Does this condition imply continuity?
Does $\lim_{h\rightarrow 0}\ [f(x+h)-f(x-h)]=0$ imply that $f$ is continuous?
Systemd is really slow in comparison to upstart I have been using Ubuntu for a long time now, this is what happened when I use:  Systemd: It performs really bad using systemd: it uses 95% of the CPU all the time and the PC gets really hot. Also it takes a really long time to boot (about 1.5 min, and sometimes it does not boot at all as it has a black screen at boot.)  Upstart: When I tried the upstart options at boot, it performs as expected, booted in seconds, and it was awesome as it should be.  Laptop:   AMD A8 Radeon SSD   Questions:   Why does upstart perform better than systemd? How can I debug systemd? Should I switch to upstart? If yes, how do I do it? Here is a DOM-based XSS flaw reported by SalesForce Security Review team in our code:   RootComponent  &lt;aura:component extensible="true" abstract="true" access="global"                 description="Root template component"&gt;     &lt;!-- ... lot of other code ... --&gt;     &lt;aura:attribute name="label"                     type="String"                     access="global"                     description="Label of the form input element" /&gt;     &lt;!-- ... lot of other code ... --&gt;  &lt;/aura:component&gt;   SubComponent  &lt;aura:component access="global" extends="c:RootComponent"                  description="Child extension of RootComponent"&gt;     &lt;!-- ... lot of other code ... --&gt;     &lt;label&gt;{!v.label}&lt;/label&gt;     &lt;!-- ... lot of other code --&gt;  &lt;/aura:component&gt;   According to SFDC, "any app can extend SubComponent component and pass in  as a label and trigger a DOM-based XSS attack." The solution would be to "sanitize" label global attribute to avoid such attack. What is meant by sanitization of global attribute?  I tried to reproduce the so-called security flaw , but as label attribute is of type "String" , when we send it HTML, it is displayed as a string, not as interpreted HTML ... so I don't see where the security flaw could be :/  &lt;aura:application &gt;     &lt;aura:handler name="init" value="{!this}" action="{!c.doInit}" /&gt;      &lt;c:SubComponent aura:id="TestXSS" label="DOM-based XSS attacks" /&gt;  &lt;/aura:application &gt;   JS Controller  ({     doInit: function(component, event, helper) {         var XssAttack = '&lt;img src=x onerror=alert(1) /&gt;';        component.find('TestXSS').set('v.label',XssAttack);     } })   Output    We have global attributes everywhere. Our components are packaged and meant to be extended by client implementation. Do we actually need to sanitize them? I am trying to determine if the sum $\sum_{n=1}^\infty \frac{n+4^n}{n+6^n}$ is convergent or divergent.   In attempting to solve this problem I began by seeing if I could do the divergence test - in this case it is not helpful. The terms $4^n,6^n$ look like geometric series type terms but the $n$ in the numerator and denominator are troublesome. I first tried factoring $n$ out of the expression:  $$\sum_{n=1}^\infty \frac{n+4^n}{n+6^n} = \sum_{n=1}^\infty \frac{1+\frac{4^n}{n}}{1+\frac{6^n}{n}}$$  Next I tried comparing to the series $$\sum_{n=1}^\infty \frac{\frac{4^n}{n}}{\frac{6^n}{n}} = \sum_{n=1}^\infty \frac{{4^n}}{{6^n}} = \sum_{n=1}^\infty{\left(\frac{2}{3}\right)}^n$$  This is a convergent geometric series as $r = \frac{2}{3}\lt1$  now I reason that the series $\sum_{n=1}^\infty \frac{1+\frac{4^n}{n}}{1+\frac{6^n}{n}}$ is neither smaller not greater than the series $\sum_{n=1}^\infty{(\frac{2}{3})}^n$ Am I able to conclude anything in this case by a direct comparison test or can I only conclude that the first series is convergent if the second is greater than the first?  Thanks What is the difference between a field and a property? In C#, what makes a field different from a property, and when should a field be used instead of a property? $P[X=x]=0$ when $X$ is continuous variable What does the second column in the output of 'ls -n' mean? Wikipedia says "In the mathematical discipline of linear algebra, a matrix decomposition or matrix factorization is a factorization of a matrix into a product of matrices. There are many different matrix decompositions; each finds use among a particular class of problems."  