Fibre bundle which is not an open map
Proving that the map from a topological space to a fiber bundle is open.
Is openssl rand command cryptographically secure? I'm wondering if the openssl rand command produces cryptographically secure random bytes. For example when in need for a random password or token:  openssl rand -hex 32   The man page unfortunately does neither state it's cryptographically secure, nor that it's not.  On the one hand, I think this is openssl, its sole purpose is to do cryptography. On the other hand, the man page states something about reading and writing seed data instead of directly querying a CSPRNG.  So it is somewhat unclear for the end user. Does someone know? Publish and/or subscribe to Platform Events between separate Orgs? Error: mysqli_stmt::bind_param(): Number of elements in type definition string doesn't match number of bind variables What do you call somebody who asks a question and somebody who answers a question? How can i check if $remote_addr IP is NOT in CIDR range in nginx? I am using nginx latest web server. How can i check if the $remote_addr ip is NOT in specified CIDR range and return appropriate error code.  i would like to return specific error codes if IP is NOT in specific CIDR IP ranges.  how can i do this for CIDR IP range ?  e.g.    If remote_addr is not in 123.123.123.123/24 then return 444 code . Ideal column width for paragraphs online There is nothing worse than coming across a website with paragraphs that span the width of your screen resolution. They are usually so hard to read, I don't even bother.  A lot of web designers use generic grid and column systems, but I don't feel these have been optimised for readability, they are more of design guide on general aesthetics.  I guess it comes down to words per line. Are the rules that apply to print media the same for screen media?  Are there any type of guidelines to help me size the width of paragraphs on the screen?  I want to take into consideration:   Major web font faces (i.e. Arial, Verdana, Georgia, Times) A range font sizes (i.e. 8px-24px) Space between columns How to simulate data that satisfy specific constraints such as having specific mean and standard deviation? I am new to the glmnet package, and I am still unsure of how to interpret the results. Could anyone please help me read the following trace plot?  The graph was obtaining by running the following:  library(glmnet) return &lt;- matrix(ret.ff.zoo[which(index(ret.ff.zoo)==beta.df$date[2]), ]) data   &lt;- matrix(unlist(beta.df[which(beta.df$date==beta.df$date[2]), ][ ,-1]),                   ncol=num.factors) model  &lt;- cv.glmnet(data, return, standardize=TRUE)  op &lt;- par(mfrow=c(1, 2)) plot(model$glmnet.fit, "norm",   label=TRUE) plot(model$glmnet.fit, "lambda", label=TRUE) par(op) Bind variable with dotted name not working in dynamic SOQL As mentioned in , it's possible to use bind variables in dynamic SOQL queries.  This seems like a great way to avoid SOQL-injection, and to build a query string once but use it multiple times with different values in the variables.  I'm working on a method that returns a list of objects.  It accepts a class with multiple properties as its only parameter.  The properties of this class are used to filter the results to just the required records.  It will eventually be driven by a Visualforce component, which will be configured by querystring parameters in the URL.  I just ran into an issue where the query fails when I use dotted bind variables.  If I copy the constructed dynamic SOQL into a static query, it works fine.  This may be a bug, because in doing tests I found that :foo.bar would actually try to use local variable bar.  Here's one of my queries, which uses related custom objects.  I've stripped it down to just the part that's failing (wrapped for legibility):  result = Database.query('SELECT Name, Another_Object__r.Name,      Another_Object__r.Custom_Field__c      FROM Custom_Object__c       WHERE Another_Object__r.Custom_Field__c = :filter.deviceType');   The error reported is System.QueryException: Variable does not exist: filter.deviceType.  As mentioned above, the query works fine as static SOQL, just not dynamic:  result = [SELECT Name, Another_Object__r.Name, Another_Object__r.Custom_Field__c FROM Custom_Object__c WHERE Another_Object__r.Custom_Field__c = :filter.deviceType];   It also works in this case:  String deviceType = filter.deviceType; Database.query('SELECT Name, Another_Object__r.Name, Another_Object__r.Custom_Field__c FROM Custom_Object__c WHERE Another_Object__r.Custom_Field__c = :deviceType');   I haven't read about this being a known limitation.  I don't know if I should be using some other syntax/notation in the query -- the dotted notation appears correct.  Time to report a bug?  Thoughts on workarounds other than creating local variables to stand in for each member of the class? Why do elementary matrix operations not affect the row space of a given matrix? How do I declare and initialize an array in Java? Use Stack Exchange icon for Stack Exchange blog posts in the Community Bulletin is used to host global Stack Exchange blog posts and is using favicon of Stack Exchange itself. All good. However, when published in the bulletin, the Meta Stack Exchange icon is used for some reason:    Can it be changed please to using the &quot;full&quot; icon? What are your thoughts on writing your text in images?  