Which site does this question belong on?  It is my contention that any and every endless loop is going to end rather sooner than later. Just for curiosity: "What is currently the longest-running known implementation of an endless loop?"  I'm in search for a technical device with an active program running an endless loop. It needs to be a known technical implementation within this universe, not some hypothetical machine / idea or abstract concept.
Stuff like polls, recommendations based on subjective constraints, puzzles, webcomics etc. do not belong on the serious main SE sites, where professionals should be considered at work and having just a few spare minutes ("code's compiling") to answer questions, so they should not be distracted by such things. However, I'd also like to have a home for these things still using the SE engine. For the reason I mentioned before, this needs to be a separate place though. Let's call it four.[sitename-here].com.
I am using \if condition in a custom command in my LaTeX document. I would like to know where I can find some good explanation about \if command. I followed a  but it's just an example; there are not any explanation. I want to subscribe to the newsletter on my work email address but still have everything else go to my normal SO email account. I don't have a way to set up a forwarding filter from my normal email account.  Any way I can do this? While accepting an offer to grad school, one is basically entering into a lasting relationship with one's adviser - most likely, someone whom the applicant has never met before, and the only exposure has been through the potential adviser's website/publications. It is in the interest of both parties to ensure (to the greatest possible extent) that there are no personal/professional traits of either that hamper the formation of a pleasant working relationship - no-one would want to go through the ordeal of having to change advisers midway!  While the faculty has a chance to have a good look at the applicant's profile as well as his motivations (through his grades and SOP), the applicant doesn't have a similar opportunity. So, I'm interested to know what parameters can be used to gauge a potential fit. I've thought of the following:   Past students:  Did anyone ever drop out/change advisers midway, and if so, for what reasons? These would be a bit hard to find though, as I don't expect the faculty concerned would list them on their website. It would be great if anyone could let me know how to find out the list of incoming students to a department for any year. Publication rate, taking into account the venues where they were accepted. Time taken to graduate - though I accept this is more dependent on the student, a median figure should be telling ... What they did post Ph.D. - did anyone get tenure if they went into academia, or is almost everyone unable to break out of being a post-doc?  Tenure status: I'm a bit unsure about this, so wanted the community's opinions about it. Just so that I'm clear, I'm only trying to calibrate the applicant's expectations about the working style of his potential adviser - and hence need to know to what extent are the following "typical" assumptions valid.  Tenured professor  A full professor is more likely to get grant funding, hence less time spent on TAship - but could also mean less time/effort spent on interactions with students (either being busy with other projects/talks, or due to more commitments to family at that age).  Tenure-track faculty (Assistant profs)  More likely to be young and energetic, and could translate to more time spent on one-to-one discussions with grad students - but funding may prove to be an issue, and may have to be on TA for a longer period.   What other factors would be relevant in this matter, and to what extent am I correct/incorrect in either the factors considered, or for undertaking this exercise at all? Does the alarm work when my phone is turned off? Is "double hashing" a password less secure than just hashing it once? Is hashing a password twice before storage any more or less secure than just hashing it once?  What I'm talking about is doing this:  $hashed_password = hash(hash($plaintext_password));   instead of just this:  $hashed_password = hash($plaintext_password);   If it is less secure, can you provide a good explanation (or a link to one)?  Also, does the hash function used make a difference?  Does it make any difference if you mix md5 and sha1 (for example) instead of repeating the same hash function?  Note 1:  When I say "double hashing" I'm talking about hashing a password twice in an attempt to make it more obscured.  I'm not talking about the .  Note 2:  I know I need to add a random salt to really make it secure.  The question is whether hashing twice with the same algorithm helps or hurts the hash. I use the scroll function with my mouse and it works fine. But either in script, or in terminal sections of Spyder, I can't use the touchpad for scrolling. I do not experience any problems with my touchpad in other programs like Word, Chrome etc. Is there any option for this in Spyder, specific for touchpad?  