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Two years ago, Joel Friedman submitted a paper purporting to prove the Hanna Neumann Conjecture, which eventually turned out to contain a fatal bug and was withdrawn. Quite recently, Friedman repeated his attempt at proof with paper "Sheaves on Graphs and a Proof of the Hanna Neumann Conjecture": http://arxiv.org/abs/1105.0129 . Has this attempt been verified by anyone or is still under review?

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Is MO the right place for this kind of discussion? –  Alain Valette Jun 3 '11 at 15:30
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I don't think it is appropriate to discuss such things here, and I believe there was a meta discussion to that effect when people started posting questions about Deolalikar's paper. –  Qiaochu Yuan Jun 3 '11 at 17:44
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My motivation for asking this question is: a) this is not a "high profile" problem as RH, Collatz or P/NP, so unlikely to attract much attention on blogs etc. (= hard to know, for me, what the community thinks of it), b) the technology used in the proof seems quite nonstandard, maybe someone knowledgeable could e.g. put this in wider context, previous proof attempts, whether this has any heuristic chance of succeeding etc –  Marcin Kotowski Jun 3 '11 at 18:45
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For those who is interested in the Hannah Neumann conjecture, both Friedman and Mineyev are going to participate in a Banff workshop birs.ca/events/2011/5-day-workshops/11w5141 in June, and Mineyev is going to participate in the AIM workshop aimath.org/ARCC/workshops/l2invfggroups.html in September. I am co-organizing the AIM workshop and Miklos Abert is co-organizing both. So if not by the end of June, then by the end of September, we will know at least if Mineyev's (shorter) proof is correct. –  Mark Sapir Jun 6 '11 at 5:50
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closed as off topic by Gerald Edgar, Qiaochu Yuan, Noah Snyder, Kevin Buzzard, Mark Sapir Jun 5 '11 at 12:08

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1 Answer

I don't think that this latest round has been independently verified.

Igor Mineyev has also announced a solution. See http://www.math.uiuc.edu/~mineyev/math/

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