I own a domain name that uses the .co extension and I'm located in France. Someone just advise me to get a .fr domain because it would make my local searches in France better.   I personally thought that Google likes brandnames and would'nt care much about extension but do you have any advice on that? Does anyone has back up numbers to back that up?

I basically have 2 questions about local TLD vs .com.  First question: There already exists a website "keyword.nl" with a crappy website, no SEO optimisation. Is it possible for a website "keyword.com" to rank higher than the "keyword.nl" website on "google.nl" when searching for "keyword"? Or will it always display the .nl website higher because it's a local TLD and the URL consists entirely and only from the searched keyword and it's searched on the .nl version of google?  Second question: I know it's good for SEO to have many websites link to your website. But I also read that local TLD's will score higher on that specific google TLD (.fr website will rank higher in google.fr, etc.) With both those facts in mind, is it better to create a "keyword.com/fr/" and "keyword.com/nl/" website or a "keyword.fr" and a "keyword.nl" website? (In other words, .com/langauge for more links to the website, or a "keyword.local-TLD" website for every different language version of the website) Or maybe even a subdomain? ("fr.keyword.com?")  Kinda new to this, so thanks in advance!  --Edit: additional info--  The reason that I phrased the original question like this is because I wanted to keep the question strictly "webmaster-side". However I feel like maybe I should clarify the background of this question more thoroughly, so the question becomes more clear, and thus the answer. But I don't know if this would make the question a more legal one instead of a "webmaster" one, so please correct me if this is the wrong place to post this question.  I'm a student working on websites in my sparetime, I have basic knowledge about SEO, but that was all local, for companies operating only in one country. However this time a friend contacted me who wants to found a company called "X" (e.g). He wants to ship/operate to multiple countries, but he will first found it (and he himself) lives in The Netherlands (.nl). However there already exists a company in The Netherlands called "x" with the website "x.nl". As far as I understood, the fact that both the companies are called "x" doesn't matter, in trademark/company registery terms, since they are both operating in different work sectors.    But the main issue here is, could my friends website "x.com/nl" outrank the "x.nl" on "google.nl" if you only search on the brand name; "x"?  @Closetnoc:  Hi, thanks a lot for your answer, it gave me some clarification however I feel you misunderstood my first question because of my use of "keyword.com" as an example URL. So I don't really know what conclussion I should draw from your first answer. I updated my question with additional info to clarify it more broadly. From your second answer this is what I understand: A .nl URL will not do that great on google.com, however a .com URL can do just as well as a .nl search on google.nl? So considering the info above, it's best to go with a x.com/fr and a x.com/nl URL, right? Please correct me if I misunderstood. However, if so, that still leaves the first question, if a "x.nl" is already taken, could a "x.com/nl" still outrank it at "google.nl"?


If $X_1, \ldots, X_n$ are iid $\sim N(\mu,\sigma^2)$,  $\frac 1 {\sigma^2} \Big((X_1-\bar X)^2 + \cdots + (X_n - \bar X)^2 \Big) \sim \chi^2_{n-1}$.  This has been , and is the starting point to derive the  distribution.  I would really like to get a proof without the advanced math in linear algebra projections (if possible), or with a detailed explanation of the steps followed in the derivation (if the use of projections is essential). Thanks!

It's a standard result that given $X_1,\cdots ,X_n $ random sample from $N(\mu,\sigma^2)$, the random variable $$\frac{(n-1)S^2}{\sigma^2}$$ has a chi-square distribution with $(n-1)$ degrees of freedom, where $$S^2=\frac{1}{n-1}\sum^{n}_{i=1}(X_i-\bar{X})^2.$$ I would like help in proving the above result. Thanks.


I'm a JavaScript newbie. Recently I'm learning about JavaScript closures and I'm stuck at the following section: <!DOCTYPE html>
JavaScript Closures

Counting with a local variable.
  <button type="button" onclick="myFunction()">Count!</button>
0
       I understand that the add() function is a self-invoking function and a closure at the same time so it will invoke itself once the webpage is load. The counter will initialize and return 1 immediately. And whenever i press the button (calling the add() function). It should be initialize again and return 1 again. But it turns out my logic is wrong, the counter keeps increasing by 1 when i press the button. I don't understand why as i thought var counter = 0; will be recognized every time and also isn't the variable inside the function should have local scope so after it has executed the counter variable will be destroyed?

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


I am using Ubuntu 16.04-64 bits. Due to the last news about these problems, please can you tell me if I have to install some patches and in that case what have I to do?  Thank you.

Any questions relating to status updates, or asking if anything is going to be patched for these vulnerabilities should be closed as duplicates of this question.    are in the news right now and sound pretty severe. I don't see any security updates from Ubuntu that cover these vulnerabilities.  What is Ubuntu doing about these vulnerabilities, and what should Ubuntu users be doing?  These are CVE-2017-5753, CVE-2017-5715 and CVE-2017-5754.


I submitted a paper to a top tier conference and it did not get accepted. The paper contains an original idea, and I am afraid that the paper could get plagiarized between the time I send it to another conference after incorporating reviewer's suggestions and making some modifications. Such things have happened in the past to a few students in my department.  I had considered posting the paper on arxiv as a means of timestamping before sending it to the aforementioned conference, but didn't, as this would have violated the double-blind review requirements of the conference. (The conference chair replied to my query as follows:)     The submission of a paper in the arxhiv.org system is not strictly   speaking a double-submission, but rather a violation of a double-blind   submission required in this conference, as the reviewers will be able to   find your name (and those of the coauthors) if they do a simple search   in Google. Thus, I am quite certain it will be rejected, and I do not   consider it an acceptable practice in this conference's submission to be    fair with all the submissions in order to handle them equally during the   review process by the reviewers.   Hence I had not posted it on arxiv. Now this paper has been rejected and I would like to timestamp this paper now, while still being able to send a modified version to some conferences in the future (including those that follow a double-blind review).   Is there a mechanism by which I can timestamp my paper that does not violate the blind review requirements?   Edit: The paper was in computer science, if that matters. A related question "" asks about ways to timestamp while keeping the information in the paper private or hidden to avoid plagiarism. However my question is about ways to timestamp such that it is still possible to publish the information while not violating blind review.

If I have a DB or set of data, and want to grant access to it to a limited group of experts in a field (not general access), and don't want others using it for their own publications, nor seeing the information being offered for free on the Internet.   What is the best approach to deposit the information somewhere to make sure, in a hypothetical future, that I can claim copyright over it?  Basically, I want to protect myself upfront against


I am new to Linux world and I would like to help me make the best partitioning choice. I am gonna use Ubuntu 14.04 LTS as my main OS on my desktop PC. Basically I use my PC for : coding, surfing Internet, watching movies, listening to music, maybe sometimes playing games.  So help me choose:   What directories will need partitions ? What file system should I use ? What type of partitions should it be ? Logical or Primary ? Should it be on the Beginning or the End of the drive ?

I would like to see a full how-to guide on how to install Ubuntu.


I cannot seem to find the right bracket to use as a hold down on the tree side for a treehouse knee brace beam.  I need to find one that can bolted to the tree and hold two 2x8's. It looks just like this but I can't find it anywhere.    Also, how do you attach the knee braces to the corners of the platform? There seems to be various ways of doing that. Thanks!

I am going to be building a Treehouse soon, and am researching the best and most cost effective means to do so.  I am good on the platform and beams (using Treehouse Attachment Bolts), and am going to use 45 degree knee braces for additional stability.  They make some great , but man are they pricey. Almost $100 each, and we'll need four of them.  Also mentioned at this .  When reading some books, and other online resources, I see mention of braces that are more like Joist Hangers.  But rather than having numerous nail holes like traditional joist hangers, they are supports by a single lag screw.  They are referred to in these resources as "Framing Connectors" or "Hold Down" brackets.  Does anyone know the real name for these, or where to find them?  Asides from having some fabricated myself, anyone know where to find these?  Like this:    As seen here:   I also saw these in the :


I am just wondering whether following is true?  Let $p>1$ If $f_n\to f$ in $L^p(\mu)$, is it then true that $f^p\to f^p$ in $L^1(\mu)$?  This is true if $||x|^p-|y|^p|\le |x-y|^p$. I know this is true for $p=1$. Is the inequality true for $p>1$?

I have the following question about $L^p$ spaces:  Suppose that $f,f_1,f_2,\ldots$ are functions in $L^p$ for some $p \geq 1$ and the sequence converges in $L^p$ to $f$, i.e. $||f_n-f||_p \to 0$. Does this imply that the sequence $|f_1|^p,|f_2|^p,\ldots$ converges in $L^1$ to $|f|^p$? Is it also true if we remove the absolute value? That is, the sequence $f_1^p,f_2^p,...$ converges to $f^p$, in case $p$ doesn't create problem with power (for example $p=3$).  I am using necessary and sufficient condition from the Vitali's convergence theorem and it seems to work. Do you have some advices or some references for this result? Many thanks


Let $P\in\mathbb{R}[X]$ be a positive polynomial.  I want to show that there exists $A,B\in\mathbb{R}[X]$ so that $P=A^2+B^2$    $\displaystyle P=a\prod_{k=0}^q(x-a_k)\prod_{k=0}^{2p}(x-b_k)=a\prod_{k=0}^q(x-a_k)\prod_{k=0}^p(x^2-2\Re(b_k)+|b_k|^2)$ where $a$ is the leading coefficient, $a_k$ are the real rooks, $b_k$ are the complex roots.  What can i do now ? I know that the identity $(a^2+b^2)(c^2+d^2)=(ac-bd)^2+(ad+bc)^2$ should come in handy, but I can't figure out :  1) How to show that the product real roots is a square  2) How to use the above identity for the complex roots.  If I can solve those two points, then I can solve the problem.

$p \in \mathbb{R}[x]$ and $ \forall x\in\mathbb{R} \ \ p(x) > 0$. Prove that $p = \sum_{k=1}^{n}p^2_k, \ \ p_k \in \mathbb{R}[x]$. I have noticed that $deg(p)$ must be even, because $p(x)$ doesn't intersect $\{x=0\}$.  How can I proceed with the proof?


I update to the newest 7.1 yesterday.  Now some of my apps will not open.  Is there a way to delete this update?

I'm trying to downgrade my iPhone from the current iOS to an older one, as per .  But every time I try, I always receive this error:     The iPhone could not be restored. This device isn't eligible for the requested build.     I have tried many times with and without DFU mode. Any ideas regarding this?


I wanna check how my application works for iOS 7.1. I have got an iPad mini 2. I know it has iOS factory 7.1 . But now it has 9.3.2 (the lates). Is it possible to reset iPad until the default iOS? How to do it?


