I wrote this sentence:     We suppose that two items are similar if they have been bought together by many people.   Should I say?     We suppose that two items are similar if they were bought together by many people    That sentence is the premise of a theory, it is a fact, not opinion.  item means product in this context

What is the difference between "were" and "have been", and are these sentences gramatically correct?  1) some of the best known writers of detective fiction in the twentieth century were women. 2) some of the best known writers of detective fiction in the twentieth century have been women.


After I used a baking pan to steam bake (in a moist environment) a cake part of it changed to this color. Why is this happening?  Can I still clean it?  (I tired soaking it with vinegar and scrubbing it but to no avail.)

I just bought my first few pot and pans "Calaphon" stainless steel trip-ply  I used my new 10" skillet tonight, and cooked pork chops. I heated the pan first, added olive oil, let it heat, then added chops. After I was done, cleaned it immediately under water, and noticed white cloud looking areas on the bottom of the skillet. They won’t wash or rub off  Do I need to return these? I did buy them for the look as well.


I am unable to exactly comprehend the following sentence (word-by-word) as I am not getting what it means by 'Inform approaches' there: Assessments like 'Uwezo' are being used to inform approaches to scale TARL program across Africa in countries like Botswana. Also in quest of making my understanding, I went through many sentences in '** but I didn't attain a clear understanding yet. Is it more figurative than literal in meaning? Hope I will find solace here.

It is the 2018 - 2019 goal of Natural Resources Canada written on the site:      Canadians have access to cutting-edge research to inform decisions   on the management of natural resources.   I can't understand what 'to inform' means. Therefore, please paraphrase it or let me understand its meaning.


What's the difference between Flat and Material design illustration? Even, Are they any different? For example, what can I call the picture below?

After Windows 8 came out all spoke about "Metro UI" and later about the "Flat design". Now, after Android Lollipop came out all speak about "Material design". Can somebody explain the difference between "Material design" and "Flat style"?


I have put myself in the task of looking for a book of real analysis in several variables that has a solid theory in critical points and theory of maximums and minimums (convex functions, Hessian, etc.) but I have not found a good text that has the proofs of the theorems on critical points, I would like you to recommend a good bibliography at the undergraduate level

Due to my ignorance, I find that most of the references for mathematical analysis (real analysis or advanced calculus) I have read do not talk much about the "multivariate calculus". After dealing with the single variable calculus theoretically, it usually directly goes to the topic of measure theory.    After reading the wiki article "", I'd like to find the rigorous proof for this test. The first book comes to my mind is Courant's Introduction to Calculus and Analysis which includes the multivariate case in the second volume.   Motivated by this, I'd like to put the question here:     What are the usual references for the   theoretical treatment for   ?


Equation: 1/(1*2) + 1/(2*3) + 1/(2*4) + ... + 1/(n*(n+1)) = n/(n+1)  I need help with solving this equation. I cannot seem to be able to do anything with (n+1)/(n+2) that I get on the right side after induction step.

$$\frac{1}{1 \cdot 2} + \frac{1}{2\cdot 3} + \cdots + \frac{1}{n(n+1)} = \frac{n}{n+1}$$  What I have so far in the induction is:  $$\frac{1}{1 \cdot 2} + \frac{1}{2 \cdot 3} + \cdots + \frac{1}{k(k+1)} + \frac{1}{(k+1)(k+2)} = \frac{k}{k+1} + \frac{1}{(k+1)(k+2)}$$  But I'm not sure where to go from there . . .


$\newcommand{\N}{\mathbb N}$Exercise 3.5.12.  This exercise will establish a rigorous version of Proposition 2.1.16. Let $f : \N×\N → \N$ be a function, and let $c$ be a natural number. Show that there exists a function $a : \N → \N$ such that $a(0) = c$ and $a(n+1) = f(n,a(n))$ for all $n ∈ \N$, and furthermore that this function is unique.  (Hint: first show inductively, by a modification of the proof of Lemma 3.5.12, that for every natural number $N \in \N$, there exists a unique function $a_N \colon \{n ∈ \N : n ≤ N\}\to\N$ such that $a_N(0) = c$ and $a_N(n+1) = f(n,a_N(n))$ for all $n \in \N$ such that $n<N$.)    Lemma 3.5.12 (Finite choice). Let $n \ge 1$ be a natural number, and for each natural number $1 \le i \le n$, let $X_i$ be a non-empty set. Then there exists an $n$-tuple $(x_i)_{1\le i\le n}$ such that $x_i \in X_i$ for all $1 \le i \le n$. In other words, if each $X_i$ is non-empty, then the set $\prod_{i\le i\le n} X_i$ is also non-empty.   Proof  We induct on $n$. Starting with the base case $n = 1$; the claim     follows from Lemma 3.1.6 (why?) now suppose inductively that the claim     has been proven for some $n$, we will prove it for $n+1$.  Let $X_1,\dots,X_{n+1}$ be a collection of non-empty sets.     By the inductive hypothesis, we can find an $n$-tuple $(x_i)_{1\le i\le n}$     such that $x_i \in X_i$ for all $1 \le i\le n$. Since $X_{n+1}$ is     nonempty, by Lemma 3.1.6 we may find an object $a$ such that $a \in  X_{n+1}$. If we thus define the $(n+1)$-tuple $(y_i)_{1\le i \le n+1}$     by setting $y_i := x_i$ when $1 \le i \le n$ and     $y_{n+1} := a$, it is clear that $y_i \in X_i$ for all $i$     with $1 \le i \le n+1$; this proves the claim.    My attempted solution was to consider the function $a_N$ as an $N$-tuple and use mathematical induction on $N$:  Base case: $a_0(0) = c$ by definition.  Inductive hypothesis: $a_N(0)=c$ and $a_N(n+1) = f(n,a(n))$ for all $n \le N$. It follows from the order of $\N$ that there exists an $n$ such that $a_N(N) = f(n,a(n))$.  Then I show by the same method of the lemma that $a_{N+1}(n) = a_N(n)$ for $n \le N$ and that $a_{N+1} = f(N,a(N))$ from the inductive hypothesis. Is my attempt true. If not I would consider a proof that follows the hint.  Note The question was asked here      but answers doesn't follow the hint.

Exercise 3.5.12. Let $ f: \mathbb N \times \mathbb N \to \mathbb N$ be a function, and let c be a natural number. Show that there exists a function $a:\mathbb N\to \mathbb N$ such that $$a(0)=c$$ and $$a(n++)=f(n,a(n))\;for\;all\;n\in \mathbb N,$$ and furthermore that this function is unique. Tao gives the hint: first show inductively, by a modification of the proof of Lemma 3.5.12, that for every natural number $N\in \mathbb N$, there exists a unique function $a_N:\{ n\in \mathbb N:n\lt N\}\to \mathbb N $ such that $a_N(0)=c$ and $ a_N(n++)=f(n,a(n))$ for all $n\in \mathbb N$ such that $n\lt N$.  In my opinion, we could solve it by proving that $\forall n\in \mathbb N,a(n)\in \mathbb N$ according to mathematcial induction.  The property P(n) is:$$\forall n\in \mathbb N, a(n)\;is\;unique$$ P(0) is true. And if P(n) holds, P(n++) is true because different natural numbers must have different successors. $$a(n++)=f(n,a(n))$$ $$a(m++)=f(m,a(m))$$ $$n++=m++\Rightarrow n=m\Rightarrow a(n++)=a(m++)$$ It's similar to the proof of  Proposition 2.1.16 (Recursive definitions): Suppose for each natural number $n$, we have some function $f_{n} : \mathbb{N} \rightarrow \mathbb{N}$ from the natural numbers to the natural numbers. Let $c$ be a natural number. Then we can assign a unique natural number $a_{n}$ to each natural number $n$, such that $a_{0} = c$ and $a_{n{++}} = f_{n} (a_{n})$ for each natural number $n$.  This proof indicates both the existence and uniqueness of the function $a$. I don't know why Tao says it's informal.  But regarding the hint, how do we get the function f even if we've got the conclusion from the hint. Also it seems like the function a(n) can be diffentent considering different N. I don't know if the hint is correct.


I recently reviewed a suggested edit on  which simply added a tag to a question.  The comment was "added derby tag based on comment", which surely made sense to the editor, but to check whether the edit was appropriate I had to visit the question in a new window to see the comments.  Would it be reasonable to show the comments on questions and answers in the reviews for suggested edits?  A possible problem with this is that the comments justifying the edit may not make sense if the comments on which they were based are later deleted.

Having recently reviewed a few suggested edits, I've found that not being able to see the comments on the post is hindering my understanding of the context of some edits.  In particular, there have been a few posts where someone has made a substantial edit to a question or answer which significantly alters its meaning. Typically I'd reject that as "too radical", since it can't be known that the new meaning of the post was what the original author intended.  However, in some cases it is clear from the comments that the original author is aware of the intended change, and as such the editor is not in fact misrepresenting the author's intentions. In these cases, it would have been useful to see the comments when making the review decision.  As an example, a common cause of this is when an inexperienced user is asked to clarify their question, and ends up writing a comment that would be better off as an edit to the question (due to length, excess code content, etc), presumably due to lack of awareness that the question can be edited. Often, other users will helpfully edit the question to include the information the OP put in the comment (see ,  and  for examples). In this situation, it is clear that the edit reflects the OP's intentions, but this information is only present in the comments which are not visible in the review interface.  Following is the suggested edit screen showing the suggested edit. It seems indentation is increased and one line is moved a few lines upwards and some empty lines added to increase readability. But it look like an invalid edit since changing the related line may cause alteration on the runtime. So not looks lie a valid edit. Better open the answer and examine it        Checking the Q&A itself reveals that a talk had taken place between the OP and the answerer and revision done by the OP with the permission of the answerer. So it was indeed a valid edit.        In short: is there any particular reason comments are not displayed in the suggested edit review interface? I think it would add useful contextual information when making review decisions, and presumably this would be trivial to implement.  Note: this is not a dupe of , as it does not concern comments posted after the suggested edit.


Normally, portrails of Spiderman  that are realisticly drawn, or live-action, have him wearing foot skins inspired by martial art fighters; sometimes it has a clearly separate big toe.  It's difficult enough to suppose that Spiderman covers his skin at all, if his power is explained by gecko-like hairs with microfiber tips.  Perhaps they go through thin spandex or special glove material.  But in The Amazing Spiderman 2, he was very clearly wearing athletic shoes with a thick sole, with a thick layer covering the bottom of his feet.  Why did they design his costume that way? What is the rational for its ability to work for him?