I am using Lenovo Legion Y520, Windows 10. I would like to . Apparently this is possible as of Minecraft 1.4.2, so how do I do it? My settlement was attacked by some Raiders and my defenses took care of them along with some of my NPC's. It seems like the Raiders didn't make it through to any of the buildings. What happens when they do?  Can you lose your items if you stored them in a house?  Can the NPC's die?  Do the enemies destroy your buildings? I have an unlocked North American (Canada) iPhone 5s, where can I buy a data only SIM card in Japan ? I'm not interested in renting nor in a voice plan, I'll be staying for 4 weeks.  I'll be landing in Tokyo, so preferably around there. Can I get them from the airport somewhere ? I'm assuming I won't have problems with the network/frequencies, am I correct ? Why does US Robotics destroy Lanning's house? Shortly after the death of Dr. Lanning, Detective Spooner travels to the doctor's house to look for clues.  While he is searching the house a demolition bot (which had been programmed to demolish the house the next day) goes on a rampage and destroys the house with Detective Spooner in it.   The house is fully furnished and appears to be in good condition. Why would US Robotics want to destroy the house with everything in it? Why not sell the house and everything inside? I downloaded and installed Ubuntu from the official site. However, I don't know if I installed the 32-bit or 64-bit version.  In Windows 7 I could right click My Computer and it listed which version it was.  Is there an easy way to check in Ubuntu? How do you convert a numerical number to an Excel column name in C# without using automation getting the value directly from Excel.  Excel 2007 has a possible range of 1 to 16384, which is the number of columns that it supports. The resulting values should be in the form of excel column names, e.g. A, AA, AAA etc. Electricity takes the path of least resistance? Electricity takes the path of least resistance!   Is this statement correct?    If so, why is it the case?  If there are two paths available, and one, for example, has a resistor, why would the current run through the other path only, and not both? Why can't Chromium suddenly access any partition except for /home? I just upgraded to Ubuntu 19.10 and to my horror I discovered that the default browser Chromium can no longer access other partitions than /home.  This means that my partitions containing music and videos (/multimedia) for instance are no longer accessible e.g. to upload into Google Drive. This includes USB partitions.   I found another description of this phenomenon here:  where it says  "Also, while we acknowledge that most users will only need to access their home folders, it’s worthy to mention that you no longer can access system files &amp; folders from inside Chromium (You can’t access anything except your home folder). This means that if you are to upload a file or an image for example into the Internet using an uploading website, then this file/image must be in your home folder, as you can not access directories such as /usr, /etc or other directories located in your root partition. In fact, you no longer can access any other partition at all, this includes USB sticks and other booted partitions:"  I wonder why this behaviour been introduced? it violates the whole idea of multiple disks, partitions and symlinks. Btw, this still works for Firefox.  My questions are   Are there any plans to fix this? I expect one reason for this behaviour is about security. If so, is it possible to explain why and how that makes for better security? The files on other partitions are legitimately accessible by the user anyway e.g. through symlinks. But with this change, I'll have to move them to /home before uploading so still accessing them although more slowly and cumbersome.  If this behaviour is now permanent, the question is how should we incorporate multiple disks in our filesystem?  Alternatively, can someone tell me how to find and install the debian package. I haven't been able to locate it?   This is not a duplicate of  because that is about a specific error during installation that I didn't get. My question is about the access chromium has in Ubuntu 19.10.  Anyway, I solved the problem via the following command by using the original debian package from Google:  sudo apt-get install google-chrome-stable   After that I can now access my other partitions again. I know this is hacky in the sense that the package isn't native to Ubuntu so I would really like to get some advice on how to incorporate multiple disks and partitions with this new restricted behaviour of Chromium.  