#15959: The hash function of combinatorial free module elements should depend on
the parent
------------------------------+----------------------------
Reporter: nthiery | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-6.2
Component: linear algebra | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
------------------------------+----------------------------
It would be desirable to make the hash value of (combinatorial) free
module elements depend on the hash value of the parent. However this
currently breaks some code (see
e.g. sage.combinat.crystals.kyoto_path_model.KyotoPathModel).
This code indeed assumes, in dictionary look-ups, that an element of
some free module over ZZ and its counter part over QQ (in the case at
hand, the weight lattice and the weight space), comparing as equal
because of a coercion, have the same hash value.
Yet another case of equality using coercion being harmful:
http://wiki.sagemath.org/EqualityCoercion
--
Ticket URL: <http://trac.sagemath.org/ticket/15959>
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/d/optout.
