#15347: yamanouchi.py: what is it for?
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Reporter: darij | Owner:
Type: defect | Status: new
Priority: minor | Milestone: sage-5.13
Component: combinatorics | Resolution:
Keywords: yamanouchi, dyck words, | Merged in:
littlewood-richardson, combinat | Reviewers:
Authors: | Work issues:
Report Upstream: N/A | Commit:
Branch: | Stopgaps:
Dependencies: |
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Description changed by darij:
Old description:
> Here is the *whole* content of `sage/combinat/yamanouchi.py`:
> {{{
> r"""
> Yamanouchi Words
>
> A right (respectively left) Yamanouchi word on a completely ordered
> alphabet, for instance [1,2,...,n], is a word math such that any
> right (respectively left) factor of math contains more entries math
> than math. For example, the word [2, 3, 2, 2, 1, 3, 1, 2, 1, 1] is
> a right Yamanouchi one.
>
> The evaluation of a word math encodes the number of occurrences of
> each letter of math. In the case of Yamanouchi words, the
> evaluation is a partition. For example, the word [2, 3, 2, 2, 1, 3,
> 1, 2, 1, 1] has evaluation [4, 4, 2].
>
> Yamanouchi words can be useful in the computation of
> Littlewood-Richardson coefficients `c_{\lambda, \mu}^\nu`.
> According to the Littlewood-Richardson
> rule, `c_{\lambda, \mu}^\nu` is the number of skew tableaux
> of shape `\nu / \lambda` and evaluation `\mu`,
> whose row readings are Yamanouchi words.
> """
> }}}
> The "math" looks like the text has been copypasted from some website;
> this is embarassing... Is anyone working on the file?
New description:
Here is the *whole* content of `sage/combinat/yamanouchi.py`:
{{{
r"""
Yamanouchi Words
A right (respectively left) Yamanouchi word on a completely ordered
alphabet, for instance [1,2,...,n], is a word math such that any
right (respectively left) factor of math contains more entries math
than math. For example, the word [2, 3, 2, 2, 1, 3, 1, 2, 1, 1] is
a right Yamanouchi one.
The evaluation of a word math encodes the number of occurrences of
each letter of math. In the case of Yamanouchi words, the
evaluation is a partition. For example, the word [2, 3, 2, 2, 1, 3,
1, 2, 1, 1] has evaluation [4, 4, 2].
Yamanouchi words can be useful in the computation of
Littlewood-Richardson coefficients `c_{\lambda, \mu}^\nu`.
According to the Littlewood-Richardson
rule, `c_{\lambda, \mu}^\nu` is the number of skew tableaux
of shape `\nu / \lambda` and evaluation `\mu`,
whose row readings are Yamanouchi words.
"""
}}}
The "math" looks like the text has been copypasted from some website; this
is embarassing... Is anyone working on the file?\\
(Also, "tableaux" should be "semistandard tableaux" and more stuff should
be changed if we are ever to work from this stub...)
--
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Ticket URL: <http://trac.sagemath.org/ticket/15347#comment:1>
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