#18175: Implement categories for topological and metric spaces and related
categories
-------------------------------------+-------------------------------------
       Reporter:  tscrim             |        Owner:  tscrim
           Type:  enhancement        |       Status:  new
       Priority:  major              |    Milestone:  sage-6.8
      Component:  categories         |   Resolution:
       Keywords:  geometry,          |    Merged in:
  topology, sd67                     |    Reviewers:
        Authors:  Travis Scrimshaw   |  Work issues:
Report Upstream:  N/A                |       Commit:
         Branch:                     |  95a30aa57fc62f23a884790b57835d107d8bdeef
  public/categories/topological_metric_spaces-18175|     Stopgaps:
   Dependencies:  #18174 #17160      |
-------------------------------------+-------------------------------------

Comment (by egourgoulhon):

 Hi Basile,

 Replying to [comment:29 bpillet]:
 >
 >
 > As I said, there are case for some fields '''K''' where '''K'''-analytic
 is weaker than expected : For example I can make a change of charts x -->
 x^p^ over F_p which is actually invertible since x^p^ is the identity on
 F_p but when computing its differential it vanishes identically since
 px^p-1^ = 0 in caracteristic p.

 Thanks for this example!

 > In my opinion (which is strongly disputable as I don't have a very wide
 knowledge of the existing theories) differential geometry is meant for
 '''R''' and '''C''' (or maybe in extremal cases over p-adic fields) but
 over other field the right way of doing geometry is through algebraic
 geometry : Manifolds or varieties are no longer given by charts but by
 equations.

 Yes, you are right, for differentiable manifolds, we should probably limit
 ourselves to '''K'''='''C''' or '''K'''='''R''' (at least in a first
 stage). In the refactoring of !SageManifolds I am preparing for #18528, I
 leave the base field generic anyway. In the documentation of class
 `TopManifold` in #18529, you can see already an example with
 '''K'''='''C''' (the Riemann sphere as a topological manifold of dimension
 1 over '''C''').

--
Ticket URL: <http://trac.sagemath.org/ticket/18175#comment:30>
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