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    • CommentRowNumber1.
    • CommentAuthorDavid_Corfield
    • CommentTimeApr 9th 2024

    Put this page into regular format.

    diff, v2, current

    • CommentRowNumber2.
    • CommentAuthorDavid_Corfield
    • CommentTimeApr 9th 2024

    I see that Connes and Consani in the article listed there define a Γ\Gamma-set as a pointed functor from Fin *Fin_{\ast} to Set *Set_{\ast} rather than functors to SetSet as we have here.

    The latter would seem to sit better with Gamma-space.

    • CommentRowNumber3.
    • CommentAuthorDavid_Corfield
    • CommentTimeApr 9th 2024

    I added something on Connes and Consani’s different definition.

    diff, v3, current

    • CommentRowNumber4.
    • CommentAuthorDmitri Pavlov
    • CommentTimeApr 9th 2024

    The category of Γ-sets in this sense is no longer a topos

    Why is it not a topos? Set_* is a slice topos, presheaves valued in a topos again form a topos.

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeApr 9th 2024

    Rather a co-slice, no?

    • CommentRowNumber6.
    • CommentAuthorDmitri Pavlov
    • CommentTimeApr 9th 2024

    Re #5: I confused slice and co-slice, I guess.

    But this does raise a question: what kind of category does the co-slice category of a topos form?

    • CommentRowNumber7.
    • CommentAuthorRodMcGuire
    • CommentTimeApr 10th 2024

    But this does raise a question: what kind of category does the co-slice category of a topos form?

    in this case it is not just a coslice but one from the global point (terminal object) which makes it have a sub object classifier I think. If that is worth anything.

    • CommentRowNumber8.
    • CommentAuthorUrs
    • CommentTimeApr 10th 2024

    There is a comment by Vladimir Sotirov in MO:a/4765697 on pointed sets having a subobject classifier but not being an elementary topos.