Wikipedia:Reference desk/Archives/Computing/2017 February 12

= February 12 =

Simcard record
would like to find out the records of my mobile dongle simcard (which websites or what I used it for…) and wish to delete some record from it… What do I do? or What software do I use? 116.58.203.177 (talk) 17:05, 12 February 2017 (UTC)


 * Are you certain that info is stored on the SIM card, as opposed to directly on the phone ? Also, I don't understand your use of the word "dongle", which to me means a flash drive that hangs out of a USB port, whereas a SIM card is inside the phone.  StuRat (talk) 17:43, 12 February 2017 (UTC)
 * By a dongle they probably mean a USB modem. Ruslik_ Zero 18:09, 12 February 2017 (UTC)
 * The user means his internet history is available when he takes it to the Sim Network Shopkeeper. 43.245.121.239 (talk) 18:44, 12 February 2017 (UTC)
 * I've looked for sim-card editing tools several years ago, but there's not much around. I've played with this . Payed software with bugs. :( My internet history wasn't on the card b.t.w., but things may have changed over time. Jahoe (talk) 00:05, 13 February 2017 (UTC)


 * The SIM stores very little information; mostly it's there to make sure that someone is paying for the network connectivity you're using, and to make sure phone calls intended for you are directed correctly to you. What you do with the phone, including emails you send and websites you visit, isn't stored in the SIM - almost nothing is. Subscriber identity module describes what is - just basic subscriber info, text messages, and (really basic) contact information. -- Finlay McWalter··–·Talk 00:15, 13 February 2017 (UTC)
 * Just to reaffirm what what Finlay McWalter has said, this info is not stored on the SIM card so there's no point trying to edit it to remove that info. There's a possibility it's stored on the USB dongle (I guess this is what you're referring to) itself. More likely the info is stored on the companies servers. In other words, you'd need to work out if you can get the company to delete it (or at least stop logging it) if this is possible. It could be there is a setting in the online account which can remove the info or at least control what is logged. Or maybe you'll have to ask them, Or maybe it simply isn't possible, if e.g. legal reasons require it to be logged. Note that if it's the later this may very well apply to any mobile provider in your location. Even if the info isn't viewable by you, it may still be recorded. BTW, the info may also be stored on your computer which the dongle is plugged in to. That will be a separate record and something you should have complete control over. P.S. Re-reading your comment, I'm not sure 47 is correct. I don't see anything to suggest you've actually seen the history. As I've said the most likely places any info is stored will be on your computer and on the mobile provider's servers. There is a possibility there is info stored on the dongle, but most likely it isn't much if anything. For your computer, there are various tools which can help you find out what info is stored on your computer depending on OS, browser etc. For your mobile provider, it may be difficult to actually find out what your ISP has logged in a place like Bangladesh unfortunately. Of course if you can't find the info, then it'll normally be difficult for other mortals. In other words, if you're just worried a partner is going to find out you regularly visit sites for Furries then you probably have nothing to worry about from the ISP records if you can't find them yourself. (But bear in mind these could be accessible via some obscure method not widely published or even known by ISP support, so you'll need to really look around.) Nil Einne (talk) 07:37, 13 February 2017 (UTC)

modifying a bipartite graph so that it would have a perfect matching
Hello,

Given a bipartite graph with equal-sized sides X and Y, how can we efficiently find the minimum number of additional edges we have to add so that the graph will have a perfect matching? is there a better solution than iterating over all 2^(|X|) subsets and adding edges until Hall's theorem is satisfied? Thanks, 77.126.86.214 (talk) 20:22, 12 February 2017 (UTC)


 * Links to bipartite graph and to Hall's marriage theorem may help. If the number of elements in X is the same as Y, then that's called a "balanced bipartite graph".


 * What form is the data in to begin with ? If for every element in X you have a list (possibly empty) of every match in Y, and vice versa, I would suggest finding every unmatched X and every unmatched Y first (push them into 2 stacks, for example).  Whichever stack is shorter can be processed first, adding an edge from the next unmatched X to the next unmatched Y.  If some unmatched X or Y elements remain at the end, they can be matched with any in the other set.


 * On the other hand, if the data is simply a list of edges and which X and Y they connect, you would first need to go through that list and generate the list of X elements, and which Y they are each linked to, and vice-versa, then do as described in the previous paragraph. Even in this worst case, the amount of processing seems low, just the number of edges, plus the number of X elements, plus the number of Y elements, plus the number of unmatched X or Y elements, whichever is greater.  No exponential growth here.


 * But your description makes me think you envision a system where you must ask a database, for every possible pair Xa and Yb, "Does an edge exist between this pair ?". Is this what you had in mind ?  StuRat (talk) 20:43, 12 February 2017 (UTC)


 * Thank you! 77.126.86.214 (talk) 09:51, 13 February 2017 (UTC)


 * You're quite welcome. I will mark this Q resolved, but you can remove the tag if you disagree. StuRat (talk) 14:57, 13 February 2017 (UTC)