How does Spider-Man's "sticky" powers work? If his ability to climb walls works in the same way as spiders and most other insects (e.g. due to ) then his hand should have microhairs or thorn-like structures as shown in 2002 Spider-Man movie, which means he should not be able to climb walls while wearing his gloves since those structures can't pierce through gloves.  If the thorny structures are sharp enough to pierce through his clothes then how does he use his hands (like giving handshake to other people) without hurting them?


that if $Y$ is Banach, the set $B(X,Y)$ of bounded linear operators from $X$ to $Y$ is Banach in the operator norm. I was now wondering about the converse. Is it true? More precisely:     Suppose $B(X,Y)$ is a Banach space, where $X,Y$ are two normed space. Is $Y$ then necessarily Banach?   I do not really know where to start, neither in trying to prove, nor in trying to find a counterexample.

Let $V,W$ be normed vector spaces, and $L(V,W)$ be the space of bounded linear operators. Usually I would only see the statement "If $W$ is Banach, then $L(V,W)$ is Banach.". But  writes that there is a converse: "If $L(V,W)$ is Banach, and if $V$ is non-trivial, then $W$ is Banach". This is pretty interesting since I never seen a converse before. I was wondering if anyone has a nice proof.  I tried reversing the proof for the usual direction, but the inequalities can't be reversed. I also tried to start with a Cauchy sequence in $W$, and construct linear operators (using Hahn-Banach to control the operator norms), but alas I cannot say much about the distance between these operators (much less say that it is Cauchy)


I have a strange situation here. I have a simple code looping through a text file for getting mail id's. If there is no mail id available then the code will sleep -> continue -> start of while. Every time i check whether i have anything in my string.IF no i will sleep again and try again. I have check on str.length()<5 (covering empty and null)/ i tried str.isEmpty + str.equals(null). All the time in the 3rd cycle the exceptions happens.  Code   public void sendButtonActionPerformed(java.awt.event.ActionEvent evt)     {         /* reading from text file at specific path*/          String str;            String attachment= "";          //String[] info = new String[2];         // int size = 0 ,i =0;          try{          FileReader fr=new FileReader("D:/data.txt");          BufferedReader br=new BufferedReader(fr);           ///read line from the file upto null           while(true)          {             str=br.readLine();             System.out.println(str);           /*  if( str.equals(null) )             {                  System.out.println("sleeping1");                  Thread.sleep(2000);                      System.out.println("woke1");                  continue;             }*/             if (str.length()<5)             {              System.out.println("sleeping");              Thread.sleep(2000);                  System.out.println("woke");             continue;              }             globalMailCount++;              String[] info = str.split(";");             toAddress = info[0];             attachment = info[1]+ "";           //  System.out.println("Email:"+toAddress+"image:"+attachment);              //System.out.println(info[i]);             ccAddress = "navaljosh@gmail.com";             subject = "Thanks from Jabong today";             message = "Hi, Thanks for being part of the event";             receipients = toAddress + "," + ccAddress;              receipientsList = receipients.split(",");              SendMailUsingAuthentication mailUsingAuthentication =                     new SendMailUsingAuthentication();             try {                 mailUsingAuthentication.postMail(receipientsList,                         subject, message, "navaljosh@gmail.com", "sanmacs88", attachment);             } catch (MessagingException messagingException) {                 messagingException.printStackTrace();             }            }       //   br.close();          }catch(IOException e)          {           } catch (InterruptedException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }     }   Exception stack trace  sleeping woke  sleeping woke  sleeping woke Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException null     at mailSent.MailSender.sendButtonActionPerformed(MailSender.java:169)     at mailSent.MailSender$1.actionPerformed(MailSender.java:65)     at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)     at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)     at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)     at javax.swing.DefaultButtonModel.setPressed(Unknown Source)     at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)     at java.awt.Component.processMouseEvent(Unknown Source)     at javax.swing.JComponent.processMouseEvent(Unknown Source)     at java.awt.Component.processEvent(Unknown Source)

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I am facing a problem in setting the combo property such that only user can select the values form given items, but I cannot write in the combo box.  How can I do so in C#?

I want to have a "select-only" ComboBox that provides a list of items for the user to select from. Typing should be disabled in the text portion of the ComboBox control.  My initial googling of this turned up an overly complex, misguided suggestion to capture the KeyPress event.


I am writing for a friend who cannot ask a question here on Meta.  He has been suspended last week, asked to delete his account[s] and a message said that accounts cannot be removed before the end of the suspension.  Since he has been suspended for ten years, that seems tantamount to right being denied.  Is that fair and acceptable? How can that be overcome? Why didn't they just remove the account permanently?  If somebody doesn't believe it, they can check , no reason is given. Not just because he's my friend but I am sure that a suspension of ten years makes no sense.

My account has been , besides the following restrictions:  an account will be locked at 1 reputation the user page will have a visual indication that the account is in timed suspension, and for how long the account holder will be unable to vote, ask, answer or comment  What else does timed suspension prevent me doing? For example, can I still edit my own posts or delete content? And what is a network-wide suspension?


The reason I want to know is because many years ago in Sunday school I learned a story that in probably 600 AD some sinner was swallowed up by a hole, and that he's still falling as of today.  I can't use the formulas I know because they all assume g as constant, and I realized that I can't assume g=9.8 the entire fall because he's getting closer and closer to the center of the earth, so I tried to use my fairly bad calculus skills and failed miserably. Can anyone do this problem? Is it even possible?

...And you jumped in.  What would happen when you got to the middle of the Earth? Would you gradually slow down, until you got to the middle and once you were in middle would every direction feel like it was up?


I saw the code for a ResNet CNN in Python3 and PyTorch  as follows: def resnet_block(input_channels, num_channels, num_residuals,                  first_block=False):     blk = []     for i in range(num_residuals):         if i == 0 and not first_block:             blk.append(Residual(input_channels, num_channels,                                 use_1x1conv=True, strides=2))         else:             blk.append(Residual(num_channels, num_channels))     return blk  To add the modules, the following code is used- b2 = nn.Sequential(*resnet_block(64, 64, 2, first_block=True)) b3 = nn.Sequential(*resnet_block(64, 128, 2)) b4 = nn.Sequential(*resnet_block(128, 256, 2)) b5 = nn.Sequential(*resnet_block(256, 512, 2))  What does "*resnet_block()" mean/do?

In the following method definitions, what does the * and ** do for param2?  def foo(param1, *param2): def bar(param1, **param2):


I've bought a VPS from a hosting provider and I want to set it up. The server is a CentOS-6.4 and the provider installed WHM on it, so it has apache installed as well.  I have 3 IPs available and I managed to install nginx and make it listen on one of the IPs, while apache still responds to the first IP and WHM/CPanel works fine.  My issue is with getting nginx to function properly. It works fine serving HTML content, but for PHP it needs php-fpm or similar to work.  I've read countless blog posts about how to get this to work and they all say: "add the epel.repo and remi.repo, set priorities and yum install php-fpm and whatever extension you might need.  The problem is when I try to yum install, I get:  No package php-fpm available. No package php-cli available. No package php-mysql available. No package php-gd available. No package php-imap available. No package php-ldap available. No package php-odbc available. No package php-pear available. No package php-xml available. No package php-xmlrpc available. No package php-magickwand available. No package php-magpierss available. No package php-mbstring available. No package php-mcrypt available. No package php-mssql available. No package php-shout available. No package php-snmp available. No package php-soap available. No package php-tidy available. Error: Nothing to do   Any clues as to why it's not working?

I believed I've downloaded and updated the EPEL rpm but I can't install php-pecl-memcached.. I'm very new to this, any help is appreciated.  #rpm -Uvh epel-release-6-8.noarch.rpm warning: epel-release-6-8.noarch.rpm: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY Preparing...                ########################################### [100%]         package epel-release-6-8.noarch is already installed  # yum update Loaded plugins: fastestmirror, security Loading mirror speeds from cached hostfile  * base: mirror.us.leaseweb.net  * epel: mirror.symnds.com  * extras: mirror.ash.fastserv.com  * updates: mirror.vcu.edu Setting up Update Process No Packages marked for Update   #yum install php-pecl-memcached Loaded plugins: fastestmirror, security Loading mirror speeds from cached hostfile  * base: mirror.us.leaseweb.net  * epel: mirror.symnds.com  * extras: mirror.ash.fastserv.com  * updates: mirror.vcu.edu Setting up Install Process No package php-pecl-memcached available. Error: Nothing to do


I can use this command   mysqldump -u"root"  myDB| gzip > mydb_`date +%d-%m-%Y`.sql.gz   but when run in crontab   * * * * * mysqldump -u"root"  myDB| gzip > mydb_`date +%d-%m-%Y`.sql.gz   ( this error cause by function date, when i remove it , crontab run good )  on ubuntu, it happen this error in log file.  ubuntu CRON[xxxx] (user) CMD(mysqldump -u"root"  myDB| gzip > mydb_`date+) ubuntu CRON[xxxx] (CRON) error ( grandchild #5353 failed with exit status 2) ubuntu CRON[xxxx] (CRON) info (no MTA installed, discarding output)

I have a crontab that looks like  0 0 * * * pg_dump DB_NAME > /path/to/dumps/`date +%Y%m%d`.dmp   which works fine when I run it manually, but not when cron runs it. After digging through the logs, I see  Dec 12 00:00:01 localhost crond[17638]: (postgres) CMD (pg_dump DB_NAME > /path/to/dumps/`date +)   It looks like a problem with percent signs, but the man page doesn't even contain the percent character at all, so I thought they were alright.


I use this function to make mysql backup it work fine but my problem is i have some data with utf-8 encode in my database and when use this function data change to "?????" how can i fix it ?  function backup_tables($host,$user,$pass,$name,$tables = '*') {        $link = mysql_connect($host,$user,$pass);     mysql_select_db($name,$link);     if($tables == '*')     {         $tables = array();         $result = mysql_query('SHOW TABLES');         while($row = mysql_fetch_row($result))         {             $tables[] = $row[0];         }     }     else     {         $tables = is_array($tables) ? $tables : explode(',',$tables);     }     foreach($tables as $table)     {         $result = mysql_query('SELECT * FROM '.$table);         $num_fields = mysql_num_fields($result);          $return.= 'DROP TABLE '.$table.';';         $row2 = mysql_fetch_row(mysql_query('SHOW CREATE TABLE '.$table));         $return.= "\n\n".$row2[1].";\n\n";          for ($i = 0; $i < $num_fields; $i++)          {             while($row = mysql_fetch_row($result))             {                 $return.= 'INSERT INTO '.$table.' VALUES(';                 for($j=0; $j<$num_fields; $j++)                  {                     $row[$j] = addslashes($row[$j]);                     $row[$j] = ereg_replace("\n","\\n",$row[$j]);                     if (isset($row[$j])) { $return.= '"'.$row[$j].'"' ; } else { $return.= '""'; }                     if ($j<($num_fields-1)) { $return.= ','; }                 }                 $return.= ");\n";             }         }         $return.="\n\n\n";     }     $handle = fopen('db-backup-'.time().'-'.(md5(implode(',',$tables))).'.sql','w+');     fwrite($handle,$return);     fclose($handle); }

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


Here is a sentence:     The major forces outside of the organization that have the potential to significantly influence the likely success of the products and services.   Is the use of the bold 'of' right in the above sentence?