But in my opinion decomposition term should be used to represent breaking a matrix in different sub-matrices or some new matrices created after some operation on original matrix which if used together and passed through some algorithm(not necessarily product), shall reproduce the original matrix.  Is there some different terminology to represent what I am expecting to say? Partner with "traditional" forums to support open ended discussions What lens characteristics are important in star photography? How can I abort a running JDBC transaction? Is there a way to prematurely abort a transaction? Say, I have sent a command to the database which runs five minutes and after four, I want to abort it.  Does JDBC define a way to send a "stop whatever you are doing on this connection" signal to the DB? I want to reinstall Ubuntu, but I also want all information and settings to disappear. So everything looks like the first time I installed it. Is it possible to do so via Terminal? Or what are the steps I should follow? Is it common to review papers assigned to your supervisor? Is it common to supervisors to email their students papers to review (which were apparently assigned to the supervisor, and not to the student). The field is Computer Science, but I  would also like to hear from the other fields. Today I was cut off in the middle of the following sentence:     Between Cook, Strauss, and Pietersen—   My friend said I was wrong. He said that for more than two entities, among/amongst are used, and that between is only for two entities.   I vaguely remember some rule like this, but I asked him to hear the whole sentence, which was:     Between Cook, Strauss, and Pietersen, they’ve notched up 56 centuries in Test cricket.   Should I have used among here? Seems correct to me to use between, but my friend was certain.   Another friend pointed out the following sentence:     I’m still choosing between Harvard, Yale, and MIT.    Certainly among doesn’t seem to fit here, and she, to me, was correct in using between. Festival stores voicepack data in the following example directory structure:  /usr/share/festival/voices/&lt;language&gt;/&lt;voicepack name&gt;  What is the simplest one-liner (preferably using ls) to print out just the &lt;voicepack name&gt;'s, in all the potentially numerous &lt;language&gt; subdirectories? Playing system sound without importing your own No chatoutput in tellraw onClick Event I'm using a /tellraw command to display some kind of menu to the player. How can I react to the clickEvent without posting something in the chat? When I try using the scoreboard, I get an output in my chat like this Set score of &lt;objective&gt; for player &lt;playername&gt; to &lt;value&gt;. The same thing happens, when trying /setblock, /entitydata or /trigger Is there any way, I can execute a command which commandblocks can detect without writing a success/fail message in the chat?  the only commands without a "real" response message I found were /say, /tell and /tellraw. But all of these are impossible to detect(also, they write something else in the chat). Use Unity API from another Thread or call a function in the main Thread "wait more than" vs. "wait FOR more than" I've got some photos with quite random names, but the dates (not exif, but when they were last edited) are correct. I'd like to rename them in that order, preferably so that the first photo is named 1.jpg and so on, but anything goes. How can I do that? I am trying get an unused server up and running, it booted fine but i was greeted with the login window and none of the known passwords seem to work. The server I am trying to get to work is not a Domain Controller and has not been used in a long time.  OS: Windows 2003 Server R2 Enterprise Edition  I tried Ophcrack XP (there is no WinServer version of Ophcrack) - it couldn't locate the partitions with hashes. I tried mounting the partitions myself (#mount /dev/hda*x* /mnt/ntfs), but it gave me an error saying /dev/hda*x* didn't exist.  Next I tried booting into a Ubuntu 10.04.3 LiveCD so that I could install and use chntpw - no go, Ubuntu Live wouldn't boot.  Based on what I've read up the following tools may be of help:   Windows Password recovery Petter Nordahl-Hagen's Offline NT Password &amp; Registry Editor Openwall's John the Ripper EBCD – Emergency Boot CD - Bootable CD (R)ecovery (I)s (P)ossible Linux rescue system   I am hoping that someone here has prior experience with Win2k3 Administrator password resets so that I don't end up having to try all of the above to find out which one works.