Timeline for Does a 10-element set have 30 3-element subsets such that each pair is in two of these 30 subsets?
Current License: CC BY-SA 3.0
11 events
| when toggle format | what | by | license | comment | |
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| Jun 19, 2012 at 16:48 | comment | added | David Wasserman | This question was motivated by communications scheduling. It concerns a n-node network in which up to m nodes can broadcast at a time; nodes can not receive while sending, but when not sending they can simultaneously receive from all m senders. The goal is to serve all source-destination pairs equally. n=10 and m=3 are arbitrary choices. 30 is the minimum possible because there are n(n - 1) = 90 pairs, n(n - m) = 21 can be served at a time, and lcm(90, 21)/21 = 30. I was assuming the 30 subsets are distinct, but now I see that my application doesn't need that. | |
| Jun 19, 2012 at 16:32 | vote | accept | David Wasserman | ||
| Jun 19, 2012 at 1:46 | answer | added | Gerry Myerson | timeline score: 4 | |
| Jun 19, 2012 at 1:41 | history | edited | Gerry Myerson | CC BY-SA 3.0 |
Put question in body.
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| Jun 19, 2012 at 0:17 | comment | added | Yemon Choi | I still think the question would benefit from some explanation as to the OP's motivation. It isn't the kind of question that pops into my head at random, although I don't claim to be representative. | |
| Jun 18, 2012 at 22:26 | history | reopened |
André Henriques David E Speyer Douglas Zare Will Sawin Benjamin Steinberg |
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| Jun 18, 2012 at 21:51 | comment | added | André Henriques | I light of Douglas Zare's answer, this question did not deserve to be closed. I vote to reopen. | |
| Jun 18, 2012 at 21:29 | history | closed |
Bill Johnson Steven Landsburg Andrés E. Caicedo Felipe Voloch Chris Godsil |
too localized | |
| Jun 18, 2012 at 21:24 | answer | added | Douglas Zare | timeline score: 12 | |
| Jun 18, 2012 at 20:28 | comment | added | André Henriques | Dear David. I fear that some will tend to think that your question is a homework, and will therefore vote to close it. To avoid that, you should indicate a little bit the context in which your questions arose. In particular, where to the numbers 10 and 30 come from? | |
| Jun 18, 2012 at 20:12 | history | asked | David Wasserman | CC BY-SA 3.0 |