#12544: Switch cones to `PointCollection`
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Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.1
Component: geometry | Resolution:
Keywords: toric | Work issues: output
formatting, base rings
Report Upstream: N/A | Reviewers:
Authors: Andrey Novoseltsev | Merged in:
Dependencies: #11599, #11634, #12541, #12361 | Stopgaps:
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Changes (by novoselt):
* work_issues: output formatting => output formatting, base rings
Comment:
This patch breaks the following code:
{{{
P3 = toric_varieties.P(3)
Sigma3 = P3.fan()
point_rays = [sum(sigma.rays()) for sigma in Sigma3]
BlP3 = P3.resolve(new_rays=point_rays)
K = BlP3.Kaehler_cone()
K._split_ambient_lattice()
}}}
The reason is that the ray matrix is constructed over rational field
(because K lives in the rational divisor class group) and Smith form does
not do what was intended. I am not yet sure what has to be tweaked here.
It seems that creating a cone explicitly in some rational vector space `V`
rather than some sublattice of it is completely reasonable. But it is
still possible to choose ray generators in the sublattice, I guess in
`span(ZZ, V.gens())`?..
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12544#comment:24>
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