check all boxes checked when click on parent checkbox only with Javascript?
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What happens if I do not honor a futures contract? I have little knowledge about futures contracts. The recent negative price of crude oil spurred my curiosity about this stuff.   I read this post about .  According to this post, when I buy a futures contract, I enter into a contractual agreement to buy some commodity on some future date, and I only need to pay a 2% initial margin.   Suppose the price of the commodity does not fluctuate but I change my mind and decide not to buy the commodity at maturity. What punishment could be exerted on me?   I do not want the 2% initial margin back because that is a little money compared to the real value of the commodity. If there is no extra penalty, it would be unfair for the seller — imagine the seller transports 1000 barrels of crude oil to your front door and you say "I do not need it any more, please take it away, thank you!"  Update: I did more research about this and have more questions.  If I buy a futures contract at $10 and the price of the contract drops to -$37 at the last trading day, at which price should I buy the commodity at the delivery day, $10 or -$37?   There seems not just one contract I enter into when I buy a futures contract: the original futures contract between me and the seller of the commodity(or the exchange?), the contract between me and my brokerage, the contract between the brokerage and the exchange. I'm not clear about the exact entities of each contract and the obligations involved in each contract. The contracts seem contradictory with each other, e.g., my brokerage may forcefully sell my futures contract if my account balance is not enough, which will prevent me from fulfilling the obligations in the futures contract, i.e., receiving the commodity on future date.  If I(or an institutional trader) trade directly (not via a brokerage) with an exchange(does CME accept individual traders?), does the exchange have the rights to forcefully sell my contracts at the last trading day at any price or close my position at the settlement price(say -$37)? If the exchange does so thus letting me own $5,000M to it, is it more justice for me to sue the exchange rather than let the exchange sue me? If I could hold the position, the loss caused by my not executing the delivery/receipt of the commodity may be less than $5,000M. Of course, the loss will be determined by the court, not by the exchange according to the settlement price formed by itself or a few possible conspirators. I consider the co-finite topology on $\mathbb{R}$ that is $$\{G\subset \mathbb{R}, card(\mathbb{R}\setminus G)&lt;+\infty\}\cup \{\emptyset\}$$  What are the convergent sequences in this space .  thank you $\forall x,y>0, x^x+y^y \geq x^y + y^x$ Prove that $\forall x,y&gt;0, x^x+y^y \geq x^y + y^x$   A friend of mine told me none of the teachers in my school have succeeded in proving this seemingly simple inequality (it was asked at an oral exam last year). I tried it myself, but I made no significant progress. Print total free memory from `free -m` free -m currently puts out something like this.     I would like to know using grep/awk how we can get the total free amount. i.e. 9083 Dimension of cone of projective variety Proof $1+2+3+4+\cdots+n = \frac{n\times(n+1)}2$ Windows file copy dialog: Why is the estimation so... BAD? I know that the Windows copy dialog (in Windows&nbsp;XP) stores the copy in memory first, and it is still copying after the dialog closes, so the time is off, but why is the estimation of the time it will take to make a copy so inaccurate, even when memory copying has been disabled (in Vista and Windows&nbsp;7)? It seems so arbitrary! How does the whole copy procedure work, and why can't Windows estimate it correctly? When I melt 16 oz of chocolate I add 4 oz of oil how long can I keep this and how should it be stored. Someone said something about botulism ?? Proper display of fractions JavaScript RegExp objects I try to write a simple Markdown parser in JavaScript. Therefore I want to check for the [link content][link id] syntax. I use the following code:  data = data.replace( /\[(.*?)\][ ]*\[([0-9]+)\]/g, '&lt;a href="$2"&gt;$1&lt;/a&gt;' );   It works well, but now I want to do this with a RegExp object. So I set up the following bit of code:  var r = new RegExp( '\[(.*?)\][ ]*\[([0-9]+)\]', 'g' ); data = data.replace( r, '&lt;a href="$2"&gt;$1&lt;/a&gt;' );   But it doesn't work. It even says that my regular expression (which works since the first example does a good job) is invalid:     unmatched ) in regular expression   I think it must have to do with some RegExp-object peculiarities I am not aware of. What am I doing wrong and how can the problem be solved? Posting to friends' wall with Graph API via 'feed' connection failing since Feb 6th 2013 "Pick up something" or "pick something up"? Seem to have lost 4 Silver badges and 10 Bronze badges Java - How to reduce the size of third-party jars to reduce the size of your application Impact of deleting 100GB table on Mirroring I'm about to delete a large table which is approximately 100GB in size.  I'd like to understand the impact on the mirroring that's in place on this db.  Can anyone confirm? systemctl --user not available for www-data user systemctl --user seems to be working fine for the desktop user:  dev@dev-VirtualBox:~$ systemctl --user &gt; /dev/null dev@dev-VirtualBox:~$ echo $? 0   But when running the same command under the www-data user I get an unexpected response  dev@dev-VirtualBox:~$ sudo su www-data -s /bin/bash www-data@dev-VirtualBox:~$ systemctl --user &gt; /dev/null  Failed to connect to bus: No such file or directory  www-data@dev-VirtualBox:~$ echo $?  1   How to enable systemctl --user here?  Running Ubuntu 16.04 Is spacetime flat inside a spherical shell? In a perfectly symmetrical spherical hollow shell, there is a null net gravitational force according to Newton, since in his theory the force is exactly inversely proportional to the square of the distance.  What is the result of general theory of relativity? Is the spacetime flat inside (given the fact that orbit of Mercury rotates I don't think so)? How is signal from the cavity redshifted to an observer at infinity? How to specify an arbitrary (possibly non-integer) font size in LaTeX I may be wrong, but it seems to me that I cannot obtain non-integer (or non-preloaded) font sizes (say, 9.876pt) using \fontsize.  If this is true, how do I do this in LaTeX?  Do I have to resort to the \font ... at ... primitive?  (The reason I need this is that I'd like to implement a more LaTeXy way to do the \diminuendo macro from .) Gapless superconductivity I don't understand what is meant by &quot;gapless superconductors&quot;. As far as I know, the superconducting gap is necessairy for both zero resistance and the Meissner effect, the two hallmarks of superconductivity. So, what does it mean to have gapless superconductivity and how does it work? Thanks in advance, Greetings "Those who qualify will be awarded a certificate" or "those who qualify will be awarded certificates"?