In model theory, for the construction of an ultraproduct one needs the existence of an ultrafilter.  I heard that one can't construct an ultrafilter by hand, one cannot write it down, just merely knowing that one exists by using the axiom of choice. How is this meant? Even if I give you a concrete base set, say $X=\mathbb N$, is it not possible to write down an ultrafilter on $X$? (I just notice, that $U$ defined by $A\in U:\Longleftrightarrow 3\in A$ probably is an ultrafilter on $\mathbb N$, but it is a boring one, so my question should ask for real examples.)  Of course, up to now, my question is quite imprecise. Maybe one can formalize it like so: in ZF (without AC), is it possible to prove the existence of an ultrafilter on $\mathbb N$ which is non-principal?  What about other base sets, say finite ones? Can ZF prove the existence of an ultrafilter on a finite set?


suggestions: Changing 'add comment' title to 'add comment/suggestion'

I've noticed that users (including myself a time or two) tend to focus on solving problems within the OP's code rather than answering the original question. This know can lead to confusing results when searching for answers since the chosen answer often solves the OP's problem yet doesnt  answer the actual question. Although this can be great help to the OP, it doesn't provide an archived answer as a Q/A is meant. I think promoting suggestions within the comments area would help guide this assistance away from the answers section.  For example, say an OP noticed that a UPD service was dropping packets and asked how to prevent the loss. A likely answer would be to use TCP, even thought this doesn't answer the underlying issue of preventing a UDP service from losing packets. TCP is a very good suggestion and in most cases the right choice - often leading to a solution - but is technically off-topic for a UDP related issue, and ultimately wrong for an answer as there are reliable UDP solutions. In such a case an individual developing a gaming or messaging system will have to wade through many questions with "just use TCP" as an answer.  I think another way to help guide suggestions away from answers would be an option where the OP can mark a comment as a 'solution' allowing users to receive similar points and badges as providing an answer.


Find out what process accesses file/device

The external hard disks attached to my Raspberry Pi spin up seemingly randomly and I don't know why. They form a RAID 1 managed by mdadm whose only partition is formatted with ext4.  Today, I set up a screen running  $ while true; do inotifywait -r /media/raid/; sleep 300; done   and refrained from using my RAID. It didn't monitor a single event the entire time, so no process seems to just randomly access the file system on my RAID.  On a different screen, I ran  # while true; do inotifywait /dev/sd{a,b}* /dev/md1; fuser /dev/sd{a,b}* /dev/md1; sleep 300; done   which recorded many events throughout the day but only a few PIDs. These where from /usr/sbin/smartd -n and /usr/lib/udisks2/udisksd --no-debug which I'm not even sure make the HDDs spin up. The culprits have likely gone unnoticed as they kept the files open only for such a short period of time that it took too long for fuser to be called and produce their PIDs.  How do I find out about the cause of those spin-ups?    In case the suspicion that this is a duplicate is correct, I posted a  about actually solving the problem.


How to hidden or lock file until task executed fully

I have Perl script which will run for some time. It created file and write some data into it. I also have another Cron job which happens at 5.00 PM everyday.  My problem comes when my 1st script runs on 5.00 PM. Even when it is running(means that file don't have all details),it picks file from specified path.  How to prevent this?  I couldn't use flock in my script. I need another way to do this.


I need to write a regular expression that stops at the first " not the last one.  For example if I check for 'list:".*"' and I have a string such as list:"dogs" it will work fine.   But if I have something like list:"dogs" "cats" that regex will catch the whole thing ending at the very last ". But I need to end the first time it sees the closing " after dog. How do I do this?


Strange difference between pwd and /bin/pwd

I added a symlink to the current directory with ln -s . aa. If I execute cd aa, and after that I executed pwd, the response is /home/sim/aa.  But if I execute /bin/pwd it prints /home/sim (the current directory hasn't changed).  Where does this difference come from?


Simplification of a special iterated sum

Is it possible to simplify this iterated sum  $$f(x)=\sum_{i_{u-1}=u}^{x}\sum_{i_{u-2}=u-1}^{i_{u-1}} \cdots \sum_{i_2=3}^{i_3} \sum_{i_1=2}^{i_2} \sum_{k=1}^{i_1} 1$$  by using a binomial coefficient?  Is this iterated sum still equivalent of $\frac{x^u}{u!}$ ?  This question is related to    In this question, the initial indices are different.  Thank you


I have put this code in my application, I want the window to hide when control + Q is clicked, why does this not work?          private void Form1_KeyDown(object sender, KeyEventArgs e)     {         if (e.Control && e.KeyCode == Keys.Q)         {             this.Hide();         }     }


Beamer template shows itemize circles as squares (but the symbol is a circle)

I created my custom Beamer template to include background graphics, logo, etc. I also changed the colour of texts, bullet points to match the images colours.  The problem I have is that the circles in the itemize environment are displayed as squares, but when I copy and paste the symbol in a text editor they are really circles (\textbullet in LaTeX).  I have the theme file plus images, these are the definitions.   beamerthememytheme.sty  \mode<presentation>  % Requirement \RequirePackage{tikz} \RequirePackage{fontspec} \RequirePackage{graphicx}  % Set graphics path \graphicspath{ {images/} }  % Set main font for the presentation % Note: the following fonts need to be installed \setmainfont{Open Sans} \setmonofont{Source Code Pro}  % tikz settings \usetikzlibrary{positioning}  % Settings %\useinnertheme{mytheme} %\useoutertheme{mytheme} %\usecolortheme{mytheme}  % here the relevant content from theme files (the ones commented above)  \definecolor{titlecolor}{RGB}{31,153,215} \definecolor{subtitlecolor}{RGB}{163,162,162} \definecolor{listscolor}{RGB}{31,153,215}  % Settings \setbeamercolor*{title page header}{fg=titlecolor} \setbeamercolor*{subtitle}{fg=subtitlecolor} \setbeamercolor*{author}{fg=black} \setbeamercolor*{date}{fg=black}  \setbeamercolor*{itemize item}{fg=listscolor, bg=white} \setbeamercolor*{itemize subitem}{fg=listscolor, bg=white} \setbeamercolor*{itemize subsubitem}{fg=listscolor, bg=white}  \setbeamercolor*{enumerate item}{fg=listscolor, bg=white} \setbeamercolor*{enumerate subitem}{fg=listscolor, bg=white} \setbeamercolor*{enumerate subsubitem}{fg=listscolor, bg=white}  % end content  \setbeamertemplate{itemize items}[circle] \setbeamertemplate{enumerate items}[default] \setbeamertemplate{navigation symbols}{} \setbeamertemplate{blocks}[rounded][shadow=false]  \mode<all>    Test.tex  \documentclass[aspectratio=1610, 8pt]{beamer} \usetheme{mytheme}  \usepackage[utf8]{inputenc} \usepackage[english]{babel} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb}  \setbeamerfont{title}{size=\huge}  \author{Author} \title{Title} \subtitle{\small{Subtitle}}  \setbeamertemplate{itemize items}[circle] \setbeamertemplate{enumerate items}[default] \setbeamertemplate{navigation symbols}{} \setbeamertemplate{blocks}[rounded][shadow=false]  \begin{document}  \begin{frame} \titlepage \end{frame}  %\begin{frame} %\tableofcontents %\end{frame}  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%                    SLIDE                    %% \begin{frame}{Slide1}  Some text here...  \begin{itemize}     \item Item 1     \begin{itemize}         \item Sub item 1         \item Sub item 2     \end{itemize}     \item Item 2     \item Item 3 \end{itemize}  \end{frame}   \end{document}    And in the attached image there is the result of the compilation with XeLaTeX (I use custom fonts)    Does anyone has any idea how to fix this issue?  Note: if I use one of the default themes it works and displays the circles correctly.  Thanks.


I'm trying to compile a java file that uses multiple jar files as imports. the command that I have used to compile my code : javac -cp jackson-databind-2.12.1.jar:jackson-core-2.12.1.jar:jackson-annotations-2.12.1.jar TestRunner.java  as a result two .class files are created : TestRunner.class and TestRunner$1.class then I run the command : java TestRunner  but it throws an error that says: Error: Unable to initialize main class TestRunner Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/type/TypeReference  I have included all the required libraries in the javac command, tested it with the IDE and it works fine. I have tried other versions of the jackson library but I'm stuck with the same error.


Why do we say the harmonic series is divergent?

If we have $\Sigma\frac{1}{n}$, why do we say it is divergent? Yes, it is constantly increasing, but after a certain point, $n$ will be so large that we will be certain of millions of digits. If we continue to let $n$ increase, we will end up with a number so large in the denominator that there will be an infinite amount of digits locked into place. What we would have left would just be an irrational number, correct? $\pi$ is an irrational number, but we still consider the value of that to be know. The common estimation of $\pi$ is 3.141592, and we can calculate it past 1,000,000 decimal places, so why can we just assume that we know the first few million places of the harmonic series, slap an irrational label on it, and call it a day? After all, the series $\Sigma\frac{1}{n^n}$ is convergent, and it basically does the same thing, it just gets there a lot faster.  I feel like argument has probably been made before, so I feel like there's probably a proof somewhere proving me wrong, if someone could point me to that.


Windows Stops Recording Run History (Run MRU list)

When opening Run via +R in Windows Server 2019, there are no items in its history or Registry key: (I believe the situation is the same in Windows 10) HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\RunMRU   I think it's because I deleted a folder in one of the Windows system directories, and while I can't think of the exact name of that folder, I remember its name contains history  Is there a way to fix this?


The product of two sequences where one is bounded and the other is convergent to zero

I'm trying to prove, given only that one sequence $B$ is bounded and the other sequence $A$ is convergent to zero, that their product also converges.  My work probably wouldn't be considered a formal proof but I'm curious if my strategy/thought process is on the right track.  My work:  Since $A$ converges to zero, there exists a point in this sequence where all terms are between $-1$ and $1$. In this case, whatever behavior $B$ has will be dictated by the terms of $A$. If $B=0$, then the conclusion is trivial. Thus, $AB$ converges to zero.


I have found an error in a textbook. What can I do about it?

In the book Electronic Devices and Circuit Theory (10th edition) by Boylestad and Louis Nashelsky, I have found a .     What can I do about this? To whom should I send an email, the authors or the publisher? (Also, there is no email address mentioned in the book or on the Internet to which I can send my suggestions.) I have never written an official email of this kind. If I should send an email, how should I write it?


How to find out where my alias are defined in CentOS?

I'm a CentOS user. In my machine, some aliases are available, they were previously defined in the past. I want to add new aliases to function as shortcuts to frequently used commands.  I don't know where to define them, since I'd like them to be in the same file as the already defined aliases. I've searched files like bashrc, /.rc, but it wasn't there.  I've checked the already defined aliases are available to all users, not just mine.


How can I create an equals method to compare two objects in an array?

