Not signed in (Sign In)

Not signed in

Want to take part in these discussions? Sign in if you have an account, or apply for one below

  • Sign in using OpenID

Site Tag Cloud

2-category 2-category-theory abelian-categories adjoint algebra algebraic algebraic-geometry algebraic-topology analysis analytic-geometry arithmetic arithmetic-geometry book bundles calculus categorical categories category category-theory chern-weil-theory cohesion cohesive-homotopy-type-theory cohomology colimits combinatorics complex complex-geometry computable-mathematics computer-science constructive cosmology definitions deformation-theory descent diagrams differential differential-cohomology differential-equations differential-geometry digraphs duality elliptic-cohomology enriched fibration foundation foundations functional-analysis functor gauge-theory gebra geometric-quantization geometry graph graphs gravity grothendieck group group-theory harmonic-analysis higher higher-algebra higher-category-theory higher-differential-geometry higher-geometry higher-lie-theory higher-topos-theory homological homological-algebra homotopy homotopy-theory homotopy-type-theory index-theory integration integration-theory k-theory lie-theory limits linear linear-algebra locale localization logic mathematics measure-theory modal modal-logic model model-category-theory monad monads monoidal monoidal-category-theory morphism motives motivic-cohomology nforum nlab noncommutative noncommutative-geometry number-theory of operads operator operator-algebra order-theory pages pasting philosophy physics pro-object probability probability-theory quantization quantum quantum-field quantum-field-theory quantum-mechanics quantum-physics quantum-theory question representation representation-theory riemannian-geometry scheme schemes set set-theory sheaf simplicial space spin-geometry stable-homotopy-theory stack string string-theory superalgebra supergeometry svg symplectic-geometry synthetic-differential-geometry terminology theory topology topos topos-theory tqft type type-theory universal variational-calculus

Vanilla 1.1.10 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to nForum
If you want to take part in these discussions either sign in now (if you have an account), apply for one now (if you don't).
    • CommentRowNumber1.
    • CommentAuthorAndrew Stacey
    • CommentTimeAug 3rd 2010

    From what I’ve absorbed about functor categories and size issues, it seems that (perhaps with a suitable choice axiom), the category of functors between two fixed categories is only guaranteed to be locally small if the source category is essentially small.

    If true, I feel it should be noted somewhere. If false, ditto since it’s a fairly obvious conclusion to draw. Unfortunately, I couldn’t find this anywhere on the nLab. I looked at small category, locally small category, functor category, and even at cat.

    I’m quite happy to put it in - indeed, by Urs’ Law then it’s my job to do so - but I’d like confirmation that it is a correct statement before doing so.

    • CommentRowNumber2.
    • CommentAuthorTobyBartels
    • CommentTimeAug 3rd 2010

    I added a bit on size issues to functor category.

    • CommentRowNumber3.
    • CommentAuthorAndrew Stacey
    • CommentTimeAug 3rd 2010

    Thanks! I knew someone else would be able to do it better than me: what you wrote is what I meant to say in my first post in this discussion but I missed off a few “locally small”s.

    • CommentRowNumber4.
    • CommentAuthorMike Shulman
    • CommentTimeAug 3rd 2010

    I added a partial converse to the last statement at functor category.

    • CommentRowNumber5.
    • CommentAuthorTobyBartels
    • CommentTimeAug 3rd 2010

    That’s a great converse! I have commented on it in another thread.

    • CommentRowNumber6.
    • CommentAuthorzskoda
    • CommentTimeAug 9th 2010

    Well, the relevant among the old entries is small presheaf.