#15143: Improvements to SetPartitions
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Reporter: tscrim | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.12
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by darij):
Here is a started review. Before I continue, I'd like you to address some
questions:
- Your {{{__mul__}}} method gives the same result as the existing
{{{inf}}} method, but seems to be faster at arriving there. Better to
reimplement the latter as an alias for the former? If you do so, the
docstrings should probably be merged.
- I don't understand the docstring of {{{ordered_set_partition_action}}},
nor do I understand the definition given in [LM2011] (but I have not
really tried). Maybe you can improve it still? What are {{{A_{i_1}}}},
{{{A_{i_2}}}} etc.?
- I have replaced the docstring and the implementation of {{{is_atomic}}}
to something that matches the definition of "atomic" in the context of
multiplicative generators of NCSym. I hope this is what you really meant.
First, the empty set partition is no longer atomic; second, [[1, 4], [2],
[3]] is now atomic despite max(2) < min(3) because there is a max(1, 4) to
spoil the game.
- I have removed the part about set compositions in the docstring of
{{{__mul__}}} because the method only appears on the SetPartition class.
- I see you have changed the parent of all set partitions to not include
the base set. I am not saying this is wrong; just letting you know that I
cannot fully test the consequences of this change and so my review will be
somewhat incomplete even when it is finished.
--
Ticket URL: <http://trac.sagemath.org/ticket/15143#comment:2>
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