#9934: Toric divisor class -> divisor lift should be integral
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Reporter: vbraun | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-4.6
Component: algebraic geometry | Keywords:
Author: Volker Braun | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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An integral divisor class should lift to an integral divisor. But:
{{{
sage: rays = [(1, 0, 0), (-1, 0, 0), (0, 1, 0), (0, 0, 1), (2, -1, -1)]
sage: cones = [(0, 2, 3), (0, 2, 4), (0, 3, 4), (1, 2, 3), (1, 2, 4), (1,
3, 4)]
sage: X = ToricVariety(Fan(cones=cones, rays=rays))
sage: X.rational_class_group().gen(1).lift()
-1/2*V(z0) + 1/2*V(z1)
}}}
The attached patch fixes this and any doctest fallout.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9934>
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