How to model entity types that can contain each other?
How to model an entity type that can have different sets of attributes?
Subdivision surface modifier problem Hello!   I've recently started learning Blender and faced one problem.  After applying subdivision surface modifier I have plenty of extra faces. I've watched some teaching videos and I suppose additional faces shouldn't be added. Is it OK ? How to avoid this problem if it isn't. Internet through wireless hotspot, intranet through wired network - can I use both at the same time? I have been tring this for a while now, without success. I have read online this can be done, either by changing the default gateway (DG) or messing with the DG's metric  The short story is: I need to connect to my company's ERP system (port 80 for some web services and port 22 for sftp and bash) with using my notebook computer's LAN card - but I can't connect to the Internet on this network. So I have my mobile phone's 3g hotspot when I need to go online. But I want to use both at the same time without so much as opening another web browser process.  At the moment, I am using the ERP system regularly - and whenever I need to go online to check a mail or research something related to work, I need to unplug the network cable so the wifi can kick in... which is starting to become annoying especially if I am connected to the ERP system using FTP (Filezilla) or Shell (putty)  Can someone help me with the configurations?  Below are some of the details I can provide:  Wired network - office LAN - for connection to the ERP system: DHCP -    Yes IPv4      10.64.200.245 Subnet    255.255.240.0 DG        10.64.193.254 DHCP Serv 10.64.17.191 DNS       10.68.72.200           10.68.20.200 WINS      10.68.77.200           10.64.20.200   Below are the details for my WiFi internet connection - over my mobile hotspot  DHCP      Yes IPv4      192.168.43.39 &lt;- I'm guessing this changes every time I restart the wifi subnet    255.255.255.0 DG        192.168.43.1 DHCP      192.168.43.1 DNS       192.168.43.1   Finally, here is the tracert results (btw, I'm on Windows 7, 64bit and the remote system should be on Linux) - the target ERP ip address is 10.76.142.39  Tracing route to 10.76.142.39 over a maximum of ...    1    &lt;1 ms    &lt;1 ms    &lt;1 ms  10.64.193.253   2    &lt;1 ms    &lt;1 ms    &lt;1 ms  10.64.4.13   3    &lt;1 ms    &lt;1 ms    &lt;1 ms  10.76.23.124   4     1 ms    &lt;1 ms    &lt;1 ms  10.76.23.93   5     1 ms    &lt;1 ms    &lt;1 ms  2xx-xx-xx-9.adsl...   6     1 ms     1 ms     1 ms  2xx-xx-xx-9.adsl...   7     1 ms     1 ms     1 ms  2xx-xx-xx-10.adsl..   8     2 ms     1 ms     2 ms  10.76.135.125   9     1 ms     1 ms     1 ms  10.76.142.39   sorry, I had to mask out some details above... wasn't sure if they would have any confidentiality issues.  Any help is much appreciated. Saving image from PHP URL Why does Newton's Third Law actually work? My father explained to me how rockets work and he told me that Newton's Third Law of motion worked here. I asked him why it works and he didn't answer. I have wasted over a week thinking about this problem and now I am giving up. Can anyone explain why Newton's Third Law works? For reference, Newton's third law:  To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. I’m writing a document in the latex and it contains some BNF grammar noations in several places of the documents. (I used verbatim package in order to write these BNF grammar notations)  Now I want to add a new section to the document that shows name of all grammar notation and their page numbers. This should be similar to “List of Figures” page.  I’m new to Latex and your help will be very helpful for me.  Thanks DOM event precedence What order of precedence are events handled in JavaScript?  Here are the events in alphabetical order...   onabort - Loading of an image is interrupted onblur - An element loses focus onchange - The user changes the content of a field onclick - Mouse clicks an object ondblclick - Mouse double-clicks an object onerror - An error occurs when loading a document or an image onfocus - An element gets focus onkeydown - A keyboard key is pressed onkeypress - A keyboard key is pressed or held down onkeyup - A keyboard key is  released onload - A page or an image is  finished loading onmousedown - A mouse button is  pressed onmousemove - The mouse is moved onmouseout - The mouse is moved off  an element onmouseover - The mouse is moved  over an element onmouseup - A mouse button is  released onreset - The reset button is  clicked onresize - A window or frame is  resized onselect - Text is selected onsubmit - The submit button is  clicked onunload - The user exits the page   What order are they handled out of the event queue?  The precedence is not first-in-first-out (FIFO) or so I believe. Subfiles failing with custom class A closed form for a triple integral with sines and cosines $\int_{0}^{\infty}\frac{\sin^{2n+1}(x)}{x} \mathrm {d}x$ Evaluate Integral Here is a fun integral I am trying to evaluate:  $$\int_{0}^{\infty}\frac{\sin^{2n+1}(x)}{x} \ dx=\frac{\pi \binom{2n}{n}}{2^{2n+1}}.$$  I thought about integrating by parts $2n$ times and then using the binomial theorem for $\sin(x)$, that is, using $\dfrac{e^{ix}-e^{-ix}}{2i}$ form in the binomial series.  But, I am having a rough time getting it set up correctly. Then, again, there is probably a better approach.   $$\frac{1}{(2n)!}\int_{0}^{\infty}\frac{1}{(2i)^{2n}}\sum_{k=0}^{n}(-1)^{2n+1-k}\binom{2n}{k}\frac{d^{2n}}{dx^{2n}}(e^{i(2k-2n-1)x})\frac{dx}{x^{1-2n}}$$  or something like that. I doubt if that is anywhere close, but is my initial idea of using the binomial series for sin valid or is there a better way?.  