The word rarely turns up  outside that context.   and     The word rarely turns up outside of that context.   Which one is correct and why?


In the course of doing differential equation substitutions, I often come across the expression $\frac{d}{dt}\frac{dy}{dx}$, where $y$ is a function of $x$, and $x$ itself is a function of $t$.  For some reason, I have a hard time figuring out how to expand this.  One possibility is to multiply the inside by $\frac{\frac{dx}{dt}}{\frac{dx}{dt}}$, yielding $\frac{d}{dt}\frac{\frac{dy}{dx}\frac{dx}{dt}}{\frac{dx}{dt}} \implies \frac{(\frac{d}{dt}(\frac{dy}{dx}\frac{dx}{dt}))\frac{dx}{dt} - (\frac{dy}{dx}\frac{dx}{dt})\frac{d}{dt}\frac{dx}{dt}}{(\frac{dx}{dt})^2}$, which looks nice because $\frac{dy}{dx}\frac{dx}{dt} = \frac{dy}{dt}$.  However, to proceed further I would need to use the expanded version, and then the initial expression $\frac{d}{dt}\frac{dy}{dx}$ reappears.  Is there a simple chain rule here I'm not spotting?  How should I think about expanding this expression?

I understand that for the parametric equations  $$\begin{align*}x&=f(t)\\   y&=g(t)\end{align*}$$  If $F(x)$ is the function with parameter removed then $\displaystyle F'(x) = \frac{\text{d}y}{\text{d}t}\big/\frac{\text{d}x}{\text{d}t}$  But the procedure for taking the second derivative is just described as " replace $y$ with dy/dx " to get   $$\frac{\text{d}^2y}{\text{d}x^2}=\frac{\text{d}}{\text{d}x}\left(\frac{\text{d}y}{\text{d}x}\right)=\frac{\left[\frac{\text{d}}{\text{d}t}\left(\frac{\text{d}y}{\text{d}t}\right)\right]}{\left(\frac{\text{d}x}{\text{d}t}\right)}$$  I don't understand the justification for this step. Not at all.   But that's all my book says on the matter then it launches in to plugging things in to this formula, and it seems to work well enough, but I don't know why.  I often find answers about question on differentials are beyond my level, I'd really like to get this, it'd mean a lot to me if someone could break it down.


We were scheduled to travel Toronto to Lisbon on April 3-April 11,2020. The flights have been subsequently cancelled. We purchased the refundable type tickets which basically mean we will be charged 350.00 for each ticket. A far cry from the 2500 I spent. Problem is that they are not allowing me to refund any portion instead offer a voucher for a year. Not only is my 8 year old crushed by the fact that his tournament in Algarve is cancelled,but I am stuck with the fact that we are not and will not need a voucher. Why on a refundable ticket is there no way to get funds returned. They said they didn't cancel the flights, the Portuguese government did! Are they not owned by the government. So Sad!!!

My international conference in Europe this May has been canceled due to the COVID-19. I have a ticket, purchased from TAP air Portugal, from Toronto, Canada to Lisbon. Because it is a non-refundable fare, they don't want to give a refund.  They won't allow me to reschedule later than May 31 of this year. This won't be useful for me.  What options do I have? I'd prefer to get a full refund.  (I am a US citizen if it matters)  Note: They offered to refund just the taxes, which is about 10% of the value. That's not horrible, but I'd rather have the whole thing returned.


When it comes to how long SSD's and HDD's will last half of the people say it usually stays healthy for 3-5 years before they die, while the other half say "Even if you write 20 GB every day you can use it for a hundred years"  Who am I supposed to believe? They're completely opposites, it's almost as if one or the other is speaking fairy tales.  I recently bought a 2TB modern SSD and am worried if it'll fail three years from now, as I bought it based on price. I download 35GB a month on average (unless for some reason web browsing use should be included).

Mean Time to Failure (MTTF) is usually given in terms of hours, and by doing some calculations, it seems that a disk should fail only after a good number of years have gone by.  It seems that disks need repair more often than that. Does anyone know why this is so?  I figured that there is something fishy about this metric. Am interpreting something wrong here?


When trying to derive badge statistics on  it would be helpful if there was an identifier (say BadgeTypeId) that would mark the badge as being   Bronze badge Silver badge Gold badge Bronze tag badge Silver tag badge Gold tag badge   Motivation: A while back (not reproducible anymore) we had an {epic} tag on . With the  having only a Name field to identify it, it wasn't easy to discern between the regular  and the bronze/silver/gold {epic} tag badge.  I can see that, in the long run, some sites might be more affected than others where there could exist an overlap between the tag names and badge names.  springs to mind where TV shows or movies might have titles similar to some badges.   requests the addition of badge class. This post requests something more: class and type (tag/regular).

According to  the following metadata is exposed for badges:  Id UserId Name Date   Why isn't class exposed in some way? It's obviously in the schema, since we can sort / filter in the UI. Come to think of it the description might be something useful to filter on in a query as well, e.g.:     Give me the name and count for all gold badges that contain the word 'vote' in the description.   I am not sure if class is exposed in a different way for tag-related badges (I suspect the schema is more complex, since their existence relies on them having been awarded in that class at least once).  (Also, the Id in the Badges table is not the badge id, it seems to be an IDENTITY / auto-increment column.)


Evaluate this multiple integral inside a limit:  $$\lim_{n\to\infty} \underbrace{\int_{0}^{1}\cdots \int_{0}^{1}}_{n}\frac{ \sum _{k=1}^{n}x_k^{505}}{\sum_{k=1}^{n}x_k^{2020}} \mathrm d x_1\cdots \mathrm dx_n$$  Someone sent me this question and apparently it was from a very hard competition/exam. I couldn't evaluate this with any techniques that I know of (my knowledge is very limited) and I have also posted this question on my Instagram account to see if anyone could evaluate it, but unfortunately still no one could evaluate it.   Since there are many people who are really good at mathematics here and it is relatively easier to gain attention here than Instagram, I would want to see if anyone can evaluate it. Probably this expression would need an advanced technique that I don't know of or an unexpected trick to evaluate. Hopefully I can learn something from this post!  Edit: some comments suggested that intuitively it would evaluate to $\frac{2021}{506}$ with similar techniques used in the evaluation of a similar integral: $$\lim_{n\to\infty} \underbrace{\int_{0}^{1}\cdots \int_{0}^{1}}_{n}\frac{ \sum _{k=1}^{n}x_k^{2}}{\sum_{k=1}^{n}x_k} \mathrm d x_1\cdots \mathrm dx_n=\frac{2}{3}$$ That question is linked to this one and it would be a good idea to have a look at the techinques used there to see if it could be implemented here.   More information: Now I think this integral doesn't involve any techniques in multivariable calculus but instead some techniques from probability theory (which I don't fully understand yet) but I really want to see the solution and learn something from it.

I have been working on a problem from a past high school Math Competition and I have been stumped. I am asked to compute $$\lim_{n\rightarrow\infty} \int_{0}^{1}\int_{0}^{1}\cdot\cdot\cdot\int_{0}^{1}\frac{x_{1}^{505}+x_{2}^{505}+...+x_{n}^{505}}{x_{1}^{2020}+x_{2}^{2020}+...+x_{n}^{2020}}\,dx_{1}\,dx_{2}\,...\,dx_{n}$$ At first I tried a lot of direct evaluations of the integral to find a simplification i.e. solving the general integrals $$\int_{0}^{1}\frac{x^{505}+a}{x^{2020}+b}\,dx$$ but this really only complicated the matter, so I began to look for more clever manipulations. I noticed for $x_i \in [0,1]$ that we would have the integrand $$ f(x_1,x_2,...,x_n) = \frac{\frac{1}{n}}{\frac{1}{n}}\cdot\frac{\sum_{i=1}^{n}x_{i}^{505}}{\sum_{i=1}^{n}x_{i}^{2020}}$$ which can be seen as a Riemann sum so at infinity, $$\lim_{n\rightarrow\infty}f(x_1,x_2,...,x_n)=\frac{\int_{0}^{1}x^{505}\,dx}{\int_{0}^{1}x^{2020}\,dx}=\frac{2021}{506}$$ My thought process was that the region in $\mathbb{R}^n$ being integrated over is the unit cube, so I could try to view the integral as the product of the volume of the region by some average value of the function in the region, which would maybe approach a constant value because of the Riemann sum? I was just unsure if any of this can be justified, especially when the number of integrals approaches infinity. Any help or advice is appreciated.


I have this TextBox where you can type in something like "1 + 2 + 3". I want the program to evaluate the answer (6 in this case) and assign it to a var. Then output the answer to a TextBlock. Tried the following but I'm getting a red underline under DataTable. It says 'DataTable' does not contain a constructor that takes 0 arguments  using System.Data;      private void ButtonCalculate_Click(object sender, RoutedEventArgs e)     {         string equation = textBoxEquation.Text;         var answer = new DataTable().Compute(equation, "");         textBlockAnswer.Text = answer;     }

Is there a function the .NET framework that can evaluate a numeric expression contained in a string and return the result? F.e.:  string mystring = "3*(2+4)"; int result = EvaluateExpression(mystring); Console.Writeln(result); // Outputs 18   Is there a standard framework function that you can replace my EvaluateExpression method with?


edit: the duplicated result was great! thanks for finding it for me. I couldn't get the right key-word to search for that but you find it for me after I could not find for 10 minutes. thanks verymuch it works well.  I'm having a weird issue where the referenced label and the actual number displaced on the document do not match. A picture probably help:    I cannot provide a minimal viable example as I am using some template file which probably is causing this issue, so if I start fresh this issue obviously do not manifest.  If anyone is interested here is a link to the template file, maybe there's something that can clue you to help with this issue?    thanks in advance. I am very very perplexed why it happens.

One of my sections seems to be using the section number rather than the appropriate figure number for \ref's that point to figures. (Theorems and the like work fine.) As far as I can tell, there's nothing differentiating the problematic section from the other sections, but there must be as the problem doesn't go away when I compile that section on its own. Any ideas?  Edit: an example of a broken figure. (Every figure in the section is broken.)  \begin{example}   Figure~\ref{fig: hasse} depicts ... \begin{figure}[htbp]\label{fig: hasse} \begin{center} \begin{tikzpicture}     \tikzstyle{every node}=[draw,circle,fill=black,minimum size=4pt,                             inner sep=0pt]     [bunch of lines for the picture]     \end{tikzpicture} \caption{Hasse diagram} \end{center} \end{figure} \end{example}   This particular instance had the figure inside the example, but that doesn't make a difference.