How I can compare each object in an array to identify if they are the same; ex. compare a hockey player to a golfer and output they are not the same, or compare two hockey players to each other and output that they are the same.  I am unsure how to implement this.  players[0] = new BaseballPlayer(...stuff); players[1] = new FootBall(...stuff); players[2] = new HockeyPlayer(...stuff); players[3] = new Golfer(...stuff); players[4] = new BaseballPlayer(...stuff); players[5] = new FootBall(...stuff); players[6] = new HockeyPlayer(...stuff); players[7] = new Golfer(...stuff); players[8] = new BaseballPlayer(...stuff); players[9] = new FootBall(...stuff); players[10] = new HockeyPlayer(...stuff); players[11] = new Golfer(...stuff); players[12] = new BaseballPlayer(...stuff); players[13] = new FootBall(...stuff); players[14] = new HockeyPlayer(...stuff); players[15] = new Golfer(...stuff);


I recently upgraded to Windows 10. It's been a pretty rocky road thus far. My current issue is Windows 10 keeps using up my SSD's disk space until it has none left and then complains I have no space left. I keep my data on a separate drive, and just the OS on the SSD.  Every time I look at the drive, there is less and less space. I clear a few gigabytes of stuff so it is at 4 GB free space, then it quickly starts going back to 0. It's not temp data, so how do I figure out what is using up all this space?


How can I map a key on Windows to a key combination (like Ctrl + PrtScr)

Basically I want the ability to temporarily rebind my "m" key to "Ctrl + PrtScr"


How do you use Xforwarding through SSH beetween two ubuntu pc's?


Why are these curves different sizes when they are using the same bevel object?

Bezier curves 1, 2 and 3 are all using the curve "Bev ob" as a bevel object. Why are they different sizes?    I saw  and checked that the radius is set the same for all vertices on all three objects.


Is it possible to save session in Ubuntu?  I mean when you switch it on and off or simply restart it and after logging in the screen looks exacly the same as before (with all windows open, and application running)?  Same as going back from 'Suspend' mode. So you can continously work on the same PC?


Google IP Address Ranges for incoming SMTP

Essentially I'm answering my own question here, but want to provide this info to anyone else who might need it. I need all the valid IP address ranges for Google Apps mail servers.   I'm configuring a firewall to only allow incoming SMTP from our Google Apps hosted (POSTINI) email and want to allow only the expected servers to connect to our internal server for delivery. In trying to setup the rules in our firewall, it does not accept CIDR notation for the allowed IP address ranges. Thus I have had to convert them from the CIDR addresses provided by the article:   NOTE: This is not a duplicate question. The article linked to as a duplicate reference is "". This is not what this question/answer asks or answers. This article is to save others the time to do each of those conversions manually from Google's published list of addresses if they have network equipment that doesn't accept CIDR notation.


How to create batch file in Windows using "start" with a path and command with spaces

I need to create a batch file which starts multiple console applications in a Windows .cmd file.  This can be done using the start command.  However, the command has a path in it.  I also need to pass paramaters which have spaces as well.  How to do this?  E.g. batch file  start "c:\path with spaces\app.exe" param1 "param with spaces"


How to center an element within a parent div vertically

I want to center below wrapper inside the parent div element with a height equal to windows view height, using CSS.  HTML

center div

   CSS  .main-header{ color: #fff; background: #16a8ec; padding: 10px; height: 100vh; position: relative; }  .wrapper{ position: absolute; left: 0px; right: 0px; transform: translate(0px, 50%); /* i used transform but it doesn't work */ -webkit-transform: translate(0px, 50%); /* i used transform but it doesn't work */ }   Please help me guys, thanks.


Dynamic Server Name in SQL Statements (from clause)

My scenario is I have a thick client side app using a SQL DB. The use of the app is divided into 10 "sites" mostly by Geography but some by Usage. I've written an SP to archive selected data out of the DB and put it elsewhere as the DBs are growing to nearly 500GB in size at this point. Further whilst most servers host one application DB there is one server (and instance) that hosts 3 DBs.  My dilemma is I want to write code that is the same everytime. Ideally I would write something like  declare @dbname varchar(20) set @dbname = 'Archive' + DB_NAME(DB_ID())  INSERT INTO @dbname.dbo.ArchiveTable (ID, DATA) SELECT (ID, DATA) from TheData WHERE Archive = 1   That way I can have the same SP installed on each server, any bug/feature fixes doesn't need me to manually type up 10 different SPs to install.  In the real world I'm also limited by SQL2000 however I'd be interested to hear in ideas using SQL2000 and/or SQL2008R2. The servers are a mixture of both.  As I understand it Synonyms wouldn't help as on the instance with 3 DBs I'd still end up with each DB having it's own copy of the SP with it's own hard coded definition of which named synonym to use.  I also don't feel dynamic SQL statements would be a good fit. There's more to it than the example snippet above and I use table variables to marshal all the work to be done- so that would be out of scope for all the other statements I need to work with.


I can't open my Minecraft maps even though they exist

I have something strange and can't figure it out by myself. I have 2 maps in my saves that I can't open. I have played on them, but one time they where gone so I searched for them in the Minecraft folder, and found them. There was nothing strange with them, so I don't really get it. Does anybody have an idea about what's wrong?  EDIT: Mrlemon is right, I found them in the map but can't open them in Minecraft itself. I compared the 2 maps with one that I can open in Minecraft (and see) but don't see a difference in between those. Here are some screenshots of it.  My world:   World that I can't see:


I wanted to update Ubuntu manually, because I used CDMA USB modem and connected using wvdial, but it won't able to update Ubuntu via Update Manager, because my Ubuntu won't showing "Connected" message via network-manager.  Can I update Ubuntu manually? Am I should download separate files, or use terminal instead?


Is the set of all functions $f:Z_+\rightarrow Z_+$ that are eventually constant countable.

another question here to see if I'm on the right track. Here is the problem that I have been proposed.   Determine if the set $H$ of all functions $f:Z_+\rightarrow Z_+$ that are eventually constant is countable.   Here is my solution.   I claim the set $H$ is countable. By definition, we say that $f$ is eventually constant if there is a positive integer $N$ such that $f(n)=c,\textrm{c a constant,}\ \forall\ n\ge N.$ Let $F$ be a set containing some $f:Z_+\rightarrow Z_+.$ Let $$H=\bigcup_{n\in\mathbb{Z_+}}F_n=\{f:Z_+ \rightarrow Z_+ |f\in F_n\ \textrm{for at least one}\ n\in Z_+\}.$$ Since $H$ is an arbitary union of sets, we can define a function $g:Z_+\rightarrow H$, where $g$ is an indexing function of $H$ and $Z_+$ is the index set given. Since $g$ is an indexing function, this implies that $g$ is surjective. By  Theorem 7.1, which states if $H$ is a nonempty set and there is a surjective function $f:Z_+ \rightarrow H$ then $H$ is countable, we have that $H$ is countable as claimed.


I was wondering which type would have better performance and which you think should be used.   For example I have a List of strings not knowing how many items I will need so having the .Add(String) function is really convenient. I can Add new strings to the list at any time easily.  What are the advantages/disadvantages of using each?  Are lists the new arrays?


How did Kiba learn the shadow clone jutsu?

The First Hokage sealed the shadow clone jutsu . If this is true, how was Kiba able to learn it?


I am a Pakistani passport holder, and a permanent resident of Canada, with PR card. Travelling via Frankfurt by Air Canada. Can I visit the city during this 8-hour layover or does it require any formality?


Simplest and robustest way to convert a Method of a static class into MethodInfo

Is was wondering if there is no easier and robuster way to convert a static Method of a static class into a MethodInfo than writing  typeof(MyStaticClass).GetMethod("MyStaticMethod")   My aim is to write a Dictionary<Type, MethodInfo> where i can map a Type to a Method.  MethodDictionary[typeof(bool)].Invoke(null, new object[] {});   I know that in C# 6 there is the possibility to write  typeof(MyStaticClass).GetMethod(nameof(MyStaticMethod))   But i'd like to stick to C# 5


Does a bonus to damage rolls apply to the damage after the roll or to the number rolled?

If something says I have a bonus to damage rolls does that number get applied to the number on the dice or to the damage after the roll?  I was looking at the  feature which says I gain a +3 bonus (my proficiency bonus) to damage rolls. From reading that it sounds to me like it would apply to the number on the dice, adding 3 to whatever I roll up to the maximum (so if I rolled a 6 on a d8 I would add 2 to get to 8 but the last bit would be lost). This also matches up with what I thought I heard in the last campaign I played. But then I looked at the Improved Pact Weapon feature which says the weapon gets a +1 to damage rolls and on the DDB character sheet it treats it as bonus damage not a bonus to the roll. So which way would I apply this?  In response to the duplicate vote that question is asking about hitting a target in the first place. I'm not asking about that. I'm asking about the bonus to damage rolls.


Is there any Ubuntu alternative for team-viewer software for Windows?


Clerical mistake in UK visa application: should I make a pen-and-ink correction or electronically edit the PDF?

I've gone through all similar questions but I believe my specific question doesn't have an answer yet.  I've applied for a Standard Visitor visa. After I completed the application, made an appointment and paid the fee, I noticed that the way I spelled my name on the application differs from how it is spelled in the passport by 1 letter (this is partially because of myself being an idiot, but mainly because my new passport has an incorrect transliteration of my name, whereas my old passport and any other document in my life has the correct one).  So here are the options I see:   Print the application and make a pen-and-ink correction with a black ballpoint pen by crossing the printed name/letter and writing the correct one - as answers to other similar questions suggests. Edit the PDF electronically and print it so that there are no visible corrections. However, as the form is saved at their end, there will be a discrepance between the printed form and saved form with no visible signs of correction.   Which way has better chance for me to have my application accepted?  Also (probably doesn't matter much but still): if it's the pen-and-ink correction, is it better to cross-out the whole name or only the wrong letter?


Public vs. Protected abstract class method

Is there any security/access difference when making a package access level abstract class's non-static methods public vs making them protected? Only classes from within the same package that extend the abstract class can access the non-static methods anyway right? So, does it matter whether those non-static methods are public or protected since the abstract class itself places restrictions on who can extend it?  abstract class MyClass {     protected void myFunction(){         System.out.println("Only child classes can print this");     } }  abstract class MyClass {     public void myFunction(){         System.out.println("Still, only child classes can print this");     } }


Can't get json_encode to work with database entry

No matter what I do, I can't seem to get json_encode to work on returned results from my fr column.  Here is an export of my table:  mctrivia.com/language.zip  I set everything to utf8mb4 as suggested by my googling this problem but no luck.  If $language is 'en' and $fileID=1 this works. If $language is 'fr' and $fileID=1 this fails.  Either way the print_r gives proper results. The echo is showing null with fr.      //get list of words in current language file     $query='SELECT `key`,`' . $language . '` FROM `language` WHERE `file`=' . $fileID;     $stmtGetWords = $conn->prepare($query);     $stmtGetWords->bind_result($wordID,$text);     $stmtGetWords->execute();     $wordList=array();       while ($stmtGetWords->fetch()) {         $wordList[$wordID]=$text;     }     print_r($wordList);     $stmtGetWords->close();      //create json file data     $fileData=json_encode($wordList);     echo '
'. $fileData . '
';   Results from language en:  Array ( [lang] => English [subPage1Intro] => Welcome to sub page 1. )  {"lang":"English","subPage1Intro":"Welcome to sub page 1."}   Results from language fr:  Array ( [lang] => Fran�ais [subPage1Intro] => Bienvenue � sous page 1. )


validation accuracy is fluctuating in a neural network?