Im trying to a really simply condition statement. I need to check if my string first character is equal to 0.  I have a string that is equal to 0123, and I want to see if the first character is equal to 0.  String timetest = "0123";  if (timetest.substring(0, 1) == "0") {     System.out.println("first character is equal to 0"); } else {     System.out.println(time.toString().substring(0,2)); }   I dont get why it isn't printing "first character is equal to 0"?  Sorry for the simple question. I don't see why this isn't working.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I recently installed ubuntu 14.10 but I forgot to partition my drive. I need a separate partition for the OS and and my media files. Do i have to renistall ubuntu or can it be done separately?  Thank you

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


has 1568 reputation yet is still a new contributor:    It's probably that .

Earlier today I saw the New Contributor indicator attached to a user who had 2,700 reputation and had been a member of the site for over 2 years. When I went to leave a comment, I saw a banner of “(User) is a new contributor. Be nice, and check out our Code of Conduct.” above the comment.  This was very confusing until I realised what was going on: this occurred on our per-site meta, and this was the first day the user had contributed to our site's meta.  Could the indicator & banner be updated on meta sites to make it clear it's not just being buggy?   Update the “New Contributor” indicator to say “New Contributor to Meta” or “New Meta Contributor” Update the comment/answer banner to say “(User) is a new contributor to this meta. Be nice, and check our Code of Conduct.”   (Text bolded just for the sake of this feature request; don't have it bolded in the released version.)


We have two estimators for samples dispersion:  $\frac{1}{n}\sum_1^n (X_i - \overline{X_n})^2$ and $\frac{1}{n - 1}\sum_1^n (X_i - \overline{X_n})^2$.  The second estimator unbiased - it has expectation equals to real dispersion.  I know the proof, but I think that there is some logic behind this formula, not only formal derivation. For example, if we have only one sample measure, then unbiased formula doesn't work. And it seems logical because one sample can be thrown from a distribution with any dispersion and we can't estimate it.  Maybe you know some simple explanation of the logic behind these formulas.

I was asked today in class why you divide the sum of square error by $n-1$ instead of with $n$, when calculating the standard deviation.  I said I am not going to answer it in class (since I didn't wanna go into unbiased estimators), but later I wondered - is there an intuitive explanation for this?!


I'm trying to prove  $1 - \frac{a}{b} \leq \ln\frac{b}{a}\leq\frac{a}{b} - 1$ where $0 < a < b$ using Lagrange's Mean Value Theorem.  Applying the theorem to $\ln x$ results in: $$\exists\epsilon\in(a,b): \ln'(\epsilon)(b-a)=\ln b - \ln a$$ $$\frac{b}{\epsilon}-\frac{a}{\epsilon}=\ln \frac{b}{a}$$  This looks very similar to the target inequality (set $\epsilon=a$ and $\epsilon=b$), but I'm not sure how to get to it.  Edit: Looks like my question is an exact duplicate of , The answer doesn't really explain how to get to the inequalities though.

I'm trying to solve this mean value theorem problem but confused where to start,     If $0<a<b$ prove that $(1-\frac{a}{b})<\ln\frac{b}{a}<\frac{b}{a}-1$   Can someone please lend me a hand?


I purchased a Corned Beef Brisket from the store and forgot to put it in the refrigerator. It was sealed. The package was cool in the morning. Is it safe to still use?

If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more?


I am landing in Canada on my immigrant visa and I will stay here for a couple of days. Then I will board flight to India which has a stop in Rome, Italy. Do I need any kind of visa for the stop in Rome? My stop is at FCO airport for 3 hours. My airlines is AlItalia.

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


American options are more expensive than European options because they give the buyer the right to early exercise.   But in a low interest environment, early exercise is   So it seems like the extra premium paid for American option is not worth it. Is it true?

Why are American-style options worth more than European-style options?   I realize I can exercise American-style options anytime before the  expire, but I can only exercise European-style options during their  "exercise period" (usually right when they expire, but no earlier).   So it makes sense that an American option is worth at least as much as  a European option.   But why is it worth more? If I exercise my American option early, I  may make more money than waiting until expiration, but I also may make  less. Mathematically, there's no advantage, since I'm equally likely  to make as much money by waiting for expiration.   Mathematically speaking, is there ever a good reason to exercise an  American option early?   I realize people don't always behave logically, but even the formulas  that valuate options show that American options are worth more.   EDIT (answering comments):    Many of the comments people made would apply to lookback options  (), but not to American  options.  American options can do everything European options can and more. I  understand that, and that means American options can't be worth any  LESS than European options, but I'm still not clear on how you would  mathematically calculate this extra value.  @Aaronaught: "The difference between an American and European  option is the difference between getting N chances to get it right (N  being the number of days 'til expiration) and getting just one  chance. It should be easy to see why you're more likely to profit  with the former, even if you can't accurately predict price  movement."    REPLY: I don't think you really get N chances. Once you exercise the  option, that's it, no more chances. And, if you decide not to exercise  the option today, and the underlying's price falls, you can't go back  in time and exercise it yesterday.    @jdsweet: Think of it this way, if you traveled back through time  one month - with perfect knowledge of AAPL's stock price over that  period - which happens to peak viciously then return to its old price  at the end of the period - wouldn't you pay more for an American  option?    REPLY: Well, no. I'd simply buy a cheaper European option that expires  right at the spike. Or, I'd buy a European option that expires later,  and sell it when the spike occurs. American options don't give you  precognition, so you're still guessing as to when to sell/exercise.    @jdsweet: "one of the more common reasons people exercise (as  opposed to sell) an American option before expiration is if an  unexpected dividend (larger than remaining time value of the option)  was just announced that's going to be paid before the option contract  expires"    REPLY: This makes sense. I'm actually trading FOREX options, so there  is no dividend. In that scenario, are European and American options  worth the same?


I have a shell script which runs commands and asks for user input.  The script is located on my computer.  I'm using the script as stdin for an ssh session to execute commands remotely.  The problem I'm having is the read command doesn't seem to wait for user input.  Is there anyway to prompt for user input in an SSH session using a script as stdin?  local shell:  ssh root@10.0.0.1 < example.sh     example.sh:  #!bin/bash #example.sh  echo "Enter Name" read user_name  #script doesn't wait for user input

I have a local script that I want to run on several remote servers. The command syntax I'm using is:  ssh <remote_server> "bash -s" < ./local_script.sh   This works fine, and even lets me pass parameters to local_script.sh. However, I'd really like to pass an input file to it, as in:  local_script.sh < local_file.txt   Combining these two statements gives:  ssh <remote_server> "bash -s" < ./local_script.sh < local_file.txt   When I run this, I get  bash: line 1: FOO: command not found bash: line 2: BAR: command not found bash: line 3: BAZ: command not found ...   where FOO, BAR, BAZ, etc. are the first word on each line of local_file.txt:  FOO     FOO_PARAM1 BAR     BAR_PARAM1 BAZ     BAZ_PARAM2 ...   So, it looks like "bash -s" on the remote server is interpreting local_file.txt as a script file, instead of an input file to local_script.sh. Is there any way to fix this (other than creating a wrapper script)?


I was trying to delete the sources.list file for apt. After deleting, instead of issuing cd /etc/apt, I did sudo rm - r /etc/apt and now I've deleted it. I tried creating the /etc/apt directory again and running:   $ sudo apt-get update && apt-get upgrade    This returns an error message as follows:  apt-get: relocation error: /usr/lib/x86_64-linux-gnu/libapt-private.so.0.0: symbol _ZTI17pkgAcquireStatus2, version APTPKG_5.0 not defined in file libapt-pkg.so.5.0 with link time reference   How do I restore my /etc/apt directory and fix apt?

I accidently removed apt-get from my Debian system by issuing:  dpkg --force-depends --purge apt   How can I reinstall it?


I'm new to advanced network administration and I would like to do some testing with UDP broadcasting, so I need a broadcast address on my loopback interface. The machine is offline, in other words, there is no network.  How can I accomplish that through ifconfig without having to buy a switch as one user in the comments suggested. In Linux all i have to do is use 127.255.255.255 and broadcasts work fine without any network or any switch. If I have a network i can just use 255.255.255.255, obviously.    Here is how you can check for yourself that it works on linux but not in os/x:   Open two terminals and type on both of them:  nc -u -l 55555 Open a third terminal, install socat if necessary and type: (in case you ask netcat does NOT support broadcast)  echo -n "TEST" | socat - udp-datagram:127.255.255.255:55555,broadcast You should see both terminals receiving the message.   If you try the same experiment with 127.0.0.1, only one terminal will get the message as expected.  Performing the same test on OS X does not exhibit the same behavior.  What I am looking for is a software workaround for broadcasts if possible. I cannot use multicast (it has to be broadcast) and I cannot test that over a network (machine offline).

I am trying to use ifconfig to turn on broadcast on my loopback interface. It currently reads:  lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384   As you can see, no broadcast address! :( :( :(  I tried this on OS/X but it did not work and it did not give any error or feedback:  ifconfig lo0 broadcast 127.255.255.255   Any guru would know that?    I have one server that sends one packet. I have two clients running on the same machine as the server. I need them to pick up the packet WITHOUT having to force the server to send it twice.


I have ubuntu 17.04 running on my Lenovo desktop with an Intel processor. My attempts to update to a newer version have all failed to load current registry. I have not used this software in a few years, and want to refamiliarize myself with ubuntu.

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


I have a system of two quadratic equations with unknowns $x$ and $y$ and the following structure \begin{cases} 0=ax^2-bxy+kx-r_1y+c_1\\ 0=by^2-axy-kx-r_2y+c_2 \end{cases}  where all parameters are nonzero positive scalars, except $a$ and $c_2$ that could also be negative. Is there a special algebraic solution for the above system? Is there any possibility to get a unique solution?

I have a system of two quadratic equations with unknowns $x$ and $y$:  $$a_{1 1} x y + a_{1 2} x^2 + a_{1 3} y^2 + a_{1 4} x + a_{1 5} y + a_{1 6} = 0,\\ a_{2 1} x y + a_{2 2} x^2 + a_{2 3} y^2 + a_{2 4} x + a_{2 5} y + a_{2 6} = 0,$$  where $a_{i j}$ are arbitrary scalars.  Is there an algebraic solution of the above system?


I want to make a portrait with the sun to the side or behind the model. I have set the shutter speed to 1/4000. If I take the photo without flash, the model's face won't be bright. But the built in flash is not firing over 1/250.   How can I take my shot with both the sun and the model visible?

How can I take a photo like the ones below? The problem is that my photos (taken with a bridge, Sony H2) will get blown up at the highlights. Is it because I'm using a weak camera? Is it because I'm shooting in JPG (can't use RAW)?  Is this dynamic range achieved by greater cameras + RAW? Or is it by post-processing?  Is there a pattern to this type of photos like: wide apperture (< f5.0), RAW, ...?  Examples:   or  or


I am new to bash scripting. This might be obvious to many. please bear with me.  I have a shell script as follows:   #!/bin/bash echo `pwd` cd /home/foo/bar echo `pwd`   Let's say I am currently in dir : /home/foo1  If I execute the above script it prints:   /home/foo1 /home/foo/bar   But once the script completes execution, I have seen that it still remains in dir /home/foo1   I have also seen some scripts where there are explicit commands to reset the working dir using 'cd -' command.  If bash executes all the lines in the script as commands, why does it again reset the working dir?