I want to remake an old multiplayer game in commercial way and I wonder how different my game has to be not to violate some IP rights. I know so far that name and logo are registered trademarks of the company that still exists so I cannot use it. But ... How about other things such as maps or mechanics of the game? Can this be somehow protected? If I make a new map that will NOT use a single asset from that old map (like textures, sounds or models) but will mimic the old map as much as possible, can this be problem from legal point of view? By mimic I mean for example putting tree in excactly same position as on the old map, but the tree would be completely different model; buildings would have same plans but all the models and walls textures would be different. Also this game has some certain amount of features (players classes, mission scenarios, types of weapons) that are being used in other games commonly so this cannot be patented. But how about given set of these features? For example having given types of classes connected with given missions scnarios and types of weapons can be protected even though seperately they cannot be??? Is that possible?

Most games build on other games' successes and many are downright clones. Where is the limit of imitation before legal issues come into play? Is it down to literary or graphic work like characters and storyline that cause legal problems, or can someone actually claim to own gameplay mechanics?  There are so many similar clone games out there that the rules are probably very slack or nonexistent, but I'd like to hear the views of more experienced developers / designers.


I need a regex to find all matches for my pattern.  The text is something like this:  "someother text !style_delete [company code : 43ev4] between text !style_delete [organiztion : 0asj9] end of line text"   And I would like to find all matches for the pattern:   !style_delete [.*]   I have tried like this:  Pattern pattern = Pattern.compile("!style_delete\\s*\\[.*\\]");   With this the match text is coming like this:  !style_delete [company code : 43ev4] between text !style_delete [organiztion : 0asj9]   But I am expected as follows:  match 1 : !style_delete [company code : 43ev4]  match 2 : !style_delete [organiztion : 0asj9]   Please help me, what will the regex in java to get above output.

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


Which preposition to use? On Or In. Sentence:  I'm working really hard on/in my English.

So I want to write the following sentence about a future job that I would like to have but I don't know which preposition should I use.     I would like to work in/on/at something related to arts.


I was wondering if you could tell me some online videos or other resources to learn theory of linear models. I am a visual learner. I learn more from video lectures. My focus is to learn:  Matrices, generalized inverses, projection matrices, multivariate distributions, conditional distributions, quadratic forms and their distributions, MLE and least square estimators, estimability and Gauss-Markov theorem, confidence intervals, general linear models, ANOVA and F-tests.  Thank you so much for your time.

I was wondering if you could tell me about some self-learning resources for linear model theories. My professor has been using "A First Course in Linear Model Theory, Ravishanker and Dey. Publisher: CRC." I found this kinda difficult. My major is mathematics. Thank you so much for your time!


We are supposed to downvote a poor quality posts but most of the times the OP takes in the suggestions and edits their post.   Shouldn't the people who downvoted be notified when the post gets edited so they can come back and remove their downvote?

To me, a downvote usually indicates a problem with an answer. When I downvote it's to mark the answer as having a problem, not the person. If the answer is fixed, I want to remove that downvote - but it's tricky to keep track of all the questions I've looked at over the last few hours.  I don't actually downvote very much, but it's very easy to forget what's going on.  It would be nice to have some way of indicating in an edit that you (the editor/answerer) believe the reason for the downvote has now been resolved, so that the downvoters could come and undo their downvotes or explain why it's still not fixed.  (Note: this isn't about rep-recovery, but quality control. I would feel a lot better about downvoting on "iffy" answers if I felt it was likely that the answer would be fixed and I could undo the vote. Whether or not I'd get back the cost of the downvote is somewhat immaterial.)


This is a problem from my introductory calculus homework.  \begin{equation}  f(x) = \begin{cases} x^2\sin\frac{1}{x}, & x \neq 0,\\ 0, &  x = 0. \end{cases} \end{equation}  Does $f'(0)$ exist?  If I approach the problem algebraically, I obtain the answer \begin{equation}f'(x)=\lim_{x \rightarrow 0}x\sin\frac{1}{x}\end{equation} This should be equal to 0 from the Squeeze Theorem. So, $f'(0)=0$.  However, something about this answer worries me. At class, the professor said to informally think of the tangent line at a point as the line that the curve begins to "look like" if we zoom around the point (or so I remember, I might be misquoting here). At the time this made a whole lot of sense to me. However, if I look at the problem from this angle, my geometric intuition goes beep, since I imagine the curve will never begin to look like a line :) So I wanted to know your thoughts on this one. Thank you in advance.

Let $f(x) = x^2 \sin{\frac{1}{x}}$ for $x\neq 0$ and $f(0) =0$. (a) Use the basic properties of the derivative, and the Chain Rule to show that $f$ is differentiable at each $a\neq 0$ and calculate $f'(a)$. You may use without proof that $\sin$ is differentiable and that $\sin' =\cos$.  Not even sure what this is asking.  (b) Show that $f$ is differentiable at $0$ and that $f'(0) =0$.  $\frac {f(x)-f(0)}{x-0} \to \lim_{x \to 0} x \sin(1/x)$. $x \sin(1/x) \leq |x|$ and $\lim_{x \to 0} |x|=0$. Thus $f(x)$ is differentiable at $0$; moreover $f^{'}(0)=0$.  (c) Show that $f'$ is not continuous at $0$.  $f{'}(x)=x^{2} \cos(1/x) (-x^{-2}) + 2x \sin (1/x)$. In pieces: $\lim_{x \to 0} \cos (1/x)$. $f^{'}(0-)$ nor $f{'}(0+)$ exists as $x \to 0$ $f^{'}(x)$ oscillates infinity between $-1$ and $1$ with ever increase frequency as $x \rightarrow 0$ for any $p>0$ $[-p,0]$, $[-p,p]$ or $[0,p]$ $f$ is not continuous. Question: How to show more rigorously?


There used to be an option in Notepad++ that when you save a file, it showed a green vertical bar on the left, and when you make any change, it turns yellow. This behavior is in Visual Studio and SQL Management Studio (example below).  How can I turn this feature on in Notepad++?    I know that the disk icon on the header, next to file name on the title bar, turns red for unsaved files and blue for saved ones (and grey for read-only files). But I'm looking for this feature so I can exactly know where the changes were made.  Thanks.

Our admins deployed a new version of Notepad++ (version 6.3) on our machines, and this version is highlighting all changes done in a file by default. It does so by setting the background color of every modified line to a bright orange, which I find very distracting.  We  have dozens of plugins installed, but I double checked and we do not have the "Change Markers" plugin (which could be the culprit).  Any idea where I can disable this feature? Changing the highlight color could also be an option.


In my undergraduate mechanics class, we just finished the section on coupled oscillators where we use eigenvalues to find solutions to the differential equations describing the motion of our spring mass system. When we finished, one of my fellow students started going on a rant about how he "knew the determinant had a physical meaning," and he went on to talk about how frustrated he was with his differential equations professor who said that the determinant was just an operation and only had physical meaning when it was given one (ie- showing the system is linearly independent by setting the determinant to $0$). I sided with the professor, but I wasn't sure how to explain it to my classmate.   What do you guys think?

In my linear algebra class, we just talked about determinants. So far I’ve been understanding the material okay, but now I’m very confused. I get that when the determinant is zero, the matrix doesn’t have an inverse. I can find the determinant of a $2\times 2$ matrix by the formula. Our teacher showed us how to compute the determinant of an $n \times n$ matrix by breaking it up into the determinants of smaller matrices. Apparently there is a way by summing over a bunch of permutations. But the notation is really hard for me and I don’t really know what’s going on with them anymore. Can someone help me figure out what a determinant is, intuitively, and how all those definitions of it are related?


I try to display the user's latitude but I get an error      java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLatitude()' on a null object reference.    GPS is well activated and is the "bestprovider".  public void getUserPosition() {     /**************Vérification des droits localisation******************/     Context mainContext = getActivity().getApplicationContext();      int permissionCheck = ContextCompat.checkSelfPermission(mainContext,             Manifest.permission.ACCESS_FINE_LOCATION);      Log.e("Droits Position : ", String.valueOf(permissionCheck));      if (ContextCompat.checkSelfPermission(mainContext,             Manifest.permission.ACCESS_FINE_LOCATION)             != PackageManager.PERMISSION_GRANTED)     {          if (ActivityCompat.shouldShowRequestPermissionRationale(this.getActivity(),                 Manifest.permission.ACCESS_FINE_LOCATION))         {             Log.e("LOCATION : ", "Localisation acceptée !");         }         else         {             Log.e("LOCATION : ", "Localisation refusée !");              ActivityCompat.requestPermissions(this.getActivity(),                     new String[]{Manifest.permission.ACCESS_FINE_LOCATION},                     REQUEST_LOCATION);         }     }      permissionCheck = ContextCompat.checkSelfPermission(mainContext,             Manifest.permission.WRITE_CALENDAR);     Log.e("DROITS :", String.valueOf(permissionCheck));     /*****************FIN vérification droits localisation************/      LocationManager locationManager = (LocationManager) mainContext.getSystemService(Context.LOCATION_SERVICE);      //On ajoute des critère pour trouver le meilleur provider (indicateur de position)     Criteria critere = new Criteria();     critere.setAccuracy(Criteria.ACCURACY_FINE);//On demande une position précise     critere.setAltitudeRequired(false);         // Est-ce que le fournisseur doit être capable de donner une altitude ?     critere.setBearingRequired(false);           // Est-ce que le fournisseur doit être capable de donner une direction ?     critere.setCostAllowed(true);              // Est-ce que le fournisseur peut être payant ?     critere.setPowerRequirement(Criteria.POWER_HIGH); //On accepte d'utiliser un provider a haute consommation électrique(GPS)     critere.setSpeedRequired(false); // Est-ce que le fournisseur doit être capable de donner une vitesse ?       List<String> providers = locationManager.getAllProviders(); //Liste des fournisseurs qui correspondent     String bestProvider = locationManager.getBestProvider(critere, true); //Le provider qui répond le mieux aux critères      if(bestProvider == null) //On affiche le nom du provider choisis     {         Log.e("Best Provider : ","NULL !");     }     else{         Log.e("Best Provider : ", bestProvider);     }      Location positionNow = locationManager.getLastKnownLocation(bestProvider); //Objet location qui contient la position de l'utilisateur     Log.e("Position user now", "Lat:"+String.valueOf(positionNow.getLatitude()));  }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


In the sentence "Start using something by October 26th", is the word "by" understood as "no later than" or from that date?  Thanks

I have read the Rules of a competition. The text of the Rules include a sentence as follows:     As per stated in the Rules the entrants will be notified by May 30th 2010.   Does the sentence above mean that May 30th is included in the term of notification or not?


