#12892: Toric fibration morphisms
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Reporter: vbraun | Owner: AlexGhitza
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.3
Component: algebraic geometry | Resolution:
Keywords: sd40.5 | Work issues: comments and rebasing
Report Upstream: N/A | Reviewers: Andrey Novoseltsev
Authors: Volker Braun | Merged in:
Dependencies: #12361, #13023 | Stopgaps:
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Comment (by vbraun):
I (still) think its unwieldy to try to support non-surjective
"fibrations". A fibration is a surjective morphism, otherwise its useless
to describe "fibers" fitting into some familiy parametrized by the base.
Its would be much easier to just raise some error in `fiber_...()` methods
if the morphism is not surjective.
It seems like there is a natural way to factor a morphism into a
surjection and an injection, first map to the image fan and then embed the
image in the codomain. The error raised in the `fiber_...()` methods could
direct the users then to do this.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12892#comment:19>
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