Hit:6 http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu disco InRelease Hit:8 http://archive.ubuntu.com/ubuntu disco-updates InRelease            Hit:9 http://archive.ubuntu.com/ubuntu disco-security InRelease           Hit:10 http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu disco InRelease Error: GDBus.Error:org.freedesktop.systemd1.UnitMasked: Unit -.mount is masked. Reading package lists... Done Building dependency tree        Reading state information... Done All packages are up to date.   Edit: Here is the results of the terminal whenever I use update. Sorry for inconvenience.


Editor sidebar is misaligned when editing an existing post

Steps to reproduce:   Click to edit an existing question or answer here, in MSE. This question itself will do. The sidebar appears below the editor block:     Tested on Chrome 35 and Firefox 29 running on Windows 7 Ultimate x64.  This would seem to be a dupe of , but it is happening here on MSE.


What does it mean 100% disk usage in Task Manager?

I see the following picture in Task Manager about my Drive C:    As you see, active is 100% most of the time, while disk transfer rate is relatively low and below 10 Mb/s.  How to understand this? What is used by 100% if transfer is low? How to know, who is providing this usage?


If $(V,\|\cdot \|)$ is a finite dimensional space, then all norms are equivalent.

I want to show that if $(V,\|\cdot \|)$ is a finite dimensional space, then all norms are equivalent. I have shown that if $\dim V=m$ all norms $$\|x\|_p=\sqrt[p]{x_1^p+...+x_m^p}$$  are equivalent, but how to show that for an unspecified norm $\mathcal N$ on $V$, there is a $p$ and two constante $A,B>0$ such that $$A\|x\|_p\leq \mathcal N(x)\leq B\|x\|_p$$ for all $x\in V$ ?


Seperate Ringtone for Unknown Caller (Android 7)

In Android 7, how can I set a separate ringtone for callers who are not in my contact list? I still want to receive the call but I want to know if it is someone in my contact list or not before answering.


"Possible duplicate" comment is not appearing when I vote to close

Starting a few days ago, when I vote to close a question as a duplicate, I don't see the auto comment when I'm returned to the question. I have to refresh the page to see it.


So during exams and as of late, I started to informally cite scholars sometimes and as much as possible to backup the written ideas, however and due to the very nature of exams, I am facing the below issues:   Sometimes I memorize ideas almost word-by-word from the textbook or course book, and as a result of answering the exam question, I almost write everything as it is and without paraphrasing or even citing, is that plagiarism? The doctor would definitely identify my answer as being from the book we learned... Other times, I get some ideas from outside the book and I do cite them in that case, however I do not paraphrase as I am learning by heart the thoughts in order to answer a specific question in the exam, is that plagiarism? (e.g. lack of paraphrasing) And lastly, since I am memorizing by heart, I sometimes misspell the name of an author or even change a bit of details in his or her idea, is that a bad thing?


"Failure to download extra data files" after installing ttf-mscorefonts-installer

After fresh install 12.04 I && updating apt and system restart, I always get this annoying message after reboot :     Failure to download extra data files      The following packages requested additional data downloads after   package installation, but the data could not be downloaded or could   not be processed.      ttf-mscorefonts-installer      The download will be attempted again later, or you can try the   download again now. Running this command requires an active Internet   connection.   But if I run attempt now, it shows flashing terminal window and like nothing happen. It'll happen again when I restart system.  I found someone have  too, but he haven't replied yet.   I'm a newbie here, please help.


I had a city with 25000 citizens, but it started to decline. As you can see on the screenshot there are a lot of empty spaces. There used to be building along those roads.       To prevent the decline I added bus routes within the city. According to the OpenTTD wiki that's a way to increase town sizes:     A bus with one passenger from the other side of town would have the same effect on growth as a large train full of passengers from the other end of the map. source:    But the city still shrinks. Does somebody know how to prevent this?


NullPointerException in array of objects

import java.util.Scanner; class TestMatrix {     public static void main(String args[]){         Scanner in=new Scanner(System.in);         System.out.println("Enter the number of matrices: ");         int num=in.nextInt();         int[][] temp=new int[10][10];         Matrix[] matrixarray=new Matrix[num];         Matrix.numberOfMatrices(num);         for(int i=0;i<num;i++)             {                 System.out.println("Enter the rows and columns of M["+(i+1)+"]: ");                 int r=in.nextInt();                 int c=in.nextInt();                 System.out.println("Enter the values: ");                 for(int x=0;x<r;x++)                     for(int y=0;y<c;y++)                         {                             temp[x][y]=in.nextInt();                         }             matrixarray[i].inputMatrixValues(temp);              }         } } public class Matrix {     static int number;     int[][] matrix=new int[10][10];     int row,col;     public static void numberOfMatrices(int n)     {number=n;}     public void inputMatrixValues(int[][] matrix)     {         for(int i=0;i<row;i++)             for(int j=0;j<col;j++)             {                 this.matrix[i][j]=matrix[i][j];             }     } }   the above code returns null pointer exception while calling the method inputMatrixValues() at line 22. matrixarray[i].inputMatrixValues(temp);  matrixarray is an object array of class Matrix. The exception occurs while accessing the ith element of object array. Matrix object array is created in line 9. Pls check what part of the code causes error.