RAW:     When an attacker reduces a creature to 0 hit points with a melee attack, the attacker can knock the creature out. The attacker can make this choice the instant the damage is dealt. The creature falls unconscious and is stable.   Is there a way other than a melee attack to achieve the same result? A spell or a ranged attack, maybe a feature or ability of a class I'm not aware of? Or is it simply impossible with RAW?

I'm working on a Paladin/Warlock combination, based off of , and as part of this, I noticed Miniman's remark that Repelling Blast won't be that useful, because as a Paladin, you want people up close and personal when you're in a combat situation, not further away.  However, as a Paladin, your creed sometimes leads you to not want to engage in full-blown combat with a potential adversary -- you may want to drive them off or incapacitate/capture them instead.  With this, I wonder: can Repelling Blast, or other spells and spell-likes (such as invocations), be made to do non-lethal damage?  If so, I'm thinking that it'd be useful in exactly that sort of situation -- halting someone/pushing them away without having to wade into a melee with them or blow them to smithereens.


This question:     I cannot remove tag because I get error "title must be at least 15 characters long." Then how was it posted in the first place?

Test to see if the title length requirement can be circumvented by appending lots of dots.


Let $A$ be the compact annulus in the real plane with radii $2$ and $3$, and $(r,\phi)$ its polar coordinates. Define $F(r,\phi)=(r,r\phi)\ (\mod\ 2\pi)$. Is it true that, for a continuous function $g:A\to \mathbb R$, the integral $$\int_A g(F^n(x))dx$$ converges as $n\to+\infty$? ($F^n$ is the n-th iteration of $F$.)  My attempt was to prove that $F^n(x)$ is Cauchy for almost every $x$. This would allow us to apply Lebesgue's dominated convergence theorem, since $g$ must be bounded on the compact $A$. But I just can't obtain the desired result, so I'm beginning to suspect that this can be false, and the convergence (if it is true) comes from weaker properties.  Thank you in advance.

Let $A \subset \mathbb{R}^2$ be the annulus defined, in polar coordinates, as  $$ A = \{ (r, \theta) \in [0, \infty) \times [0, 2\pi) : 2 \leq r \leq 3 \} \, .$$ Let $F: A \to A$, $F:(r, \theta) \mapsto (r, r \theta \text{ (mod } 2\pi))$. Let $g : A \to \mathbb{R}$ be a continuous function. Discuss the existence of the limit $$ \lim_{n \to \infty} \int_A g \circ F^{(n)}(x) \, \text{d}x \, ,$$ where $F^{(n)} = F \circ F \circ \dots \circ F$ denotes the composition of $F$ with itself $n$ times.  I cannot find a way to attack this problem. Here's what I tried: if $g \circ F^{(n)}$ converged, I think we could take the limit under the integral sign. So I tried to show the convergence of $F^{(n)}$. If it converged, then the limit function must send every point to a fixed point of $F$. So I determined the fixed points of $F$. But I don't think $F^{(n)}$ converges.


I'm trying to install Ubuntu on a virtual box and I get this error "This kernel requires an x86-64 CPU, but only detected an i686 CPU." When I go to General -> Basic -> Version I do not find any 64 bit options. Also, in Bios menu I don't have all advanced options (UEFI Firmware Options is missing).   VirtualBox.xml:  <?xml version="1.0"?> <!-- ** DO NOT EDIT THIS FILE. ** If you make changes to this file while any VirtualBox related application ** is running, your changes will be overwritten later, without taking effect. ** Use VBoxManage or the VirtualBox Manager GUI to make changes. --> <VirtualBox xmlns="http://www.virtualbox.org/" version="1.12-windows">   <Global>     <ExtraData>       <ExtraDataItem name="GUI/DetailsPageBoxes" value="general,system,preview,display,storage,audio,network,usb,sharedFolders,description"/>       <ExtraDataItem name="GUI/GroupDefinitions/" value="m=a33345a6-95b1-4c24-b4ee-13625b013b79,m=f790da3a-50f7-444d-9111-aee4bdbb1a79,m=66477e7d-ded9-42fd-9825-fa70fa67a5b9,m=08eb0d4b-5ae3-4285-86dd-d1a77dcd1919"/>       <ExtraDataItem name="GUI/HideDescriptionForWizards" value="NewVM"/>       <ExtraDataItem name="GUI/LastItemSelected" value="m=Loredana"/>       <ExtraDataItem name="GUI/LastWindowPosition" value="319,91,770,550"/>       <ExtraDataItem name="GUI/RecentFolderCD" value="C:/Users/Loredana/Downloads"/>       <ExtraDataItem name="GUI/RecentListCD" value="C:\Users\Loredana\Downloads\ubuntu-18.04.1-desktop-amd64.iso,C:\Users\Loredana\Downloads\mini.iso,C:\Users\Loredana\Downloads\ubuntu-18.04.1-desktop-amd64 (1).iso,C:\Users\Loredana\Downloads\ubuntu-16.04.2-desktop-i386.iso,C:\Users\Loredana\Downloads\ubuntu-16.04.2-desktop-amd64.iso"/>       <ExtraDataItem name="GUI/SplitterSizes" value="255,510"/>       <ExtraDataItem name="GUI/Toolbar/MachineTools/Order" value="Details"/>       <ExtraDataItem name="GUI/UpdateCheckCount" value="37"/>       <ExtraDataItem name="GUI/UpdateDate" value="1 d, 2018-12-04, stable, 5.2.22"/>     </ExtraData>     <MachineRegistry>       <MachineEntry uuid="{a33345a6-95b1-4c24-b4ee-13625b013b79}" src="C:\Users\Loredana\VirtualBox VMs\Ubuntu\Ubuntu.vbox"/>       <MachineEntry uuid="{f790da3a-50f7-444d-9111-aee4bdbb1a79}" src="C:\Users\Loredana\VirtualBox VMs\lore\lore.vbox"/>       <MachineEntry uuid="{66477e7d-ded9-42fd-9825-fa70fa67a5b9}" src="C:\Users\Loredana\VirtualBox VMs\Ubuntu-16.04\Ubuntu-16.04.vbox"/>       <MachineEntry uuid="{08eb0d4b-5ae3-4285-86dd-d1a77dcd1919}" src="C:\Users\Loredana\VirtualBox VMs\Loredana\Loredana.vbox"/>     </MachineRegistry>     <NetserviceRegistry>       <DHCPServers>         <DHCPServer networkName="HostInterfaceNetworking-VirtualBox Host-Only Ethernet Adapter" IPAddress="192.168.56.100" networkMask="255.255.255.0" lowerIP="192.168.56.101" upperIP="192.168.56.254" enabled="1"/>       </DHCPServers>     </NetserviceRegistry>     <SystemProperties defaultMachineFolder="C:\Users\Loredana\VirtualBox VMs" defaultHardDiskFormat="VDI" VRDEAuthLibrary="VBoxAuth" webServiceAuthLibrary="VBoxAuth" LogHistoryCount="3" exclusiveHwVirt="false"/>     <USBDeviceFilters/>   </Global> </VirtualBox>

I was trying to install Ubuntu 12.04 in VirtualBox 4.2.12r84980. I see    this kernel requires an x86-64 CPU, but only detects an i686 CPU, unable to boot   But I am using a 64 bit Windows 8, and trying same .iso for trying Ubuntu. Then what is the problem?


I would like to start developing a GIS web application for mapping and editing vector data with attributes. I'm familiar with Desktop GIS (ArcGIS, QGIS) and basic SQL. I've also little experience with GeoServer, XML and GML but I've no real programming experience (Java, etc.). I would like to do something similar like in this . It can be simple, for the start than shown in this video but there should be a possibility to create a feature (point, line, polygon) and enter various attribute data.  So my question is, how to start with the whole thing, what are the basics to read and which software (open source) is recommended?

I've got PostGIS installed and would like to create a web application to do some simple edits:   Draw manually (over a Basemap) points, lines and polylines, using snapping  points (points, end of lines, intersections, center of circles)  Delete points, lines and polylines  Rotate a line or group of lines around a point  Move a line or group of lines with a base point  Move polylines and points (manually and to a point given by the coordinates) Edit position of vertices of polylines and lines (manually and to a point given by the coordinates)  Create buffers around points, lines and polylines    Which is the best way to do this via web? Is there any already-built JavaScript library?


The month first format. Do you, as an American, find this unnatural?  And: If you were in a hurry, would you start typing the month first (as this is most natural for you)?  Edit: This question differs from  because I'm asking how likely you would enter mm-dd-yyy in a dd-mm-yyyy input if you were in a hurry (even if it was labelled). The other question is about appearance rather than entry. A nuance, yes, but this is UX and it is not a nuance in this context.

Almost everywhere outside the United States, when short dates, e.g. 01/02/2013, are shown on computer screens, the user can't be sure whether the first two digits represent the day or the month. Is it January second or February first?  This is a big problem for people outside the United States, as they encounter both formats regularly, and can't know if the system has adapted to their locale, or has stuck with the American format. But I assume American users see mostly the American format (because many, if not most, information systems are built by or for Americans). What I'm curious about is whether American users also are confused in this scenario?  If you can point to some evidence or research, great. If not, I'll settle for your knowledgeable experience.  Note: I'm not asking for the wonderful solution of naming the month, e.g. May 21, 2013. I'm asking about the cases where a short date format has to be used.