I'm not saying throughout the whole website... But in certain key locations like image carousels. And I'm not talking about the special cases where you have font types that browsers can't render. I'm talking about text that uses standard fonts and is not too big (3/4 bullets).  Should I embed the text in the images that compose the carousel? Or should I apply the text to the images as "real text" HTML?  What are the advantages/ disadvantages of using text in an image? Let $G$ be a group, where $(ab)^3=a^3b^3$ and $(ab)^5=a^5b^5$. Prove that $G $ is an abelian group. What is the most efficient way given to raise an integer to the power of another integer in C?  // 2^3 pow(2,3) == 8  // 5^5 pow(5,5) == 3125 BAD signature when trying to verify SHA256SUMS for Bionic Beaver ISO I am attempting to verify my download of Bionic Beaver on Windows 7.  I feel like I am missing something very obvious.  I went to  and clicked on both SHA256SUMS and SHA256SUMS.gpg  It seems like this does not download the files, but opens the text in the files in new tabs.  I used Ctrl-A and then copied the text into Notepad, naming the files SHA256SUMS and SHA256SUMS.gpg.  I made sure that windows didn't add any weird extensions when saving.  I manually downloaded both keys I used from https://keyserver.ubuntu.com, one with fingerprint  C598 6B4F 1257 FFA8 6632 CBA7 4618 1433 FBB7 5451   and the other with fingerprint  8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092   After I downloaded both keys I certified them with my personal key using Kleopatra, after verifying the key fingerprint with those at .  When I ran   gpg --verify SHA256SUMS.gpg SHA256SUMS   I got   gpg: Signature made 11/29/18 16:27:43 US Mountain Standard Time gpg:                using DSA key 46181433FBB75451 gpg: BAD signature from "Ubuntu CD Image Automatic Signing Key &lt;cdimage@ubuntu.c om&gt;" [full] gpg: Signature made 11/29/18 16:27:43 US Mountain Standard Time gpg:                using RSA key D94AA3F0EFE21092 gpg: BAD signature from "Ubuntu CD Image Automatic Signing Key (2012) &lt;cdimage@u buntu.com&gt;" [full]   When I ran   gpg --verbose --verify SHA256SUMS.gpg SHA256SUMS   I got  gpg: armor header: Version: GnuPG v1 gpg: Signature made 11/29/18 16:27:43 US Mountain Standard Time gpg:                using DSA key 46181433FBB75451 gpg: using pgp trust model gpg: BAD signature from "Ubuntu CD Image Automatic Signing Key &lt;cdimage@ubuntu.c om&gt;" [full] gpg: binary signature, digest algorithm SHA512, key algorithm dsa1024 gpg: Signature made 11/29/18 16:27:43 US Mountain Standard Time gpg:                using RSA key D94AA3F0EFE21092 gpg: BAD signature from "Ubuntu CD Image Automatic Signing Key (2012) &lt;cdimage@u buntu.com&gt;" [full] gpg: binary signature, digest algorithm SHA512, key algorithm rsa4096   I tried copying the data from SHA256SUMS and SHA256SUMS.gpg tabs over TOR instead, in case it was a local network problem, but no dice either.  What am I missing here? Is there some way to download the SHA256SUMS and SHA256SUMS.gpg files directly, as opposed to copying the data into a text editor and saving it?  Any help would be very appreciated. I am very confused and frustrated at this point. \ref, make figure/table reference automatically toggle between "above" or "below" Is it possible to automatically include a reference to the position of a labeled object (Table, Figure) in text? By this I mean the following:  Say I have labeled a figure in chapter 1:  \label{fig:one}   Then I refer to it in text by using:  See Figure~\ref{fig:one}   Which produces "See Figure 1.1" as desired. I'd like to be able to have it produce: "See Figure 1.1, above" or "See Figure 1.1, below", automatically detecting whether to produce "above" or "below" depending on whether the figure will be placed above that position on the final page. How do I manage how many revisions snapd keeps of an application? Simple example of non-arithmetic ring (non-distributive ideal lattice) Can anyone provide a simple concrete example of a non-arithmetic commutative and unitary ring (i.e., a commutative and unitary ring in which the lattice of ideals is non-distributive)? I've installed drush in /usr/local/lib/drush/drush and composer in /usr/local/bin/composer.  When I try to run drush /usr/local/lib/drush/drush I get the following:     /usr/local/lib/drush/drush: line 129: /Applications/MAMP/bin/php/php5.2.17/bin: is a directory /usr/local/lib/drush/drush: line 129: exec: /Applications/MAMP/bin/php/php5.2.17/bin: cannot execute: Undefined error: 0 –    OR the following:     Unable to load autoload.php. Drush now requires Composer in order to install its depedencies and autoload classes. Please see README.md   What am I doing wrong? I'd like to install drush to use with MAMP if anyone has any suggestions. I've done through the readme and nothing seems to be working.