What qualifies a dragon as "ancient"?
How long are the life phases of a dragon?
Consolidate tag wiki excerpt and body contents with regards to suggested edits At the moment, in major part because they are two separate post objects in the system, the excerpt and the body of a tag wiki count as two separate posts with regards to suggested edits in the queue. Mechanically, this is sane, but when it comes to handling the actual queue, it can be confusing. A body edit might consist of little more than a bed of links, which looks bad. But then an excerpt is shown that includes the rest of the data, and since excerpts can be included on the actual wiki page, it makes a lot more sense when they're taken in the same space.  And this is how they are composed, too. The actual edit interface for working on tag wikis has both the excerpt and the body on the same page. In a sense, the excerpt behaves a lot like the "title" of the wiki, if we make a parallel to normal post edits.  Thus, my suggestion (which is to say a suggestion that I repossessed from Robert Cartaino) is that when suggested edits are reviewed for tag wikis, that they be presented in a single unit, treating the excerpt the same as how a title is treated in a question edit. This way, relevant information that is crossed between the two isn't lost because they are reviewed separately. $(K[x,y,z]/(x^2+y^3+z^7))_{(x,y,z)}$ is a UFD. Does Google use the Meta Description Tag for Description of Page? When you do a Google search, there is typically a snippet of sample content from the page. I seem to recall that the Meta Tags can influence this choice of descriptive sentences. Is that correct(?) and if so, is it the Meta Description Tag?  Also, how many characters is Google's descriptive sentences limited to? Is there any good reason that an empty set of round brackets (parentheses) isn't valid for calling the default constructor in C++?  MyObject  object;  // ok - default ctor MyObject  object(blah); // ok  MyObject  object();  // error   I seem to type "()" automatically everytime. Is there a good reason this isn't allowed? Windows 10 Search not loading, showing blank window If $f(x)=x-\int^{\frac{\pi}{2}}_0f(x)\sin(x)dx$ find the explicit function for $f(x)$ in its simplest form How to replace plain URLs with links? Find $\lim_{n\to\infty}2^n\underbrace{\sqrt{2-\sqrt{2+\sqrt{2+\dots+\sqrt2}}}}_{n \textrm{ square roots}}$. Find $\displaystyle \lim_{n\to\infty}2^n\underbrace{\sqrt{2-\sqrt{2+\sqrt{2+\dots+\sqrt2}}}}_{n \textrm{ square roots}}$.   By geometry method, I know that this is $\pi$. But is there algebraic method to find this ?   Thank you. How do I design a user friendly survey with more than 150 questions? I am designing UI/UX for a survey webapp which has more than 150 questions. Right now they are using 5 radio buttons for each question. Similar to the image below:      So the question is, how to make it super user friendly, easy and fun to do?   Further I am looking for a solution from responsive web design perspective too.  I hate designing it like the following image below but what are some other options. Why does my Nikon D3100 give the error "Lens not attached" with a Vivitar 200 telephoto lens? I have a Nikon D3100 camera, and am trying to use an "Automatic Fixed Mount Vivitar 200mm lens" with it. When I attach the lens, I get the message "Lens not attached". and nothing works. HELP!  I can't easily take it to a camera shop, as I live in the Mojave Desert, about 200 miles away from any camera shop. This is a new lens, and a new camera. Some people (me) would prefer the straight GNOME experience as opposed to the Unity style desktop offered in Ubuntu 17.10.  How can I get the standard GNOME desktop and interface? When studying weak border conditions (in Sobolev Spaces), the usual motivation for the weak meaning of inequalities is that the boundary of most open sets in $\mathbb{R}^n$ has zero Lebesgue measure. But is there any open set $U\subseteq\mathbb{R}^n$ such that it's boundary has positive Lebesgue measure? I really can't think of anything like that. For a Google account, you are allowed to sync Contacts and People details. What is the difference between these two? At some point in (I think) the 90s, I saw an episode of something like Outer Limits or Twilight Zone where nobody was allowed to have more than average intelligence. Smarter children had to wear headsets which inhibited them from being too intelligent, administering minor electric shocks if intellectual thought was detected.  I can remember a final (or near final) scene of somebody watching his suicide and being upset but not remembering why because of the headset.  Can anybody identify the show and episode? Can't install wine from winehq.org on Ubuntu (actually Lubuntu) 18.04 LTS I have followed all the instructions on .  