When i am running my any application it gives this error in androdi studio. please help  null java.lang.NullPointerException     at javax.swing.plaf.basic.BasicComboBoxUI.getMinimumSize(BasicComboBoxUI.java:934)     at javax.swing.plaf.basic.BasicComboBoxUI.getPreferredSize(BasicComboBoxUI.java:911)     at javax.swing.JComponent.getPreferredSize(JComponent.java:1661)     at com.intellij.openapi.ui.FixedSizeButton.getPreferredSize(FixedSizeButton.java:89)     at com.intellij.openapi.ui.FixedSizeButton.getMinimumSize(FixedSizeButton.java:80)     at java.awt.FlowLayout.minimumLayoutSize(FlowLayout.java:463)     at java.awt.Container.minimumSize(Container.java:1840)     at java.awt.Container.getMinimumSize(Container.java:1825)     at javax.swing.JComponent.getMinimumSize(JComponent.java:1745)     at java.awt.BorderLayout.minimumLayoutSize(BorderLayout.java:653)     at java.awt.Container.minimumSize(Container.java:1840)     at java.awt.Container.getMinimumSize(Container.java:1825)     at javax.swing.JComponent.getMinimumSize(JComponent.java:1745)     at com.android.tools.idea.run.AvdComboBox.<init>(AvdComboBox.java:81)     at com.android.tools.idea.run.ExtendedDeviceChooserDialog$2.<init>(ExtendedDeviceChooserDialog.java:92)     at com.android.tools.idea.run.ExtendedDeviceChooserDialog.<init>(ExtendedDeviceChooserDialog.java:92)     at com.android.tools.idea.run.ManualTargetChooser.getTarget(ManualTargetChooser.java:54)     at com.android.tools.idea.run.editor.ShowChooserTarget.showPrompt(ShowChooserTarget.java:97)     at com.android.tools.idea.run.AndroidRunConfigurationBase.getState(AndroidRunConfigurationBase.java:267)     at com.intellij.execution.runners.ExecutionEnvironment.getState(ExecutionEnvironment.java:201)     at com.intellij.execution.runners.BaseProgramRunner.execute(BaseProgramRunner.java:58)     at com.intellij.execution.runners.GenericProgramRunner.execute(GenericProgramRunner.java:31)     at com.intellij.execution.runners.BaseProgramRunner.execute(BaseProgramRunner.java:53)     at com.intellij.execution.runners.GenericProgramRunner.execute(GenericProgramRunner.java:31)     at com.intellij.execution.ProgramRunnerUtil.executeConfiguration(ProgramRunnerUtil.java:94)     at com.intellij.execution.impl.ExecutionManagerImpl.start(ExecutionManagerImpl.java:396)     at com.intellij.execution.impl.ExecutionManagerImpl.access$400(ExecutionManagerImpl.java:61)     at com.intellij.execution.impl.ExecutionManagerImpl$5.run(ExecutionManagerImpl.java:384)     at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)     at com.intellij.util.Alarm$Request$1.run(Alarm.java:351)     at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:332)     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:312)     at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:745)     at java.awt.EventQueue.access$300(EventQueue.java:103)     at java.awt.EventQueue$3.run(EventQueue.java:706)     at java.awt.EventQueue$3.run(EventQueue.java:704)     at java.security.AccessController.doPrivileged(Native Method)     at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)     at java.awt.EventQueue.dispatchEvent(EventQueue.java:715)     at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:734)     at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:569)     at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:382)     at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)     at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)     at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)


How can I contact the managua airport vip service?

At the Augusto C. Sandino International Airport (the airport in Managua, Nicaragua), I have heard there is a VIP service you can pay for, where an agent will meet you when disembarking from the plane and guide you through the immigration and customs process, or somehow make it easier. How exactly does this VIP service work? What does it cost, how do you sign up, and what does it include?


If $m_{0},m_{1},\dots,m_{r}$ are positive integers with $(m_{i},m_{j})=1$ for $i\neq j$, prove that exists consecutive integers $s,s+1,\dots,s+i$ such that $m_{i}|s+i$ for all $1\leq i \leq r$.  I really don't know how to approach to this problem. Any tips?

Prove that for any positive integers $m$ and $n$ , there exists a set of $n$ consecutive positive integers each of which is divisible by a number of the form $d^m$, where $d$ is some positive integer not equal to $1$.  I don't know how to approach this question.


Given two lines $\vec{x} = \vec{a} + s\vec{b}, s\in \mathbb R$ and  $\vec{x} = \vec{c} + t\vec{d}, t\in \mathbb R$ in $\mathbb R^2$, where $\vec{d} \not= k\vec{b}, k\in \mathbb R$, prove algebraically these two lines intersect.   I know logically that this is true since if two lines are not parallel then they must intersect eventually, but how do I show this algebraically?

let $x,y,a,b,c,d$ be vectors and $r,k \in \Bbb{R}$ with vector $d$ not being a scalar multiple of vector $b$ How would you prove that the line $\vec{x}=\vec{a}+r\vec{b}$ intersects the line $\vec{y}=\vec{c}+k\vec{d}$ algebraically in $\Bbb{R^2}$?  Geometrically In $\Bbb{R^2}$ since $\vec{b}$ and $\vec{d}$ are not scalar multiples then they are not parallel and since they are in the x-y plane then obviously the two lines will not intersect, however i am having trouble expressing this algebraically


I am confused as to which is the correct way of saying       I am migrating to Australia   OR   I am immigrating to Australia   Which one is appropriate?

What's the difference between emigrate and immigrate? They seem to have the same definitions in the dictionary but they are antonyms...


The only sense I can make of this question is that $m = dq$ and $a \cong b (mod\,m)$ is the same as $as+mt=b$, or $as+(dq)t=b$. I feel as though proving that this holds since $m$ is just a multiple of $d$ is not enough.  Any help is appreciated.

I noticed relation between modulo operation and number which is power of two  Example I have to calculate $ 3431242341 \mod 2^5 $, which is $ 5 $ but it is equivalent to  $ ( 3431242341 \mod 2^9 ) \mod 2^5 $   I tried many examples and it seems to be true in general, and I am not sure if it is a coincidence or true in general that I can use first modulo operation ( greater number) and the result will be the same.


In the Stargate universe, the vortex from the naqahdah disc which occurs once an address is correctly dialed emits a fluid-like substance. Is this substance an ionized radiation or a chemical exposed to the breathable oxygen?  The question: 'Is the Chappa'ai vortex ionized or toxic?'

The Stargate in Stargate, Stargate: SG-1, and it's derivatives, creates a wormhole between two Stargates, which most of the time has an unstable vortex kawoosh that tends to destroy anything that's sufficiently away from it's surface, before falling back in and leaving a mostly flat water or pool like surface. But what is the surface made of? It tends to ripple like water, but it's obviously not water. And in the season 2 episode "A Matter of Time", a large gravitational force of a black hole on the other side was enough to make it spin down/inwards like an eddy or .    In-Universe answer please.


I was looking at , and noticed that:   The accepted answer was below another answer. It's not like the other answer had more votes, it had the same amount of votes. The accepted answer is by the asker (which I though wasn't possible).   Screenshot here:    Is it something to do with the fact that the asker answered and accepted their own question and answer?

On , sorted by votes, the accepted answer is #3 in order of votes.  It appears as number 3 in the list as well. Is this new behavior intended?


I just bought new laptop which is Lenovo ThinkPad E455 posted on the H/W partner.  And it is found that 14.10 has kernel 3.16 which is older than currnet release.  It is wanted to know if Ubuntu 15.XX with new kernel would be released SOON  Thank you.  HELLOVENUS Fantagio

I want to know where I can find updated information about all the stable and in-development versions of Ubuntu, where I can find this information?     This question is meant to be a canonical question. It expects to answer the following questions:         Is X version stable yet?   Is X version in beta?   Is X version still supported?   What versions are still supported?   What are the versions in Beta/Alpha?   Until where X version will be supported?   Have X version ceased support?   When will be X version released?   Where I can download any release?   When will the next LTS version of Ubuntu be released?         The list is not exhaustive.


Since object creation of an interface is not allowed in java.  Going through the button event creation code, i passed through this:         View. OnClickListener ocl=new   View. OnClickListener ();   As per Android documentation onClickListener is an interface then how can we create its object. Object creation of interface is not allowed but the keyword new clearly does that. How is it possible?  Please excuse any mistakes, i am new to Android development.

What is the use of anonymous classes in Java? Can we say that usage of anonymous class is one of the advantages of Java?


I'm looking for a free (not shareware, because I have many files to convert and I don't want limits), stable, relatively simple way to convert my phd thesis coded using "ClassicThesis" package, into a .doc (Word) document, since one of my Committee's member explicitly requested this format. I have coded my thesis in separate files applying the package to each file for my convenient elaboration.  Thus, I will convert each .tex into .doc.  Please help me, I am having hard times with this last moment news!  I must deliver the thesis on Feb., 20th! Many thanks in advance,  MChiara

I often have to write up reports based on the analysis of some data. I use R to analyse the data and export tables, figures, and text. This is then included into a LaTeX document either using input or Sweave ().  However, when I collaborate with others, I sometimes need to provide a document in Open Office / MS Word format.  Question:  Thus, assume the simplest scenario   I have a LaTeX document with text, tables, and figures I need to export this reliably into Open Office or MS Word format: this includes mathematical formulas, table formatting, and quality figures) I don't need to go back from MS Word to LaTeX   What is a reliable, efficient, and preferably free process?  Initial Thoughts:   Export to HTML,  LaTeX - LyX - ODF Use odfWeave  that deals with some specific issues associated with LaTeX to Open Office conversion    I was hoping that there is an expert out there who has worked out a good system already.


I am new to ubuntu server and still pretty mystified by all the scripts and such.  I have been reading different things available on the web and have successfully created my server and have several folders that I am able to write to using my windows computers.  The problem is, when I was following one of the tutorials to start, I created a partition of 20gb to use for the OS.  I have a 2tb disk and now I am out of space, even though I have another 1.8tb available.  I used the lvm option when I loaded the system and was lead to believe I could expand the partition easily.  The problem is, I don't know how and I can't seem to find an example that seems to fit my situation. Any help would be greatly appreciated.  I am using ubuntu server 14.04

In a nutshell, i have a VM that ran out of space. I increased the size of the VM's harddrive to be 4 times bigger but the OS partition is still only using 1x the space. I need to change the LVM partition to take up the extra 4x space but I don't know how to extend the LVM partition.  (NOTE: To make the screenshots given below I had to boot from a live-cd for gnome-partition-manager (aka gparted). .)  Here is what "gparted" shows. Please notice that the "resize" option is not available:      The Problem:  I can't find good directions<1> on how to grow the LVM partition via GUI or command-line! How do you grow a LVM partition that was created by the default Fedora install?  If you are giving command line directions. Please explain what each line of commands does.


I'm trying to type the following sequence recursively on Overleaf but I'm not exactly sure how to format it exactly as it is shown below. More specifically, I need help on how to type the info past the left brace.

Is there an intelligent way to left-align the parts right of & of the two cases environments shown below (if x >= 0, otherwise, if y < 0, otherwise). I wonder if there is a better way than using manual spaces:  \begin{align*}  u(x) &=   \begin{cases}    0        & \text{if } x \geq 0 \\    1        & \text{otherwise}   \end{cases}   \\  \tau &=   \begin{cases}    a+b+c+d  & \text{if } y < 0 \\    1        & \text{otherwise}   \end{cases} \end{align*}


I installed ubuntu 12.04 using wubi. But there is no application named " uninstall-ubuntu ". Now how can I uninstall it ?

