#15303: Coercion discovery fails to be transitive
-------------------------------------+-------------------------------------
Reporter: nbruin | Owner:
Type: defect | Status: needs_work
Priority: major | Milestone: sage-5.13
Component: coercion | Resolution:
Keywords: | Merged in:
Authors: Simon King | Reviewers:
Report Upstream: N/A | Work issues: Analyse recursion
Branch: | error
u/SimonKing/ticket/15303 | Commit:
Dependencies: #14711 | 74821fe5409c3104b5d6eb7407a8287d54170df9
| Stopgaps:
-------------------------------------+-------------------------------------
Comment (by SimonKing):
Hi!
First of all, note that the latest recursion errors refer to not-yet-
committed code. It could be that by copy-and-pasting I somehow destroyed
the backtracking algorithm by not properly marking a used arrow as not-to-
be-tested-again. Thus the recursion.
Replying to [comment:46 nbruin]:
> Hm, where does `AtoC.register_as_coercion()` fit in with the "only
initialize coercions upon `__init__` of the parent"?
Both `AtoC.register_as_coercion()` and `A.register_embedding(AtoC)` add an
arrow to the coerce digraph ''after'' initialisation of C. With regard to
the above lemma, one should only cache the absence of a coercion until an
arrow is inserted with a previously existing codomain. Hence, in both
cases we need to increase the cache version number.
--
Ticket URL: <http://trac.sagemath.org/ticket/15303#comment:47>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/groups/opt_out.