I'm trying to write a small script to change the current directory to my project directory:  #!/bin/bash cd /home/tree/projects/java   I saved this file as proj, added execute permission with chmod, and copied it to /usr/bin. When I call it by: proj, it does nothing. What am I doing wrong?


I have tried everything. I cannot get this centered on the screen.  It just sits on the left of the webpage. Thank you for any help.   .form {     margin-top: 29px;     margin-left: 130px;     padding-top: 63px;     padding-left: 350px;     padding-right: 40px;     background-image: url(form.png);     background-repeat: no-repeat;     height: 100px;     width: 100px;     position: center;      overflow: hidden; }

»FORMULAR

     <form action="/action_page.php">       Nume:
       <input type="text" id="fname" name="fname" placeholder="Ion">
       Prenume:
       <input type="text" id="lname" name="lname" placeholder="Popescu">
     <input type="submit" value="Trimite">   </form>

How can I horizontally center a
 within another
 using CSS?

Foo foo


If you go to 'tags' and click a tag, you get questions filtered by that tag.  How can you refine the filter with another tag (without having to type the tag name into the search bar)?  Clicking another tag from inside the search results resets the filter.  Found the answer - in the sidebar on the right is 'related tags'. Click on one of these and you get a double tag search.

After an extended alpha period, we are pleased to announce the release of Custom Filters (formerly known as Custom Question Lists).  Custom Filters provide a rich UI for building more tailored views of questions around your specific needs  (e.g. ) as well as the ability to save those lists for quick access later.  So, what does it look like?  The change in the UI is subtle, and if you never use the feature it shouldn't impact you too much.  We're going from this:    To this:    With this component in the sidebar:    Notably, the order of tabs has rearranged slightly, Featured has been renamed Bounties, and a few items have been tucked into a "More" dropdown.  There's also a blue Filter button.  Once you click Filter or "Create a custom filter", though, you're brought into a new UI that lets you select tags, choose a sort order, and specify the attributes of the questions that you want to view.    From there, you can apply your filter to the current page or save it so that you can quickly access it again from the sidebar or More dropdown.  .  What about new content indicators?  If you've been following this project, you know that new content indicators have been "just around the corner" for a while.  It's not a trivial problem to get right at scale, and while we've been close for a while, there's one last issue we want to resolve before shipping.  That is targeted for mid-July.  Where do I file bugs and feature requests?  You can file on meta using the  tag.  Special thanks to our alpha testers  You have all been a huge help both not just in finding bugs but also in shaping the direction of the product.  For a history of the project, you can view these previous meta posts:


Apex error : You have uncommitted work pending. Please commit or rollback before calling out. I get the above error when I try to make two http callout one after the other and store the result in database in between the http calls. Below are the apex steps which are done:  DML statement to get the number of HTTP callouts to be made. For ex: if it has two HTTP calls to be made. The first HTTP call is made and then store the result of HTTP callout. Make the next HTTP callout and then store the result of the HTTP callout.  I can't make the HTTP callout as future as I require the output to be displayed to the end user for all the HTTP callout. Please let me know if the question is not clear, and  how we can handle this scenario.

What else, other than insert/update/upsert/delete, can cause "System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out"?  I've search the debug logs multiple times, and there absolutely is not a DML statement executed between the startTest and the failing callout.  Are there any other commands, or perhaps another callout (even though it's only an inquiry), that can cause this?  Does anyone know how to get around this problem?


Example: In a Terminal command xdpyinfo | grep resolution (that I have taken from an answer), does the | character mean that the xdpyinfo output shall be sent to the grep program input for printing a line containing the resolution string? Where should I seek for such an information to avoid filling this forum by too simple questions? Thanks.

This question may sound a bit stupid, but I can not really see the difference between redirection and pipes.  Redirection is used to redirect the stdout/stdin/stderr, e.g. ls > log.txt.  Pipes are used to give the output of a command as input to another command, e.g. ls | grep file.txt.  But why are there two operators for the same thing?  Why not just write ls > grep to pass the output through, isn't this just a kind of redirection also? What I am missing?


My specific question is that I have 3.9GB of ram, but I don't have an AMD processor. I have the Intel i5. Do I install i386, or the AMD x64 version of 14.04? Let me know if there are other specifics I should tell you guys.

What is the difference between standard i386 download and the amd64 download of Ubuntu 11.04? I am currently running the i386 on an amd machine, would my system work better with the amd64 download instead? (my machine was running Windows 7 64bit, but I neglected to look at that prior to installing Ubuntu).


I'll mostly be using the Physics Stack Exchange (PSE), but I may send occasional questions to the astronomy one (ASE).  My user name's Edouard on the former, and Edward Slattery on the latter. ASE recommended that I merge the accounts through a moderator. Please advise through my e-mail (which is  edslattery11@gmail.com) how I should accomplish that. The information at PSE is the most complete, and I'd like to keep it intact, through its substitution for similar details at ASE. Thanks.  (I should add, in this connection, that I may stop using both exchanges if a charge for their use is instituted. Thanks again.)

I accidentally posted a question without being logged in. Is there a way to associate that question with my account?   For more information, visit "" in the .   a.k.a. How can you link a registered account to a cookie-based account? a.k.a. How do I merge an unregistered account with a registered account a.k.a. Merging users a.k.a. How do I associate anonymous questions I’ve asked with my registered account? a.k.a. Is there a way to claim an unregistered user? (in case anyone searches with those terms)


How can I use the subdivision surface modifier to create more high poly meshes without ruining sharp edges? For example this mesh  The sphere should be subdivided but the rim of the cylinder should stay the same because it is a sharp edge. This is the result of the subdevision  How can I get sharp edges to not be affected by the sub surf mod?


I am a beginner in photography and trying to understand about camera lenses. This morning I came across Mike Matas' video which was made using this thousand dollars .   I also have a 50mm lens for my , but it only cost me way less than his lens did. Other than the obvious maximum aperture difference, what makes their prices differ so much - and how does it will affect the quality of the pictures taken?

For example, a  is about US$110, while another  is about 14 times as expensive, at about $1450.  Is the 1.8 or 1.2 the main reason for the price difference?  The same goes for some variable lens, such as , and , which costs several times more.


I have many power plans in my desktop PC - one is optimized for downloading (PC doesn't sleep but turns the display off), one for reading, one for games and so on.  But the problem is that I have no power icon in tray (notification area), so I created a shortcut of Power Plans on my desktop, but it's really annoying.    So how can I make Windows show power icon in tray?  For moderators: this may seem duplicate of  and , but they are about laptops. And their answers didn't work for this case.

I used to have an icon on the Windows Vista taskbar showing the battery amount remaining (laptop). It has mysteriously vanished.  How can I get it back?  I followed the Windows  (see How can I hide the battery icon in the notification area? - hoping to reverse the instructions) but the Power checkbox on the Notification Area tab was greyed out and could not be checked or unchecked (it is currently unchecked).


I'm currently working through some old code and I started to wonder,  is there actually any difference between:  public class XmlExport : IXmlExport {     private readonly IJobRepository jobRepository = new JobRepository(); }   and  public class XmlExport : IXmlExport {     private readonly IJobRepository jobRepository;      public XmlExport()     {         jobRepository = new JobRepository();     } }   Are there any advantages to initializing inside the constructor?  or is it just the same code?

I've been programming in C# and Java recently and I am curious where the best place is to initialize my class fields.  Should I do it at declaration?:  public class Dice {     private int topFace = 1;     private Random myRand = new Random();      public void Roll()     {        // ......     } }   or in a constructor?:  public class Dice {     private int topFace;     private Random myRand;      public Dice()     {         topFace = 1;         myRand = new Random();     }      public void Roll()     {         // .....     } }   I'm really curious what some of you veterans think is the best practice. I want to be consistent and stick to one approach.


I wrote some code to find whether the multiplication of two integers will result in overflow or not. And can the result be stored as an integer or not?  I am using the GNU GCC compiler and when I compile and run the following code it works but when I use any optimization like O1, O3, etc it does not work.  #include <iostream>    bool mul_overflows(int a,int b)  {     cout<<"checking overflow for"<<a<<" "<<b<<endl;     if(a==0 || b==0)     {       return false;     }     int result = a*b;     cout<<"result = "<<result<<endl;     cout<<"result/b = "<<(result/b)<<endl;     if(a==result/b)       return false;     return true;  }  int main()  {     if(mul_overflows(253955520,12)       cout<<"caught overflow!"<<endl;  }  Following is the output of code with default optimization -O0 checking overflow for 253955520 12 result = -1247501056 result/b = -103958421 caught overflow!  And when I use any other optimization it gives this output checking overflow for253955520 12 result = -1247501056 result/b = 253955520  The overflow is not caught and we can clearly see that the result is negative and has overflowed, but still dividing the result by b gives a? What is causing this? Are there any compiler options that I am missing?

I was writing a program in C++ to find all solutions of ab = c, where a, b and c together use all the digits 0-9 exactly once. The program looped over values of a and b, and it ran a digit-counting routine each time on a, b and ab to check if the digits condition was satisfied.  However, spurious solutions can be generated when ab overflows the integer limit. I ended up checking for this using code like:  unsigned long b, c, c_test; ... c_test=c*b;         // Possible overflow if (c_test/b != c) {/* There has been an overflow*/} else c=c_test;      // No overflow   Is there a better way of testing for overflow? I know that some chips have an internal flag that is set when overflow occurs, but I've never seen it accessed through C or C++.    Beware that signed int overflow is undefined behaviour in C and C++, and thus you have to detect it without actually causing it. For signed int overflow before addition, see .


Would like to create a WINDOWS ubuntu boot-from-CD using latest OS X system. Trying to help a friend recover from an MS "registration key" and disk loss and subsequent registry trash. Any ideas?

I have a working MacBook Pro and a crashed Windows 7 PC. I was running Ubuntu on my PC, but after a recurrent issue now I can't boot either OS. I would like to install only Ubuntu on my PC and will make Windows 7 history for good, but I am a bit puzzled by the instructions for creating a bootable USB options on the website.  If I create a bootable USB on my Mac following the instructions for OS X, would it boot in a PC?


