#13183: Implement index(cone) for fan morphisms
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Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: new
Priority: major | Milestone: sage-5.2
Component: geometry | Resolution:
Keywords: toric | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Andrey Novoseltsev | Merged in:
Dependencies: | Stopgaps:
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Comment (by vbraun):
How about `fiber_index()` to distinguish it from the already existing
index method?
The point of `_split_ambient_lattice` was that you only had to compute the
Smith normal form once for the cone. Why not make use of cached data?
The index is always finite according to p.464.
If there is no preimage cone, I would also be fine with returning 0
instead of `None` in accord with counting fiber connected components.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13183#comment:2>
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