#14772: Remove CombinatorialClass from Permutations
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Reporter: tscrim | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.11
Component: combinatorics | Resolution:
Keywords: days49 | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Dependencies: #8386 #14519 #14808
Stopgaps: |
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Comment (by tscrim):
`Permutations` is suppose to be a common abstract base class for all
permutations (in some way it models the category of all types of
permutations), so having permutations of length k inherit from it makes
sense. However I think we need to implement a stronger `__contains__()`
for the non-standard permutations, perhaps a stupid `return x in
list(self)` (which, somewhat surprisingly to me, the category of
`FiniteEnumeratedSets` does not provide by default).
Also, to fix the backtracker issue, what needs to be done is some simple
corner case checking in the `__iter__` methods for `n == 0`. Only if `n >
0` do you call `PatternAvoider`.
Best,[[BR]]
Travis
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Ticket URL: <http://trac.sagemath.org/ticket/14772#comment:37>
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