I asked a question on Movies &amp; TV about a series that did not have a tag yet.  Not having the 300 rep to add a new tag, I posed the question with the closest tag I could find, and then went to meta to ask someone to add the tag...  Only to find out that I was rate limited on meta as well (at least from the iOS app).  I wanted to ask for community help on meta, since I do not believe this issue warrants a mod flag.  Why does the question rate limit apply to meta questions as well?  Is it to prevent new users from (incorrectly) flooding meta with bad, potentially off-topic questions?  That's great for keeping new users in check, but hurts more experienced users wishing to start a discussion on meta around their question.  You can see my original post on Movies.SE , as well as a second time I ran into this on ReverseEngineering.SE .
People like myself are Stack Exchange trusted users with thousands of reputation points and hundreds of badges.  In other words, we've proven ourselves as people who are assets to Stack Exchange and are a key component in making it so profitable.  As such, I was surprised when I posted  on the  site, and then shortly afterwards tried to  on that same meta site, but was blocked with a message in red stating I had to wait 40 minutes before posting again.  Why is this limit present for trusted Stack Exchange contributors, and can it be changed?
Pipe sound output to file? Let $X$ and $Y$ be independent $Exp(1)$-distributed random variables. Find the conditional distribution of $X$ given that $X + Y = c$ ($c$ is a positive constant).  this is my idea:  $$f_{X \mid X+Y}(x\mid c) = \frac{f_{X,X+Y}(x,c)}{f_{X+Y}(c) } $$  if this is the right definition then i might calculate the righthand side to obtain the distribution but Iam unsure Which is the rarest badge awarded/the least popular one/the one hardest to get? Understanding QGIS buffer tool units I  have had no luck getting the buffer tool to accept anything but degrees as units of measure.  I have found lots of stuff saying the layer needs to be reprojected and saved but it hasn't worked at all for me.   Is there a way I could create a buffer without using ftools or at least force the units to meters somehow?  As a workaround I converted meters to degrees (lat) and used that but the final product needs to be as close to reality as possible.  Things I've tried:   setting every unit option I could find to meters (where possible). setting everything to NAD83/Maryland (data is for Washington, DC) and saving it as such (as layers in ESRI shape files). reimporting the reprojected layers setting relevant layers to Google Mercator   The was tried followed by creating a buffer. Many were tried in combination. QGIS 1.7.3 Slackware64 current (qgis from SBo-13.37 repo, tried on multilib and plain 64it with same results) Map preserving intervals but discontinuous Many To Many Relationships I am working on a conceptual model for a database. I have the following entities:  Student (id, name, date of birth, department)  Subject (id, name)   This is a many-to-many relationship, one student may be enrolled in many courses, each course has many students. From what I understand, as I should break this many-to-many relationship by introducing a new into a entity, say 'registered' which allows a one-to-one relationship or one-to-many relationship?  Is this correct design decision? RC4 , Is it possible to find the key if we know the plaintext and ciphertext? Is it possible to find the key if we know the plaintext and ciphertext with RC4. How should I write the algorithm? I was trying to do some of these questions to check my understanding about the topic, but I'm not sure if they're correct. Here are my answers.   1) Suppose $f$ is continuous on $[0,1]$. Must there be a nondegenerate closed subinterval $[a,b]$ of $[0,1]$ for which the restriction of $f$ to $[a,b]$ is of bounded variation?   No, because $f(x)$ might be a constant function. In this case, $f(x)$ will not be the difference of two increasing functions...and so will not be of bounded variation.  2) Let $f$ be the Dirichlet function, the characteristic function of the rationals in $[0,1]$. Is $f$ of bounded variation on $[0,1]$?   No, because we cannot express it as the difference of two increasing functions.  3) Let $f$ be a step function on $[a,b]$. Find a formula for its total variation.  If we partition $[a,b]$ in such a way that for each $[x_{i-1}, x_i]$ (which is part of the partition), $x_{i-1}$ and $x_i$ each correspond to the midpoint of a step. I know this is not a formal answer, but I'm just trying to check my understanding. Lighting in a Minecraftian World Minecraft is a game that is largely based on a heightmap and uses that heigtmap information to flood the world with light.  From my understanding the highest point in the heightmap is the end of the sunlight influenced area.  Everything above that is lit by sunlight, everything below that just is influenced by light nearby in a radius of 8 blocks.  Thus if you have a floating island on the top of your world everything below that will be seen essentially as a cave.  When two lights influence the same point the brighter light wins (unsure about that).  Either way there are a couple of problems with minecrafts lighting model: first of all, if your world does not have a heightmap it becomes trickier to figure out what exactly is supposed to emit sunlight and what not.  A simple way would be to assume that the world is (in my case) a floating rock and then traverse each axis from both directions and figure out where the rock starts and ends.  But this does not fully eliminate the problem as dents in the rock are not supposed to be in darkness.  Minecraft itself will cache the light information in its chunks together with the information about the material of a block.  Thus only if the world is modified the lighting has to update.  