#11200: Add fibration check to FanMorphism
----------------------------+-----------------------------------------------
Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-4.7.1
Component: geometry | Keywords: toric
Work_issues: | Upstream: N/A
Reviewer: Volker Braun | Author: Andrey Novoseltsev
Merged: | Dependencies: #10140, #10882
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Comment(by vbraun):
Since our naming theme is to use `method()` for the inherited method on
vector spaces and `method_fan()` for the induced function of the fan, how
about `restrict_domain_fan()` and `restrict_codomain_fan()`. The
restriction to the image would then be
{{{
phi.restrict_codomain_fan( phi.image_fan() )
}}}
For the restriction of the vector space map you have to use this
construction as well, I think; as far as I can tell there is no method
that restricts to the image in one go.
Also, I don't think `image_fan()` is overly confusing. After all, the fan
is a collection of cones over `\QQ`.
For injectivity you need to check that the index of each domain cone is
one (Def 2.1.7 in HLY). Are you going to override the
`FanMorphism.index()` method? I would have thought that this is a logical
place to put this functionality.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11200#comment:9>
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