Timeline for iterating over subsets by switching one element at a time
Current License: CC BY-SA 3.0
19 events
| when toggle format | what | by | license | comment | |
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| Jan 8, 2014 at 21:29 | answer | added | Yuval Filmus | timeline score: 1 | |
| Jan 8, 2014 at 20:43 | history | reopened |
john mangual Gilles 'SO- stop being evil' |
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| Jan 5, 2014 at 21:10 | comment | added | john mangual | @Raphael this question has more details thanks to your suggestions. I didn't know that specific programming languages were frowned upon on this StackExchange. | |
| Jan 5, 2014 at 19:49 | comment | added | Raphael | @johnmangual Even researchers may repost exercise problems without displaying effort, and your original question sure read that way. (If you browse the site, you'll find that we get many of these questions and we (try to) close them all, no matter who posts them.) Your edit may render the question valid for the site; I'll read it when I find the time. You may want to include the background you state (esp. the paper you are reading) into the question; these are the items that make a question interesting and answerable. | |
| Jan 5, 2014 at 18:08 | history | edited | john mangual | CC BY-SA 3.0 |
added 584 characters in body
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| Jan 5, 2014 at 18:01 | comment | added | john mangual | @Raphael This is not a homework problem. I got my Master degree 2 years ago (not in Computer Science). I am reading an math paper and would like to verify some of their claims with code. One step requires iterating over subsets. | |
| Jan 5, 2014 at 17:59 | comment | added | john mangual | @D.W. Enough with your accusations The buggy code is mine - an implementation of the algorithm I was reading about. The equations are from the textbook, whose notation is not very clear. Here it is again, Combinatorial Algorithms by Nienhuis and Wilf. | |
| Jan 5, 2014 at 17:52 | comment | added | D.W.♦ |
Finally, if your question is about code, then this isn't the place for the question. We're focused on algorithms. Perhaps you might try rewriting your code in mathematics, so everyone can understand. Also, you need to provide explanation of what you're trying to accomplish and define all symbols. What is gc(n,k) supposed to output? S(n,k,a)? P(n,k,a)? Finally: a code dump of some buggy code you found somewhere that you don't fully understand might not be especially helpful to people here.
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| Jan 5, 2014 at 17:50 | comment | added | D.W.♦ | Thanks for the edit, but I think we need more. You give an equation out of nowhere, but what does that equation mean? What is $A(n,k)$ supposed to "mean"? What quantity is it intended to capture? Why is it relevant here? What is the definition of your notation? For instance, what does $A(n-1,k), \overline{ A(n-1,k-1)}\otimes \{n\}$ mean? What is the definition of the $,$ operator, the $\otimes$ operator, and the $\overline{\cdot}$ operator? The question is a bunch of statements; I think it would help to add more connective tissue and explanation to make it self-contained. | |
| Jan 5, 2014 at 17:42 | review | Reopen votes | |||
| Jan 8, 2014 at 20:43 | |||||
| Jan 5, 2014 at 17:25 | comment | added | john mangual | @D.W. Here is what I have done so far... I am reading a paper where a set requires me to iterate over subsets and evaluate a certain function. | |
| Jan 5, 2014 at 17:24 | history | edited | john mangual | CC BY-SA 3.0 |
more details
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| Jan 5, 2014 at 17:01 | history | closed |
D.W.♦ Raphael |
Needs details or clarity | |
| Jan 5, 2014 at 17:01 | comment | added | Raphael | This is a dump of a homework/exercise problem, not a question. If you have a specific question regarding the wording of the problem or about concrete steps in your own attempts at solving the problem, feel free to edit accordingly and we can reopen the question. See also here for our homework policy, and here for a relevant discussion. | |
| Jan 5, 2014 at 7:54 | comment | added | Yuval Filmus | Check out Knuth's new volume, which has algorithms of this kind. | |
| Jan 5, 2014 at 4:13 | review | Close votes | |||
| Jan 5, 2014 at 17:02 | |||||
| Jan 5, 2014 at 3:57 | comment | added | john mangual | @D.W. Other than lexicographic order, which doesn't switch 1 element at time at certain places anyway. The same chapter explains this confusing "Revolving Door" algorithm. There may be other ways, so I am asking on here. | |
| Jan 5, 2014 at 3:53 | comment | added | D.W.♦ | What have you tried? We're not here to solve your exercise for you, but if you've made a serious effort and if you show us what you've tried so far and where you got stuck, the question might be suitable for this site. If you haven't made a serious effort so far, it's probably premature to ask. For instance, have you tried some small examples (for various small values of $k$ and $n$)? | |
| Jan 5, 2014 at 3:35 | history | asked | john mangual | CC BY-SA 3.0 |