TITLE: Tutte's conjecture on Petersen graphs
QUESTION [16 upvotes]: I'm trying to find out whether Tutte's conjecture (that every snark has the Petersen graph as a minor) has been satisfactorily proved. Wikipedia claims that Robertson, Saunders, Seymour and Thomas announced a proof but that it has not been published. Indeed, I cannot find a published paper which confirms the proof of the theorem.
Does anyone know what the status of this conjecture and proof are?
Thanks!

REPLY [5 votes]: I think this is considered proved at this point. A list of relevant papers can be found at http://people.math.gatech.edu/~thomas/FC/generalize.html. 
In this paper, the conjecture is reduced to proving it for two classes of graphs- apex and doublecross. The doublecross case has been published. I'm not sure if the apex paper has been published yet.
Note that the proof does indeed make use of a computer program that is no less complex than the one Robertson et al. used for their proof of the four-colour theorem. To my knowledge there is no accepted proof of 4CT that isn't computer assisted.