Although I'm aware that , this is the first time I've come across a question answered by a user with the same display name as the OP ().  The problem this poses is that if I want leave a comment on the answer that notifies the asker, I have to play a guessing game:    There's no clear way for me to tell which Kareem is the real Kareem (short of ) and I wouldn't want to mistakenly .  This is confusing (if infrequent). I can't tell whether it actually breaks notifications but even if a comment using @Kareem would "correctly" notify both users, a system that allows arbitrary identifiers should be prepared to handle collisions a bit more gracefully. How many people read ? (More importantly, how many remember all of the implementation details?)  What I'd like to see is a slightly expanded notification syntax; for example, @: could allow notification by the user ID such that I would use @:2561 to notify the OP in the above conversation.  Being able to type @: to show autocomplete options as Kareem:2561 and Kareem:1661 instead of just Kareem and Kareem would be a nice additional functionality.   I'm assuming here that an arbitrary display name could be 2561 or user2561 but . Another approach that avoids expanding the syntax would be to reserve display names of the format ^user\d+$ to avoid spoofing the "default" display name of another user and then allow @-notification by either of the current and default display names.  One additional benefit of this feature is that it would be much easier to distinguish when a reply is made to a deleted comment vs. a comment from a user whose display name had later changed. Again, this will be infrequent, and it relies on people using the feature - but if user2561 changes their display name on realizing there's an active user already going by "Kareem," the @reply by the other "Kareem" will start to look a bit schizophrenic. It's in just those cases where a user is most likely to want the alternative syntax that it might be expected to carry this added benefit.
Suppose there are two users that have commented on an answer. Both have the same user name, and I want to reply to one of them. How can I do this?  It appears that, under the current system, there is no way for me to do this. Specifically, from , I see that:     4. Matching is performed in reverse chronological order, so if five people named John are participating, @john will match the most recent John   So, consider this a request to add this feature using an -n suffix or something similar; e.g. @john-2 could be used to reply to the second John from the top.  Update Thanks to  for nice answer of @name(userid) based auto-complete suggestion which has no loophole. It involves no counting from top &amp; has no consequences when a comment is deleted. But, I think @name(userid) should be used directly in comment as all form inputs at SE are text (nothing embedded).  Now, I'm trying to finalize it based on it: The system should allow optional @name(userid) format for reply. Provided userid with this format, system should ignore name. And, in the situation of duplicate name based confusion, system should demand this format as mandatory to submit comment.  How to get userid? In case of duplicate name based confusion, system should append (userid) in hypertext to their profile. It'd work for mobile version too. On full version, for easy fill-up, a hover reply icon would be fine (like hover vote up icon). Upon clicking it, system should fill @name(userid) in comment text box.  From reply reader side: Multiple Johns could be confused even if they didn't come from notification (because nobody remembers his/her own userid). So, highlight the background of comments which are replied to them.
"Abusing" bounties for unlimited profit Six days ago I put a +50 bounty on  which wasn't asked by me, but to which I'd previously posted a pretty decent answer. Since then I've earned 130 reputation from upvotes on my answer, netting me +80 reputation and a bronze badge from no work.  It seems possible to slowly generate free reputation by "investing" in your answers like this. I expect I could repeat this perpetually and continue to profit from it.  This strikes me as an abuse of the bounty system. Should anything be done to prevent it?  EDIT: For more concrete questions:   If I put another bounty on this question after this one expired, would that be considered abuse? What if I did it several times? ( the answer was  "yes", but the author was doing so to promote his own project.) What if I didn't do it to the same question, but was constantly promoting questions I'd answered, in order to promote my answers? euler's theorem of homogeneuos function suppose that $f$ is a mapping from $\mathbb R^n \to \mathbb R$.  a positively homogeneous of degree $n$ and suppose $f_1, f_2, .... f_N$ are continuous for $a \neq 0$. then   $$\sum_{i=1}^n a_if_i(a)= n*f(a)$$   now, they asked me to prove this. (Which is a total no no to me)  I write my proof as;  $f$ is a mapping from $\mathbb R^n \to \mathbb R$  A homogeneous function of degree $n$ if for all $a \in \mathbb R^n$ and all $L&gt;0$, $f(La)=L^n\,f(a)$. let $a \in \mathbb R^n$ and define function $g$ be a mapping from $[0,\infty) \to \mathbb R$. so I write $g(L) = f(La)-L^nf(a)$. then $L≥0$ let $L=0$ then, $g(L)=0$ and therefore $g'(x) =0$?  