I'm wondering if I've stumbled on a bug here.  I noticed recently that I'd achieved the silver badge on "concurrency" on SO.  Yay to me.        There are 3 other guys that have done so -- of course Jon is one.  So then I wondered who else is close to their silver for this category and so I go to the top-users page:        I was surprise to see Don Stewart above me at 450 points and yet has not gotten the silver badge for concurrency as far as I can tell.  It's not on his user page or in the concurrency badge page.  Is this a bug or am I not understanding how the badge is calculated?  As always, thanks for SO.  Always a great resource.
Formerly List of all badges with full descriptions.  What are badge name's requirements? Why didn't I get badge name ? Which badges can I earn multiple times?    Jump to:                    Note: Some badges are awarded based on score. The term score means the total number of upvotes minus the total number of downvotes.  Any badge with a *** next to it is one of 20 badges that count towards the  displayed on a moderator candidate in an election. The candidate score is a total of 40 points: the first 20 are awarded based on the user's rep divided by 1000 and rounded down; the second 20 represents the total number of unique badges earned of the 20 that count. Note that if the same badge is earned multiple times, it will only count once towards the candidate score.  Any badge with a &quot;(retired)&quot; next to it is no longer awarded, but is retained by users who previously earned them. See  for more info on what it means for a badge to be retired.       Visit the  of the  on any site to see a complete list of badges that you can filter by earned, unearned, or type.
I need to calculate no of possible substrings containing "00" as a substring. I know the length of the binary string.  Eg: for a string of length 4, possible substrings are: 0000 0001 0010 0011 0100 1000 1001 1100  I just need the number of possible combinations, not enumerate all of them. Why separate Stack Exchange accounts? I understand the reason why Stack Exchange has different sites to separate  from  or . I understand too why the reputation is associated on each site.   Why do I have to create a new  for each web site? I know that when I create a new account, it is automatically associated to my other accounts. But, is there a reason why, when I originally create a user on the first site, I can't go on another site with this user? Auto-expand TAB character in code formatting Related:       Note that this question, while related, is not the same as the ones linked.  In many cases, when people put code into questions or answers, they copy/paste the code from their editor.  If their editor is using tab characters, the formatting will be broken after the post is submitted.  For example, if a code is indented using TAB characters, then one TAB character in the beginning of a line will be treated as one level of indent and align with the left edge of the code, effectively indenting equally to 4 spaces.  However in the post editor it looks indented twice - the same as 8 spaces.  I often edit other people's posts to improve code formatting and I find this TAB issue being the biggest annoyance.  Most of the times (I think) on SO, we use 4 spaces to format/indent the code.  I think it would be an easy thing to auto-expand TAB characters inside &lt;code&gt; blocks by replacing them with 4 spaces when the post is submitted. What is the purpose of the /etc/shadow file in Linux Operating system?  Also, is it same for SUSE clients? There is one shadow cache file is maintained what is purpose of that? What does $\dot\sim$ notation (dot over tilde) mean, in the context like $x \mathrel{\dot\sim} \mathcal N(0,1)$?  Turns out it is easier to find how to typeset it correctly:  that one should type \mathrel{\dot\sim} instead of simply \dot\sim to fix the spacing issue -- than to find what it actually means. It has only been used  on CV until now; is it standard? Asymptotic expansion for Fresnel Integrals I use youtube-dl to download videos for watching later offline. Usually, it works fine. However, due to frequent changes on the video sites, it sometimes requires a quick update. It wasn't a problem before on 13.04 but after upgrading to 13.10, I get  # youtube-dl -U It looks like you installed youtube-dl with a package manager, pip, setup.py or a tarball. Please use that to update.   I tried updating it via apt-get but there is no new package. So the app's update mechanism has been disabled and the maintainers aren't keeping up, what is the solution? How do I update it?  And why was it changed at all? It was updating a package manager version just fine in raring.   I'm already running into compatibility problems.   $ youtube-dl "http://vimeo.com/55784152" [vimeo] 55784152: Downloading webpage [vimeo] 55784152: Extracting information ERROR: Unable to extract info section; please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl with the --verbose flag and include its complete output. Make sure you are using the latest version; type  youtube-dl -U  to update.   QUICK UPDATE:  As requested,  # type youtube-dl youtube-dl is hashed (/usr/bin/youtube-dl)  # apt-cache policy youtube-dl youtube-dl:   Installed: 2013.08.29-1   Candidate: 2013.08.29-1   Version table:  *** 2013.08.29-1 0         500 http://pl.archive.ubuntu.com/ubuntu/ saucy/universe amd64 Packages         100 /var/lib/dpkg/status Is there a way of conditionally triggering a compile-time error in verilog? I have a parameterised module in verilog, where the parameters are a clock rate and refresh rate, which is used to calculate how many cycles of inactivity are inserted between instances of a repeating operation.  