Show that is not possible to form a unity ring structure on $(\Bbb Q /\Bbb Z , + )$
Showing there is no ring whose additive group is isomorphic to $\mathbb{Q}/\mathbb{Z}$
Why aren't hash values for "nothing" (empty) defined as all zeros? Any decent hash algorithm will produce basically "random like" values for any given input including the empty input.  For example MD5 produces d41d8cd98f00b204e9800998ecf8427e on an empty input.  I wonder, however, why the MD5 algorithm wasn't defined to have a final step where the output is XORed with d41d8cd98f00b204e9800998ecf8427e. This should not affect the cryptographic strength of the hash algorithm, and it would have the convenient property that a hash of all zeros represented a zero input.  Would it simply just because adding that step would slow the hash down a bit? I can't seem to figure out how to get past this step. Any suggestions? Individual community preferences vs. SE network policy: who wins? In the recent question , the OP asks where the following question would be appropriate:     What would be the best way to approach someone that works for me about bad odor?   CHAOS team member Abby Miller  by suggesting the proposal  &#8212; which is in commitment as I'm writing this &#8212; because     One of the up voted example questions there is about dealing with an irritating coworker. This question will be perfectly on topic for that site.   In my opinion,  qualifies for the not constructive close reason*, which applies to all sites in the network, and therefore, the question shouldn't be allowed, no matter how much it has to do with workplaces.  I know Abby isn't the only one who disagrees with me about this. I once had a talk with a mod of some beta about the presence of poll/GTKY questions on his site. His position, in short, was that his community had different rules from SO and its members enjoyed such questions. I don't remember which site it was, it might even be graduated now, but I never did end up participating there.  Anecdotal examples are nice and all, but here's the real question: to what extent can individual communities/sites override network policies? To what extend should they be able to do so?  *: not constructive comes with the description "This question is not a good fit to our Q&amp;A format. We expect answers to generally involve facts, references, or specific expertise; this question will likely solicit opinion, debate, arguments, polling, or extended discussion." What's the difference between asymptotic unbiasedness and consistency? Does each imply the other? If not, does one imply the other? Why/why not?  This issue came up in response to a comment on an answer I posted .  Although google searching the relevant terms didn't produce anything that seemed particularly useful, I did notice  on the math stackexchange. However, I thought that this question was appropriate for this site too.  EDIT after reading the comments  Relative to the math.stackexchange answer I was after something more in depth, covering some of the issues dealt with in . Also, as I see it the math.stackexchange question shows that consistency doesn't imply asymptotically unbiasedness but doesn't explain much if anything about why. The OP there also takes for granted that asymptotic unbiasedness doesn't imply consistency, and thus the sole answerer so far doesn't address why this is. Are Canon EOS and Nikon DSLR lenses interchangeable? Can we use the lenses from, say a Canon EOS 550D kit (Canon EF-S 18-55mm) with a Nikon DSLR D5000 for example) ? Also, is the reverse possible ?  I'm looking at interchangeability between recent DSLR lenses only, and not with older lenses. Also, for "average" lenses, and not ultra wide/ultra zoom.  The reason for this question is that I'm trying to decide between a Nikon D5000 and a Canon EOS 500D. I like the Nikon better, but Canon is more popular here amongst people I can interchange lenses with :) sed delete option change of delimiter How to create SHA512 password hashes on command line In Linux I can create a SHA1 password hash using sha1pass mypassword. Is there a similar command line tool which lets me create sha512 hashes? Same question for Bcrypt and PBKDF2. $X$ and $Y$ are independent $U(0,1)$ random variables.   I have to find $E[X|X&gt;Y]$.   I found it out by integrating $\int_0^1 \int_y^1 x dxdy$ to get $\frac{1}{3}$ as the answer but this is wrong according to the answer key. What is the mistake that I have made? Show that:  If $U$ is a principal ultrafilter, then the canonical inmersion $j$ is an isomorphism between $\mathcal A$ and $Ult_{U}\mathcal A$ How are we able to calculate specific numbers in the Fibonacci Sequence? I was reading up on the Fibonacci Sequence,  $\text {{1,1,2,3,5,8,13,....}}$ when I've noticed some were able to calculate specific numbers. So far I've only figured out creating an array and counting to the value, which is incredibly simple, but I reckon I can't find any formula for calculating a Fibonacci number based on it's position.  