Network architecture is as follows:  dataset features(input_expansion) are expanded by using chebshy polynomial then i got(Exp_layer),  split the dataset into train and test and applied back propagation between exp_layer and output layer(1 node) using keras.  where when evaluating accuracy is fluctuating.  and please suggest me how to increase the accuracy. dataset is used is JM1 from Promise repository  from keras.models import Sequential from keras.layers import Dense import numpy as np from keras.optimizers import SGD,adam from keras import backend as kb from sklearn.model_selection import train_test_split import pandas as pd from sklearn.ensemble import ExtraTreesClassifier##model used for feature selection from sklearn.feature_selection import SelectFromModel##for feature selection from sklearn.feature_selection import RFE from sklearn.linear_model import LogisticRegression data=pd.read_excel('jm1_csv.xls') dataset=data.dropna(how='any') input_expansion = dataset.iloc[:,:-1].values Y = dataset.iloc[:,-1].values rows = dataset.shape[0] columns=input_expansion.shape[1] print(columns)  def funexp(x):      a = np.array([])      for i in x:           t0x=1           t1x=i           t2x=2*(i**2)-1           t3x=4*(i**3)-3*i           t4x=8*(i**4)-8*(i**2)+1           a = np.append(a, np.array([t0x,t1x,t2x,t3x,t4x]))      return a   Exp_layer = np.array([]) for i in input_expansion:      Exp_layer=np.append(Exp_layer,funexp(i)) Exp_layer=Exp_layer.reshape(len(input_expansion),(columns)*5)  X_train, X_test, Y_train, Y_test = train_test_split(Exp_layer, Y, test_size=0.2) keras_model = Sequential() keras_model.add(Dense(1, input_dim=(columns*5), activation='relu')) optimizer=SGD(0.001) keras_model.compile(loss='mean_absolute_error',optimizer=optimizer,metrics=['accuracy']) keras_model.fit(X_train,Y_train,epochs=20,batch_size=50) results = keras_model.evaluate(X_test, Y_test, batch_size=50) print('Loss:', results[0]) print('Accuracy of FLANN:', results[1]) ```


How do you "Save as" /"open" a document using a Python Tkinter interface

Lets say I have a document file named sample.docx added to an IDE python project. I have a python tkinter program and I want the user to be a able to click a button that will automatically open the sample.docx file. I think the only way is by opening the windows save as window with the file already loaded.  How do I do this?


Get another function to return timestamp in PostgreSQL

Can I have another function to return the last timestamp. I want to compare with this query to use the best query. My query: CREATE OR REPLACE FUNCTION f_last_update1(nomTable text , OUT updated timestamp)   LANGUAGE plpgsql AS $func$ BEGIN    EXECUTE 'SELECT max(updated) FROM ' || nomTable    INTO updated;    END $func$;


Pycharm and other packages don't appear in the apt-cache search list

I can find PyCharm Pro, PyCharm CE, and PyCharm EDU in Ubuntu Software app, but I am trying to get better with apt-get commands in a terminal window.  Yet when I type  apt-cache search PyCharm   I am unable to see it in the list that is returned.  Is some software not available through apt-get?  Do I need to connect to some repository to complete my apt-cache list?  I have been using Linux for 2 days.  Thanks!


I know how to use  ${parameter#word} Remove matching prefix pattern   and  ${parameter%word} Remove matching suffix pattern.   but is there a way to nest them in a single call, such as  ${${variable#foo}%bar}   ?  It looks like I should be able to use this somehow     If the first character of parameter is  an  exclamation  point  (!),  a level  of  variable  indirection is introduced.  Bash uses the value of the variable formed from the rest of parameter as the name of the variable; this variable is then expanded and that value is used in the rest of the substitution, rather than the value of parameter  itself.   but I can't figure  it out.


I have a javascript function which I want to execute only if the browser screen with is bigger than 1024px.  if ($(window).width() > 1024) {   The problem with this code is that if a user first load the webpage in a browser screen 800px and then just rescale the browser screen to 1024 (or more) the function is not executed. In order to be executed the screen needs to be refreshed.  Do you have any suggestion how to fix it?


How do I edit applications panel menu in Lubuntu?

Main menu (alacarte) cannot record changes as it should. Some time it does, but randomly and rarely.  Is this a bug?  This question is not a clone of . In that case the Main menu would not open, in this case it does but changes are rarely recorded.


Always answer Yes to replace package Arch Linux

I am trying to build the latest KDE Frameworks git packages. However, I currently have installed the stable non-git packages. In order to install all of the git packages I need to answer 'y' to all of the replace prompts one by one. I usually use --noconfirm to skip prompts, but when it asks to replace a package, it defaults to 'no'. I want it to default to 'yes' in this case.


How to get host server CPU info from SSMS

Help please! I need to get number of CPU's and cores per cpu for each host server running SQL Server. Querying master.sys.dm_os_sys_info is not producing the same result as what is seen when checked on the host server.  kindly point me in the direction of a code I can use please.  What is the difference between physical_cpu and logical_cpu and which one do I need? I'm trying to calculate total cores on each machine for licensing purposes.  Can i take the number of cores returned by the query pasted below as what I need to calculate my license requirement?  In performance monitor on the server, I have sockets =2, Cores = 16, logical processors = 32. Is 16 cores what I need for my SQL 2012 and 2016 licence calculations?   Here the query that  I'm using right now: USE master;  SET NOCOUNT ON  SELECT 'physical_cpu' = cpu_count / hyperthread_ratio     ,'cores' = CASE          WHEN hyperthread_ratio = cpu_count             THEN cpu_count         ELSE (cpu_count / hyperthread_ratio) * ((cpu_count - hyperthread_ratio) / (cpu_count / hyperthread_ratio))         END     ,'logical_cpu' = CASE          WHEN hyperthread_ratio = cpu_count             THEN cpu_count         ELSE ((cpu_count - hyperthread_ratio) / (cpu_count / hyperthread_ratio))         END FROM master.sys.dm_os_sys_info  Anything better than that?


how to write théorème instead of theorem in beamer presentation

I am doing a math presentation in beamer. How can i have "théorème" written instead of "theorem" and "définition" instead of "definition" ? This is what i have as of now :  \documentclass[11pt]{beamer} \usetheme{Warsaw} %\setbeamertemplate{theorems} \usepackage[utf8]{inputenc} \usepackage[french]{babel} \usepackage[T1]{fontenc} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} %\author{} \title{ccc} %\setbeamercovered{transparent}  \begin{document} %\logo{}  \institute{}  \date{01/06/2014}  %\subject{}      \def\O{\mathcal O} \def\Q{\mathbb Q} \def\R{\mbox{$\mathbb R$}} \def\Z{\mathbb Z} \def\C1{\mathbb C}


Bash script doesn't run from nautilus, but does run from terminal

Before I add more detail to my question, I have to say something very important: Yes, my script has "Allow executing file as program" turned on. The question itself: For programming reasons (shared libraries), I can't execute my program just from the executable, because I need to access LD_LIBRARY_PATH before executing the program. I created this script to do this (baring in mind this is my first time ever writing a script): #!/bin/bash #Get the current directory and append the SO's location currentDir=$(pwd)'/libs/'  #Change the library path export LD_LIBRARY_PATH=$currentDir  #Run the program ./program  After running this from the terminal I thought that it has worked, there were no errors and the program didn't complain about shared libraries. But unfortunately, if I try to double-click the .sh file from Nautilus, nothing happens. The worst part as well, is that since I'm running it from the GUI, I have no idea what error it is getting. I'm running Ubuntu 14.04 and the executable is a C++ program using the SFML libraries (Yes I could just have the dependencies, but SFML isn't commonly installed on Linux computers, and this is besides the point).


Quantum information Science PhD position interview

Recently I got in touch with a professor in the field of quantum information science. I am really interested in the PhD program. After extensively talking with the professor he has agreed for an interview on skype. What should i expect from this interview and how can i be better prepared.


Is there a way to block all numbers from an area code but keep one number unblocked. I see applications for blocking unwanted calls but nothing on saving a number from being blocked on iPhone.


why Permission denied when to write something into a log file?

debian8@hwy:~$ sudo cat /etc/sudoers |grep debian8 debian8  ALL=(ALL:ALL) NOPASSWD:ALL   It means debian8 is a permitted user to execute a command as the superuser. I want to write something into a log file.  debian8@hwy:~$ trafficlog="/var/log/traffic.log" debian8@hwy:~$ sudo echo -n `date "+%Y-%m-%d %H:%M:%S"` >> $trafficlog bash: /var/log/traffic.log: Permission denied   debian8 has root permission,why can't write date record into the trarric log?


My mother in law (Russian national) has a Schengen visa issued by Austria. The itinerary says she is entering Germany initially then travels to Austria in a few hours and stays there as her main destination.  We would now like to change this to a direct Austrian entry. Am I right in assuming that there will be no problem at the border since, while we dropped the point-of-entry country, it is not the one that issued the visa and so it's fine to just enter Austria with an Austrian-issued visa?  A side question is, is it also OK to add another country (Italy) and stay there for a few days longer than Austria, thereby making Italy the main destination? Obviously still within the original visa validity time frame!


My 2019 16" MacBook Pro with 2.6GHz 6-core i7 processor on macOS 11.3.1 is constantly running . I've checked the ActivityMonitor, but no app is using excess amounts of CPU, energy, or memory. I've obviously tried rebooting & updating my Mac. I also make sure my fans aren't blocked so there's enough room for air flow and I have cleaned the interior from dust. What else can I do?


Let $A\in GL_2\left(\mathbb{Z}\right)$, the group of invertible matrices with integer coefficients, and denote by $\omega(A)$ the order of $A$.  How we prove that $$\left\{\omega(A);A\in GL_2\left(\mathbb{Z}\right)\right\}=\{1,2,3,4,6,\infty\}.$$


central limit theorem: do we care about standard deviation within one sample of size n?