I want to uninstall Ubuntu because I just don't like it...  I have windows 7 and no boot disk or anything special to uninstall, when I installed Ubuntu it said easy to uninstall and I would love to know how to actually uninstall it. Thank You.


Consider these     There is an apple, an orange and a banana on the table.      There are an apple, an orange and a banana on the table.   which one should I use?

This question is also open on EL&U:   Considering the amount of controversy it aroused, I believe it's past "Learners'" level.    An edit was suggested to my sentence.     There was were an orange, some grapes, two apples and a small pile of cherries on the plate.   In my native language plurality of the verb always follows plurality of the first element on the list. There were an orange,... sounds awkward to me, no matter what follows up. My simple solution was reordering:     There were some grapes, an orange, two apples and a small pile of cherries on the plate.   But that's not the first time I faced this situation and I'd like to know what the rules of grammar say about that — was my editor overzealous or am I trying to copy rules of my language that don't apply in English?


I had Linux mint installed in my computer in one partition and had another partition for Data.  I just installed Ubuntu Kylin 14.04 and during the installation there was an option like "install Ubuntu replacing Linux Mint", which was the one I chose, thinking it would just mess with the partition of Linux mint.  Now I boot in Ubuntu, and I have a huge partition with Linux (bootable), including the space that was before of the data partition...  Do I still have a chance to recover some stuff that was in my previous Data partition?  If so how can I do that?

I accidentally deleted a file from my laptop. I'm using Fedora. Is it possible to recover the file?


Is there really a way to change Krusader's time format from PM/AM to 24 hours, in Ubuntu? I've seen the other post (marked as duplicate) and the real one, but it's not clear which are the steps or the files to change inside Ubuntu. If anyone knows the right way, please put the complete steps or terminal commands. Thanks!

Using Ubuntu 16.04. I like Krusader, but can't figure out how it is possible to change date/time format for the Modified column. I truied to change system regional settings, but Krusader ignores them (while, e.g., Midnight Commander uses system settings). Switching application language (in Help menu) also does not affect the date/time format. I like the 24-hour format, not PM/AM, and I may prefer even to hide time, and leave only date. Is that possible in Krusader?  The other post is of no help, as there is no even such file in mys systems as ~/.kde/env/setlocale.sh


I am wondering how to represent these kinds of circuits as a matrix. Is there any formula for doing this?

When constructing the matrices for the two CNOT based on the target and control qubit, I can use reasoning:  "If $q_0$==$|0\rangle$, everything simply passes through", resulting in an Identity matrix style $\begin{bmatrix}1&0\\0&1\end{bmatrix}$ in the top left. "If $q_0==|1\rangle$, we need to let $q_0$ pass and swap $q_1$, resulting in a Pauli X $\begin{bmatrix}0&1\\1&0\end{bmatrix}$ in the bottom right.  $CNOT \equiv \begin{bmatrix}1&0&0&0\\0&1&0&0\\0&0&0&1\\0&0&1&0\end{bmatrix}$  "If $q_1$==$|0\rangle$, everything simply passes through", results in leaving $|00\rangle$ and $|10\rangle$ unaffected. "If $q_1==|1\rangle$, we need to let $q_1$ pass and swap $q_0$, mapping $|01\rangle$ to $|11\rangle$ and  $|11\rangle$ to $|01\rangle$  $CNOT \equiv \begin{bmatrix}1&0&0&0\\0&0&0&1\\0&0&1&0\\0&1&0&0\end{bmatrix}$  This all seems to check out, but here comes my question: I would like to know if there is a more mathematical way to express this, just as there would be when combining for instance two hadamard gates: $H \otimes H \equiv \frac{1}{\sqrt{2}}\begin{bmatrix}1&1\\1&-1\\ \end{bmatrix} \otimes \frac{1}{\sqrt{2}}\begin{bmatrix}1&1\\1&-1\\ \end{bmatrix} = \frac{1}{2}\begin{bmatrix}1&1&1&1\\1&-1&1&-1\\1&1&-1&-1\\1&-1&-1&1 \end{bmatrix}$  And a bonus question:  How I can, using notation like "CNOT", show which qubit is the control bit and which qubit the target bit?


So far the solution given here worked perfectly until I upgraded to 18.04, where I had to install other elements to make the icon appear. In the beginning it worked quite well, but now I am getting this:  Exception in thread "main" java.awt.AWTError: Assistive Technology not found: org.GNOME.Accessibility.AtkWrapper     at java.desktop/java.awt.Toolkit.newAWTError(Toolkit.java:472)     at java.desktop/java.awt.Toolkit.fallbackToLoadClassForAT(Toolkit.java:488)     at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)     at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)     at java.base/java.util.HashMap$KeySpliterator.forEachRemaining(HashMap.java:1608)     at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)     at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)     at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)     at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)     at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)     at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)     at java.desktop/java.awt.Toolkit.loadAssistiveTechnologies(Toolkit.java:532)     at java.desktop/java.awt.Toolkit.getDefaultToolkit(Toolkit.java:613)     at java.desktop/java.awt.SystemTray.isSupported(SystemTray.java:221)     at tav.TAV.main(TAV.java:93) Caused by: java.lang.ClassNotFoundException: org.GNOME.Accessibility.AtkWrapper     at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)     at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:190)     at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)     at java.base/java.lang.Class.forName0(Native Method)     at java.base/java.lang.Class.forName(Class.java:374)     at java.desktop/java.awt.Toolkit.fallbackToLoadClassForAT(Toolkit.java:485)     ... 13 more   As the app is still working on a Windows machine, I do think the app has changed, so my question is, what is wrong here and why, and why did it work before? Thank you very much in advance.

I tried it and the errors are:  Exception in thread "main" java.awt.AWTError: Assistive Technology not found: org.GNOME.Accessibility.AtkWrapper at java.desktop/java.awt.Toolkit.newAWTError(Toolkit.java:472) at java.desktop/java.awt.Toolkit.fallbackToLoadClassForAT(Toolkit.java:488) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177) at java.base/java.util.HashMap$KeySpliterator.forEachRemaining(HashMap.java:1608) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497) at java.desktop/java.awt.Toolkit.loadAssistiveTechnologies(Toolkit.java:532) at java.desktop/java.awt.Toolkit.getDefaultToolkit(Toolkit.java:613) at java.desktop/javax.swing.UIManager.getSystemLookAndFeelClassName(UIManager.java:660) at com.cburch.logisim.gui.start.Startup.parseArgs(Startup.java:250) at com.cburch.logisim.Main.main(Main.java:32)   The error seems to be...     Caused by: java.lang.ClassNotFoundException: org.GNOME.Accessibility.AtkWrapper       at  java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)       at   java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:190)       at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)       at java.base/java.lang.Class.forName0(Native Method)       at java.base/java.lang.Class.forName(Class.java:374)       at java.desktop/java.awt.Toolkit.fallbackToLoadClassForAT(Toolkit.java:485)       ... 14 more     OUTPUT for  apt-cache policy logicsim logisim  logisim:   Installed: 2.7.1~dfsg-1   Candidate: 2.7.1~dfsg-1   Version table:  *** 2.7.1~dfsg-1 500         500 http://in.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages         500 http://in.archive.ubuntu.com/ubuntu bionic/universe i386 Packages         100 /var/lib/dpkg/status N: Unable to locate package logicsim   OUTPUT for update-java-alternatives -l  java-1.11.0-openjdk-amd64      1101       /usr/lib/jvm/java-1.11.0-openjdk-amd64 java-1.8.0-openjdk-amd64       1081       /usr/lib/jvm/java-1.8.0-openjdk-amd64


If you can slow down the speed of a photon, how does it speed back up to the speed of light once the slowing down is disabled?

As I learned today in school, my teacher told me that when light enters a glass slab it slows down due to the change in density and it speeds up as it goes out of the glass slab. This causes a lateral shift and the light emerges out from the point different than that from where it should have actually emerged from.  Okay so what I mean to ask is, when light enters point A on glass slab and emerges from point C why does the light speed up? Where does it get the energy it has lost when it entered the glass slab?  P.S.: Also, if I place a very very very large glass slab and make a beam of light pass through it will the light never come out as all the energy was lost in place of heat?


So I imported a model of my sim into blender to mess around with renders and maybe try and make some CC, but (as usually the case with game extracted models) the model has these 'artifacts':  How do I get rid of them? I removed doubles, reset vectors and recalculated normals, cleared sharps, have 2 light sources with a plane underneath to bounce light off of, idk what else to do... Edit: Subdivision surface doesn't fix it, and on the other model I imported smooth shading doesn't work at all Sims likes to use overlapping geometry for things like beards and hair and upon removing doubles the polygons still look messed up. I remember there might be double polygons sometimes but I don't remember how to clean them. This one shows only with subsurf  And random walk subsurf for some reason looks like this (after removing doubles) Ok, I see why the second model is messed up now  The first one looks alright though, must be something else... The proposed answer was wrong, I mentioned I checked the normals and then someone proposes to check the normals and closes the question.

I am relatively new to Blender so please excuse me if this is rather amateur!   The bottom of my torus has poor surface quality, I have scaled the vertices down for a smaller (variable) tubular radius all the way around the torus and at the bottom the surface quality is awful, with inaccurate shading. Any ideas as to what is wrong and/or how I could fix this?  Thanks, itsanate


How could I add logical branching conversation dialogue in C# with XNA? What I mean by this is a dialogue tree similar to this:  If the user is wearing red:      DisplayText "You're wearing a red shirt!" Else:      DisplayText "You're not wearing a red shirt!"   The key is that I can't hard-code these logic questions into C# itself; it has to be readable from some sort of external file and still executable.  My question is very similar to this question:   But my focus is more on how I can actually begin to implement this feature into my game.

What is the best way to implement a dialog tree system in my game? I want an NPC to give the player different sets of responses, some which may only appear when the Player has an item or a previous event has occurred.


I have the following problem:    Where I'm using $$$$ twice to make the equation of the linear model fit horizontally.  But I don't like white space that's left between the two lines.   Is there a way to perhaps make the two lines with less white space between them?

I'm trying to split up the following equation so that it fits the margins of my document, so far I have:  \documentclass{article}  \usepackage{amsmath}  \begin{document}   \begin{equation} 0 = n_1^3 n_2 n_3^2(\lambda+\mu)^2 +n_1 n_2^3 n_3^2(\lambda + \mu)^2  + (\lambda + \mu)(\mu - \rho c^2)n_1^3 n_2 + (\lambda + \mu)(\mu - \rho c^2) n_1 n_2^3 + n_1 n_2 n_3^2 (\lambda + \mu)(\mu - \rho c^2) + n_1 n_2 (\mu- \rho c^2)^2 - n_1^3 n_2 n_3^2 (\lambda + \mu)^2 - n_1 n_2^3 n_3^2 (\lambda + \mu)^2  \end{equation}  \end{document}    How do I make the equation split so that it fits?


