#9972: Add fan morphisms
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Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.6.1
Component: geometry | Keywords:
Author: Andrey Novoseltsev, Volker Braun | Upstream: N/A
Reviewer: Volker Braun, Andrey Novoseltsev | Merged:
Work_issues: |
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Comment(by vbraun):
In the aforementioned blow-up example, I get now
{{{
sage: f.preimage_cones(f.image_cone(ray))
(2-d cone of Rational polyhedral fan in 2-d lattice N, 2-d cone of
Rational polyhedral fan in 2-d lattice N)
sage: filter(lambda c:f.image_cone(c).is_equivalent(f.image_cone(ray)),
flatten(domain_fan.cones()))
[1-d cone of Rational polyhedral fan in 2-d lattice N, 2-d cone of
Rational polyhedral fan in 2-d lattice N, 2-d cone of Rational polyhedral
fan in 2-d lattice N]
sage: ray in f.preimage_cones(f.image_cone(ray)) # should be True
False
}}}
The `preimage_cones` misses the 1-d cone that maps to (in the fan morphism
sense) the single 2-d cone of the codomain fan.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9972#comment:61>
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