I'm learning applications on Central Limit Theorem and got really confused with a few points.  Think of an example of applying Central Limit Theorem:    We have a whole population of 10 billion items  It's not possible to measure the whole population, so we take a sample from it instead. Our sample size is 10000, meaning that we randomly select 10000 items from the whole population. We can calculate the sample mean, which is the mean of these 10000 items We repeat step 2, say 8888 times, and we get 8888 samples, each has 10000 randomly selected items; We therefore also have 8888 sample mean values.    OK. Now there are 3 places where we can take standard deviations and I'm really confused with their relationship to each other:   value #1: the standard deviation of the whole population, 10 billion items.   value #2: the standard deviation within one sample, or the SD of 10000 randomly selected items.   value #3: the standard deviation of 8888 sample means.   I think when people talk about applying the Central Limit Theorem and the equation of "standard deviation" and "standard error":      SE = SD / sqrt(n)   , the SD refers to value #1 and SE refers to value #3, and n refers to sample size of 10000 in the above example.   So, is value #2 totally irrelevant in the story? Is it something we should never care about??


I am playing the Neverwinter online RPG and there's plenty of stuff that one needs to keep in their bags: besides the usual loot, enchantments, runestones, seals, emblems and kits seem to take up 90% of my bags.  After the starting Adventurer's satchel and Adventurer knapsack, how do I obtain more bags?


It's very basic, but I am confused as to what regression actually is in the case of econometrics. What is it useful for? Why do we use it instead of other methods? I understand that one of the main ideas of statistics is to make generalizations about a population from samples of data, but how does regression relate to this? And what is regression analysis?


Is this approximation for a factorial a known formula?

I saw this approximation in some notes:    $n! \approx   e^{-n}*n^n*\sqrt{2\pi n}$    What is this approximation? How is it derived? Is it a known formula?


How do I show that:  $$\frac{1}{\sin^{2}\frac{\pi}{14}} + \frac{1}{\sin^{2}\frac{3\pi}{14}} + \frac{1}{\sin^{2}\frac{5\pi}{14}} = 24$$  This is actually problem B $4371$ given at this . Looks like a very interesting problem.   My attempts: Well, I have been thinking about this for the whole day, and I have got some insights. I don't believe my insights will lead me to a $\text{complete}$ solution.   First, I wrote $\sin\frac{5\pi}{14}$ as $\sin\frac{9 \pi}{14}$ so that if I put $A = \frac{\pi}{14}$ so that the given equation becomes, $$\frac{1}{\sin^{2}{A}} + \frac{1}{\sin^{2}{3A}} + \frac{1}{\sin^{2}{9A}} =24$$ Then I tried working with this by taking $\text{lcm}$ and multiplying and doing something, which appeared futile. Next, I actually didn't work it out, but I think we have to look for a equation which has roots as $\sin$ and then use $\text{sum of roots}$ formulas to get $24$. I think I haven't explained this clearly.         $\text{Thirdly, is there a trick proving such type of identities using Gauss sums ?}$ One post related to this is:  I don't know how this will help as I haven't studied anything yet regarding Gauss sums.


On , the sidebar has a Hot Meta Post whose title contains a URL, and this URL overflows outside the edge of the sidebar.    The displayed title of the question is Why is this question https://hinduism.stackexchange.com/q/40266/20829 marked... where the URL starts on a new line and extends beyond the edge of the sidebar. I expect the same issue will come up whenever a very long word appears in a title. It is known that the same error occurs in the chatroom sidebar if the name of a chatroom is very long:


Given that $A$ and $B$ are abelian groups, prove that the direct product of them $$A\times B$$ is an abelian group. Given that $A\times B$ is an abelian group, prove that $A$ and $B$ are both abelian.   I used the basic property of Descartes product: $$(a,b)\cdot(c,d)=(a\cdot c,b\cdot d)$$ to prove each argument.   $(a,b)(c,d)=(ac,bd)=(ca,db)=(c,d)(a,b)$; $(a,b)(c,d)=(c,d)(a,b)\implies (ac,bd)=(ca,db)\implies ac=ca, bd=db$.   I am not sure whether this property of Descartes product can be applied to groups. This question appears to be the 30th question out of 36 questions in an exercise, so I guess it's not that easy.  This is my first post, so please forgive me for any wrongdoing!:)


How to find sum of the infinite series $\sum_{n=1}^{\infty} \frac{1}{ n(2n+1)}$

$$\frac{1}{1 \times3} + \frac{1}{2\times5}+\frac{1}{3\times7} + \frac{1}{4\times9}+\cdots $$  How to find sum of this series?  I tried this: its $n$th term will be = $\frac{1}{n}-\frac{2}{2n+1}$; after that  I am not able to solve this.


I have just watched the movie , released in 2006.   In this movie, who is behind the mask? Is this character's real face shown in the film?


I was playing around with a method of how to do negative logs and cane  up with the following method using Euler's identity:  $$e^{i\pi} = -1$$ $$\therefore \ln{-1} = i\pi$$  So therefore the following can be used for negative numbers:  $$\ln{x} = \ln{-x} + i\pi$$  E.g.  $$\ln{-e} = \ln{e} + i\pi$$ $$\ln{-e} = 1 + i\pi$$  However, I decided to try to use this with $\ln{e}$:  $$\ln{e} = \ln{-e} + i\pi$$ $$\ln{e} = 1 + 2i\pi$$  Since $\ln{e} = 1$, does this mean that $1 = 1 + 2i\pi$? Or have I made a mistake at some point?


For which $a,b \in\Bbb R$ does there exist the inverse of matrix $A$

For which $a,b \in\Bbb R$ does there exist the inverse of $A$: $$A=\begin{pmatrix} a&b& b &\ldots &b\\ b& a &b &\ldots&b\\ b& b & a &\ldots &b\\ \vdots&\vdots&\vdots& \ddots&\vdots\\ b&b& b&\ldots & a \end{pmatrix}\in M_n$$  So we want to see for which $a,b$ will the $\det(A)\neq 0$ .  $$\begin{vmatrix} a&b &b  &\ldots &b\\ b& a &b &\ldots&b\\ b& b & a &\ldots &b\\ \vdots&\vdots&\vdots& \ddots&\vdots\\ b&b& b&\ldots & a \end{vmatrix}=\begin{vmatrix}a &b &b &\ldots &b\\ b-a& a-b &0 &\ldots&0\\ b-a& 0 & a-b &\ldots &0\\ \vdots&\vdots&\vdots& \ddots&\vdots\\ b-a&0& 0&\ldots & a-b \end{vmatrix}$$  This is almost a lower triangular matrix, only there should be zeros instead of $b$s in the 1st row. So if I put $b=0$, then I get a lower triangular matrix. The main diagonal will only have $a$s on it, so then $a\neq 0$? Is that it?


Creating cross-sections in ArcGIS Desktop?

Is there the possibility if I have a polyline (named "Linedivide") which is divided into,  let's say, 5 parts to make ArcGIS draw perpendicular lines of special length at the middle of all 5 parts of the Linedivide?  Can someone tell me where I can find a tool for this in the toolboxes?


That is, I have created a Twitter list with some 100 members and would like to search for a particular word within all users of the list.


Keychain won't let copy passwords after 10.11.1 update

After the 10.11.1 update, I can not get access to some of encrypted data stored in my keychains with Keychain Access.app. Most notably, I can not see or copy passwords stored.  Normally, to do so, you'd have to:   unlock a keychain with keychain password; unlock an item itself with keychain password.   During 2nd step, when password is typed in, you can select 2 options: "Allow" and "Always allow". The difference is that if you click "Always allow", you won't have to perform 2nd step for this item again.  Here's some things I was able to detect:   if I had clicked "Always allow" on an item before OS X update, I can access it fully; if I haven't clicked "Always allow", I can not copy password from right click menu, nor see it when ticking "Show Password" checkbox on Info Screen. if I add new item, I can not copy password from right click menu, but can still see it on Info Screen.   I get what seems to be mostly full keychain data using following command (though, I am not sure everything's there):  security dump-keychain -d elmigranto.keychain     UPD: After more detective work, I found following message appearing in Console.app when I click anything in password dialog:  26.10.15 10:19:52,345 SecurityAgent[770]: Ignoring user action since the dialog has received events from an untrusted source     UPD2: Pretty sure this is caused by , which among other changes lists the following:     SecurityAgent      Available for: OS X El Capitan 10.11      Impact: A malicious application can programmatically control keychain access prompts      Description: A method existed for applications to create synthetic clicks on keychain prompts. This was addressed by disabling synthetic clicks for keychain access windows.      CVE-ID      CVE-2015-5943


Question says it all:  Should users edit other users' posts to correct grammar and spelling problems?  I've seen arguments both ways, and lean toward yes...but...


JavaScript RegExp isn't matching the correct group

This regular expression: /\{(\w+)\}/g returns ["{name}", "{color}"] and ignores my parenthesis around (\w+)  Why doesn't this work? What is the correct regular expression?    Token replacement:  const item = {   name: 'foo',   color: 'bar' };  let str = `'{name} - {color}'`  console.log( str.match( /\{(\w+)\}/g ) );


One of my friends wants to visit me in Austria. We have made a plan to visit other countries too (Poland, Italy, CZ, SK, etc.). In which consulate should he apply for the Schengen visa?  He is going to land in Bratislava, Slovakia. The German consulate is near to him compared to other consulates.  Does it matter in which consulate he applies for his visa?


Javascript not bound on thymeleaf fragment update

I have a page fragment returned from a spring controller as a result of an Ajax form submit. The fragment updates a table in the page. The table contains buttons that use jquery onclick function selecting button class.    The jquery select does not work if the table is returned as part of a fragment, the javascript seems not to be bound to the replaced html in the page even though the classes etc are all the same as previously.  Any ideas how to get the javascript to work with the returned HTML in the thymeleaf fragment?


I am working on a school project where I have to create a basic webpage.  How can I make the main_content div reach each ends, because that will allow me to centre the webpage text.  1]:     .main_content {   position: relative;   padding: 0.8em;   margin: auto;   width: 50%; }

Welcome to TK Digital Arts

The #1 modern design and media company in New Zealand.


Covariance of order statistics (uniform case)

Let $X_1, \ldots, X_n$ be uniformly distributed on $[0,1]$ and $X_{(1)}, ..., X_{(n)}$ the corresponding order statistic. I want to calculate $Cov(X_{(j)}, X_{(k)})$ for $j, k \in \{1, \ldots, n\}$.  The problem is of course to calculate $\mathbb{E}[X_{(j)}X_{(k)}]$.  The joint density of $X_{(j)}$ and $X_{(k)}$ is given by $$f_{X_{(j)}, X_{(k)}}=\binom{n}{k}\binom{k}{j-1}x^{j-1}(y-x)^{k-1-j}(1-y)^{n-k}$$ where $0\leq x\leq y\leq 1$. (I used the general formula .)  Sadly, I see no other way to calculate $\mathbb{E}[X_{(j)}X_{(k)}]$ than by $$\mathbb{E}[X_{(j)}X_{(k)}]=\binom{n}{k}\binom{k}{j-1}\int_0^1\int_0^yxyx^{j-1}(y-x)^{k-1-j}(1-y)^{n-k}\,dx\,dy.$$  But this integral is too much for me. I tried integration by parts, but got lost along the way.  Is there a trick to do it? Did I even get the limits of integration right?  Apart from that, I wonder if there's a smart approach to solve the whole problem more elegantly.