I'm reading up on npn (and by extension pnp) transistors, and I got tripped up on a note from my book (Practical Electronics for Inventors, 3rd edition, p. 433)  "For an npn transistor, the voltage at the collector must be greater than the  voltage at the emitter by at least a few tenths of a volt; otherwise, current will not flow through the collector-emitter junction..."  As far as I'm aware, an npn transistor is symmetrical in construction, so it shouldn't matter that the emitter voltage is higher. What is the physical distinction between collector and emitter?  Thanks

What will happen if for a BJT transistor, it's emitter terminal is treated as collector and collector as emitter in a common emitter amplifier circuit?


I am reading Field theory from Algebra by Hungerford and I have a question in remark on page 295. Image of remark :  Question is : How does in line 5 of remark , how does if char K doesn't divide n then $nx^{n-1} \neq 0 $, but how does it implies $x^{n} -1$ is relatively prime to it's derivative? Let d be it's gcd so d|($ x^n-1 , n x^{n-1} $). But I am not able to prove d=1 ? Can you please help.

Why is $\gcd(X^n - 1, nX^{n-1}) = 1$ in a field $K$ of characteristic $0$ or characteristic $p \nmid n$.  Most book on abstract algebra don't prove explicitly this, but I wonder what technique I should use to prove this to be formal. Perhaps induction?


i have a CSV file that looks like this:  aaa bbb ccc, 2015-01-01 fff ggg ddd, 2015-01-01 ggg hhh sss, 2015-01-02 ddd fff aaa, 2015-01-03 sss kkk www, 2015-01-03   i want to group by the second field (date).  cat myfile.csv | sort -t, k2 |uniq -c  printed 1 next to every line which is wrong.  i want this:  2015-01-01 2 2015-01-02 1 2015-01-03 2

Suppose you have a file that contains IP addresses, one address in each line:  10.0.10.1 10.0.10.1 10.0.10.3 10.0.10.2 10.0.10.1   You need a shell script that counts for each IP address how many times it appears in the file. For the previous input you need the following output:  10.0.10.1 3 10.0.10.2 1 10.0.10.3 1   One way to do this is:  cat ip_addresses |uniq |while read ip do     echo -n $ip" "     grep -c $ip ip_addresses done   However it is really far from being efficient.  How would you solve this problem more efficiently using bash?  (One thing to add: I know it can be solved from perl or awk, I'm interested in a better solution in bash, not in those languages.)  ADDITIONAL INFO:  Suppose that the source file is 5GB and the machine running the algorithm has 4GB. So sort is not an efficient solution, neither is reading the file more than once.  I liked the hashtable-like solution - anybody can provide improvements to that solution?  ADDITIONAL INFO #2:  Some people asked why would I bother doing it in bash when it is way easier in e.g. perl. The reason is that on the machine I had to do this perl wasn't available for me. It was a custom built linux machine without most of the tools I'm used to. And I think it was an interesting problem.  So please, don't blame the question, just ignore it if you don't like it. :-)


I was doing some performance evaluation of Java aggeragate operations to iterate over collections. I was doing an evaluation of performance stream and parallelStream. But I found that the output of parallelStream is wrong most of the times. For example in the following code i got wrong output from parallelStream more than 80% of the time:      public class ParallelStreamPerformance {     static int totaleven = 0;     public static void main(String[] args) {         List<Integer> randomList = new ArrayList<>();         Random rnd = new Random();         for(int i = 0 ;i < 1000;i++) {             int r = rnd.nextInt(500000);             randomList.add(r);         }          long s1 = System.currentTimeMillis();          randomList.stream().filter(e -> e%2 ==0).forEach(e -> count());         System.out.println("Even: "+totaleven);         long e1 = System.currentTimeMillis();         System.out.println(e1 - s1);          totaleven = 0;         long s2 = System.currentTimeMillis();          randomList.parallelStream().filter(e -> e%2 ==0).forEach(e -> count());         System.out.println("Even: "+totaleven);         long e2 = System.currentTimeMillis();         System.out.println(e2 - s2);     }     public static void count() {         totaleven++;     } }   My question is: Am I using parallelStream in a wrong way? Is there any way to ensure the correctness of parallelStream. Thanks

How do you write (and run) a correct micro-benchmark in Java?  I'm looking for some code samples and comments illustrating various things to think about.  Example: Should the benchmark measure time/iteration or iterations/time, and why?  Related:


Which is the best way to check for multicollinearity between two binary explanatory variables in logistic regression..? I use SPSS, if anyone could answer with special regards to that programme it would be extra helpful!

I'm doing a multivariate logistic regression where all my independent variables are categorical and binary. I have transformed all my categorical variables into dummies in order to have  reference groups and interpret my odds-ratios. However, I would like to check if there are eventually  multicollinearity issues.   I plan to calculate Spearman correlation between my independent variables and calculate VIF too. Nevertheless, I have several questions: Is Vif appropriate in this case? Do I have to calculate VIF and Spearman correlation on my categorical variables or their associated dummies?   I have tested other ways to detect multicollinearity (I check if the coefficients vary a lot if I increase my sample size or drop or add variables) and I'm pretty sure there is not a collinearity issue but I would like to have a "quantitative" proof.


I have a static assets server with 1 million+ images sitting in a folder, most of them I don't need anymore.  I have a list of the filenames I do still need in a .json file.  How in bash can I delete every file in that directory, except if the file name exists in the json list?  Thanks in advance!

Given the following files:  data/A/a.txt data/B/b.pdf ... date/P/whatever.log ... data/Z/z.jpg   I would like to delete all files in the data/A/, data/B/, ..., data/Z/ directories except those files that are situated under one of the directories listed in the file data/dont_clean.txt. For example, if we have data/P listed in data/dont_clean.txt then nothing should be touched under data/P/, etc.  Something like:  find data/ -mindepth 2 -maxdepth 2 -type f -not -path {listed in data/dont_clean} -delete   Of course it is not a valid command.  I have also tried variants of   find data/ -mindepth 2 -maxdepth 2 -type f -exec grep data/dont_clean.txt '{}' \;   but I only created either an invalid command or I had no idea why I got the output I did.  I am using bash on Ubuntu 12.10


I currently have an app that displays about 4,000 items. I am pulling this from a mysql database. I am trying to create a button that will force a download of all of the items from the database into a csv file. How can I go about this?  csv.php  <?php  header('Content-Type: text/csv; charset=utf-8'); header('Content-Disposition: attachment; filename=data.csv');  $output = fopen('php://output', 'w');  fputcsv($output, array('Column 1', 'Column 2', 'Column 3'));  mysql_connect('localhost', 'root', 'root'); mysql_select_db('wp_xroads'); $rows = mysql_query('SELECT first_name,last_name,phone FROM bags');  while ($row = mysql_fetch_assoc($rows)) fputcsv($output, $row); ?>   html
        <form action="csv.php" method="get">                    Export CSV               </form>
   thanks in advance. -ken

Is there an easy way to run a MySQL query from the Linux command line and output the results in  format?  Here's what I'm doing now:  mysql -u uid -ppwd -D dbname << EOQ | sed -e 's/        /,/g' | tee list.csv select id, concat("\"",name,"\"") as name from students EOQ   It gets messy when there are a lot of columns that need to be surrounded by quotes, or if there are quotes in the results that need to be escaped.


Is there a finite group $G$ for which there exist infinitely many finite groups $A$ (up to isomorphism) with automorphism group $\mathrm{Aut}(A)\cong G$?

It is an easy exercise to show that all finite groups with at least three elements have at least one non-trivial automorphism; in other words, there are - up to isomorphism - only finitely many finite groups $G$ such that $Aut(G)=1$ (to be exact, just two: $1$ and $C_2$).  Is an analogous statement true for all finite groups? I.e., given a finite group $A$, are there - again up to isomorphism - only finitely many groups $G$ with $Aut(G)\cong A$?  If yes, is there an upper bound on the number of such groups $G$ depending on a property of $A$ (e.g. its order)?  And if not, which groups arise as counterexamples?  And finally, what does the situation look like for infinite groups $G$ with a given finite automorphism group? And what if infinite automorphism groups $A$ are considered?


The main ones I had in mind were Tickle Wobbuffet and Sludge Wave Gengar

Someone on a trading group offered me an 'Event Pikachu', which was a Pikachu that knows Surf (normally impossible to teach to Pikachu).  Unfortunately it was a previous Generation's Event, and as such doesn't count as a 'Kalos-Born' Pokemon for tournaments/rating battles and the like.  So assuming I got a hold of it, could I breed this Pikachu to get a Kalos-born Pikachu with Surf?


I have the stack Exchange app on my phone, but I can't seem to find out how to change my username. It's the Stack Exchange Android app version 1.0.95.

It would be nice to update the profile page from within the app.  Perhaps not many people update their profiles more frequently, but when required to do so, I would prefer to do it from the app instead of the mobile browser.


The below exception flown     LINQ to Entities does not recognize the method 'Boolean   Contains(Int32)' method,      and this method cannot be translated   into a store expression.   while trying to execute the below query  List<int> studentIDs = Common.getFilterStudents(); var query = from a in studentTable             where studentIDs.Contains(a.StudentID)             select a;   How can I filter the query using the studentIDs list?

I'm trying to create a query which uses a list of ids in the where clause, using the Silverlight ADO.Net Data Services client api (and therefore Linq To Entities). Does anyone know of a workaround to Contains not being supported?  I want to do something like this:  List<long?> txnIds = new List<long?>(); // Fill list   var q = from t in svc.OpenTransaction         where txnIds.Contains(t.OpenTransactionId)         select t;     Tried this:  var q = from t in svc.OpenTransaction where txnIds.Any<long>(tt => tt == t.OpenTransactionId) select t;   But got "The method 'Any' is not supported".


What are these birds eye view stock photos called and where can I find them?    I am trying to find pictures of the birds eye view images above, such as the book, stapler, pencil, and hand.


I copy pasted cells of a long google spreadsheet into a txt file that is a list of email addresses separated by commas. There are many "blank" cells as well, i.e. a blank space surrounded by commas. So I could have the following list:  bob@aol.com, ,john@aol.com, , , , email@email.com  In vim, when I try to add separate each address by a new line with this command:  :%s/, /,\n/g   instead of adding a new line after the comman, I get "^@" instead.   I know this has something to do with character sets, but I don't know how to fix it.

I'm trying to replace each , in the current file by a new line:  :%s/,/\n/g    But it inserts what looks like a ^@ instead of an actual newline. The file is not in DOS mode or anything.  What should I do?  If you are curious, like me, check the question  as well.