#11599: Wrap fan moriphism in toric morphism
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Reporter: vbraun | Owner: AlexGhitza
Type: enhancement | Status: new
Priority: major | Milestone: sage-4.7.2
Component: algebraic geometry | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by vbraun):
Thanks for pointing out the reference. Its fairly obvious that one has to
use roots to write the maps but still its good to see that somebody worked
out all the details. Though from a quick browse it seems like they don't
elaborate on the relation with fan morphisms. E.g. the embedding of the
obit closure can be written as a polynomial map in homogeneous coordinates
but is not a toric morphism (given by a fan morphism).
My plan is to implement maps by homogeneous coordinate polynomials and
maps by fan morphisms separately, with conversion methods from one to the
other if it exists.
Eventually we should also have maps involving roots. I'm not sure how we
should implement them; Just using symbolic ring variables would be simple
but not play nice with compositions. At one point it would be good to
write our own "Homogeneous coordinate ring" class that knows about the
homogeneous rescalings. This would then allow for fractional powers in
some nicer way. But I'll leave it for another ticket ;)
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11599#comment:3>
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