Using biblatex, with the option to use initials for first name (as found in the question: ):  \usepackage[     giveninits=true,     style=numeric-comp,     backend=biber ]{biblatex}   Is there a way to ignore this option for SOME references?  i.e. I want most of my references to have initals and surnames, but I wan't a couple references to have full names. Is this possible? (i.e. when an author is an organisation)

I want to list a company name in the author field of a bibliographic entry:  @book{CUDA,   author    = {NVIDIA Corporation},   title     = {NVIDIA CUDA Compute Unified Device Architecture Programming Guide},   publisher = {NVIDIA Corporation},   year      = {2007} }   But the entry keeps showing up "N. Corporation".  Is there a way to get the full author name to show up?  I'm currently using the siam BibTEX style.


Let $(v_n)_{n \geq 1} \in \ell ^2$ be a fixed bounded sequence of real numbers. Define a mapping $T$ on $\ell^\infty$ using the formula $$T(a_1, a_2,\ldots)=(v_1a_1,v_2a_2,\ldots), \qquad x=(a_1,a_2,\ldots) \in \ell^\infty$$  We can use the fact that, $Tx \in \ell^2 $ for every $x \in \ell^{\infty}$ and $T: (\ell^\infty,\|\cdot \|_\infty) \rightarrow (\ell^2,\|\cdot \|_2)$ is a linear operator and $\|Tx\|_2 \leq \|(v_n)\|_2 \cdot \|x\|_\infty$ for all $x \in \ell^\infty$    $$||T||_{\ell^{\infty} \rightarrow \ell^2}= \sup _{*}||Tx||_{\ell^2}$$  Where $*$ can be $||x||_{\ell^{\infty}}$ $\leq 1$ or $<1$ or $=1$ according to my notes. There is also the infimum definition of it. I don't know which one is best to use but I also have no idea how to evaluate it because of stuff like $||x||_{\ell^{\infty}}$, I have no idea what the subscript would mean because it is a set - not a number (or infinity).

Let $(v_n)_{n \geq 1} \in \ell ^2$ be a fixed bounded sequence of real numbers. Define a mapping $T$ on $\ell ^{\infty}$ using the formula $$T(a_1, a_2,...)=(v_1a_1,v_2a_2,...), \, \, \, \, \, x=(a_1,a_2,...) \in \ell^{\infty}$$  We can use the fact that, $Tx \in \ell^2 $ for every $x \in \ell^{\infty}$ and $T: (\ell^{\infty},||\cdot ||_{\infty}) \rightarrow (\ell^{2},||\cdot ||_{2})$ is a linear operator.  Show $||Tx||_2 \leq ||(v_n)||_2 \cdot ||x||_{\infty}$ for all $x \in \ell^{\infty}$    Here is what I tried:  $||Tx||_2 = \bigg( \sum v_k^2 a_k^2 \bigg)^{1/2} \leq (||x||_{\infty}^2 \sum v_k^2 )^{1/2}= (||x||_{\infty}^2 ||(v_k)||_2^2 )^{1/2} = ||(v_k)||_2 \cdot ||x||_{\infty}$  Is this OK?


I am adding an alias to search for a file for a string that leads to me a snippet.   alias snippets="find /oneDrive/Work/Snippets -type f -exec grep -Hi $1 '{}' + "   And calling as   snippets "target"   And getting error as   find: target: unknown primary or operator   Any help greatly appreciated.

For bash script, I can use "$@" to access arguments. What's the equivalent when I use an alias?


I have Ubuntu 16.04 LTS installed on my Acer E5-473G-399E machine with a non formatted 1 Terabyte HDD.  How do I install and dual boot Windows 8 Pro alongside Ubuntu 16.04LTS, (I already installed Ubuntu first)?

I have Ubuntu on my laptop. Now I want install Windows 7 in a dual-boot. How can I do this? I can't lose my Ubuntu files, and I'm afraid that I might break . Go  for UEFI only!


Question states: "Show that if $n+1$ integers between $1$ and $2n$ (inclusive) are chosen, the set of chosen integers will contain at least one number which divides another member of the same set."  I have found a non-inductive proof online, which uses pigeonhole principle and expressing each number of the chosen set as $2^{aj}$ where $j$ is an odd number from $\{1,3,5,...,2n-1\}$. (so there are $n$ boxes of $j$) So pretty much divide a number repeatedly by 2 until that number becomes odd. For example, we can express $56$ as $2^3 \times 7$. we have $n+1$ numbers which can fit into $n$ boxes, and by the Pigeon Hole Principle we conclude that there are two numbers in a given $j$ boxes; one of them divides the other.  However, my book says that I can prove the question by using induction. Obviously, the base case holds. Here is my progress so far:  Assume true for an integer $n$. We need to prove that an arbitrary set of $n+2$ integers from $\{1,...,2n,2n+1,2n+2\}$ have a number which divides another number from the chosen set. If either one or none of the two new numbers ($2n+1$ and $2n+2$) is chosen, we are done, since we must pick at least $n+1$ elements from the rest of the set $\{1,...,2n\}$ .  A problem arises if BOTH of the two new numbers are chosen. Then we are required to prove that an arbitrary set of $n$ numbers from the set $\{1,...,2n\}$ contains two numbers, one of which divide another, or that the same arbitrary set of numbers must contain a number that divides either $2n+1$ or $2n+2$. If the arbitrary set of $n$ numbers contain either $1$, $2$, or $n+1$, then we are done. So we must prove that an arbitrary set of $n$ numbers from the set $\{3,4,...,n-1,n,n+2,...,2n\}$ contains two numbers, one of which divide another, or that the same arbitrary set of numbers must contain a number that divides either $2n+1$ or $2n+2$.  How do I show this?

Given a set of $n+1$ numbers out of the first $2n$ natural numbers, $\{1,2,\ldots,2n\}$, prove that there are two numbers in the set, one of which divides the other.  I can't tell if I'm reducing the problem in the right way.  Would it be something like:  Induction Hypothesis: A set of $n+1$ numbers from the first $2n$ natural numbers contains two numbers, one of which evenly divides the other.  Base Case: $n=1$, $\{1,2\}$, 2 is divisible by 1.  Consider a set of $n+2$ numbers, $A$, from the first $2n+2$ natural numbers. There are three cases:   Each number in $A$ is less than or equal to $2n$.  The proof follows from the induction hypothesis. One number in $A$ is greater than $2n$.  The remaining set of $n+1$ numbers must each be less than or equal to $2n$.  The proof follows from the induction hypothesis. $A$ contains both $2n+1$ and $2n+2$. I'm not sure how to solve this case.   I'm working through Udi Manber's Introduction To Algorithms: A Creative Approach for personal development, so in keeping with the spirit of the book, I'm trying to use induction.  Without induction, the question is identical to


If you discount species that only have one gender (which are homosexual by default), and species that change their appearance or body (like Changelings and Trills), are there any homosexual characters in the prime universe?  I am aware of Ezri and Lita being homosexual or bisexual in the Mirror Universe, but I am interested in the canon prime universe.  This question is explicitly about homosexuality. I am not focusing on those who are bisexual characters (there is one, Garak) or transgender characters (there is an entire episode covering that topic.)  This is also not a question about the legal status of LGBT peoples in Star Trek - its about if there were any on screen characters who were homosexual (identified as such on screen or in the background by the actor or producers.)

I am aware of the picture of the man wearing the 'dress' from TNG, which promotes gender equality, but are gay rights ever addressed in Star Trek at all? (All seasons accepted.)


I know it's been asked all over but I get nowhere applying the suggestions. I have a community build with custom template. At the moment I want to just use the public site and public pages. Launch of the community is not on the roadmap. I thought I will additionally block the default login page to stop more salesforce aware folks from venturing where they should not. I'm not convinced business will get a custom domain sorted in time and I want to prevent people from guessing url and seeing the standard salesforce login pages. External user registration is disabled but people can still hang I created a  custom VF page, because I can and because the doc says it should work, and I could re-use the generic page for some standard pages on the site. I configured the login in  however when I go to the url   I see the login page from experience builder. Is there something I'm doing  wrong? Worst case I can override the lightning page but I would like to understand what is wrong. Custom home page works but this is also configured in the site settings.

When setting up Login & Registration pages in community, it's possible to select different page types.    Each of these type accessible by different URL:   Login - Default  Page URL -  Login - Community Builder Page URL -    When a community is published and activated, BOTH URLs are active. That is when I go to this URL /login, it opens the default page. When I click this URL /s/login/, the community builder page is opened. What I need is when I select Community Builder Page as a page type for login, then default page should not be accessible. I have custom logic in the community builder page custom controller which prevents certain users from login. But if standard default page is alive, then users can simply bypass our custom validations. This is not good.  Is it possible to deactivate default page at all?


Write a command or logic , which will read the contents from the given input file and fetch the Students of School named as Sangamithra.  Input File format: The sequence of columns in the input file(input.txt ) is as below, columns separated by "|"(excluding the double quotes).  StudentName|Class|SchoolName  The sequence of Column in the output is as below, columns separated by "|"(excluding the double quotes) ,  SchoolName|Class|StudentName  Example: suppose input.txt  Deepu|First|Meridian  Neethu|Second|Meridian  Sethu|First|DAV  Theekshana|Second|DAV  Teju|First|Sangamithra   And Output :  Sangamithra|First|Teju

The table looks like this:  1|Hunk|First|London 2|Hero|Second|London 3|Will|First|Pow 4|Thomas|Second|Pow 5|Venus|First|Berlin   I want to print the output as:  Berlin|First|venus|5   i want to print only the final line.


I'm working on creating a online quiz program. I want to change questions every time new user logging in. Is there any way to get questions from database randomly?  I have tried rand() function but it generates same question again and again.

I am using MSSQL Server 2005. In my db, I have a table "customerNames" which has two columns "Id" and "Name" and approx. 1,000 results.   I am creating a functionality where I have to pick 5 customers randomly every time. Can anyone tell me how to create a query which will get random 5 rows (Id, and Name) every time  when query is executed?


I want to take a collections data backup on a different host, with renaming the Collections.   I am very new to MongoDB. Please help me with this task.

I've got a mongo cluster with three nodes, running 2.6, but probably going to 3.2 What is the best method to back-up a database in a replica set of three mongodb servers? Should I use mongodump --db [dbname] --out [path]? And do I back-up from the primary node, or the slaves? The database is about 30GB, so will the performance decrease during the backup of the other nodes? I looked at the documentation  and , but could not find my answer.


I've been learning Python for about 5 days and I have no prior programming experience, so apologies if this is too basic a doubt; I've checked some other similar questions but the issue wasn't the same.  I'm defining some input check functions for the program that I'm making and my idea was to rely on while loops and boolean conditions to make them work, but I found out that the loop doesn't end regardless of the input being valid.  This is the simplest one I've written:  def is_num(num):     try:         num = float(num)         num_check = True     except:         print("Incorrect value. Please, enter a number.")  num_check = False while not num_check:     user_num = input("Enter a number: ")     is_num(user_num) print("Valid number.")   I do get the error message if I enter something other than a number, but if I do enter a number I just get the input prompt over and over.  I thought maybe the problem was coming from num_check only being defined inside the function so I tried out this version, but it changed literally nothing:  def is_num(num, num_check):     try:         num = float(num)         num_check = True     except:         print("Incorrect value. Please, enter a number.")  user_num_check = False while not user_num_check:     user_num = input("Enter a number: ")     is_num(user_num, user_num_check) print("Valid number.")   What should I change for this to work? Thanks!

