Timeline for Geometrisation of inclusion-like epimorphisms to free groups
Current License: CC BY-SA 3.0
4 events
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| Feb 9, 2015 at 22:16 | comment | added | HJRW | @FrancoisLaudenbach, I would say that a theorem referred to several times in the literature but with no proof written down is the definition of a folk theorem! Clearly the proof was known to Stallings, anyway. | |
| Feb 8, 2015 at 19:55 | comment | added | Ryan Budney | @FrancoisLaudenbach: Welcome to MO, Francois! | |
| Feb 8, 2015 at 15:49 | comment | added | user66870 | It is a bit more than a folk theorem! The arguments seem similar to those of Stallings' papers on Grushko's theorem and fibration over $S^1$ that I read more than forty years ago. Recently a colleague asked me about the equivalence between Poincaré's conjecture and an algebraic conjecture (conjecture D in "How not to prove..." by Stallings, 1965). There Stallings proved that Conjecture D implies P. IMO, the converse requires Waldhausen's paper on Heegaard splitting of the 3-sphere (1967) and of course, the geometrisation of epimorphisms $\pi_1(S_g)\to F_g$ (not proved in the mentioned paper). | |
| Feb 5, 2015 at 16:30 | history | answered | HJRW | CC BY-SA 3.0 |