C# Regex and email format
How to validate an email address using a regular expression?
What do you call a person who does/thinks the opposite of the crowd for just that reason? Your summary page shows "N Edits to your posts" for the selected time period but you really have to be looking for it.  Could we add edits to the notification feed? You could put the reason for the edit (entered--or not--when the editor changes it) and just a link to the post. Accessing my Windows 7 files from my Ubuntu account How to undelete notes on iPhone "Notes" app? iPhone has a default "Notes" app which allows us to store notes. Stored notes can be deleted by hitting the "Delete Note" button:    How do we recover a note that is accidentally deleted?  Is there anyway to undo the delete? How to create and design hoops net and attach ot to a hoop? I've fitted my model and am trying to understand whether it's any good. I've calculated the recommended metrics to assess it ($R^2$/ AUC / accuracy / prediction error / etc) but do not know how to interpret them. In short, how do I tell if my model is any good based on the metric? Is an $R^2$ of 0.6 (for example) sufficient to let me proceed to draw inferences or base scientific/business decisions?     This question is intentionally broad, to cover a wide variety of situations that members frequently encounter; such questions could be closed as duplicates of this one. Edits to broaden the scope beyond the metrics mentioned here are welcome, as are additional answers - particularly those that offer insight about other classes of metrics. Can an Indian citizen holding a valid USA visa visit Colombia without a visa? I am planning to travel to Colombia for about a week to attend an academic conference. I am an Indian passport holder currently living in USA with a F-1 visa. Do I need to obtain a visa beforehand from the Colombian consulate?  I have found   that claim that Indian citizens holding a valid USA visa are not required to apply for Colombian visa.     However, I am not sure if these sources are "official" and trustworthy.Is there a more official source? Also, does this rule apply to "tourists" only? Does anyone have any personal experience with this rule? How to install Flash player on Ubuntu? Even though I have the latest Adobe Flash player 11.2 for Linux in Firefox -   - a particular online flash game still requests that I update to the latest flash player.  I've tried this online game on my laptop (Windows 8 with Flash Player 11.8) and it has no problems.  Is there a way to trick Ubuntu or this game into thinking Flash Player 11.8 is "installed"? How do I install and manage GNOME Shell extensions? How do I install GNOME Shell extensions?  Is it possible to update, remove and manage the extensions? Is there a GLM bible? Is there consensus in the field of statistics that one book is the absolute best source and completely covering every aspect of GLM - detailing everything from estimation to inference? I'm trying to show the following:  Let $f:X\to Y$ be a proper holomorphic map between connected, non-empty Riemann Surfaces. Show that a map $g:Y\to\mathbb{C}$ is  holomorphic if and only if  its composition with f is holomorphic.  So far I know that $f$ is surjective, since it's proper and holomorphic. My next step was to look at the charts, but it's there, I get stuck. Cannot modify files installed by `snap` I have installed a package using snap and I need to modify one of the files but when I try to change its ownership or permissions, I always get the following message:  sudo chmod +x ./my_file.js chmod: changing permissions of '/snap/my_app/my_file.js': Read-only file system   How can I modify files that are installed via snap? Difference between  and  in Java Disable App Update Notifications on OSX? Cutting features to do opposite of clipping in ArcGIS Desktop? What´s the easiest/smartest way of getting the opposite output of the clipping tool?   I just need the area of feature A1 which is not covered by feature A2 in a new Layer/File.  Now, I get the result by union´ing both features and deleting the "wrong" parts by hand.  I'm using ArcGIS Desktop 10. Can I update an early Airport Time Capsule? How to replace text between quotation marks with something from another file? I have the following kind of text: $OU = 'or'; $DINHEIRO_CAIXA = 'Cash balance'; $PAGINA = 'Page'; $DE = 'from'; $ENVIAR = 'Send'; $PRINCIPAL = 'Main';  I've already got all the text within the single quotation marks using cat arquivo | grep -oP &quot;'[^']+'&quot; | tr -d &quot;'&quot; This extracted text was then translated to Portuguese, but now I don't know how to replace the original text between single quotation marks with the translated text, I was looking for something like $OU = 'ou'; $DINHEIRO_CAIXA = 'Dinheiro em caixa'; $PAGINA = 'Pagina'; $DE = 'de'; $ENVIAR = 'enviar'; $PRINCIPAL = 'Principal';  I've tried using grep -F to replace the file itself, but it failed miserably because the pattern didn't match since I don't have the quotation marks on the new file, is there a way to do this? I'd like to know your opinion on citations in abstracts. At my university, there is no rule on that matter so it's basically a question of preference.  Do you think it's okay to have citations in an abstract or do you  personally prefer to have the abstract be a ``stand-alone'' piece of  work? An instructor has an exam of 5 questions and a question bank of 50 questions. Are there $50\choose 5$ or $(50)_5$ possible exams? What keeps mass from turning into energy? I understand the energy and mass can change back and forth according to Einstein. It is fluid; it can go from one to the other. So, what keeps mass from just turning into energy? Is there some force holding a subatomic particle together? What keeps mass in it's state? I hope this is not a silly question but I am clueless. Thanks