What exactly are the Python scoping rules?  If I have some code:  code1 class Foo:    code2    def spam.....       code3       for code4..:        code5        x()   Where is x found?  Some possible choices include the list below:   In the enclosing source file In the class namespace In the function definition In the for loop index variable Inside the for loop   Also there is the context during execution, when the function spam is passed somewhere else. And maybe  pass a bit differently?  There must be a simple reference or algorithm somewhere.  It's a confusing world for intermediate Python programmers.


The events of "Time's Arrow" clearly indicate that Guinan knows who Picard is when he takes command of the Enterprise.  But is the converse true: does Picard know who Guinan is at that time?   is related, but has several conflicting answers, some of which also conflict with other episodes of the series, and therefore does not adequately answer this specific question.

In the show they often allude to the history between Guinan and Picard but, to my knowledge, there has never been anything more than allusions.  What exactly happened that created this bond between the two?


In Avengers: Infinity War, when Gamora is explaining what Thanos intends to do with the Infinity Stones,      Gamora: The entire time I knew Thanos, he only ever had one goal: To   bring balance to the Universe by wiping out half of all life. He used   to kill people planet by planet, massacre by massacre.      Drax: Including my own.      Gamora: If he gets all six Infinity Stones, he can do it with the snap   of his fingers, like this. [She snaps her fingers.]     Avengers: Infinity War (2018)    Later, when Thanos arrives at Titan,      Doctor Stephen Strange: Who wants to murder trillions.      Thanos: With all six stones, I could simply snap my fingers, and they   would all cease to exist. I call that... mercy.     Avengers: Infinity War (2018)    Both instances indicating that the "Snap" is intended for living beings only. However, in Avengers: Endgame, we see that       when Tony snaps, the cavalry like the Chitauri ships and Outriders' ships etc. are dusted as well.       Avengers: Endgame (2019)    Have the writers given any explanation on this?

I repeated the avengers movie yesterday in HD and saw something weird - were the Chitauri 'ships' living creatures? They kinda looked like they had flesh underneath all that metal stuff or did I just see my own stuff?  This is what I'm talking about


I have an App published in google app store and i get strange log about a crash from an unknown source.  This happens on devices like Xiaomi Redmi Note 5 Pro (whyred), 3840MB RAM, Android 9.  I try to find the same issue reported anywhere but i couldn't.  java.lang.NullPointerException:       at com.baruchi.simpletime.main.Ud.f (Unknown Source:43)     at b.j.a.h.k (Unknown Source)     at b.j.a.v.m (Unknown Source:13)     at b.j.a.v.w (Unknown Source:77)     at b.j.a.h.k (Unknown Source:7)     at b.j.a.v.m (Unknown Source:13)     at b.j.a.v.w (Unknown Source:77)     at b.j.a.m.m (Unknown Source:4)     at b.j.a.k.onSaveInstanceState (Unknown Source:8)     at androidx.appcompat.app.m.onSaveInstanceState (Unknown Source)     at com.baruchi.simpletime.main.MainActivity.onSaveInstanceState (Unknown Source)     at android.app.Activity.performSaveInstanceState (Activity.java:1599)     at android.app.Instrumentation.callActivityOnSaveInstanceState (Instrumentation.java:1444)     at android.app.ActivityThread.callActivityOnSaveInstanceState (ActivityThread.java:4872)     at android.app.ActivityThread.callActivityOnStop (ActivityThread.java:4214)     at android.app.ActivityThread.handleSleeping (ActivityThread.java:4340)     at android.app.ActivityThread.access$2400 (ActivityThread.java:200)     at android.app.ActivityThread$H.handleMessage (ActivityThread.java:1772)     at android.os.Handler.dispatchMessage (Handler.java:106)     at android.os.Looper.loop (Looper.java:201)     at android.app.ActivityThread.main (ActivityThread.java:6810)     at java.lang.reflect.Method.invoke (Native Method)     at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:547)     at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:873)

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


I have a product with three radio button options, and I want to replace those radio buttons with clickable images. This is how those radio buttons appear in the code:

      <input type="radio" class="form-radio" value="136" name="attributes[51]" id="edit-attributes-51-136">Red, +$3.00

      <input type="radio" class="form-radio" value="135" name="attributes[51]" id="edit-attributes-51-135">Green, +$5.00

      <input type="radio" class="form-radio" value="137" name="attributes[51]" id="edit-attributes-51-137">Blue, +$10.00

   Instead of the radio button and label, I'd like to simply display a image color swatch. How can I accomplish this? I assume I'd need to somehow reference the "for" value in the "label", but I'm not sure how to do so. I'd prefer not to go the "nth child" route, but I can if I need to.  Thanks!

I would like the user to choose the category when he creates a new node content. However, instead of radio buttons or dropdown list I would like to have selectable images, with exactly the same logic. Is it possible to somehow ovveride radio buttons / dropdown lists with options being displayed as images? So, for example instead of a radio button with 'Cars' label I would like to have a picture of a car, then for the next category another picture, etc. Any advice appreciated.


(a) $x+40 ≡ 1 \pmod {99}$.  (b) $40x ≡ 1 \pmod {99}$.  Is the answer for a $x \equiv -39 \pmod {99}$ and b $x\equiv\frac{1}{40}\pmod {99}$?  I believe I am doing it correctly.

I am having trouble finding mod arithmetic questions.  Can you show how to solve these?  $x + 30 \equiv 1 \pmod {12}$  $30x \equiv 1 \pmod {12}$  $x + 3y \equiv 1 \pmod {12}$ and $2x + y \equiv 7 \pmod {12}$


I am getting a NullPointerException int the following code.For the complete program refer .  Logcat  FATAL EXCEPTION: main                                                                             Process: com.example.android.googleplaces, PID: 2813                                                                             java.lang.NullPointerException                                                                                at com.example.android.googleplaces.MainActivity$ParserTask.onPostExecute(MainActivity.java:200)                                                                                at com.example.android.googleplaces.MainActivity$ParserTask.onPostExecute(MainActivity.java:169)   and code:  class ParserTask extends AsyncTask<String, Integer, List<HashMap<String,String>>>{  JSONObject jObject;  // Invoked by execute() method of this object @Override protected List<HashMap<String,String>> doInBackground(String... jsonData) {  List<HashMap<String, String>> places = null; PlaceJSONParser placeJsonParser = new PlaceJSONParser();  try{ jObject = new JSONObject(jsonData[0]);  /** Getting the parsed data as a List construct */ places = placeJsonParser.parse(jObject);  }catch(Exception e){ Log.d("Exception",e.toString()); } return places; }  // Executed after the complete execution of doInBackground() method @Override protected void onPostExecute(List<HashMap<String,String>> list){  // Clears all the existing markers if(mGoogleMap!=null) mGoogleMap.clear();  for(int i=0;i<list.size();i++){  // Creating a marker MarkerOptions markerOptions = new MarkerOptions();  // Getting a place from the places list HashMap<String, String> hmPlace = list.get(i);  // Getting latitude of the place double lat = Double.parseDouble(hmPlace.get("lat"));  // Getting longitude of the place double lng = Double.parseDouble(hmPlace.get("lng"));  // Getting name String name = hmPlace.get("place_name");  // Getting vicinity String vicinity = hmPlace.get("vicinity");  LatLng latLng = new LatLng(lat, lng);  // Setting the position for the marker markerOptions.position(latLng);  // Setting the title for the marker. //This will be displayed on taping the marker markerOptions.title(name + " : " + vicinity);  // Placing a marker on the touched position if(mGoogleMap!=null) mGoogleMap.addMarker(markerOptions); } } }

I have a simple setter method for a property and null is not appropriate for this particular property. I have always been torn in this situation: should I throw an , or a ? From the javadocs, both seem appropriate. Is there some kind of an understood standard?  Or is this just one of those things that you should do whatever you prefer and both are really correct?


I wanted to reinstall Ubuntu from the hard drive. I followed the instructions from the official site to install grub and move the Ubuntu iso in the grub folder. After rebooting, the grub>  prompt shows up.  ls shows:  hd0, lvm/ubuntu--vg-root, lvm/ubuntu--vg-swap_1   but there is no /dev/sda1 in hd0 nor in --vg-root  How to fix this? What can be done to boot Ubuntu?

I can no longer boot Ubuntu following a corruption problem initially reported here ().   When I power my laptop, I now get the following message:  GNU GRUB version 2.02~beta2-9ubuntu1.7 Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists possible device or file completions." and then the prompt  grub>   Can anyone help me get back to Ubuntu ?


Rendering an edited video keep exporting as a "file" instead of an MP4 despite there being nothing wrong with the export settings. What's going on here? I suspect that the splits and strips are screwing with the rendering process. rendering export here.  split here

After Blender 2.79 dropped, I can't seem to render in MP4. I have attempted to use the FFmpeg video option they added, but no matter what I choose in the encoding tab, even presets, the render always ends with a useless unreadable file.  Does anyone know what I have to do to fix this?


In a library i'm working on, I have something like this template class in a header file:  template <int something> class Base { public:     virtual ~Base();  // Implemented in c++ file }  class Derived : public Base<100> { public:     ~Derived() override = default(); }   The destructor is implemented like so:  template <int something> Base<something>::~Base() {     destroyBase(); }   This code is compiled as a static library.   Then, I have this code in a sample:  {    Derived x;    x.doSomething(); } // X gets destroyed   I compile the executable and link the static library. This works fine on Ubuntu, but when I try it on mac, the linking fails with  Undefined symbols for architecture x86_64:    "Base<100>::~Base()", referenced from:        _main in my_sample.cpp.o   In both cases, I'm using clang and compiling with the exact same cmake settings. All the other symbols defined in the cpp file are defined. This is the only undefined symbol. What is happening?

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I've read that the answer to such a problem is the inverse probability. So here getting a one has probably 1/6, so the number of tries you would be expected to run in order to get a 1 is 6.  I'm not sure I understand this.

On average, how many times must I roll a dice until I get a $6$?  I got this question from a book called Fifty Challenging Problems in Probability.   The answer is $6$, and I understand the solution the book has given me. However, I want to know why the following logic does not work: The chance that we do not get a $6$ is $5/6$. In order to find the number of dice rolls needed, I want the probability of there being a $6$ in $n$ rolls being $1/2$ in order to find the average. So I solve the equation $(5/6)^n=1/2$, which gives me $n=3.8$-ish. That number makes sense to me intuitively, where the number $6$ does not make sense intuitively. I feel like on average, I would need to roll about $3$-$4$ times to get a $6$. Sometimes, I will have to roll less than $3$-$4$ times, and sometimes I will have to roll more than $3$-$4$ times.  Please note that I am not asking how to solve this question, but what is wrong with my logic above.  Thank you!


