Timeline for Counting monomials in skew-symmetric+diagonal matrices
Current License: CC BY-SA 4.0
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9 events
| when toggle format | what | by | license | comment | |
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| Mar 11, 2019 at 6:18 | vote | accept | T. Amdeberhan | ||
| Mar 4, 2019 at 16:26 | history | edited | T. Amdeberhan | CC BY-SA 4.0 |
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| Mar 4, 2019 at 7:13 | comment | added | Fedor Petrov | Why do you still call it a guess? The exponential generating function from the answer of Richard Stanley proves it. | |
| Mar 4, 2019 at 6:35 | history | edited | T. Amdeberhan | CC BY-SA 4.0 |
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| Mar 4, 2019 at 5:38 | history | became hot network question | |||
| Mar 4, 2019 at 5:04 | history | edited | T. Amdeberhan | CC BY-SA 4.0 |
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| Mar 4, 2019 at 1:43 | answer | added | Richard Stanley | timeline score: 5 | |
| Mar 4, 2019 at 0:57 | comment | added | Fedor Petrov | If we fix all $n-2k$ diagonal elements, it remains a $2k\times 2k$ squared Pfaffian. It should contain $(2k)!/2^k$ monomials. On purely combinatorial language, the squared Pfaffian monomials correspond to permutations with even cycles only, but we count these permutations up to the change of order of cycles. In other words, we count the spanning subgraphs of $K_{2n}$ in which every component is either an even cycle or an edge. | |
| Mar 3, 2019 at 23:18 | history | asked | T. Amdeberhan | CC BY-SA 4.0 |