However, it is very easy to set parameters that cannot be attained (because the operation takes a non-trivial length of time, so the repeat would have to occur before it had completed), and at the moment the design does not give any feedback on this.  I was wondering if there was some way I could trigger an error during synthesis (or compilation prior to simulation) if the conditions cannot be met (i.e. if one localparam is less than another)?  Some equivalent of the popular C/C++ compile-time-assert hack, perhaps. After starting Ubuntu, I see the following lines. Should I be worried?  /dev/sda6: recovering journal /dev/sda6: clean, 355773/1835008 files, 470404803/7335680 blocks Using Rule of Three to obtain confidence interval for a binomial population I have a large population of data instances (say, 1000 instances) that are either of class1 or of class2. I would like to obtain a confidence interval for how many instances are of class1 without exhaustively checking all instances. I have randomly sampled 50 instances, and all 50 were of class1. I used the  to determine that a 95% confidence interval for the percentage that an instance is of class1 is  [0.94, 1].  From my sampling, I know that at least 50 instances are of class1. For the remaining 1000 – 50 = 950 instances whose classes are unknown, I assume I can apply the [0.94, 1] confidence interval found above. Therefore, can I conclude that, with a 95% confidence, there are at least 50 + (1000 – 50)(0.94) = 943 instances from the population of 1000 that are of class1?  If this conclusion isn’t statistically sound, how can I obtain a confidence interval for class1? "The operation couldn’t be completed. (BKAgentServiceErrorDomain error 8.)" I have been getting this question lately from students and although I have a lot of information to offer, I have not found a source that I can point people to where they can read an update answer (I have found a lot of misinformation and obsolete information). So, some of the questions I have for package formats like snap, appimage, flatpak and others in this evolution of universal packaging systems are:   Who created the package format? What features does it offer? What features are unique to it? (That the others do not yet have) Who supports it? What Distributions use it? What focus does the package have? (For Desktop, Clouds, Mobile, etc..) Which are more actively developed? Why is 248x248 the maximum bi dimensional array size I can declare? What is this Disney scifi movie from the late 80s/early 90s? Using select by attributes then calculate field on selection in ArcPy? ArcGIS Pro 2.3  I want to create a standalone script which runs outside of ArcGIS Pro (for automation purposes), which selects features (with blank attributes) in a feature class and runs calculate field on those selections.  The code below doesn't work. It updates all fields, not the selected ones.  import arcpy arcpy.management.SelectLayerByAttribute(r"C:\Automation\Categories\Coal\Coal_automation.gdb\CLAIMS", "NEW_SELECTION", "Claim_Spend_in_£ = ''", None)  arcpy.management.CalculateField(r"C:\Automation\Categories\Coal\Coal_automation.gdb\CLAIMS", "Claim_Spend_in_£", '"Unrecorded"', "PYTHON3", None) print ("Done")   How can I write the code to run calculate field on a selection? Does one need to be affiliated with a university to publish papers? Assume you have already completed your undergrad and have been working for a number of years. Does one need to be part of a university or a learning institution to publish papers? How can one differentiate between "who" and "whom"? I'd like to be able to tail the output of a server log file that has messages like:  INFO SEVERE   etc, and if it's SEVERE, show the line in red; if it's INFO, in green.  What kind of alias can I setup for a tail command that would help me do this? How to reduce the spacing in chemical symbols? Currently, if want to write a chemical symbol, for example, ${}^{239}Np$, this is what I type in: {}^{239}Np. The result:    But it looks bad, I feel as if the "N" and "p" should be closer, or a different font should have been used.  How could I make better looking chemical symbols? Currently I am using mainly the MathJax of the SE, but sometimes I use other TeX as well. Why does the question's closed status disappear when clicking to load a new edit? I've come across a small issue which occurs when a question has been closed but the question itself or one of its answers are being edited.  Steps to reproduce:   Visit a closed question. (even closed years ago)   In a different tab or browser, edit the question or one of its answers. "an edit has been made to this post; click to load" message will appear above the edited post in the first tab/browser, click it. The .question-status div becomes hidden, which includes the closed notice below a question and, for a duplicate-closed question, the list of duplicates above the question body. This gives the appearance that the question is no longer closed (until you refresh).   Some screenshots:                I know it isn't common/important but it did confuse me when looking at a particularly bad question - I thought it had been reopened.   Is this an intentional feature? If so, what was the thinking behind it?    Another example  Before    After