How to center horizontally the text area in the "tufte-book" class?

In the following code, I want to center horizontally the text area (main body+margin area), but the centering option of the geometry package doesn't have any affects. Is there a way to do this?  \documentclass[a4paper,symmetric,showframe,centering]{tufte-book} \usepackage{lipsum} \begin{document}  \lipsum[1-2] \end{document}     I know that something like \PassOptionsToPackage{right=8.2cm}{geometry} can do the job, but I think it should be there a logical way.


A word/expression: more "valuable" than "valuable"?

I would like to say that something is "very valuable". Do we have better word/expression that can do the job? The suggestions in the other thread sound extravagant compared to what I would like to express.


Sorry I do not know latex. Why is $\sqrt x \times \sqrt y = \sqrt {xy}$? It also applies for division, but why not addition and subtraction? i.e., why is $\sqrt x + \sqrt y$ not equal to $\sqrt {x+y}$?  Thank you for editing and answering.


Friend B and C have eaten zero apples. How many more apples has C eaten?

Friend $A$ claims that he has eaten $1$ apple today.  Friend $B$ responds. Congrats, I have eaten $0$ apples, so that is $\infty$ more apples than me.  Friend $C$ says, but I have also eaten $0$ apples. So how many times more than you have I done? $0$ or $\infty$?


Cannot remove hiberfile on NTFS partition

I've been looking at questions like  and  and they all say "Boot into windows" which I am unable to do. Then after much cautioning, the option remove_hiberfile is suggested. I would love that option. I don't care about the programs I had open, or the data in them. The windows partition is on /dev/sda5, so I ran  sudo mount /dev/sda5 /mnt/win   Lots of reading later...  sudo mount -t ntfs-3g -o remove_hiberfile /dev/sda5 /mnt/win sudo mount -t ntfs-3g -o debug,remove_hiberfile /dev/sda5 /mnt/win   Still no luck. It's like the remove_hiberfile option isn't being recognized, because I don't get an error when trying to use the option remove_hiberfile3ejeiofe but rather the same message.  This is the message given as a result of all above commands (adding debug did not change anything):  The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Failed to mount '/dev/sda5': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.   I am able to mount read-only, but that doesn't help me much.


Wrongfully received consecutive days badge for the third time

For the third time now, I've received a consecutive days badge when I know for a fact that I haven't earned it. The first time was reported  and the second time .   I just looked at my achievements menu, and saw this:    While I love PPGC, I know I haven't visited it for a month straight, let alone 100 days. I've been busy with work and a Neural Net project, so I haven't been checking it frequently. I think I checked it last a few days ago, and before that a week or two prior.   Things to note:   I don't have any scripts, browser or otherwise that check or even have access to SE.  My SE account is tied to Google, which has two-step verification in place, and monthly activity reports. My account is spotless. This isn't a case of someone logging in to my account (and checking PPCG!?). Again, I know for a fact that I haven't even visited the site daily for at least a month, if not more.  I predominantly use the Android app. PPCG is listed as one of my favorite sites in the left menu.   While I'd like to keep the badge(s), I thought I'd post another report since the first 2 didn't have any kind of resolution.


Is it unethical to accept extra time on exams when I still do well?

I have ADHD (real, diagnosed ADHD, not just "I-say-I-have-ADHD-because-it's-trendy" ADHD). I have never taken the extended time exams that are offered for ADHD students, because I have never needed to, and it was diagnosed just a year ago. However, exams do stress me out and I am certain I would do better on them with some more time - but this is true for almost anyone, not just ADHD students. Thus, would it be unethical to make use of the ADHD services offered to me?  (Edit: You might ask - why would you want to / feel it is justified? Well, hypothetically say ADHD students only achieve 75% of their "non-ADHD" potential in a standard-time setting. Maybe, even though I am doing well, I would be doing even better if I did have the extended time or didn't have ADHD, i.e. due to my exhaustive preparation, even with the disadvantage of my ADHD I am still managing to get a high score. But, with a "level playing field" [extended time for me], I would be at the top of the class. However, I still don't know if this is logical / ethical.)


Does having a known plaintext prefix weaken AES256?

I plan on storing data, encrypted with AES256, where the first dozen bytes are known plaintext.  ('Hello World!' for example.)  Does having this known plaintext prefix weaken AES256?  I do not care about modifications being made to the ciphertext, which result in modifications to the decrypted plaintext.  I do care about an attacker being able to decrypt any plaintext beyond the known plaintext prefix.  I expect to use counter mode, as random access is required.  Does GCM have any advantage?


Doing something in/at the company, which one is correct?

Would you say?  I won employee of the month in my company.  or  I won employee of the month at my company.


What are the blood groups for human beings?

Human blood groups are of 4 types with negative and positive of each types . But according to  there are some other types too:     A+,A-,B+,B-,O+,O-,AB+,AB-,A1+,A1-,A2+,A2-,A1B+,A1B-,A2B+,A2B-   I'm going to make software for blood donation, where I need to put a dropdown list of actual blood types. I had intended to use:   [ Select Blood Group V ] [ O Negative           ] [ O Positive           ] [ A Negative           ] [ A Positive           ] [ B Negative           ] [ B Positive           ] [ AB Negative          ] [ AB Positive          ]   But now I am uncertain whether this is appropriate. What is the most suitable list of blood types for donors?


Let $f:S^1 \rightarrow \mathbb{R}$ be a continous function. Show that exists $x\in S^1$ such that $f(x)=f(-x)$

Since $f$ is continous, and $\mathbb{R} \setminus\{a\}$ is disconected for every $a \in \mathbb{R}$, but this doesn't hold for $S^1$, then exists $y \in \mathbb{R}$ such that $|f^{-1}(y)| > 1$. I'm not sure how to proceed to show that it must be at least an $x \in S^1$ such that $f(x)=f(-x)$


obj == JSON.parse(JSON.stringify(obj)) is false

I was looking at the JavaScript console in Chrome and noticed something strange, even though they appear the same, obj and JSON.parse(JSON.stringify(obj)) are not the same. Why is that?  var obj = {test:'this is a test', another: {omg:'ay dios mio', check:true}}; console.log(obj, JSON.parse(JSON.stringify(obj))); console.log(obj == JSON.parse(JSON.stringify(obj)));   They look identical but return false when you check equality. Why is that?


from where I come from ,they taught us in high school that it is possible to project holograms in thin air simply by illuminating the hologram with the "correct light" , and having a semi transparent medium in the path of the reflecting light "e.g. Water vapor or smoke" resulting in something like this image  -is this true & if not is there any technology that can project such 3dImages in thin air ?


Find all $f: \mathbb{Q} \rightarrow \mathbb{R}$ such that $f(x+y) = f(x)+f(y)$

i have to find all functions $f: \mathbb{Q} \rightarrow \mathbb{R}$, such that $f(x+y)=f(x)+f(y)$.  So functions of the form $f(x) := ax, a \in \mathbb{R}$ satisfy the above condition: $$ f(x+y)=a(x+y)=ax+ay=f(x)+f(y) $$  But how do i proove that all functions that satisfy the above condition have the form $f(x) := ax, a \in \mathbb{R}$?  Thanks in advance!


Unable to install npm on ubuntu 14.04 due to broken packages error

Tried installing npm on ubuntu 14.04 however the following error has occurred   gwt@gwt-Aspire-E1-571:~$ sudo apt-get install npm  Reading package lists... Done  Building dependency tree   Reading state information... Done  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:   npm : Depends: nodejs but it is not going to be installed         Depends: node-abbrev (>= 1.0.4) but it is not going to be installed        Depends: node-ansi but it is not going to be installed        Depends: node-archy but it is not going to be installed        Depends: node-block-stream but it is not going to be installed        Depends: node-fstream (>= 0.1.22) but it is not going to be installed        Depends: node-fstream-ignore but it is not going to be installed        Depends: node-github-url-from-git but it is not going to be installed        Depends: node-glob (>= 3.1.21) but it is not going to be installed        Depends: node-graceful-fs (>= 2.0.0) but it is not going to be installed        Depends: node-inherits but it is not going to be installed        Depends: node-ini (>= 1.1.0) but it is not going to be installed        Depends: node-lockfile but it is not going to be installed        Depends: node-lru-cache (>= 2.3.0) but it is not going to be installed        Depends: node-minimatch (>= 0.2.11) but it is not going to be installed        Depends: node-mkdirp (>= 0.3.3) but it is not going to be installed        Depends: node-gyp (>= 0.10.9) but it is not going to be installed        Depends: node-nopt (>= 2.1.1) but it is not going to be installed        Depends: node-npmlog but it is not going to be installed        Depends: node-once but it is not going to be installed        Depends: node-osenv but it is not going to be installed        Depends: node-read but it is not going to be installed        Depends: node-read-package-json (>= 1.1.0) but it is not going to be installed        Depends: node-request (>= 2.25.0) but it is not going to be installed        Depends: node-retry but it is not going to be installed        Depends: node-rimraf (>= 2.2.2) but it is not going to be installed        Depends: node-semver (>= 2.1.0) but it is not going to be installed        Depends: node-sha but it is not going to be installed        Depends: node-slide but it is not going to be installed        Depends: node-tar (>= 0.1.18) but it is not going to be installed        Depends: node-which but it is not going to be installed E: Unable to correct problems, you have held broken packages. gwt@gwt-Aspire-E1-571:~$    Kindly advice a solution to this problem as unable to proceed further.


I am new at using QGIS. How can I simply split features in QGIS? The manual tells to simply draw a line through the polygon you want to split. But it doesn't work. The line disappears when finishing it. When I select the polygon and then split it, it sometimes works and sometimes doesn't (an info appears after which it does not split the feature). Does anybody have an idea why the tool does not work properly?


Philippine passport holder stop over in Vancouver Canada

I hold a Philippine passport, with a C1 visa (transit visa to US). I had booked flights traveling back to Manila from Barbados.  My iterinary is from BGI to JFK, then on JFK New York then Cathay Pacific. I still need to stop over in YVR - Vancouver - Canada before heading to Hong Kong. Do I still need to have a transit visa from Canada , even will just stop over for 3hrs just to pick up passengers from there and heading to Hongkong?  Or am I eligible to TWOV transit without visa as holding a Philippine passport and have a C1 transit visa from US.  Thanks in advance.


Difference between bandwidth and actual speed ?

I leased a line from an ISP that offers me a bandwidth of 4mb/s.But I receive only a speed of 160 kbps when downloading files over internet.I found that the actual speed I receive is the ISP throughput.  Why should i pay for unused bandwidth if i can only get a speed that is in kbps range ?  Also, what is the significance of ISP advertising in terms of bandwidth rather than throughput ? what are the factors that determine  ISP throughput ?  I find most of the people confusing Bandwidth with the actual speed they receive.People think that they get 4mb/s speed  while  accessing a file over internet when they have a leased line of 4 mb/s bandwidth.


