#15303: Coercion discovery fails to be transitive
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Reporter: nbruin | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-5.13
Component: coercion | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by nbruin):
Replying to [comment:4 SimonKing]:
> Would this really be soooo expensive? I don't think so. Of course, it
depends on how often we create non-sink non-source nodes---and I doubt
that the combined use of `.register_embedding()` and
`.register_coercion()` (which is the only way to create non-sink non-
source) will happen very often.
I don't think you can establish whether something is a non-sink, since
`_coerce_from_map` gives programmatic answers about that. Things are very
rarely going to be non-sinks, though, since usually ZZ will coerce into
them (but ZZ will never be a problem. perhaps we can leave it out of
consideration)
A start might be to only version up on "embedding" creations. That might
very well be usable. I expect "embeddings" to be relatively rare, and I
think we can declare in our documentation they are not the preferred way
of expressing relations (they are vary prone to creating non-commutative
diamonds).
--
Ticket URL: <http://trac.sagemath.org/ticket/15303#comment:5>
Sage <http://www.sagemath.org>
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