Validating email format in java
How to validate an email address using a regular expression?
Inequality involving the sup of a function and its first and second derivatives How to use unnumbered chapters with KOMA-script? I am having some issues with the hyperref package. I would like to create a Introduction chapter without a number so I use \chapter*{Introduction} and \addcontentsline{toc}{chapter}{Introduction} because I want it in the table of contents (see example).  But then the link in my PDF viewer gets it wrong and also the automatically created header is no longer correct (see picture). The table of contents shows the right page number (p.1) but the link is also wrong.   What is my mistake here?  \documentclass{scrbook}  \usepackage{hyperref} \usepackage{blindtext} \usepackage{glossaries}   \makeglossaries  \newacronym{eg}{e.g.}{% for example }   \begin{document}   \frontmatter  % abstract before the table of contents \chapter*{Abstract} \addcontentsline{toc}{chapter}{Abstract} \blindtext  \tableofcontents  % chapter with acronyms \cleardoublepage \phantomsection  \printglossary[type=\acronymtype] \addcontentsline{toc}{chapter}{Glossary}  \cleardoublepage \mainmatter   \phantomsection % \chapter{Introduction} % with this everything is correct but I don't want the number \chapter*{Introduction} \addcontentsline{toc}{chapter}{Introduction}  \blindtext  \pagebreak  \blindtext  % first chapter \chapter{Chapter1}  \gls{eg} \blindtext  \pagebreak  \blindtext   \end{document} Solving Hardy Weinberg problems I really fail to understand Hardy-Weinberg equilibrium and can't find an easy enough source of information.  Can you help me to understand Hardy-Weinberg equilibrium?  My goal is to be able to solve the following kind of problem     In a population with two alleles for a certain locus, B and b, the allele frequency of B is 0.7. What is the frequency of heterozygotes if the population is in Hardy-Weinberg equilibrium? ON creating BITMAP INDEX on a table in mysql throws error I have database named "demo_dev" and added a table named "countries".  I wanted to create a bitmap index on a column, say, region as it has fewer unique values, using following query.   CREATE BITMAP INDEX ON countries (region);   It threw an error as shown below:     You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'BITMAP INDEX ON countries (region)'   What shoud be done for it to run successfully?  I just refered the following link :   mysql version : 5.5 Set origin to vertex in edit mode? I want to make the origin in edit mode at a vertex, but it keeps setting it to the last clicked-on face :( So now in edit mode the pivot is on the last clicked-on face ;( The  is a proposed propulsion mechanism for spacecraft in which some form of microwave device provides the propulsion. The consensus from the physics community, including many voices on this site, is that the proposed device would violate conservation of momentum.   Several experiments have been conducted, by three main groups: (i) , from Satellite Propulsion Research Ltd, (ii) a research group at the Northwestern Polytechnical University in Xi'an, China, and (iii) Eagleworks Laboratories at NASA's Lyndon B. Johnson Space Center in Houston, Texas. However, few of these experiments have been performed in vacuum (and none of the vacuum tests has been published in a peer-reviewed journal), which means the effect of air currents around the device cannot be ruled out.  This device has been the subject of many questions on this site, including          and their many closed duplicates.  Many of these questions ask what the proposed explanations are, but then veer off into territory of the form "assuming it is true, how does it work?", so they have been (rightfully) closed as counterfactual physics. I feel this sort of bundling does a lot of harm to the discussion, and there is some scope to ask what exactly is being proposed as an explanation. So:     What do the proponents of EmDrive claim is the theoretical justification of the device's function?   Please limit answers exclusively to references, and indicate whether they are peer-reviewed or not. Please limit answers to serious attempts at explanations, as opposed to vague claims about the 'quantum vacuum' - or indicate if an experimental paper does not have any such theoretical explanation or reference.  To be clear, this is not the place to discuss whether the explanations are correct or not. If you have specific questions about any of these sources, ask it separately. (However, if your question starts with "assuming that this works", be prepared for it to be closed.) If you feel there are not enough resources on this thread, you can  but please do not post another question asking people to look for more references. When should I use the new keyword in C++? Why are so many different types of objects white, yet appear gray when they are wet? There are many things with different textures that appear white – salt, beer foam, paper, shaving cream, snow, talcum powder, white paint, etc. The most common answer is all of the frequencies must be reflected in order for us to perceive white, which I already know. There must be more underlining details why such a huge variety of things are white. Furthermore, if you wet paper, snow or talcum powder, they appear off-white or gray. Why is this? Can't delete folder in Windows 7 I'm trying to delete a folder in Windows 7 and get a perplexing error message: "Could not find this item:  This is no longer located in G:\Graphics.  