Does the Affordable Care Act (Obamacare) require insurance to be paid with pre- or post-tax dollars?

I would like to continue paying for health insurance with pre-tax dollars.  But, according to , buying healthcare through the Affordable Care Act (Obamacare) requires post-tax dollars.   Is the article accurate, or can I continue to use pre-tax dollars to pay for health insurance?


Hyphen: “well defined” vs. “well-defined”

Traditional English grammar teaches us that a well-defined function is a function that is well defined. With the hyphen in the adjective role before the noun and without the hyphen in the role of an adverb with a past participle after the noun. (E.g., see a question about , which is following the general rule, while the current one is about mathematical jargon.)  However, continuing an  of Mr. West, a function that is well defined is a function for which we have done a good job of giving a definition, but a function that is well-defined is an object that has been given a valid definition as a function, with every domain element given a unique image. Said that, in the second meaning (an object that has been given a valid definition as a function, with every domain element given a unique image), should the mathematicians use the hyphen in "well?defined" in the after-the-noun position?  PS. I asked the  at math.se, but they put it on hold, claiming that it could be off-topic there. Only one person gave his/her opinion, which I liked, but I'd like to hear other arguments, too.


Are getters and setters poor design? Contradictory advice seen

I'm currently working on a simple game in Java with several different modes. I've extended a main Game class to put the main logic within the other classes. Despite this, the main game class is still pretty hefty.  After taking a quick look at my code the majority of it was Getters and Setters (60%) compared to the rest that is truly needed for the logic of the game.  A couple of Google searches have claimed that Getters and Setters are evil, whilst others have claimed that they are necessary for good OO practice and great programs.  So what should I do? Which should it be? Should I be changing my Getters and Setters for my private variables, or should I stick with them?


Inequality with sum of Binomial coefficients: $\sum\limits^n_{k=1}k \sqrt{\binom nk}\leq\sqrt{2^{n-1}n^3}$

Prove that for every positive integer $n \ge 2$ $$\sum^n_{k=1}k \sqrt{\binom nk}\leq\sqrt{2^{n-1}n^3}$$ I tried it by induction but I didn't know how to end it.


I'm writing a paper in LaTeX and want to include some figures from Matlab.  I have 2d plots and 3d surfaces to include.   Are there any guides to academic writing / published papers which show best practices of including Matlab-type figures? (Eg axis labeling, legends, angle of view for 3d surfaces) What's the best way to port my Matlab figures into LaTeX that'll allow me flexibility with axes, angle of view, etc. I can export as PDF to get the job done, but it looks quite amateur.


Find all files that are NOT of a specific type/extension in folder?

Windows 7 Ultimate 64bit:  I'm looking for a way to find all the files in a directory that are NOT of a specific file type or extension.  Example: I'd like to find every file that isn't an .mp3 in my music folder (and all sub folders).


My class extends AppCompatActivity  This is my class  public class Login extends AppCompatActivity {      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_login);          final Button loginBtn = (Button) findViewById(R.id.login_btn);         loginBtn.setOnClickListener(new View.OnClickListener() {             public void onClick(View v) {                 // Perform action on click                 Login login = new Login();                 try {                     login.getAccessCode();                 }                 catch (IOException e){                     Log.e("LOGIN", "I got an error", e);                 }              }         });     }      public void getAccessCode() throws IOException {         RequestParams params = new RequestParams();         params.put("a", "a");          QuidoRestClient.post("/login/generateCode", params, new JsonHttpResponseHandler() {             @Override             public void onSuccess(int statusCode, Header[] headers, JSONObject response) {                 // If the response is JSONObject instead of expected JSONArray                 Log.d("LOGIN",response.toString());                 String code = "";                 try {                     code = response.getString("code");                 }                 catch (JSONException e){                  }                 Context context = getApplicationContext();                 CharSequence text = "Hello toast!";                 int duration = Toast.LENGTH_SHORT;                  Toast toast = Toast.makeText(context, text, duration);                 toast.show();             }              @Override             public void onSuccess(int statusCode, Header[] headers, JSONArray data) {                 // If the response is JSONArray instead of expected JSONObject             }         });     } }   This is the error  java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference   I've also tried   Toast toast = Toast.makeText(Login.this, text, duration);   I've solved the issue by calling my method directly instead of Login login = new Login();


I am trying to use the new colorbrewer library and get the following error:     Error: I do not know the key '/pgfplots/colormap/YlOrBr' and I am   going to ignore it.   \documentclass{standalone} \usepackage{pgfplots} \pgfplotsset{compat=1.13} \usepgfplotslibrary{colorbrewer} \usepgfplotslibrary{colormaps}  \begin{document}  \begin{tikzpicture}   \begin{axis}[]     \addplot3[surf, colormap/YlOrBr, samples=41, domain=0:360] {sin(x)*sin(y)};   \end{axis} \end{tikzpicture} \end{document}   Where is my mistake?  Edit: I previously updated pgfplots to 1.13 with the TexLiveUtility under Mac OS 10.11.3. It tells me now that I have the newest version. Also \pgfplotsset{compat=1.13} does not throw an error.


Prove that $\sum_{k=1}^\infty \sqrt{k+1}-\sqrt{k}$ diverges. I know that this diverges but I don't know how to prove it rigorously. Should I use the comparison theorem? I know that $\sqrt{k+1}-\sqrt{k}>-\sqrt{k}$ so I just need to show that $\sum_{k=1}^\infty -\sqrt{k}$ diverges. But that is where I am stuck.


I am getting a null pointer exception when I call my method to create a new String copy of the passed argument. This method is called from my main.   Why am I getting this error and how do I fix it so it's not pointing to null?  It says the error is happening on this line :front.data = original.charAt(i);  and if I change the size to -1 it gives the error on this line back.next = newNode;  Main (relevant part of method):  public class TestLString {   /** Main method */    public static void main(String[] args) {        String str1 = "Hello, my name is Alphose!";       LString lstr1 = new LString(str1);   EDIT: This seemed to work!     public LString(String original){   size = 0;   for(int i = 0; i< original.length(); i++){      if(original.length() == 0){                              ///changed         front = new Node();         front.data = original.charAt(i);         front.next = back;         size++;      } else{            Node newNode = new Node();            newNode.data = original.charAt(i);            Node back = new Node();            back.next = newNode;            newNode.next = null;            back = newNode;        }   }   }    my initialized data field(sorry about that). Let me know if I can add anything else.  public class LString{      private Node front = null;  //first val in list    private Node back;   //last val in list    private int size = 0;    private int i;    private int offset;     public LString(){       //construct empty list       Node LString = new Node();       front = null;     }


Cardinality of a finite $\sigma$-algebra

Can you help me to prove, that the cardinality of a finite $\sigma$-algebra is $2^n$ for a $n\in\mathbb{N}$.  My first idea was to look at an easy example, but even there i have a problem. I look at two subsets $A,B\subset\Omega$ and want these to be in the $\sigma$-Algebra. I get $\{\Omega, \varnothing, A, B, A^C, B^C, A\cup B, (A\cup B)^C, A\cup B^C, (A\cup B^C)^C, A^C\cup B, (A^C\cup B)^C, A^C\cup B^C, (A^C\cup B^C)^C\}$. So here at least two elements are missing or there are two elements too much. Can you please tell me where my mistake is and give me a hint how to prove the statement.


How do I remove excess whitespace being generated by an EL tag in JSP?

The idea is to print the authors of each book and to add a comma in between each author. The generated HTML is adding tons of white space, which creates a single space between the comma and the next name. See screenshot. I'm trying to remove that excess space.

         <c:forEach items="${book.authors}" var="author" varStatus="loop">             ${author.firstName} ${author.middleInitials} ${author.lastName}             <c:choose>                 <c:when test="${author.postNominalInitials != null}">                     ${author.postNominalInitials}                 </c:when>             </c:choose>             <c:if test="${!loop.last}">,</c:if>         </c:forEach>

   The goal is to remove the space after each author's name (and eventually replace the final comma with 'and')    Here's the readout from the Google inspector, where I'm seeing the additional   white space being added.     Thank you for the help!


I would like to create the following table bases on the answer of @Zarko  since i use the same code for another kind of table     \documentclass{article} \usepackage[utf8]{inputenc} \usepackage[table]{xcolor} \usepackage{tabularx} \usepackage{enumitem} \usepackage{etoolbox} \AtBeginEnvironment{center}{%     \setlist[itemize,1]{nosep,                         topsep     = 0pt,                         partopsep  = 0pt,                         leftmargin = *,                         label      = \textendash,                         before     = \vspace{-0.6\baselineskip},                         after      = \vspace{-\baselineskip}                         }     \setlist[itemize]{  nosep,                         leftmargin=*,                         label = $\bullet$                       } }  \begin{document}     \begin{center} \bfseries \begin{tabularx}{\linewidth}{ | l | X |X| }     \hline \multicolumn{2}{|>{\centering\arraybackslash}%                  p{\dimexpr\linewidth-2\tabcolsep-2\arrayrulewidth\relax}|}{\cellcolor{gray!30}     Very long text here and centered     Very long text here and centered     Very long text here and centered}    \\     \hline \multicolumn{3}{c}{}                    \\     \hline Year &   Cycle & Issues     \\     \hline 2018-2019   & High School & very \\     \hline \end{tabularx}     \end{center} \end{document}


I don't know whether this has been raised before, but I can't find a question on it so I'm raising it here.  I think there should least be a configurable option to change the behavior of the Stack Exchange inbox.  I like that I'm told that I have (say) 4 new 'notifications' waiting for me, but I have 2 issues with the behavior.   When I click on the Stack Exchange dropdown and go to inbox, those 4 new 'notifications' are not highlighted.  Am I just to assume that the 4 most recent are the new ones?  It would be very convenient if they were highlighted. When I click on one of the links and go to a reply or something, suddenly my 'new notifications' drops to zero.  I only visited one of the notifications... I still want to know what the other 3 were!  Argh.  Could we have it so that the new ones are highlighted, and when I click one, it becomes un-highlighted, but doesn't mark all new notifications as if they had been read?


I am investigating the slicing of a string with the following code: s='abcdefgh' print(len(s)) print(s[-1:-9:-1]) print(s[-8])  whose output is: 8 hgfedcba a  Why when printing reverse we need to slice till -9 while the last character i.e 'a' at -8?


Rigorous proof of the closure of irrational numbers are reals

I am wondering how I can prove that the closure of irrationals are reals. It is intuitively and logically sensible since irrationals and rationals are dense everywhere; thus, taking the closure of irrationals means it is also reals containing the irrationals. But how can I put this into a rigorous mathematical proof?


