Talk:Grinberg's theorem
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9 is nonzero mod 3?[edit]
... unbounded face has nine edges, nonzero mod 3. ?!? Jumpow (talk) 12:14, 3 May 2017 (UTC)
- From the article: "contribute 0 mod 3 to the sum in Grinberg's theorem, because of the factor of k − 2 in the sum". 9 itself may not be nonzero mod 3, but that's not the amount that a 9-face contributes to the sum. 9-2=7 is indeed nonzero mod 3. —David Eppstein (talk) 15:34, 3 May 2017 (UTC)
- Ah, I see now, what I referred to above is in the Formulation section, but there was a typo in the first paragraph of the Applications section claiming that 9 is nonzero mod 3. The actual claim should be that it is unequal to 2 mod 3. Fixed. Thanks for catching this. —David Eppstein (talk) 16:19, 3 May 2017 (UTC)