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Jan
12
comment A Converse to Cartan–Hadamard theorem?
Igor, a manifold without conjugate points can have some amount of positive Ricci curvature. There are 2-dimensional examples. The paper you cite claims that it should have negative Ricci curvature somewhere in a certain set.
Jan
12
reviewed Approve trace-formula tag wiki excerpt
Aug
19
awarded  Good Answer
Jul
17
awarded  Popular Question
Jun
24
comment An unfair marriage lemma
@Dominic van der Zypen: Yes we have just finished it. It is on arxiv.org/abs/1506.06781
Jun
24
awarded  Good Answer
Apr
29
comment An unfair marriage lemma
@David: Because we tested it on live analysts. It turns out that the very language of graph theory is not as widely understood as one might hope.
Apr
29
comment An unfair marriage lemma
@bof: I think we are going to thank you in acknowledgements. Do you prefer to be mentioned as an anonym or by some real name?
Apr
24
awarded  Popular Question
Apr
24
accepted An unfair marriage lemma
Apr
24
comment An unfair marriage lemma
Thanks! I tracked it from Mirski & Perfect's paper down to Dulmage & Mendelsohn, Coverings of bipartite graphs, Canad. J. Math. 10 (1958) 517-534, Theorem 1. And there (unlike the other sources) it is exactly it, not something that one has to combine with Hall's Theorem.
Apr
23
comment An unfair marriage lemma
Yes, we have the very same argument. It would be 5 lines long if we were aiming at combinatorialists. But it took more than a page to make the text consumable by analysts.
Apr
23
awarded  Nice Question
Apr
23
comment An unfair marriage lemma
@darij: Yes, of course we will prove it in the paper if there is no reference. It just looks too natural to be unknown.
Apr
23
revised An unfair marriage lemma
fixed language
Apr
23
asked An unfair marriage lemma
Apr
14
awarded  Nice Answer
Mar
6
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Mar
3
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Jan
24
awarded  Popular Question