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• CommentRowNumber1.
• CommentAuthorUrs
• CommentTimeOct 28th 2010

I tried to brush-up the entry fundamental infinity-groupoid which had been in a rather sorry state. Some things I did:

• stated the definition (!) $Sing X$

• removed Ronnie’s remark that there is a problem with this definition due to lack of chosen fillers and instead added Thomas Nikolaus’s theorem that when you choose fillers to get an algebraic Kan complex $\Pi X$ there is (still) a direct proof of the homotopy hypothesis

• made the statement that $Sing X$ is equivalently computed by the abstract $\infty$-topos-theoretic definition of fundamental $\infty$-groupoid a formal proposition.

• CommentRowNumber2.
• CommentAuthorMike Shulman
• CommentTimeOct 28th 2010

That looks good. I added a comment before the definition to the effect that we’re choosing Kan complexes as a notion of $\infty$-groupoid in order to make that definition.