Thank you very much Show $\inf_f\int_0^1|f'(x)-f(x)|dx=1/e$ for continuously differentiable functions with $f(0)=0$, $f(1)=1$. Let $C$ be the class of all real-valued continuously differentiable functions $f$ on the interval $[0,1]$ with $f(0)=0$ and $f(1)=1$. How to show that $$\inf_{f\in C}\int_0^1|f'(x)-f(x)|dx=\frac{1}{e}?$$  I have been able to show that $1/e$ is a lower bound. Indeed, $$\begin{align*} \int_0^1|f'(x)-f(x)|dx &amp;= \int_0^1|f'(x)e^{-x}-f(x)e^{-x}|e^xdx \\ &amp;\geq \int_0^1\left(f'(x)e^{-x}-f(x)e^{-x}\right) dx \\ &amp;= \int_0^1 \frac{d\left(f(x)e^{-x}\right)}{dx}dx  \\ &amp;= f(1)e^{-1}-f(0)e^{0}\\ &amp;=\frac{1}{e}. \end{align*}$$ But how to show this is the infimum? Is there a function $f\in C$ such that we get $\int_0^1|f'(x)-f(x)|dx=1/e$? Let $\kappa, \lambda,\theta$ be infinite cardinals of $M$ where $M$ is a transitive model of ZFC. Let $\mathcal{P}=Fn(\kappa\times \omega,2)$ (finite functions from $\kappa\times \omega$ to 2) and G is a (M,P)-generic set. I want to show $(\lambda^\theta)^{M[G]}=(max(\kappa,\lambda)^\theta)^M$. One direction is easy $(\lambda^\theta)^M \leq (\lambda^\theta)^{M[G]}$ and $(\kappa^\theta)^M\leq (\kappa^\theta)^{M[G]}\leq ((2^\omega)^\theta)^{M[G]}=(2^\theta)^{M[G]}\leq (\lambda^\theta)^{M[G]}$ where $(\kappa \leq 2^\omega)^{M[G]}$ is by the forcing construction. But now I am not quite sure how to get the other direction. Any thoughts? I try to resolve a problem, how to implement a xor gate with nand's gate.  A xor B = A'B + AB'  So, this becomes :  A xor B = A'B + AB' + AA' + BB' = A(A' + B') + B(A' + B') = (A + B)(A' + B') =   (with De Morgan apllied on the second term)  = (A + B)(AB)' = ..... ?  In this point i am blocked. If someone can help me, please. Thank you. improper integral calculation I do not know how to solve this integral and then expand the result in powers of $t$  $$(1-t)^{-1/2}\int_{-\infty}^{\infty}\frac{\exp\left(\frac{2x^2t}{1+t}\right)}{1+x^2}dx=?,~~~~|t|&lt;1.$$  any idea? I am having an issue where DHCP (I though as I read in other similar topics) is clearing the /etc/resolv.conf file on each boot. I am not sure about how to deal with this since the post I have found (,  and some others) are for Debian based distros or other but not Fedora.  This is the output of ifcfg-enp0s31f6 so for sure is DHCP:  cat /etc/sysconfig/network-scripts/ifcfg-enp0s31f6  HWADDR=C8:5B:76:1A:8E:55 TYPE=Ethernet DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=no IPV6_AUTOCONF=no IPV6_DEFROUTE=no IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=enp0s31f6 UUID=0af812a3-ac8e-32a0-887d-10884872d6c7 ONBOOT=yes IPV6_PEERDNS=no IPV6_PEERROUTES=no BOOTPROTO=dhcp PEERDNS=yes PEERROUTES=yes   In the other side I don't know if Network Manager is doing something else around this.  Update: Content of NetworkManager.conf (I have removed the comments since are useless)  $ cat /etc/NetworkManager/NetworkManager.conf  [main] #plugins=ifcfg-rh,ibft dns=none  [logging] #domains=ALL   Can I get some help with this? It's annonying be setting up the file once and once on every reboot.  UPDATE 2  After a month I'm still having the same issue where file gets deleted by "something".   Here is the steps I did follow in order to make a fresh test:   Reboot the PC After PC gets restarted open a terminal and try to ping Google servers of course without success:  $ ping google.com ping: google.com: Name or service not known  Check the network configuration were all seems to be fine:  $ cat /etc/sysconfig/network-scripts/ifcfg-enp0s31f6  NAME=enp0s31f6 ONBOOT=yes HWADDR=C8:5B:76:1A:8E:55 MACADDR=C8:5B:76:1A:8E:55 UUID=0af812a3-ac8e-32a0-887d-10884872d6c7 BOOTPROTO=static PEERDNS=no DNS1=8.8.8.8 DNS2=8.8.4.4 DNS3=192.168.1.10 NM_CONTROLLED=yes IPADDR=192.168.1.66 NETMASK=255.255.255.0 BROADCAST=192.168.1.255 GATEWAY=192.168.1.1 TYPE=Ethernet DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=no  Restart the network service:  $ sudo service network restart [sudo] password for &lt;current_user&gt;:  Restarting network (via systemctl):                        [  OK  ]  Try to ping Google servers again, with no success:  $ ping google.com ping: google.com: Name or service not known  Check for file /etc/resolv.conf:  $ cat /etc/resolv.conf  cat: /etc/resolv.conf: No such file or directory  File doesn't exists anymore - and this is the problem something is deleting it on every reboot Create the file and add the content of DNS:  $ sudo nano /etc/resolv.conf   Ping Google servers this time with success:  $ ping google.com PING google.com (216.58.192.110) 56(84) bytes of data. 64 bytes from mia07s35-in-f110.1e100.net (216.58.192.110): icmp_seq=1 ttl=57 time=3.87 ms    Any ideas in what could be happening here? How to check if a column exists in a SQL Server table? I need to add a specific column if it does not exist. I have something like the following, but it always returns false:  IF EXISTS(SELECT *           FROM   INFORMATION_SCHEMA.COLUMNS           WHERE  TABLE_NAME = 'myTableName'                  AND COLUMN_NAME = 'myColumnName')    How can I check if a column exists in a table of the SQL Server database?