I have an old YU Yureka piece, and it has gone into a boot loop.  What happens is, CYANOGEN logo comes up in the beginning, and then "Android is starting - Optimizing x/123 apps" comes up. As x reaches 123, the phone reboots again, and the same thing starts all over again.  One thing note worthing is that it's not always x/123. Sometimes it goes till x/9, x/29, x/27, x/120 etc.. It's not in any decreasing/increasing order. I have let this thing run many times, and for many hours (I was hopeful it would just magically show up my home screen after x reached whatever).  But thanks to my hopefulness, Once it so happened that when it was x/9, and x reached 9 and the phone rebooted, it did not do the same thing again but the phone started!! But only until I connected my cable to get all the data, it rebooted again and the boot loop continued from x/123 this time.  Other things you might want to know:   My phone is pattern protected (locked) It is not rooted ADB was not set up from the settings AND I AM CONCERNED ABOUT MY DATA, so no wiping/formatting of Internal SD card!   Oh, and Cyanogen rescue mode has the following options:   Reboot system now Apply update Wipe data/factory reset (I want to avoid this) Wipe cache partition (I have tried this) Wipe media Reboot to bootloader Power [???] [???] logs   Sorry for [???] as whatever is written there I can't read it due to a screen display problem.  Right now I am just waiting for that magic to happen again, hopefully if the home screen comes up, this time instead of connecting it with cable, I will first remove the lock pattern, and set up ADB. But I have no clue how it happened last time, or how/when will it happen again.  Also I am unable to connect with fast boot, as I guess we need ADB set up for that. Is that right? adb devices does not list my device. I haven't really worked much with fast boot, flashing, etc. But I will be comfortable to follow instructions. All I want is to rescue my data.  Any help is appreciated :)


How do I opt-out of the new Reply in Gmail?

Today, when trying to reply to a message in Gmail, I was told that there is a new reply mode and then it was automatically enabled. I find it difficult to use, and it doesn't let you reply to the message in accordance with the netiquette I'm used to.  How do I opt-out of this brand new reply mode? It wasn't there yesterday.


Infinite series sum which have infinite terms

Sum of series $\displaystyle \frac{15}{16}+\frac{15}{16}\cdot\frac{21}{24}+\frac{15}{16}\cdot\frac{21}{24}\cdot \frac{27}{32}+\cdots\cdots $  what i try   $\displaystyle S =\frac{15}{16}+\frac{15\cdot 21}{16\cdot 24}+\frac{15\cdot 21\cdot 27}{16\cdot 24\cdot 32}+\cdots \cdots $  i am trying to convert numerator and denomiantor terms into arithmetic progression  $\displaystyle \frac{9S}{8}=\frac{9\cdot 15}{8\cdot 16}+\frac{9\cdot 15\cdot 21}{8\cdot 16\cdot 24}+\cdots \cdots $  $\displaystyle \frac{9S}{8}+\frac{9}{8}+1=1+\frac{9}{8}+\frac{9\cdot 15}{8\cdot 16}+\frac{9\cdot 15\cdot 21}{8\cdot 16\cdot 24}+\cdots \cdots $  but  it is divergent series  i did not know how i solve that infinite series  Help me how to solve


What does the command ./ mean? For example, sometimes we call a file with ./config, sometimes ../config, thanks


How to reach $\dfrac{(n-1)n(2n-1)}{6n^3}$

I am trying to refresh my Maths after a lot of years without studying them, and I am finding a lot of difficulties (which is actually nice). So, my question:  I don't understand the next equality. How to reach $\frac{(n-1)n(2n-1)}{6n^3}$ from $$\frac{1^2+ 2^2+...+ (n-1)^2}{n^3}$$?  Thank you very much (and sorry if I make mistakes; my English is also rusty :))


Delete first 10 Lines From Multiple Files

The files are named file00 through file99 (hundred files). They are all in the same directory. How do I grab all the hundred files and delete the first 10 lines from each file? I am using CentOS 7.


Ubuntu 15.10 updates - Failed to download repository information - check internet connection

I had previous problems like this, first it did not want to update anything. It always sad:  Failed to download repository information check your internet connection,  but i have internet connection and i discovered just to uncheck the PPA packadges that caused the problem and i successfully update all my software. After that a exclamation mark in triangular sign appeard next to Wifi icon that says:  The update information is outdated. This may be caused by network problems or by a repository that is no longer available. Please update manually by selecting 'Show updates' from the indicator menu, and watching for any failing repositories.  After clicking on that it says your software is up to date, but when i try to press update it's checking for cache and says, as always, FAILED TO DOWNLOAD REPOSITORY INFORMATION CHECK YOUR INTERNET CONNECTION.  Is this problem with a wirelles driver, or some packadges that needs to be removed? Solutions? Suggestions?


Book about a technologically advanced society which reverts to a medieval style one when all energy is drained away by a God-Computer

I read this some 5 to 10 years ago (in German). It was a series of books, afaik not yet finished. In a future world, science had advanced to basically magic. At some point however, the key holders for a neutral God-Computer start a coup. Suddenly energy for technical stuff for everyone except the key holders is taken away. No personal shields, etc. Society reverts to something more or less medieval. No black powder for example is possible because the energy is absorbed by the computer. There are dragons and elves. In a later book a spaceship to refuel power plants arrives.


Dual citizenship (Australia/Canada). ESTA and smart gates

I have a roundutrip planned from Sydney to Los Angeles. I think the easiest would be to get an ESTA on my Australian passport and just travel on that passport alone. But I'm looking to avoid this if possible as I would rather use my Canadian passport to enter the US (no fingerprint… eye scan; may get preferred line at immigration; no ESTA fee or application).  I have valid passports for both countries (identical personal information, name, dob). Australia rules suggest that I must leave/enter Sydney with my Australian passport. From reading dual citizenship posts on this website, it seems an ESTA may not be needed on for an Australian passport.  Departure flight: I can check in with the airline (Delta) in Sydney with my Canadian passport, then proceed to immigration and leave with my Australian passport. I enter the US at LAX with my Canadian passport. For the return flight: at LAX, I should check in with the airline with my Australian passport (even though I don't have an ESTA) to show I have status to return to Australia, exit at US customs on my Canadian passport (because I entered the US on that passport).   Is it ok to travel without an ESTA on an AU passport even though I will need the AU passport at LAX to fly back to Australia? Will the new smart gates used at airport security/immigration allow passage if the airline ticket and country of passport do not match (ie in Sydney having checked in with the airline with my Canadian passport but use the Australian passport at smart gates or vice versa at LAX)?


Best way to cater to two audiences on one website

We are re-designing our corporate website and we need to cater to two distinct audiences: small business owners and large enterprises. The products we offer are the same for both audiences - but how we message the value of these products vary by audience. Management suggests making visitors choose who they are on the homepage, directing them to a personalized products page. But I'm skeptical of this approach. Is there a better way to "split" our website to address both audiences?


Is there a difference between Cursor.Current and this.Cursor (where this is a WinForm) in .Net? I've always used this.Cursor and have had very good luck with it but I've recently started using CodeRush and just embedded some code in a "Wait Cursor" block and CodeRush used the Cursor.Current property. I've seen on the Internet and at work where other programmers have had some problems with the Cursor.Current property. It just got me to wondering if there is a difference in the two. Thanks in advance.  I did a little test. I have two winforms. I click a button on form1, set the Cursor.Current property to Cursors.WaitCursor and then show form2. The cursor doesn't change on either form. It remains Cursors.Default (pointer) cursor.  If I set this.Cursor to Cursors.WaitCursor in the button click event on form1 and show form2, the wait cursor only shows on form1 and the default cursor is on form2 which is expected. So, I still don't know what Cursor.Current does.


I' ve got this string:  DealerCode = [MAZ3].AccountID:[4340].StartDate=[2015-06-01]  select parsename('DealerCode = [MAZ3].AccountID:[4340].StartDate=[2015-06-01]', 1)    and so on gives me null. How should i change my query to get values between dots?


Background: I've been having some sleep issues so I have started tracking my sleep habits along with some other data but so far, they are just entries in Evernote and as such it is not possible to see any patterns. Obviously I need a spreadsheet app with charting capabilities (doh!). I've been using a great iPhone app called  for data collection for sleep times and then enter those into Evernote.  I have the iWork set so I have been looking at Numbers and going through some tutorials but I still can't tell if it will do what I want. Given that my data set will increase daily, I'd like to be able to "page through" a chart/data set, so it shows say the last 30 data entries. With all the tutorials I have seen, the charts are of fixed size and adding more data to a linked table just causes the chart to cram more stuff in.  Can Numbers do this sort of "paging" of data? I would like to have this sort of "on the fly" charting rather than having to explicitly build a chart each time I want to visualize the data.   (sorry the question is rather garbled: I don't know really anything about using a spreadsheet type app)


I was trying to resize my EXT4 partition and something went wrong. I lost it. The space in once consumed is now being represented as Unallocated. How do I recover the partition?


Review late answers to old questions asking for tools or libraries: What should I do?

What should I do when I have to review a late answer to an old question asking for tools or libraries?  A few days ago, I had an answer to review to an old question. I flagged the answer as spam and my flag was declined. I do not contest it: in addition to a link for a tools, the answer contains a part of the answer to question.   But I have seen later that the question has been closed. So I am not sure about what  should be do now.   I just had an answer to review, answer to this old question:   . The answer is a link-only answer, but it is what is asked. So:   I skipped the answer (I can't say this is not an answer) I flagged the question to be closed (Questions asking us to recommend or find a tool, library or favorite off-site resource are off-topic for Stack Overflow as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it.)   Is it the correct thing to do? Or what should I do instead (with the answer And the question)?


Selective breeding of organisms to survive on Mars

It seems that there may have been life on Mars, and it's also tempting to terraform and colonize the planet. This question is about testing the hypothesis "Can primitive life survive on Mars?". This is closely linked to the , that life can be seeded from bacteria on meteorites. The hypothetical experimental setup is as follows:  Take microorganisms that live in the upper atmosphere and  Recreate their natural environment in a lab, and let them live there Slowly change the environment to be more similar to Mars: pressure, temperature swings, radiation, relative gas concentration See if they are able to adjust  My question is: Is this possible? Has anyone done it, or is doing it currently? I know tardigrades are being sent to the moon, but they're hardly thriving there. My apologies if the non-expert question is off topic. If you can suggest a more appropriate place to ask, I'll keenly do so.