In particular, I have run the following commands: sudo dpkg --add-architecture i386  wget -nc https://dl.winehq.org/wine-builds/winehq.key sudo apt-key add winehq.key sudo apt-add-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ bionic main'   The first three of the above seemed to work fine.  However, the last command gives me the following error: Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  winehq-stable : Depends: wine-stable (= 5.0.0~bionic) E: Unable to correct problems, you have held broken packages.  I'm running Lubuntu 18.04.3 on a USB live stick.  (However, if I remember correctly, a couple days ago I got the exact same error on a normal hard disk Lubuntu 18.04.3 installation.) I've read that a lot of people get similar errors.  Unfortunately I haven't found any solutions online that worked. Any help would be much appreciated.  Thanks! EDIT:  Thanks for the comments and suggestions everyone.  I'll try them out later today. In the mean time, here's something I don't understand.  Ubuntu 18.04 has been around for almost two years now.  In all that time, surely somebody has successfully installed wine, right?  What did they do to get it working? I have something like that  how do I convert this to a YouTube playlist? Can't login with Google using Internet Accounts If $ \langle G, \star \rangle $ is an abelian group, then for all $a, b \in G$, show that $(a \star b)^{n} = a^{n} \star b^{n}$. If $ \langle G, \star \rangle $ is an abelian group, then for all $a, b \in G$, show that $(a \star b)^{n} = a^{n} \star b^{n}$.  I am stuck at the first step, unable to figure out how to start. I am just beginning on group theory, and know that an abelian group obeys commutativity, associativity, has an identity element, and each element is invertible. I am unable to figure out how to apply this for the proof. Any hints on how I should get started? My earliest PhD graduation date is 10 months away. Funding permits me to stay 1–3 months longer, so the final date is still uncertain.  It is never too early to make contacts for possible post-docs. But how long in advance is too early to formally apply to post-doc job openings or funding opportunities? Depending on the bureaucracy, the path from applying to starting can probably be anything from a week up to a year — someone I know is applying with  which had the opening advertised in August, application deadline in October, will have interviews in December/January, and the commencement of work only in September, 13 months after the initial job advertisement. My personal guess is that the long time between interviews and starting is to create a level playing field between those who do and those who don't need to go through a visa application procedure.  If I'm too early in applying for a post-doc, a hosting institution might prefer someone who can start earlier and where the graduation date is more certain. For example, in my case the graduation date is still uncertain, so there is a risk in accepting even if they are willing to wait. Project funding might also require the money to be spent rather soon.  If I wait too long, there might be a considerable period where I'm between jobs. Having a long (>6 months) period between jobs is a disadvantage for me. Maybe it's also a disadvantage for a hosting institution (I'm not sure).  How do I find the balance? For example, considering the duration of funding and visa applications, does it make sense to apply e.g. ? Or is it in any case virtually inevitable to have at least several months before my PhD graduation and the start of a post-doc? How can wifi penetrate through walls when visible light can't? I did search the question on Physics S.E considering it would be previously asked. I found this  But in this question , the answers are w.r.t to or in comparison with microwaves , their absorption and certain other things. I didn't find a sort of general answer that could be the answer to the question. So the question is - wifi or radio waves  reach us through concrete walls . They also reach us through the ceiling (if some one is using it in the flat above ours ). Even through the air they travel such a lot , bending around corners or doors . Now I would not compare them to microwaves (because I don't want the answer in terms of properties of the material but physics). Visible light which is so much powerful than them can't penetrate black opaque paper leave alone the walls. Same is true for gamma rays (penetration through a very thick wall). So why then radio waves being so very less powerful than light  waves are able to travel through walls? There should be a general concept as to why the radio waves are able to pass through walls but microwaves or light waves cannot ! A linked question is also that sound travels much faster in solids(walls) but is not audible in it though it is in air. After reading @BillN's answer, it would be really helpful if any one could explain it in terms molecular resonance or crystalline structure or electrical conductivity or how does molecular resonance or crystalline structure or electrical conductivity cause this.