#8549: Implements cycle index for permutation groups, toward Polya enumeration
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Reporter: nborie | Owner: nborie
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.4.3
Component: combinatorics | Keywords: permutation
groups, cycle index, Polya enumeration
Author: Nicolas Borie, Nicolas M. Thiéry | Upstream: N/A
Reviewer: Nicolas M. Thiéry, Nicolas Borie | Merged:
Work_issues: |
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Comment(by rbeezer):
Nicolas(s),
This is a nice addition, and I can already think of a use for it in a
classroom example.
Some small comments/suggestions:
1. One small bit of language, in
{{{
Here are the cycle index of some permutation groups
}}}
I would write the plural as "cycle indices." Nicely written otherwise.
2. Would there be some way to qualify a value for the parent keyword as
being legitimate? For example, with {{{D=DihedralGroup(7)}}},
{{{14*D.cycle_index(parent=QQ)}}} goes boom. It doesn't seem that there
is a simple type to test on (but maybe I'm wrong on this), but it does
look like parent need only implement term() and sum(). Would it work to
put something like {{{parent.term(Partition([1]), 1)}}} in a try/except
block?
3. Documentation.
(a) Do you want to add this into the reference manual?[[BR]]
(b) Last doctest block needs a preceding "::" to make it render as
verbatim.[[BR]]
(c) Two instances of "cycle_type" near the top print weird due to the
underscore.[[BR]]
Important stuff: builds and passes long tests, works as advertised. So
I'm ready to give this a positive review subject to the above minor items.
Rob
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8549#comment:9>
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