Verify the item's location and try again.  I can see the folder -- I can find it.  I just can't delete it.    I also get a second error message (sometimes) when I click on the folder: G:\Graphics 2009-11-17 refers to a location that is unavailable...this information might have been moved to a different location.    I'm using Windows 7; this folder is on an external hard drive.  I've emptied the folder (there were items in it); I've scanned that external hard drive for errors.  Trying to rename the folder yields the same enigmatic error message.    Is there a way to delete this folder? What is the sum of this series: $\displaystyle\sum_{n=0}^{\infty} \dfrac{a^n}{(3n)!}$ I tried getting it into a closed form but failed. Could someone help me out?  $$\sum_{n=0}^{\infty} \dfrac{a^n}{(3n)!}$$ The pronunciation of the word "a" Most times we hear that the letter A is pronounced as [ə], but sometimes I hear that it is pronounced as [eɪ] in American English. Such as the following sentence: From VOA Special English:  She says governments must make that goal of a continental free trade area a reality.  The first A is pronounced as [eɪ], the second A  is pronounced as [ə]. Why? Does it have some regularity in it? Can't understand how to draw it. How can I see the source of built-in JavaScript functions? Now, that Adobe has stopped issuing new releases for Linux desktops, the only option for users is to use Google Chrome, for those who want to use the latest Flash updates. I use Chromium. Is there any way to get Chromium use the Flash from Google Chrome? The reason I as this question is that I have noticed both these browsers run in the background, so technically, the browsers' plugins are available to use. Does English have any singularia tantum besides mass nouns? and  are, respectively, nouns that have only a singular form and nouns that have only a plural form.  In English, we have a handful of pluralia tantum that are mass nouns which take the plural form (e.g. "riches" and "remains"), a whole load of pluralia tantum that refer to things that come in pairs (e.g. "trousers", "sunglasses", "knickers", or "scissors"), and at least one plurale tantum that fits into neither of the above categories ("clothes", meaning multiple items of clothing - it's clear what the hypothetical singular "clothe" would mean, yet it mysteriously isn't a word). Singularia tantum, on the other hand, seem less varied. As far as I can tell, they are all  - things like "information", "milk", and "racism".  One can imagine there being a singulare tantum that is not a mass noun. For example, we can imagine an alternate universe in which it is still correct English to talk about "a dog", but talking about "dogs" in the plural is incorrect and funny in the same way that it is incorrect and funny to talk about a "scissor". It might seem unintuitive to think that such a noun even could exist - surely, if it is not a mass noun, then people would just pluralise it with an "s" on the end like most other words? But the converse argument could just as well be made about countable pluralia tantum, and I still cannot go to a shop and buy a "clothe". Hence my question: do we have any such countable singularia tantum in the language? Have we in the past? How do I get started with Translations? My friend and i would like to translate Ubuntu. where should we start? where to find translation tools? Can I remove inline event handlers using jQuery? Connection pooling in PHP Is it possible to cache database connections when using PHP like you would in a J2EE container?  If so, how? Efficiently replace all accented characters in a string? A little background:  I do not know what the specifics are, but I've noticed that a quick edit after a post will often times not result in an edit being posted. It's as if there was no edit. Edit: According to Bart this amount of time is five minutes.  The problem:  A user made a really bad post (said that ~ in C# wrt integers was used for deconstruction). I down-voted said post. Post quickly disappeared (I guess poster realized they screwed up and took back the post). Later, I come back and see my down vote but the answer is now correct (that ~ is the bitwise complement operator). I try to get rid of my down vote because it is no longer appropriate. However, it has been about half an hour and there is no edit posted (presumably the poster made an edit within the non-posting edit window) so I can't take my vote back.  Suggested solution:  If post gets edited (even within the non-post edit window) mark all the votes as changeable. I would guess that this would either involve an update on a table of votes or adding a column for last edit time which is not bypassed by the grace period. I realize that this may be an entirely non-trivial change, but unless the non-posting of edits is somehow changed to make sure the edit was trivial it seems this is necessary.