Is there a way to do this? If so, how are we able to apply these formulas to arrays? Showing that $f_0 (x_1, \ldots, x_m) \mathrm tr A =\displaystyle{ \sum_{i=1}^n} f_0(x_1, \ldots, Ax_i,\ldots, x_m)$ I'm looking for some insight into how Stack Overflow releases are deployed and managed.   What software/tooling is used? What time are releases generally performed? How many and what steps are involved?   I'm assuming it's not too stringent given the light team working on the codebase. But considering the high rate of change, I could see some kind of tooling and automation becoming increasingly relevant, so I'm curious to learn what kind of decisions are being made to deal with the changes in scale and feature set over time.  Is this information available somewhere? Export each image from a collection in Google Earth Engine I am trying to export each image in a filtered stack of Sentinel-1 images and cannot seem to get it right.   suggests using imageCollection.map() and a custom function (such as a geometric clip).  // Create a geometry representing an export region. var roi = ee.Geometry.Rectangle([-63.0, 9.2, -63.1, 9.3]);   // Load the Sentinel-1 ImageCollection. var sentinel1 = ee.ImageCollection('COPERNICUS/S1_GRD');   // Filter by metadata properties. var IW_H = sentinel1   // Filter to get images with VV and VH dual polarization.   .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))   .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))   // Filter to get images collected in interferometric wide swath mode.   .filter(ee.Filter.eq('instrumentMode', 'IW'))   // Filter IWs to get High res.   .filter(ee.Filter.eq('resolution', 'H'))   // Filter IW-Highs to get 10m res   .filter(ee.Filter.eq('resolution_meters', 10));   // Filter to get images from different look angles  var DescCollection = IW_H.filter(ee.Filter.eq('orbitProperties_pass', 'DESCENDING'));   var ClipFunc = function(iImage, geom) {   var iClip = clip(iImage, geom);   return(iClip); };   imageCollection.map(ClipFunc(DescCollection, roi)); I have a 3TB Seagate Backup Plus Desktop USB 3.0 drive, which works fine when in its enclosure, but when I get it off its enclosure and directly plug it as an internal SATA drive, it's just not properly recognized (it works again when used in the enclosure). My systems’s motherboard is an , which has two SATA 6.0 Gb/s and four SATA 3.0 Gb/s ports.  When used as an internal SATA drive Windows 7 asks if I want to format the drive, as if it didn’t have a proper filesystem, and if I use the DISKMGMT.MSC tool (typing that in the start menu) I get completely wrong information about the drive.  It says the drive has 3 partitions (349,31GB of RAW data and two unassigned partitions of 1698,68GB and 746,52GB). This information is plain wrong, since the drive, when used in the USB enclosure, works as a single NTFS partition (2794,52GB). How come it’s shown as 3 partitions without filesystem when connected through SATA?!  Is Seagate using some proprietary way of storing the data when using the drive in its provided USB 3.0 enclosure? I didn’t use any kind of encryption. I just plugged the drive with USB 3.0 and started using it straight away, since it apparently came pre-formatted with an NTFS filesystem. What's the best way make an "augmented" coefficient matrix? When studying systems of linear equations, it's nice to remind people that the last column of the coefficient matrix holds the constants.  This is often done in books by putting a vertical line between the last column and the next to last column.  What is a good way to do this in LaTex? Is it legal to add your publications to ResearchGate? I recently created a profile on . And to add your publications list it requires you to upload the paper. Is it legal to upload published journal articles on public servers, where everyone can download it for free? I've been looking for some addon or something to render only the marked frames on timeline, i found this answer here on the stackexchange   The thing is this script only works with multiple cameras, i have only one camera that goes all aorund the scene but i only want to render the frames that i've marked on timeline.  Is there someone who can help me modify this script? Or find a better solution? If a drive doesn't know about partitions and files systems why moving a file from one partition to another takes relatively long time, unlike the instantaneous move on the same partition? Is that file system inefficiency? In this case, NTFS. It seems like the file is being copied and then original is erased, instead of removing the entry about that file in one partition and making it in another? Why did Voldemort stop employing Occlumency against Harry in Deathly Hallows? Table overflowing outside of div