GeoServer 2.10.0 - How to use CreateStoredQuery

I need to create the GetSpatialDataSet stored query in my WFS service to follow the INSPIRE rules.  That WFS service is in a GeoServer 2.10.0. I have checked the official docs about how to create a stored query:   The problem is I don't know what I am supposed to do with that piece of code.  <wfs:CreateStoredQuery service='WFS' version='2.0.0'  xmlns:wfs='http://www.opengis.net/wfs/2.0'  xmlns:fes='http://www.opengis.org/fes/2.0'  xmlns:gml='http://www.opengis.net/gml/3.2'  xmlns:myns='http://www.someserver.com/myns'  xmlns:topp='http://www.openplans.org/topp'> <wfs:StoredQueryDefinition id='myStoredQuery'> <wfs:Parameter name='AreaOfInterest' type='gml:Polygon'/> <wfs:QueryExpressionText  returnFeatureTypes='topp:states'  language='urn:ogc:def:queryLanguage:OGC-WFS::WFS_QueryExpression'  isPrivate='false'>   <wfs:Query typeNames='topp:states'>     <fes:Filter>       <fes:Within>         <fes:ValueReference>the_geom</fes:ValueReference>          ${AreaOfInterest}       </fes:Within>     </fes:Filter>   </wfs:Query> </wfs:QueryExpressionText>      Where should I paste it? It says it's a POST request, but that doesn't tell me anything.  EDIT: I have tried the following script from another answer:  <html> <head> <title>WFS Test</title> <script language="JavaScript">   function doit()   {     var url = 'http://myserver:8080/geoserver/test/wfs';     var method = 'POST';     var postData = '<wfs:CreateStoredQuery\n'     + 'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"\n'     + 'xsi:schemaLocation=\n'     + '"http://www.opengis.net/wfs/2.0\n'     + 'http://schemas.opengis.net/wfs/2.0/wfs.xsd"\n'     + 'xmlns:cp_inspire="urn:x- inspire:specification:gmlas:CadastralParcels:4.0"\n'     + 'xmlns:fes="http://www.opengis.org/fes/2.0"\n'     + 'xmlns:wfs="http://www.opengis.net/wfs/2.0"\n'     + 'xmlns:gml="http://www.opengis.net/gml/3.2"\n'     + 'xmlns:xsd="http://www.w3.org/2001/XMLSchema"\n'     + 'service="WFS"\n'     + 'version="2.0.0">\n'     + '<wfs:StoredQueryDefinition\n'     + 'id=\'' +  'http://inspire.ec.europa.eu/operation/download/GetSpatialDataSet' + '\'>\n'     + '<wfs:Parameter name=\'' + 'CRS' + '\' type=\'' + 'xsd:string' + '\'/>\n'     + '<wfs:Parameter name=\'' + 'DataSetIdCode' + '\' type=\'' + 'xsd:string' +'\'/>\n'     + '<wfs:Parameter name=\'' + 'DataSetIdNamespace' + '\' type=\'' + 'xsd:string' +'\'/>\n'     + '<wfs:Parameter name=\'' + 'Language' + '\' type=\'' + 'xsd:string' + '\'/>\n'     + '<wfs:Parameter name="count" type="xsd:integer"></wfs:Parameter>\n'     + '<wfs:QueryExpressionText\n'     + 'returnFeatureTypes=\'' + 'cp_inspire:CP.CadastralParcel' + '\'\n'     + 'language=\'' + 'urn:ogc:def:queryLanguage:OGC-WFS::WFS_QueryExpression' + '\'\n'     + 'isPrivate=\'' + 'false' + '\'>\n'     + '<wfs:Query typeNames=\'' + 'cp_inspire:CP.CadastralParcel' + '\' srsName="${CRS}">\n'     + '</wfs:Query>\n'     + '</wfs:QueryExpressionText>\n'     + '</wfs:StoredQueryDefinition>\n'     + '</wfs:CreateStoredQuery>\n';  var req = new XMLHttpRequest(); req.open("POST", url, true); req.setRequestHeader('User-Agent', 'XMLHTTP/1.0'); req.setRequestHeader('Content-type', 'test/xml'); req.onreadystatechange = function () {   if (req.readyState != 4) return;   if (req.status != 200 && req.status != 304) {     alert('HTTP error ' + req.status);     return;   }   alert(req.responseText); } if (req.readyState == 4) return; req.send(postData);   }        But I'm getting this error:    Does anyone see where is the problem?


Barchart of Differences of Prime Numbers. - Why do multiples of six occur more frequently?

Looks like 6,12,18,24 etc. are peaks compared to their near neighbors. Any insights why? Click on   to see Bar Chart


Can't log in: Can I get files using tty1?

My Ubuntu wont log in. If I type a correct password it just goes to a blank unity wallpaper and back to the log in screen. Funny It's being buggy when I decide to switch back to windows after a month of learning fun Linux commands.  How can I restore 1 text file from my documents folder in tty1? Since I can't log in, I only have guest and tty1. What should I do to recover things back? Can I reinstall unity through tty1 or something?


How do I prevent object distortion when applying a curve modifier?

This is the profile of the object I'd like to wrap...    Here is the object's profile after being wrapped...    Is it possible to prevent the distortion? The following post here:  did not affect my object. It seemed very promising, maybe I'm missing something?  Note: I have applied the scale to both my object and curve.


Does concealment allow a rogue to make sneak attack?

Can a rogue use cover or concealment in order to Hide, and thereafter make sneak attacks against enemies he is hidden from?  For example:   A rogue sneak attacks an ogre in melee, then runs behind a wall and hides. Having successfully hidden, the rogue runs out the next round and attacks the ogre again. Can he make Sneak Attack? The party is walking through the woods when one is hit by a rogue sniper, who remains hidden. The sniper deals sneak attack damage. The party is now aware of the sniper, but all fail their Spot checks and can't see him. Do the rogue's subsequent attacks deal sneak attack damage?   Rules-as-written, does hiding due to concealment, total concealment or cover explicitly allow you to make sneak attacks? Invisibility or a blinded opponent specifically do, but is there a rule somewhere that you lose Dexterity to AC against opponents who are merely hidden?


Why does LIGO have an arm length of few kilometers? Is the distance dependent on Gravitational Wave wavelength?

Antennas for capturing radio waves need to have $\frac{\lambda}{2}$  length for optimum reception of signal. Does it imply LIGO arm length is $\frac{\lambda}{2}$ of Gravitational Wave it is trying to capture?


Main method is not static in class error

class useTent {     Scanner keyboard=new Scanner (System.in);      public void main (String[] args)     {          Tent t= new Tent();         HireContract hc = new HireContract();         ProcessHire(t, hc);     } }   this is my code, and i keep getting the same error:     " Main method is not static in class useTent, please define the main method as:      public static void main(String[] args) "   and when i make the it static i get the following error:     "C:\Users\Emma\Documents\opps ass1\useTent.java:22: error: non-static method    ProcessHire(Tent,HireContract) cannot be referenced from a static context ProcessHire(t, hc);"   and also still the     "Error: Main method is not static in class useTent, please define the main method as:      public static void main(String[] args)"


How to finish PhD and get through the academic job market as a new mother and primary caregiver?

I am a female graduate student in a competitive phd program.  I recently had a baby.  Although this is a planned pregnancy, and I thought I had thought through the complications having a baby would bring, I am still very overwhelmed by how much different my life is now.  I don't have any time besides taking care of a newborn, and I am very sleep-deprived.  Baby's dad works full-time to support the family.  Even though it brings me a lot of joy, I just can't help but wonder whether I would ever have time for my research again.  I initially planned to go back to school in September, when baby will be about 3 months old.  But I am not sure whether I would be able to do anything next semester.  Or even the semester after next.  I initially planned to graduate next fall, but now I feel that might be a stretch.  The application starts next semester, and I should be going around giving talks and preparing for my applications.  But that feels impossible now.  And there is the financial stress.  I want to put my child in daycare at some point (like around 7,8 months), so I can have some time to do work.  But it's very expensive, and I don't know if we can afford this with our current income.  Sometimes I thought about finding an industry job after graduate school, so things would be easier.  But I don't want to give up research.  What is an effective way to deal with the stresses of being a new mother while on the job market? Specifically, how can I complete my research and apply to jobs in a situation where I am sleep deprived and child care is expensive?    This is a different question than  because I believe a female student's experience is different than a male student's experience.  Especially at infant stage, mother's role cannot be placed by others due to constant feedings.  The author in the other post also has his girlfriend/wife staying at home with the baby, so there will be much less work for him.  In my case, I would be the one taking care of the baby since my husband works full-time.  Another thing is I am already at the stage that I am about to graduate as opposed to the other post is debating whether to start the program, so I am more concerned about the graduation timeline.


On Linux, I've downloaded the "" Beamer theme to my ~/texmf folder. I've run texhash ~/texmf, which happily creates an ls-R file containing this:  % ls-R -- filename database for kpathsea; do not change this line. ./: .: beamerthemediepen-master ls-R  [some lines omitted]  ./beamerthemediepen-master/themes/theme: beamerthemediepen.sty   But if I then run kpsewhich beamerthemediepen.sty, it prints nothing. And, indeed, trying to use \usetheme{diepen} in my Beamer file results in this error message:   File `beamerthemediepen.sty' not found.   What am I missing?


I have been having an issue with my viewport that I can't seem to figure out. The mesh that I have for my ground plane has strange clipping and perspective issues in wireframe mode and object mode. When I am in render view or lookdev mode the plane appears as normal.        I have tried deleting the ground plane and the camera. When I delete the camera the 'shadow' of the camera position remains. When I try to add a new plane I still have the same perspective and clipping issue. It seems like I have somehow locked the camera in this position, but I am still able to move the camera around and into new positions, but there is strange clipping on them within this new perspective I somehow manage to create.     Does anyone have any idea what I managed to do here? I have been trying to figure it out for 2 hours...  Many thanks, Collin


Find all rational solutions to $x^2+y^2=2$   I rewrote the equation to $x= \sqrt{2-y^2}$ and thought that $x$ is rational if and only if $2-y^2$ is a square. So the only solution to the first problem is $x=1$ or $-1$ and $y=1$ or $-1$.   Is there another approach? Thank you.  Edit: Another question: Is there maybe a way to show this using elliptic curves?


“Sets,” “classes,” and “collections”: what’s the difference?

After reading about Russel’s Paradox and the Burali-Forti paradox, I’ve been doing some research into how classes work. , a class is defined loosely as  a collection of sets (or sometimes other mathematical objects) that can be unambiguously defined by a property that all its members share.  What exactly does “collection” mean here? I was under the impression that the purpose of formally defining sets was to formalize the intuitive notion of a “collection” - but the existence of classes that aren’t sets implies that sets don’t actually formalize our notion of a “collection” adequately. If $\Omega$ (say) is the class of all sets, and classes are forbidden from containing themselves, we might define $\Omega’$ as the “collection” of all classes, such that $\Omega’$ is a type of collection that is not a class (call it a meta-class). Similarly, we can define the meta-meta-class $\Omega’’$ as the class of all meta-classes, and so on... eventually we can define $\Omega^n$ for any finite number $n$, and $\Omega^\alpha$ for any ordinal $\alpha$, and even define $\Omega^\Omega$ as the “collection” of all objects of the form $\Omega^\alpha$, where $\alpha$ is an ordinal. And so on. Basically, we have to keep defining new “higher” types of containers to contain previous types of containers, in order to avoid paradox. But all of these things are apparently still “collections” (intuitively). Does it make sense to talk about a “collection of all collections,” or does this result in a paradox? So my question is: what exactly does “collection” mean? Why is it so hard to formalize our intuitive notion of a “collection”, and why have sets and classes failed? What properties do “collections” have that sets and classes (and meta-classes, and meta-meta-classes, etc) don’t have?