Not signed in

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

• Username
• Password
• Remember me

• Sign in using OpenID
• Remember me

• Forgot your password?
• Apply for membership

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 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 internal-categories k-theory lie-theory limits linear linear-algebra locale localization logic mathematics measure measure-theory modal modal-logic model model-category-theory monad monads monoidal monoidal-category-theory morphism motives motivic-cohomology 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

1. • CommentRowNumber1.
   • CommentAuthorChris SchommerPries
   • CommentTimeDec 1st 2015
   • PermaLink
   Author: Chris SchommerPries
   Format: MarkdownItexThere is a very large literature on `classical' 2-category theory largely coming from the Australian Category Theory school. There we have various kinds of weak limits (pseudo limits/bilimits) and, even better, many kinds of weighted colimits. Now we also have the theory of quasicategories and also $(\infty,2)$-categories. The former, at least, has a well established theory of colimits as well. I am wondering what tools we have in the literature to compare these notions? Now obviously there should be a way to take a bicategory and obtain a $(\infty,2)$-category. Also we should be able to take the (2,1) version of a bicategory (all 2-morphisms invertible) and get a quasicategory. Does anyone know how to do this in such a way that it is clear that weak limits in the two situations are preserved? Ideally this would give us models for the adjunction between $(\infty,2)$-categories and (2,2)-categories and between $(\infty,1)$-categories and (2,1)-categories (so then we could also say something about what happens with weak colimits).

   There is a very large literature on ‘classical’ 2-category theory largely coming from the Australian Category Theory school. There we have various kinds of weak limits (pseudo limits/bilimits) and, even better, many kinds of weighted colimits.

   Now we also have the theory of quasicategories and also $(\infty,2)$-categories. The former, at least, has a well established theory of colimits as well.

   I am wondering what tools we have in the literature to compare these notions?

   Now obviously there should be a way to take a bicategory and obtain a $(\infty,2)$-category. Also we should be able to take the (2,1) version of a bicategory (all 2-morphisms invertible) and get a quasicategory. Does anyone know how to do this in such a way that it is clear that weak limits in the two situations are preserved? Ideally this would give us models for the adjunction between $(\infty,2)$-categories and (2,2)-categories and between $(\infty,1)$-categories and (2,1)-categories (so then we could also say something about what happens with weak colimits).

2. • CommentRowNumber2.
   • CommentAuthorZhen Lin
   • CommentTimeDec 1st 2015
   • PermaLink
   Author: Zhen Lin
   Format: MarkdownItexFor (2, 1)-categories it would seem most convenient to go via Kan-enriched categories. Then the problem would be reduced to the equivalence of various definitions of homotopy limits of diagrams of Kan complexes.

   For (2, 1)-categories it would seem most convenient to go via Kan-enriched categories. Then the problem would be reduced to the equivalence of various definitions of homotopy limits of diagrams of Kan complexes.

3. • CommentRowNumber3.
   • CommentAuthorMike Shulman
   • CommentTimeDec 6th 2015
   • PermaLink
   Author: Mike Shulman
   Format: MarkdownItexIn principle, it should follow from the ∞-version of "change of base" adjunctions induced by adjunctions between enriching monoidal categories. The adjunction $\infty Gpd \rightleftarrows 1Gpd$ should induce by "change of base" the adjunction $(\infty,1)Cat \rightleftarrows (2,1)Cat$, and similarly the adjunction $(\infty,1)Cat \rightleftarrows Cat$ should induce $(\infty,2)Cat \rightleftarrows 2Cat$, and there are general facts about limit-preservation under change of base. But I don't know whether this sort of change of base has been done in the ∞-context yet.

   In principle, it should follow from the ∞-version of “change of base” adjunctions induced by adjunctions between enriching monoidal categories. The adjunction $\infty Gpd \rightleftarrows 1Gpd$ should induce by “change of base” the adjunction $(\infty,1)Cat \rightleftarrows (2,1)Cat$, and similarly the adjunction $(\infty,1)Cat \rightleftarrows Cat$ should induce $(\infty,2)Cat \rightleftarrows 2Cat$, and there are general facts about limit-preservation under change of base. But I don’t know whether this sort of change of base has been done in the ∞-context yet.