#19055: Tableau hash depends on subclass
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Reporter: darij | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.9
Component: combinatorics | Resolution:
Keywords: tableaux, hashing | Merged in:
Authors: Darij Grinberg | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/combinat/tableau_hash | 27788705a3241374377904895b341c9c504605df
Dependencies: | Stopgaps:
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Comment (by tscrim):
I recall Nicolas telling me that having equality and the hash dependent on
the parent was the goal in order to better conform to the hash
requirement. However, this means we have to be much more careful about our
return types. Plus it might be surprising for a user, say, a combinatorics
student using Sage for a class.
Here's a possible approach I just thought of. We put a private attribute
in the parent class that points to a particular class, and we use it to
compare equality and the hash of that class in the element's `__hash__`.
So it would preserve some information about the parent, but it would be
controllable. So we could still have, e.g., tableaux and semistandard
tableaux compare as equal, but have a be different than GT patterns. A
variant of this would be to make it a method, so once can return instances
of the parent class if necessary. Thoughts?
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Ticket URL: <http://trac.sagemath.org/ticket/19055#comment:6>
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