For a given sequence $\left\{x_n\right\}$ we define its sequence of geometric means to be $\left\{G_n\right\}$, where $G_n=\sqrt[n]{x_1x_2 \cdots x_n}$. We have to show that if $x_n \rightarrow L$ then $G_n \rightarrow L$.  One method that I have implemented to prove this theorem is that I have used the property of continuous function (i.e if $f : A \rightarrow \mathbb{R}$ is a continuous function, then a convergent sequence $\left\{x_n\right\}$ in $A$ implies $\left\{f(x_n)\right\}$ is convergent, and $f(x_n) \rightarrow f(x)$ if $x_n \rightarrow x$ ) and the fact that the sequence of arithmetic mean of a convergent sequence preserves its limit (same statement as in the paragraph above but it's replaced with arithmetic mean in place of geometric mean, which I've proven).   But suppose you don't know anything about continuous function. Can anyone give me a hint as to how could I solve my original problem, without using any properties of continuous function ?

I would appreciate your help!  How can we show that if a sequence of positive real numbers $a_n$ converges to $a\in\mathbb{R}$ with $a>0$, then $(a_0 a_1\cdots a_n)^{\frac{1}{n}}$ converges to $a$.


In the connection of my previous question.     Codes:  \documentclass[12pt, a4paper]{article} \usepackage[a4paper,top=1 in,bottom=1 in,left=0.7 in,right=0.7 in]{geometry} \usepackage[utf8]{inputenc} \usepackage[misc]{ifsym} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{graphicx} \usepackage{tikz} \usepackage{pst-tree} \psset{levelsep=1,treesep=1,nodesep=2pt} \usepackage{fancyhdr} \pagestyle{fancy} \usepackage{lastpage} \lhead{} \rhead{} \chead{} \rfoot{Page \thepage \hspace{1pt} of \pageref{LastPage}} \lfoot{} \cfoot{} \renewcommand{\headrulewidth}{0.4pt} \renewcommand{\footrulewidth}{0.4pt} \begin{document}     \psTree{\TR{36}} \Tcircle{2} \psTree{\TR{18}} \Tcircle{2} \psTree{\TR{9}} \Tcircle{3} \Tcircle{3} \endpsTree \endpsTree \endpsTree \end{document}   Errors:  line 49: Undefined control sequence. \Tcircle{2} line 49: Undefined control sequence. \Tcircle{2} line 49: Undefined control sequence. \Tcircle{2} line 49: Undefined control sequence. \Tcircle{2} line 50: Undefined control sequence. line 50: Undefined control sequence. line 50: Undefined control sequence. line 50: Undefined control sequence. line 51: Undefined control sequence. \psTree{\TR{18}} line 51: Undefined control sequence. \psTree{\TR{18}} line 51: Undefined control sequence. \psTree{\TR{18}} line 51: Undefined control sequence. \psTree{\TR{18}} line 53: Undefined control sequence. \Tcircle{2} line 53: Undefined control sequence. \Tcircle{2} line 53: Undefined control sequence. \Tcircle{2} line 53: Undefined control sequence. \Tcircle{2} line 54: Undefined control sequence. line 54: Undefined control sequence. line 54: Undefined control sequence. line 54: Undefined control sequence. line 55: Undefined control sequence. \psTree{\TR{9}} line 55: Undefined control sequence. \psTree{\TR{9}} line 55: Undefined control sequence. \psTree{\TR{9}} line 55: Undefined control sequence. \psTree{\TR{9}} line 57: Undefined control sequence. \Tcircle{3} line 57: Undefined control sequence. \Tcircle{3} line 57: Undefined control sequence. \Tcircle{3} line 57: Undefined control sequence. \Tcircle{3} line 58: Undefined control sequence. line 58: Undefined control sequence. line 58: Undefined control sequence. line 58: Undefined control sequence. line 59: Undefined control sequence. \Tcircle{3} line 59: Undefined control sequence. \Tcircle{3} line 59: Undefined control sequence. \Tcircle{3} line 59: Undefined control sequence. \Tcircle{3} line 60: Undefined control sequence. line 60: Undefined control sequence. line 60: Undefined control sequence. line 60: Undefined control sequence. : You have requested release `2014/05/01' of LaTeX, but only release `2011/06/27' is available.

See the code given below. Actually, I am looking for a tree of number 36.  Can somebody let me know what I did wrong?  \documentclass[12pt, a4paper]{article} \usepackage[a4paper,top=1 in,bottom=1 in,left=0.7 in,right=0.7 in]{geometry} \usepackage[utf8]{inputenc} \usepackage[misc]{ifsym} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{graphicx} \usepackage{tikz} \usepackage{pst-tree} \psset{levelsep=1,treesep=1,nodesep=2pt} \usepackage{fancyhdr} \pagestyle{fancy} \usepackage{lastpage} \lhead{} \rhead{} \chead{} \rfoot{Page \thepage \hspace{1pt} of \pageref{LastPage}} \lfoot{} \cfoot{} \renewcommand{\headrulewidth}{0.4pt} \renewcommand{\footrulewidth}{0.4pt} \begin{document} \preview \psTree{\TR{36}} \Tcircle{2} \psTree{\TR{18}} \Tcircle{2} \psTree{\TR{9}} \Tcircle{3} \Tcircle{3} \endpsTree \endpsTree \endpsTree \endpreview \end{document}


When a 250 KVA DG set with four wire out put (3 phases and one neutral wireis working on full load with 0.8 pf lagging, it will deliver 347.8 A which is the rated current.Then what will be the current on R Y B phases? Will the current on all phases will be almost same? Is there any meaning if we add the current on each phase to find the total current?

When the rated current of a 250 KVA DG set is shown as 347.8 A, does it mean that it is the line current or phase current or sum of currents on all phases say R Y B phases


My laptop is T400 coming with 32-bit Windows 7 Home edition. Since T400 CPU is 64-bit, I am considering to install 64-bit Windows instead, probably Windows 7 or 8 Home or Professional or Ultimate. I don't have the installation CD or DVD of any of the OSes. If I can find someone has one, is it allowed to borrow  and install it on my laptop?

I just bought a laptop with Windows 7. I have a desktop that is still running Windows XP. Wil it let me install Windows 7 on my desktop with that CD or does Windows only allow that CD to be used for the laptop?


Consider a table in SQL Server has a column Item, I tried to created a query to covert all values in the column into a single cell result into comma separated string, for example: Table: | Item | -------- | milk | | sugar| | salt | | .... |  Query result: |       Item List         | --------------------------- | milk, sugar, salt ..... |  It would be better to have some customization as |                    Item List                     | ---------------------------------------------------- | milk as milk, sugar as sugar, salt as salt ..... |  I saw there is option as unpivot however it has to be definitive amount of values in the column. Just wondering any available functions to support this goal if target column value is dynamic

Consider a database table holding names, with three rows:  Peter Paul Mary   Is there an easy way to turn this into a single string of Peter, Paul, Mary?


I'm trying to build a circuit for controlling the speed of a fan from an ESP8266 MCU.  I have a PN2222 transistor with the base connected through a 1K resistor to a digital out of the MCU.  The voltage at the digital out is +3.3V when it's high and I verified that I can successfully set it high and low on the MCU reading it with a DMM.  So that part seems to be working.  The power supply for the fan that is being switched by the transistor reads ~18V unloaded using a DMM.  However when I read the voltage of the emitter of the transistor using a DMM it reads 8V no matter whether the base is high or low.         – Schematic created using   I was expecting it to read 18V when the base of the transistor was high and 0V when it was low.  Clearly there is something I am misunderstanding here with my first foray into transistors being very new to electronics in general.

This is really a followup to  to provide an updated schematic and photograph at the request of a commenter on that question.  I'm not sure if there is a better way to provide such an update to a question but here it is anyway...  I have the following circuit:         – Schematic created using   When I measure the voltage across R2 I don't see the 18V being supplied into the collector of transistor scaling linearly with the value of the PWM GPIO of the NodeMCU.  It ranges from 9.35V with the GPIO at 0 (i.e. off) and 17.14V with the GPIO at 1023 (on "full").  With a GPIO value of 512 it reads 13.16V.  I tried my best a photograph of my set up:    About the only thing that is not clear in the photo I think is that the resistor "above" the transistor is between the GPIO with an orange wire and connects to the base (middle pin) of the transistor.


I am doing python programming in notepad++ ,   so as suggested in many posts I have downloaded a tool called "python indent" and set it as enable.  Even after this , when I type in the print statement still I get the indentation errors such as "IndentationError: unindent does not match any outer indentation level" , any other tool is available for this purpose? Because in javascript ,when I select the entire file and go to jshint tool and select indentation, I just get the properly indented file .   I am searching for a tool in python , but not able to get it. Anybody has any suggestions please?  edit:  try:      print "hi"     keys = mgt.get_keys(name)   I am getting the error after inserting print statement

When I compile the Python code below, I get      IndentationError: unindent does not match any outer indentation level     import sys  def Factorial(n): # Return factorial     result = 1     for i in range (1,n):         result = result * i     print "factorial is ",result     return result   Why?


If n friends go to a diner, and when leaving, each of them take a hat randomly, what is the probability of "nobody gets his original hat"? My book says it goes to 1/e, but I don't have more explanation...  Can you help me?

A derangement is a permutation $\sigma$ of $\{1,2,3,\dots,n\}$ such that $\sigma(i) \neq i$ for every $i$.  A common application of inclusion/exclusion in undergraduate combinatorics and probability classes is to compute the number of derangements, and in the process show that the probability a random permutation is a derangement approaches $\frac{1}{e}$ for large $n$.    There's also a "standard" intuition for this probability, which goes roughly as follows:  Let $E_i$ be the event that $\sigma(i)=i$.    1) For a given $i$, the probability of $E_i$ is exactly $\frac{1}{n}$.  2) If $n$ is large, than these events should be "nearly" independent ($E_i$ occurring means that $\sigma(i) \neq j$, making it a tiny bit more likely that $\sigma(j)=j$, but this shouldn't have much of an effect for large $n$), so we'd expect the probability none of the $E_i$ occur to be roughly $\left(1-\frac{1}{n}\right)^n$.  3) For large $n$, $\left(1-\frac{1}{n} \right)^n \approx \frac{1}{e}$.    Now the last approximation alone already has an error proportional to $\frac{1}{n}$.  What's suprising then is that, after , you find that the probability is not just approximately $\frac{1}{e}$, but incredibly close -- the error is less than $\frac{1}{(n+1)!}$.   Is there some alternative intuitive explanation for the $\frac{1}{e}$ asymptotic probability that gives a sense of why the convergence is so fast?