then i don't know what's goes next. can anyone help me about this? $F_\sigma$-subsets in a normal space can be separated Let $X$ be a normal Hausdorff space and let $C,D$ be two $F_{\sigma}$ subsets of $X$ such that $\overline{C} \cap D = \emptyset$ and $C \cap \overline{D} = \emptyset$.  Prove there exists disjoint open subsets $U,V$ such that $C \subset U$ and $D \subset V$.  No idea how to show this. Can you please help? Include sorting of accepted answer on profile I have few things on my mind:   I viewed my profile and I wanted to sort my answers by  "Accepted Answer, Votes" Wanted to know how many answers I've made that is marked as  the accepted answer. Sort by Most liked Question: I'm referring to my question who  have the most numbers of favorites. I wanted to sort the questions I created order by accepted or  unaccepted questions.    1 &amp; 2 seems useful to me but 3 &amp; 4 I don't think are that useful. But who knows, someone in this site might find it useful one day!  My POV: My answer is only sorted by Votes, I also want to see a list of accepted  answers on my profile probably not just to know how many accepted answers  I have but also to know what are the accepted answers that I have. Does throwing a watch into the air cause it to gain or lose time? Suppose I'm on a non rotating planet. I have two identical, perfect watches. I synchronize them. Then I throw one of them into the air and catch it. Does the one I throw into the air gain or lose time with respect to the one I was holding? If $G$ is isomorphic to $H$, then ${\rm Aut}(G)$ is isomorphic to ${\rm Aut}(H)$ If a group $G$ is isomorphic to $H$, prove that ${\rm Aut}(G)$ is isomorphic to ${\rm Aut}(H)$.   Can someone provide a step by step solution? Explaining along the way our strategy in proving this. Can X.org Load Two Different Drivers? (Triple-Head Setup with Intel and NVidia Card) We want to set up a 3 screens with an onboard intel graphics adapter and an nvidia card.  Both cards are recognized in lspci   01:00.0 VGA compatible controller: NVIDIA Corporation GT218 [GeForce 210] (rev a2) 00:02.0 Display controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)   And bascially work: If I switch to the console, I see output on the Intel card, X is only running on the Nvidia card.  But when I type xrandr | grep conn I get only one connected port:   DVI-I-0 disconnected (normal left inverted right x axis y axis) VGA-0 disconnected (normal left inverted right x axis y axis) DVI-I-1 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm HDMI-0 disconnected (normal left inverted right x axis y axis)   I am on Ubuntu 12.10 (and XFCE) and installed the proprietary nvidia driver.  I was assuming that X maybe has a problem to autodetect both cards, so I thought the following xorg.conf could help:   Section "ServerLayout"     Identifier     "Layout0"     Screen      0  "Screen0"     Screen      1  "Screen1"     InputDevice    "Keyboard0" "CoreKeyboard"     InputDevice    "Mouse0" "CorePointer" EndSection  Section "Files" EndSection  Section "InputDevice"     # generated from default     Identifier     "Mouse0"     Driver         "mouse"     Option         "Protocol" "auto"     Option         "Device" "/dev/psaux"     Option         "Emulate3Buttons" "no"     Option         "ZAxisMapping" "4 5" EndSection  Section "InputDevice"     # generated from default     Identifier     "Keyboard0"     Driver         "kbd" EndSection  Section "Monitor"     Identifier     "Monitor0"     VendorName     "Unknown"     ModelName      "Unknown"     HorizSync       28.0 - 33.0     VertRefresh     43.0 - 72.0     Option         "DPMS" EndSection  Section "Device"     Identifier     "Device0"     Driver         "nvidia"     VendorName     "NVIDIA Corporation"     BoardName      "GeForce 210" EndSection  Section "Screen"     Identifier     "Screen0"     Device         "Device0"     Monitor        "Monitor0"     DefaultDepth    24     SubSection     "Display"         Depth       24     EndSubSection EndSection   Section "Monitor"     Identifier     "Monitor1"     VendorName     "Unknown"     ModelName      "Unknown"     HorizSync       28.0 - 33.0     VertRefresh     43.0 - 72.0     Option         "DPMS" EndSection  Section "Device"     Identifier     "Device1"     Driver         "intel"     VendorName     "Intel"     BoardName      "Internal Intel Graphics" EndSection  Section "Screen"     Identifier     "Screen1"     Device         "Device1"     Monitor        "Monitor1"     DefaultDepth    24     SubSection     "Display"         Depth       24     EndSubSection EndSection   But it is still not working.   Is this generally possible to use two different drivers in X ? Is it necessary to create an xorg.conf manually then? (because Ubuntu 12.10 normally works without the xorg.conf) Are there any errors in my xorg.conf? Question Staging SE Been a few blogs on , and I get the point. However, would a staging SE help solve some of these issues like community overlap. I understand , but how can someone not yet a part of a community know to do so. Some of the point of SO is that you often don't know what to ask exactly, and we help clear that up. So, I wonder, rather than &quot;playing hot potato&quot; would it be useful to have a site that's simply for temporarily holding questions and such.  