Change of style in the table of contents

Following is mwe of what I'm doing. I want to get a couple of things.    Instead of bold 1, 2, I need it to be replaced by Chapter 1 and Chapter 2 respectively, followed by the name. I want the References appeared in the table of contents, separately not under a Chapter, with the heading References.   Thank you for any suggestions.   \documentclass[11 pt]{article}  \usepackage{amsmath, mathrsfs} \usepackage{amssymb}  \usepackage[utf8]{inputenc} \usepackage[english]{babel} \usepackage{blindtext}    \linespread{1.4} \pagestyle{myheadings}      \title{This is the title} \author{Author A and Author B} \date{} \begin{document} \let\conjugatet\overline \maketitle  \tableofcontents   \section{This is section 1} \subsection{This is a subsection}  \section{This is section 2} \subsection{This is a subsection}   \bibliographystyle{abbrv} \bibliography{References}{}  \end{document}


How come Dropbox gets an icon in Finder sidebar?

How come Dropbox gets a non-generic icon in Finder's sidebar, when other directories like Google Drive and Sites (native in OS X before Lion) all have the same generic one?    How can I customise the icons used by the folders in the sidebar? OS X used to show individual icons of all folders there — not any longer.


Scientific notation when importing from Excel in .Net

I have a C#/.Net job that imports data from Excel and then processes it. Our client drops off the files and we process them. I don't have any control over the original file.  I use the OleDb library to fill up a dataset. The file contains some numbers like 30829300, 30071500, etc... The data type for those columns is "Text".  Those numbers are converted to scientific notation when I import the data. Is there anyway to prevent this from happening?


Why does the tree property hold for regular cardinals but not singular cardinals? (I.e. There exists a tree of height $\kappa$ with countable levels and no cofinal branch for $\kappa$ a singular cardinal)


How to force Latex print out reference items from Bibtex file?

I am writing a thesis. I put all the references, including my own publications in a BIB file.   I want to create two sections like before:  \section {My Publications}  [1] my pub 1   [2] my pub 2  ...  [9] my pub 9  \section {References} #other reference  [10] other pub 1  [11] other pub 2  ...  The idea is to put all my references to the beginning of reference list. How could I do that in Latex?   Thank you very much


How to secure a sql statment through a prepared statement

Let's say I execute a query like this:  $assignments = $database->getDataAsArray("SELECT * FROM assignments WHERE userId = '$id'");   The function (getDataAsArray) looks like this:  public function getDataAsArray($myQuery){         $this->connection = mysqli_connect($this->host, $this->dbUsername, $this->dbPassword, 'portal');         $statement = $this->connection->prepare($myQuery);         $statement->execute();         $result = $statement->get_result();         $results = array();         while($line = $result->fetch_array()){             $results[] = $line;         }         return $results;     }   This is unsafe because I do not parameterize the query with items like :ID  Is it safe if I do it like this:   $id = mysqli_real_escape_string($database->getConnection(), $_SESSION['id']);         $assignments = $database->getDataAsArray("SELECT * FROM assignments WHERE userId = $id AND closed = 0 AND completed = 0");   In case this it not safe how can I parameterize my queries with one function. For instance I have this query:   "SELECT * FROM assignments WHERE userId = $id AND closed = 0 AND completed = 0"   and I have this query:   "SELECT * FROM state WHERE id='$stateId'"   Both have different number of parameters which need to be added to the query. How can I handle this in one function?   Thanks in advanced


Linux tools to treat files as sets and perform set operations on them

Does anyone know of any linux tool specifically designed to treat files as sets and perform set operations on them? Like difference, intersection, etc?


how to delete windows? I only want ubuntu

How can i delete windows? I only want ubuntu on my pc. I dont want windows. It came together with windows when I am downloading ubuntu but I dont want windows. Is there any way to delete windows 7? I am using ubuntu 13.04 please help me.  Please explaing me how to delete that windows 7  I tried to reinstall my ubuntu but my windows 7 still exist. I cant delete that windows 7. Please explain how to delete that os. I only want ubuntu on my pc because ubuntu is best os ever in this planet!


How to make an image look like an all-white sculpture in Photoshop?

I'm wondering how they actually achieved this kind of effect?    image from   Could you give me some suggestions: are there any techniques to get the same effect? I tried many ways in Photoshop. I have more than 5 years of experience in Photoshop, but my results are not the same?  What should I do?


How can I recover an Android device after a factory reset?

My two-year-old was playing with my (locked) Galaxy Nexus, and when she eventually handed it back to me, it was at the "Welcome" new phone setup screen.    I'm guessing that she managed to hold down buttons and eventually end up at the factory reset option.  So I guess my first question is, was the phone definitely factory reset?  Is there any other case in which the phone would boot up to this screen?  Second, assuming it was a factory reset, and I have never setup any backup software or anything like that, what are my options for recoving pictures and SMS messages?  I assume that my only real option is to somehow snapshot the raw disk device(s) onto my computer and from there run file recovery software on the image.  Is that the case, or are there other options?  If so, how do I copy the raw disk device(s)?  Thanks.


After installing xubuntu, I did not get a boot loader, help?

I searched on google and tried the boot repair program that you install on a flashdrive and boot from it to reinstal/fix grub but when I use the program, I get an error that says "The boot of your pc is in legacy mode. Please change it to EFI-mode" and it gives me this link;   Any help is appreciated!