I have the following matrix, call it A: $\begin{bmatrix} 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 \end{bmatrix}$ I need to find its eigenvalue using its characteristic polynomial. I already did this on smaller matrices which were comfortable to calculate. But calculating an eigenvalue for this matrix seems too complex - Possibly there's a better method?  Edit: This needs to be done without an external help (e.g. Wolfram Alpha).

This question aims to create an ""  of numerous questions that ask about determinants of specific matrices (I may have missed a few):              The general question of this type is  Let $A$ be a square matrix of rank$~1$, let $I$ the identity matrix of the same size, and $\lambda$ a scalar. What is the determinant of $A+\lambda I$?  A clearly very closely related question is  What is the characteristic polynomial of a matrix $A$ of rank$~1$?


I am facing issue in below code -  int precision = 3;  String value1 = "2.0425";  String value2 = "2.1425";  DecimalFormat dfForm = new DecimalFormat();  dfForm.setMinimumFractionDigits(precision);  dfForm.setMaximumFractionDigits(precision);  System.out.println(dfForm.format(value1));  System.out.println(dfForm.format(value2));   Output -  2.042  2.143  1st output is expected to be 2.043. Can anyone help me in this?

What I would like is a method to convert a double to a string which rounds using the half-up method - i.e. if the decimal to be rounded is 5, it always rounds up to the next number. This is the standard method of rounding most people expect in most situations.  I also would like only significant digits to be displayed - i.e. there should not be any trailing zeroes.  I know one method of doing this is to use the String.format method:  String.format("%.5g%n", 0.912385);   returns:  0.91239   which is great, however it always displays numbers with 5 decimal places even if they are not significant:   String.format("%.5g%n", 0.912300);   returns:  0.91230   Another method is to use the DecimalFormatter:  DecimalFormat df = new DecimalFormat("#.#####"); df.format(0.912385);   returns:  0.91238   However as you can see this uses half-even rounding. That is it will round down if the previous digit is even. What I'd like is this:  0.912385 -> 0.91239 0.912300 -> 0.9123   What is the best way to achieve this in Java?


What do you call a family you create yourself through marriage or having children?   I want to distinguish between the family I was born into (my birth family) versus the one I made.

Is there any lingual way to differentiate between the family that I’m a child of and the family that I am a parent of? (I.e., the first family consists of my parents, my siblings, and me; the second one consists of my spouse, my children and me.)


When a moderator closes a question on a beta site, if there is no comment on the question, Community raises a flag:     Please explain the nature of this closed question via a comment   This happens even when the question was closed as off-topic with a custom comment. Obviously, in that case, there is a comment — the flag indicator even says so. So Community should not raise this flag.

On beta sites, when a post gets closed without comment, Community ♦ flags it for moderator attention.   Apparently, a comment entered through the freeform close reason doesn't count:    As you can clearly see, there should be no doubt that a comment already exists on the post  Could this be fixed? I don't think it's that important -- I just have to decline the flag, however on larger sites this may lead to a lot of extra flags.


I've found it in the book "Introduction to Quantum Optics" written by Grynberg, et-al... and I'd like to use it in my discussion on this title.  I've already try on Detexify but failed.

Does anybody know how to make the following symbol in LaTeX? I think it is some calligraphic \mathcal{E}.     It is not anywhere in  and online font recognizers do not recognize it.   The general font in the book I got this symbol from, Introduction to Quantum Optics by Grynberg, is not very extraordinary: this is a formula containing the strange symbol:


Steps to reproduce:   Open some of StackExchange sites, for example  Click one of the links in "Recent achievements" dropdown list on the navbar Watch the  address in browser's address bar   The same about "Recent inbox messages" dropdown list.

When I'm on, for example, the secure SO site, and then open the "StackExchange" drop-down, links to other SE sites include their "https" equivalent as well, which is expected. (If I'm on the the regular http site, then the links are all http.)    But links to questions via the "Inbox" and "Achievements" drop-downs lead back to the insecure, http equivalent, even when I'm on a secure page.      Can those links be generated in such a way that we're kept on the secure version of the site?


When I install a program on ubuntu, the installation run on terminal, no setup wizard window is opened. What can I do so that new window will open?

The title says it all. I'd like to know how I can install software - an example is the Chromium web browser.


Let $\Bbb{Z}^+$be the set of all non-negative integers where $n$ and $k$ are given natural numbers. We consider the following non-decreasing function,  $$f:\Bbb{Z}^+ \to \Bbb{Z}^+$$ such that   \begin{align} f\left(\sum_{i=1}^{n} a_{i}^{n}\right)  =\frac{1}{k}\sum_{i=1}^{n} \left(f(a_{i})\right)^{n}\\ \end{align}  Found all functions for $n=2014$ and $k=2014^{2013}$  Found, how many functions and which satisfy the condition of the problem depending on the values of parameters $n$ and $k$.  PS. I've tried to make some operations with this function and found $f(0) $, but I can't imagine what can I do with it

Let $\Bbb{Z}^+$be the set of all non-negative integers where $n$ and $k$ are given natural numbers. We consider the following non-decreasing function,  $$f:\Bbb{Z}^+ \to \Bbb{Z}^+$$ such that   \begin{align} f\left(\sum_{i=1}^n a_i^n\right)  =\frac 1 k \sum_{i=1}^n \left(f(a_i)\right)^n \end{align}  1.Find all functions for $n=2014$ and $k=2014^{2013}$  2.Find, how many functions and which satisfy the condition of the problem depending on the values of parameters $n$ and $k$.  I have some ideas for this problem . I know how to found $f(0)$ (just take $a_1=a_2=\cdots=a_n=0$) . I also can found $f(1)$ (take $a_1=1$ and $a_2=\cdots=a_n=0$) Then if $f(0)=0$ I've get that $f(a_n)+f(b_n)=f(a_n+b_n)$. I also think thas all functions will be as $f(x)=kx$ but I can't prove it . Can you help me with some partical solution or some ideas which can help to find it.  And can someone tell me how in first example ($n=2014$ and $k=2014^{2013}$) found f(2015) or  $f(2016)$ using that $f(i^n)=i\cdot f(1)$ ( for $2015>i>1$)and $f(1)=0$ or $f(1)=2014$


I have a bunch of pictures and I need to change the time on some of them. I'm using Windows 8.1.  The Details pane shown and I've selected one of the pictures in question, however when I click on the Date taken field, it only allows me to change the date, not the time. I've included a couple images below to show this  Is it possible to change the date of a picture in Windows 8.1? Thanks.  On the left is how the Date taken field is displayed to the user, and on the right is the only edit option you get when you click on the field.

I use F-Spot to manage my images. For one set of images, the dates somehow got messed up and they all are marked as September 1st 2007. I'd like to change the date taken information to a different date. How can I do this?


I tried this using a terminal with the disk dump command. After everything was done the thumb drive appears to have everything there. But I'm trying to go from Ubuntu 14.4 32x to Ubuntu 18.4 64x and it is not booting. Can someone please help?

This is the third time I've tried to install Ubuntu Server 14.04.03 64-bit on the same laptop, and each time it caused different problems.  Each time I wrote the same iso image to a USB flash drive by using a different application and OS.   Universal USB Installer (pendrivelinux.com) from Windows WinImage writer from Windows built-in image writer from Linux Mint 17.2    The iso image is the same in all three cases, the USB flash drive is the same, and the laptop is the same. However each time the installation of Ubuntu gave me different installation options. For example, the last time I installed Ubuntu, it didn't show all the packages to choose while installing (Basic Ubuntu server, etc.).


I want to be able to share answers using anchor links, such that when the link is visited, the page scrolls to the particular answer instead of showing the top of the page.  A good example is seen with this .

Is there a permalink I can use for answers/comments?


This is question from abstract algebra. I know that every prime element of integral domain is irreducible. And I think that its inverse does not hold in general. But I can't think about counterexample. Is there an example? Or does its inverse hold?

I am looking for a ring element which is irreducible but not prime.    So necessarily the ring can't be a PID. My idea was to consider $R=K[x,y]$ and $x+y\in R$.  This is irreducible because in any product $x+y=fg$ only one factor, say f, can have a $x$ in it (otherwise we get $x^2$ in the product). And actually then there can be no $y$ in $g$ either because $x+y$ has no mixed terms. Thus $g$ is just an element from $K$, i.e. a unit.  I got stuck at proving that $x+y$ is not prime. First off, is this even true? If so, how can I see it?


Isn't it obvious for $|a|=|a^{-1}|$, since $\langle a\rangle = \langle a^{-1} \rangle$?  For $|ab|=|ba|$, I think we should go like this: $e=(ab)^n\Rightarrow e=(ab)(ab)^{n-1}\Rightarrow (ab)^{-1}=(ab)^{n-1}\Rightarrow b^{-1}a^{-1}=(ab)^{n-1}\Rightarrow a^{-1}=b(ab)^{n-1}$ But I get stuck here, since I don't know whether to get from here to $e=(ba)^n$.  For $|a|=|cac^{-1}|$, do I have to show that $\langle a\rangle = \langle cac^{-1}\rangle$?

Let $G$ is a group and $a, b \in G$. If $a$ has order $6$, then the order of $bab^{-1}$ is...  How to find this answer? Sorry for my bad question, but I need this for my study.


Let $G = a_0,a_1, \cdots, a_6$ where $a_i\cdot a_j = a_{i+j}$ if $i+j <  7$ and $a_i\cdot a_j = a_{i+j-7}$ if $i+j \ge 7$.   I'm trying to see whether this is a group or not. The problem is I can't see what the identity element or the inverses would be from the definition. I tried to prove closure and associativity:  (a) By definition for any $a_i, a_j \in G$ we have $a_i\cdot a_j = a_{i+j} \in G$ if $i+j <7$ and $a_i\cdot a_j = a_{i+j-7} \in G$ if $i+j \ge 7$.   (b) For any $a_i, a_j, c_k \in G$ we have $$a_i \cdot (a_j \cdot a_k)=\begin{cases}  a_i \cdot a_{j+k} = a_{i+j+k} & \mbox{if } i+j+k < 7 \\    a_i \cdot a_{j+k-7} = a_{i+j+k-14} & \mbox{if } j+k \ge  7 \\ a_i\cdot a_{j+k} = a_{i+j+k-7} & \mbox{if}  ~i+j+k \ge 7, j+k < 7  \end{cases}$$  And similarly we have $$(a_i \cdot a_j) \cdot a_k=\begin{cases}  a_{i+j} \cdot a_{k} = a_{i+j+k} & \mbox{if } i+j+k < 7 \\    a_{i+j-7} \cdot a_{k} = a_{i+j+k-14} & \mbox{if } i+j \ge  7 \\ a_{i+j}\cdot a_{k} = a_{i+j+k-7} & \mbox{if}  ~i+j+k \ge 7,  i+j < 7 \end{cases}$$  Is this correct?