It would be the alternative to migrating to another site where you dump all responsibility on that site. This area, all communities are responsible for. It would be a good place to ask a question if you don't know where to ask. The blog I linked talks about phrasing to a specific audience. For someone that doesn't know, the audience is better at selecting which questions are directed at them. As SE grows, the amount of communities will mean more overlap. Right now it may be reasonable to expect people to be able to predict the best community, but will it always be that way?  Some restrictions:  It would be accessible by all communities. The question could be edited, but not answered. The question could be exposed to more easily tracked/understood/etc. automated janitorial work.  Just a helpful thought. Why I can't edit "Your Communities" list in stackexchange.com and Area 51? I can edit &quot;YOUR COMMUNITIES&quot; in the upper left drop-down menu from any of my communities: (e.g. )    But in  portal there's no &quot;edit&quot; link:    Why is that and how can I edit the list in  portal? Closest points on two line segments I am looking for a general formulation to find the closest points on two line segments. What I was thinking about is to define our lines as:  $$ P1 + s  (P2-P1)$$  $$ Q1 + t  (Q2-Q1)$$  Where $P1 , P2, Q1$ and $Q2$ are the beginning and the end points on each segment.  Now we should go through an optimization problem as: $\min f(s,t)$ such that $0&lt;s&lt;1$ and $0&lt;t&lt;1$.  Where $f(s,t)$ is the point-to-point distance function.  Is there any straight forward solution? How to remove uninstalled snaps from cache? Why is transferring money online to someone else's bank account so difficult in the U.S.? I have a shapefile and I want to change the order of the features. Is that possible? I want to sort the features in the shapefile because I'm embedding this shapefile in a mobile app. The app will display a list of features, and although I could do the sorting at load time, I'd prefer to have them sorted. Should I use the datetime or timestamp data type in MySQL? What software can I use to write on PDFs? I'm used to OS X where the system PDF viewer will let you draw and write text on top of any PDF document. You can then flatten it and save as a new PDF. It saves paper and time so you can fill in any form without printing it and scanning it back to the computer.  It also lets you insert a scanned image of your signature.  Is there software for Ubuntu that would do that? Did something change in the behavior of blocking users' votes if they don't have sufficient rep to vote? I've just noticed that if you try to vote without having a privilege to vote, you're greeted with such message:        So, that's interesting. Does it mean that if I gain 125 (or 15, in case I'm upvoting not having 15 reps) rep on that site, my "suggested" vote goes public and until then it would be recorded as it's done with anon feedback?  And until this change, the votes weren't recorded as anonymous, or has the new message saying that it acts as feedback been added just to not upset users? A limit question (JEE $2014$) The following is a JEE (A national level entrance test) question:  Find the largest value of the non-negative integer ( a ) for which:  $$ \displaystyle \lim_{x \to 1} \left( \dfrac{-ax + \sin(x-1) + a} { x + \sin(x-1) -1 } \right)^{\dfrac{1-x}{1-\sqrt x} } = \dfrac 1 4 $$  On solving this, we get $ a = 0 $ or $ a = 2 $. So we take the answer as $ 2 $. But the official answer key says that the answer is $ 0 $. The reason given (not in the official key - they simple contain the answer. I saw the reason in an "unofficial" solution to the question paper) is that if $ a = 2 $, then the term $\displaystyle \dfrac{-ax + \sin(x-1) + a} { x + \sin(x-1) -1 } $ tends to a negative value ( $-0.5$ ). So $ a = 0$.  BUT:  By putting $a = 2$ in the limit, and inputting that to wolframalpha (), the answer turns out to be $0.25$. So, by putting $ a = 2$ also, we get the same value of the limit - $0.25$.  How to solve this dispute? Also, could you please check with Mathematica? Unfortunately, I don't have access to it!  (This is very important as the change in the answer key will affect the rankings in a dramatic way) Proving $\sqrt{ab} = \sqrt a\sqrt b$ I am currently in high school and we are studying radicals. I had asked my math teacher why $\sqrt{ab}=\sqrt{a}\sqrt{b}$ (for all a,b>0) and he tries to prove it by arguing that $a^{1/2}*b^{1/2}=(ab)^{1/2}$ (an exponent law). However, I find this proof problematic since $x^{1/2}$ is simply defined as $\sqrt{x}$, so the reasoning is circular.   My view is that $\sqrt{ab}=\sqrt{a}\sqrt{b}$ because once we square both sides we get $ab=ab$. Since we're obviously referring to the positive root, and the function $f(x) = \sqrt{x}$ is injective, it necessarily follows that the original expressions $\sqrt{ab}$ and $\sqrt{a}\sqrt{b}$ are equivalent because for injective functions it is not possible to map distinct elements in the domain to the same element in the range ($ab$). Hence they are equivalent expressions.   My question therefore is, is my proof valid and/or rigorous (I find it convincing but maybe it's wrong; I just want to be clear) and secondly was my teacher's proof correct? How to generate a random alpha-numeric string Render looks darker than Look Dev mode