Thanks everyone. command not found and syntax error near unexpected token Can I levitate an object without using an electromagnet? Arrays in Unix Bourne Shell I am trying to use arrays in Bourne shell (/bin/sh). I found that the way to initialize array elements is:  arr=(1 2 3)   But it is encountering an error:  syntax error at line 8: `arr=' unexpected   Now the post where I found this syntax says it is for bash, but I could not find any separate syntax for Bourne shell. Does the syntax stand the same for /bin/sh as well? Raise bounty on question I have this question here:  I chose 500 then before accepting decided that was too much and halfed it, but now I just want the answer so I'd like to raise it to 500 but I can't find how to it. Also it's just such an irritating problem that I'd give all my rep away if I could to the clever person who has the answer. It would be nice to have a few minutes after creating the bounty to be able to raise it. But for now could a mod or something please raise it for me to 500. Should we have a down-vote “safe zone” for new users with less than 50 reputation? i want to create new event in SharePoint calendar list in which I have some custom columns,i tried below code but it is not working      function bookingRoomForMeeting() {         var ctx = new SP.ClientContext(appWebUrl);//Get the SharePoint Context object based upon the URL           var list = ctx.get_web().get_lists().getByTitle("MyCalendarList"); //Get the List based upon the Title         var listCreationInformation = new SP.ListItemCreationInformation(); //Object for creating Item in the List         listItem = list.addItem(listCreationInformation);         listItem.set_item('Title', $("#txt_Title").val());         var date = $("#txt_startTime").val();         var dateTime = moment(date, 'DD/MM/YYYY HH:mm a').format("MM/DD/YYYY HH:mm a");         listItem.set_item('EventDate', dateTime);         var enddate = $("#txt_endTime").val();         var enddateTime = moment(enddate, 'DD/MM/YYYY HH:mm a').format("MM/DD/YYYY HH:mm a");         listItem.set_item('EndDate', enddateTime);         listItem.set_item('EmailId1', $("#txt_EmailId1").val());         listItem.set_item('EmailId2', $("#txt_EmailId2").val());         listItem.update();         ctx.load(listItem);         ctx.executeQueryAsync(             Function.createDelegate(this, success),             Function.createDelegate(this, fail)            );     } function success() {     alert("Completed"); } function fail() {     alert("operation failed"); }   list am using is SharePoint hosted app list,can any one tell me where am going wrong? Apex compile error : variable does not exist I'm having issues with creating a pretty simple test Utility Class. I want to create two records: an account and a related child contact. The error I see in the developer console is:     Variable does not exist: a.ID   My code, based on the Salesforce Apex Workbook, is as follows. I've played around with various things, but it's not working. Where am I going wrong? Thanks in advance.  @isTest public class AccountSaveTestSuite {      public static Account createOneAccount(){           Account testAccount = createAcct('ABC Computing inc.');              Contact testContact = createContact();          return testAccount;             }      // Helper methods //     //        private static Account createAcct(string accountName) {          Account a = new Account(             Name=accountName);         insert a;         return a;     }      private static Contact createContact(){         Contact c = new Contact (             FirstName = 'Jane'              , LastName = 'Smith'             , Account = a.ID); // *** Error is here ***         insert c;         return c;      }  } Why and how is the speed of light in vacuum constant, i.e., independent of reference frame? I was told that the Galilean relative velocity rule does not apply to the speed of light. No matter how fast two objects are moving, the speed of light will remain same for both of them.   How and why is this possible?   Also, why can't anything travel faster than light? Windows 98 on a modern computer? In my cssh config file, I have:  terminal_font=6x13   this default font is too small for me.   man cssh says, I can specify other font size with the -f argument, while using "standard X font notation".  is a wikipedia page containing some other fonts types. Unfortunately, none of these work for me:  $ cssh host1 host2 -f "7x14" Fatal: Unrecognised font used (7x14). Please amend $HOME/.clusterssh/config with a valid font (see man page).   Why does "7x14" not work?  How can I use bigger fonts with cssh ? The weighted sum of two independent Poisson random variables Using wikipedia I found a way to calculate the probability mass function resulting from the sum of two Poisson random variables. However, I think that the approach I have is wrong.  Let $X_1, X_2$ be two independent Poisson random variables with mean $\lambda_1, \lambda_2$, and $S_2 =  a_1 X_1+a_2 X_2$, where the $a_1$ and $a_2$ are constants, then the probability-generating function of $S_2$ is given by $$ G_{S_2}(z) = \operatorname{E}(z^{S_2})= \operatorname{E}(z^{a_1 X_1+a_2 X_2}) G_{X_1}(z^{a_1})G_{X_2}(z^{a_2}). $$ Now, using the fact that the probability-generating function for a Poisson random variable is $G_{X_i}(z) = \textrm{e}^{\lambda_i(z - 1)}$, we can write the probability-generating function of the sum of the two independent Poisson random variables as $$ \begin{aligned} G_{S_2}(z) &amp;= \textrm{e}^{\lambda_1(z^{a_1} - 1)}\textrm{e}^{\lambda_2(z^{a_2} - 1)}  \\ &amp;= \textrm{e}^{\lambda_1(z^{a_1} - 1)+\lambda_2(z^{a_2} - 1)}. \end{aligned} $$ It seems that the probability mass function of $S_2$ is recovered by taking derivatives of $G_{S_2}(z)$ $\operatorname{Pr}(S_2 = k) = \frac{G_{S_2}^{(k)}(0)}{k!}$, where $G_{S_2}^{(k)} = \frac{d^k G_{S_2}(z)}{ d z^k}$.  Is this is correct? I have the feeling I cannot just take the derivative to obtain the probability mass function, because of the constants $a_1$ and $a_2$. Is this right? Is there an alternative approach?  If this is correct can I now obtain an approximation of the cumulative distribution by truncating the infinite sum over all k?