Let $n$ be any integer. We construct a group of order $n$ as  follows:   $G$ will consist of all symbols $a^i$, $i=0,1,2 \cdots, n-1$ where we   insist $a^0 = a^n = e$, $a^{i}\cdot a^{j} = a^{i+j}$ if $i+j \le n$   and $a^{i}\cdot a^{j} = a^{i+j-n}$ if $i+j > n.$ The reader may verify   that this is a group. It is called a cyclic group of order $n$.   I'm trying to verify that this indeed is a group.  (a) For any $a^i, a^j \in G$ we have $a^i\cdot a^j = a^{i+j} \in G$ if $i+j \le n$; and $a^i\cdot a^j = a^{i+j-n} \in G$ if $i+j > n$.  (b) For any $a^i, a^j, a^k \in G$, for $i+j+k \le n$ we have $a^i \cdot ( a^j \cdot a^k) = a^i \cdot a^{j+k} = a^{i+j+k}$ since $j+k \le n$ is implied by $i+j+k \le n.$ If $i+j+k > n$ we have $a^i \cdot ( a^j \cdot a^k) = a^i \cdot a^{j+k}$ $= a^{i+j+k-n}$ if $j+k \le n$; and if $j+k > n$ we have $a^i \cdot ( a^j \cdot a^k) = a^i \cdot a^{j+k-n}$ $= a^{i+j+k-2n}$.   For any $a^i, a^j, a^k \in G$, for $i+j+k \le n$ we have $(a^i \cdot  a^j) \cdot a^k = a^{i+j} \cdot a^{k} = a^{i+j+k}$ since $i+j \le n$ is implied by $i+j+k \le n.$ If $i+j+k > n$ we have $(a^i \cdot  a^j) \cdot a^k = a^{i+j} \cdot a^{k}$ $= a^{i+j+k-n}$ if $i+j \le n$; and if $i+j > n$ we have $(a^i \cdot  a^j) \cdot a^k = a^{j+k-n} \cdot a^{k}$ $= a^{i+j+k-2n}$.   (c) There's $a^0 \in G$ such that for any $a^i \in G$ we have $a^i \cdot a^0 = a^{i+0} = a^i$ and $a^0a^i = a^{0+i} = a^i.$  (d) For every $a^i \in G$ there's $a^{-i} \in G$ such that $a^i \cdot a^{-i} = a^{i-i} = a^0$ and $ a^{-i} \cdot a^i  = a^{-i+i} = a^0.$  Is this correct?


ACRONYM - An abbreviation formed from the initial letters of other words and pronounced as a word    Much has been written about acronyms and abbreviations here at EL&U. See   However, I see no mention to this type of acronym where the first half of a word is joined to the second half of another.        Sitcom - a situation comedy, certainly doesn't fulfill the classic criterion for an acronym.  But it might be a variety and might be called by a diferent name. Is it?

TLA is an acronym for "Three Letter Acronym". Is it also an abbreviation, since it abbreviates the original phrase?


I often use these shortcuts in Eclipse, and the shortcut will bring you to the next capital letter in the word- for example:  variableName|   pressing ctrl + left arrow will make the cursor go like this:  variable|Name   However, this is not how it works in Visual Studio. It goes to the next word, rather than the next capital letter. I don't know how to search for this problem on Google.  I'm using Visual Studio Community 2017.

Is there a way that I can configure Visual Studio 2008 to understand CamelCase?  Specifically, I'd like to be able to get Ctrl + right or left cursor to take me to a subsection of a variable or type name. i.e., if my cursor was at the start of this line: LongNamedExampleClass longNamed = new LongNamedExampleClass();  and I hit Ctrl + right, I'd like to jump to "Named" in the class name, rather than the start of the variable name.  If I hit it again, I'd like to go to "Example".  I hope that makes sense. I used this navigational feature in Eclipse quite a lot, and find it difficult to unlearn something so ingrained.


I know my password on my server, but is there a command to check the password?  I can't use ssh because my ssh key is already copied, so is not useful.  I need something to ask me for the root password, and then tell me if it's wrong or not.   The question is not about checking whether a password is valid or right, but if the password is the real password, because when you login with ssh keys, you don't really use the password.

The scenario:  In a bash script, I have to check if a password given by a user is a valid user password.   I.e suppose I have a user A with password PA.. In the script I asked user A to enter his password, So how to check if the string entered is really his password?...


When I changed my Minecraft name I logged out of my launcher and relogged.  When I tried to connect to a server, it said : "Not authenticated with Minecraft.net"  Any help ?

I don't understand this and I'm now worried as I have donated to a lot of servers and I don't want to lose this account. On the launcher it says my new username but when I log on it says "Account not Authenticated with minecraft.net" and "Non-Valid Username".  How can I regain the ability to use my account online?


What I'm trying to do is add a delay of 0.5 seconds everytime it prints something. But the problem I have is that it lags for a while and then prints it all at once.      import time  x = [(0, 1), (2, 3), (4, 5), (6, 7), (8, 7)]  for i in x:     print(i)     time.sleep(0.5)   what this should do:  (0, 1) wait 0.5 seconds (2, 3) wait 0.5 seconds (4, 5) etc   however the problem with mine is that it doesnt print the first one and wait 0.5 and print the next, what mine does is it waits for so long and then prints all at once, I was wondering what's a way to fix this.

Is output buffering enabled by default in Python's interpreter for sys.stdout?  If the answer is positive, what are all the ways to disable it?  Suggestions so far:   Use the -u command line switch Wrap sys.stdout in an object that flushes after every write Set PYTHONUNBUFFERED env var sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)   Is there any other way to set some global flag in sys/sys.stdout programmatically during execution?


When I log off my system and after some time try to log back in it displays "wrong password". I need to go to "switch user" and there select my username and then I can enter my password and log in. But, it doesn't open directly from the log off screen.

I have upgraded Ubuntu to 12.04 and now I have a problem in logging in after locking the screen: it says the password is incorrect even though I provide the valid password. I found a temporary solution by switching users and logging in again with the same user.


A friend of mine told me that because water heat capacity is higher. He also mentioned that it was similar to alcohol on skin effect.  Assume that there are 3 situations. 1. I did not get wet 2. I got wet by water 3. I got wet by pure alcohol  I believe the cold order is 3>2>1  Base on the heat capacity order is water>alcohol>air. This does not match with the cold order.   I also think about whether it would be due to the burning point of the material. At the burning point, the material may need more energy because change from liquid to gas. But the burning point of alcohol is still  much higher (78.2C) than outdoor temperature (25C).   Why?

The title says it all. If I'm standing in the wind and I'm wet, I feel much colder than when I'm dry. This is true no matter how warm or cold the water. Why is this?


I followed the  to upgrade from Ubuntu 19.10 to the  of 20.04 LTS—   Ensure that you have all updates installed. Set "Notify me of a new Ubuntu version" to "For any new version". Run update-manager -c -d.   —and was greeted by this message:     This release is still in development. Do not install it on production machines.   Why does it say this? What would happen if I continue anyway? I double-checked the instructions and there's no indication of how to handle this. I'm not sure if I should:   ignore the warning and continue with the upgrade, take some action to resolve a problem on my end, or wait for a problem to be resolved externally.   Details   The message seems to be coming from . There's an  with the messaging I'd expect. Maybe something is just showing me the wrong one?  (and later DEBUG_UPDATE_MANAGER=1) led me to the  and  manifests, which link correspondingly to the two message variants. The release manifest doesn't include 20.04 LTS, which might help explain . That the upgrade instructions specify  suggests that 20.04 LTS is indeed expected to be a development release. Perhaps I'm mistaken about what it means to be a final release (it's a type of development release?), or the project is simply running behind schedule? I asked about this in . A member of the Ubuntu Security Team confirmed that the omission from the release manifest is deliberate, to be changed "when 20.04 is a bit more stable and better tested". This is consistent with the hypothesis that 20.04 LTS is actually a development release, but contradicts the  and . The mailing list  says:     Users of Ubuntu 19.10 will be offered an automatic upgrade to 20.04 LTS   via Update Manager shortly.   recounts precedent for delaying the update of the release manifest for a few days after the official release, and warns that bypassing the delay with -d constitutes an acceptance of risk as a tester.

Update  appear to have been updated recently (as of writing this the last update appears to have taken place on 3rd of June) to include the following statement:  The -d switch is necessary to upgrade from Ubuntu 18.04 LTS as upgrades have not yet been enabled and will only be enabled after the first point release of 20.04 LTS.  Also note that .  TLDR (as of 15 Aug 2020):   is the canonical tracking document for the first Focal Fossa point-release (20.04.1). It’s a live document. The Ubuntu release team will be updating it as we work on releasing 20.04.1. […] Upgrades from 18.04 to 20.04.1 are still disabled as we are working through a few upgrade blockers   Edit The answers (so far) do not answer the question. The question is pretty simple. Ubuntu.com points to a "FinalRelease", which turns out to be a "Development Release", see evidence below. I'm not asking how and when to upgrade. I'm pointing out what seems to me to be an apparent inconcistency (in semantics, linguistics, logic) in the way Ubuntu names or labels its releases. From an answer to the question I'd except someone to pick up and acknowledge this inconsistency. An answer could start with a "Yes, ..." or a "No, ...", for starters. (Moreover, a good answer could distinguish between the release being in dev stage and/or the upgrade process (e.g. from LTS to LTS) being in dev stage, if appropriate.) This question, as I see it, is not a duplicate. Futher, I think it is a question which deserves a non-patronizing answer. Thanks.   indicates that today (23rd April 2020) the new Ubuntu 20.04 LTS is to be released.  See "condensed screenshot" here:  Indeed, it seems that that's what happened, see  and :  However, when following the instructions to upgrade (from 18.04 LTS to 20.04 LTS) found  and elsewhere (edit: actually , too!), even prior to the July point release, I'm a bit confused to see that the instruction is to use update-manager -d which also points to the "Development Release" (see screenshot below) rather than the "FinalRelease" (see screenshot and link above). Is the "Final Release" (which I'm after) the/a "Development Release"? Why isn't it called something like "Production Release" or "Final Release"? When will it no longer be referred to as "Development Release"? In July? I'm confused :(


I can set the processes to run under special uid's and use the technique from this :   -A OUTPUT -m owner --uid-owner 400 -j DROP   ...But are there any other ways to blacklist based on the PID or its parent's PID without setting up new user accounts?  Relevant links:      EDIT:  A possible duplicate of   EDIT #2:  unshare -n doesn't work on CentOS/RHEL 6.5, since the kernel is compiled without CONFIG_NET_NS=Y.

Is it possible to block the (outgoing) network access of a single process?