#9972: Add toric lattice morphisms
-------------------------------------+--------------------------------------
Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.6
Component: geometry | Keywords:
Author: Andrey Novoseltsev | Upstream: N/A
Reviewer: Volker Braun | Merged:
Work_issues: switch to FanMorphism |
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Comment(by novoselt):
Some more thoughts:
1. When there is an attempt to check if a point is in the fan, should we
try to interpret this point as a ray, i.e. 1-d cone?
2. The last line of `_contains` should be replaced with the original
version:
{{{
try:
return data.is_equivalent(self.cone_containing(data.rays()))
except ValueError: # No cone containing all these rays
return False
}}}
For example, if you take a fan which is a subdivision of a cone, then
this cone will trickle down to this block, but `cone_containing` will
raise an exception. There probably should be a test for such a situation
(although I certainly don't claim that all other places test all possible
exceptions...)
3. `Fan.contains` should no longer accept many arguments after your
change - let's replace `*arg` with `cone`.
4. Typo: "or a something" should be without "a".
5. Typo: "class associated to cones" should be "classes".
Otherwise looks great: the new approach allows users to create their own
shortcuts and write `HH(cone)` instead of `cone.cohomology_class()`. While
I like names exposed in Sage to be descriptive, I certainly don't want to
force users do it in their code ;-)
I will base other patches of the ticket on top of this one.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9972#comment:15>
Sage <http://www.sagemath.org>
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