Unfortunately that process is still pretty slow on updates and on quick light changes one can see the lighting lag behind.  That's especially true if a lot of blocks change (TNT, sunset etc.) and you're not running the fastest computer (Or Java on Mac).  From my still limited understanding of 3D graphics lighting a world like minecraft shouldn't be the biggest issue.  How would you tackle the problem?  I think the basic requirements for lighting in a voxel world would be   update fast enough that it could happen in a single frame.  One might be able to do the lighting in the graphics device and download the changed light information to the main RAM. light information must be quickly available for the main game logic so not entirely based on the graphics device: reasoning: light affects the growth of grass, spawning of monsters etc. light updates would have to be local to a chunk or have some other limit so that one does not have to relight the whole world which might be very large in size.   The main idea would be to make the light updates fast, not necessarily more beautiful. For general light rendering performance improvements one could easily add SSAO on top of that which should result in much nicer worlds. Java Code for calculating Leap Year When do I use a dot, arrow, or double colon to refer to members of a class in C++? How to test whether a set of four points can form a parallelogram Given four points $(x_1,y_1)$,$(x_2,y_2)$,$(x_3,y_3)$,$(x_4,y_4)$. How can we efficiently test them to make sure whether they are vertices of a parallelogram?  I think evaluating and comparing the distance between two points seems to be inefficient. What do you think? Do you have any better method? No upgrade available for 19.04 from 18.10 I'm pretty new to running linux, but I know that 19.04 was released today and I wanted to upgrade from my current 18.10. However, when I follow the release notes here:  I get the message "The software on this computer is up to date". I made sure that my update settings are set to "any new version" and "normal" in the /etc/update-manager/release-upgrades file.   What am I doing wrong?  Thanks for the help!  Side note: I had to disable this PPA:  because it would cause errors in apt updating. Do I need to re-add it? If so how do I do so without it giving me an error?  Edit: I have followed the procedure recommended in the documentation which is identical to the suggested duplicate, but I am not given the option to upgrade. I have not yet tried the   do-release-upgrade -d    option as I don't want to upgrade to the developer version. How to download image using requests Run a batch file in a completely hidden way I'm looking for some way to run a batch file (.bat) without anything visible to the user (no window, no taskbar name, .etc..).  I don't want to use some program to do that, I'm looking for something cleaner. I've found  that uses VBScript, but I don't really like using VBS, either. I am trying to restore a database with the following command:  $ sudo -u postgres pg_restore -C -d dvdrental dvdrental.tar  [sudo] password for t:    However, I am receiving the following error message:      could not change directory to "/home/t/mydata/.../relation model/SQL/implementations/Implementations, i.e. relational database management systems/postgreSQL/general/web/postgresqltutorial/databases": Permission denied      pg_restore: [archiver] could not open input file "dvdrental.tar": No such file or directory   I was wondering why I can't change directory to the current directory with permission denied?  File permission bits are:   -rw-rw-r-- 1 t t 2838016 May 26  2013 dvdrental.tar   Is it because one of its ancestry directory is not both readable and executable by any one?  The file has  many ancestry directories, and how can I verify that? Let $G(r, n)$ be the Grassmannian of the set of all $r$-planes in a $n$-dim vector space. How to show that the cohomology of a Grassmannian has a basis consisting of the equivalent classes represented by Schubert cycles? I am confused since I don't know how to compute the cohomology of a variety (how to construct the co-chain complex). I am really appreciate if you can compute the cohomology of, for example, $G(2,4)$ and show that it has a basis consisting of the equivalent classes represented by Schubert cycles. How do I combine standard deviations of two groups? I have 2 groups of people. I'm working with the data about their age. I know the means, the standard deviations and the number of people. I don't know the data of each person in the groups.  Group 1 :  Mean = 35 years old; SD = 14; n = 137 people  Group 2 :  Mean = 31 years old; SD = 11; n = 112 people  I want to combine those 2 groups to obtain a new mean and SD. It's easy for the mean, but is it possible for the SD? I do not know the distribution of those samples, and I can't assume those are normal distributions. Is there a formula for distributions that aren't necessarily normal? Check if this proof about real numbers with an irrational product is correct. Can anyone confirm if my proof is correct, please?  Claim:- “If $x$ and $y$ are real numbers and their product is irrational, then either $x$ or $y$ must be irrational.”  Proof:-   Assume that both $x$ and $y$ are rational. Now, let $x = \dfrac pq$ and $y = \dfrac mn$ since both of them are rational. $xy =\dfrac pq * \dfrac mn = \dfrac{pm}{qn}$ Thus, if the product $xy$ can be written as a fraction, it's not a irrational number. Therefore if one of $x$ and $y$ is not irrational, then the product is not irrational.  By the principle of proof by contraposition, If $x$ and $y$ are real numbers and their product is irrational, then either $x$ or $y$ must be irrational. Say i have this PHP code:  $FooBar = "a string";   i then need a function like this:  print_var_name($FooBar);   which prints:  FooBar   Any Ideas how to achieve this? Is this even possible in PHP?