#17777: unsigned infinity cannot be coerced into SR
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Reporter: rws | Owner:
Type: defect | Status: needs_info
Priority: major | Milestone: sage-7.2
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: Ralf Stephan | Reviewers: Karl-Dieter Crisman,
Report Upstream: N/A | Marc Mezzarobba
Branch: | Work issues:
u/mmezzarobba/17777-infinity_to_SR | Commit:
Dependencies: | 3a3fd027c33f1bab636ac761caf636ce8fe8bfad
| Stopgaps:
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Changes (by mmezzarobba):
* status: needs_review => needs_info
Comment:
Wait: with this change, lots rings would coerce into `SR` both directly
and through `InfinityRing`, with different results. But coercions are
supposed to form a commutative diagram. I understand that both the
infinity ring and the symbolic ring are a bit special, and that, with the
current coercion discovery algorithm, things probably will work fine even
if that assumption is broken... but still, I really don't like the idea of
breaking it if that can be avoided.
Is there really no other way to make infinities and symbolic expression
play well together? For example, what about having `SR` coerce into the
infinity ring (and making the global identifier `infinity` refer to
`SR(infinity)`?) Or, perhaps better, adding an intermediate “symbolic
infinity ring” that would coerce into both `SR` and `InfinityRing`, but
have no ingoing coercions?
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Ticket URL: <http://trac.sagemath.org/ticket/17777#comment:20>
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