Opened 18 months ago

Last modified 3 months ago

#31241 new enhancement

Forgetful Functors for Manifold Objects — at Version 8

Reported by: gh-mjungmath Owned by:
Priority: major Milestone: sage-9.7
Component: manifolds Keywords:
Cc: tscrim, egourgoulhon, mkoeppe Merged in:
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Report Upstream: N/A Work issues:
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Description (last modified by gh-mjungmath)

It would be nice to allow forgetful functors for manifolds. In particular:

  • differentiable manifolds -> topological manifolds
  • (Pseudo-)Riemannian manifolds -> differentiable manifolds (not a category yet)
  • topological manifolds -> sets (?)

and probably even more. The last point, if getting to work somehow, might also be useful and/or should be seen in view of #30832.

At the moment, we have the following behavior (which could be seen as a bug): 

sage: from sage.categories.functor import ForgetfulFunctor
sage: from sage.categories.manifolds import Manifolds
sage: F = ForgetfulFunctor(Manifolds(RR).Differentiable(), Manifolds(RR).Topological())
sage: M = Manifold(2, 'M')
sage: F(M)
2-dimensional differentiable manifold M

Change History (8)

comment:1 Changed 18 months ago by gh-mjungmath

  • Description modified (diff)

comment:2 Changed 18 months ago by gh-mjungmath

  • Description modified (diff)

comment:3 Changed 18 months ago by gh-mjungmath

  • Description modified (diff)

comment:4 Changed 18 months ago by gh-mjungmath

  • Cc tscrim egourgoulhon mkoeppe added

comment:5 Changed 18 months ago by gh-mjungmath

  • Description modified (diff)

comment:6 Changed 18 months ago by gh-mjungmath

  • Description modified (diff)

comment:7 Changed 18 months ago by gh-mjungmath

  • Summary changed from Forgetful Functors for Manifolds to Forgetful Functors for Manifold Objects

comment:8 Changed 18 months ago by gh-mjungmath

  • Description modified (diff)
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