#12943: Tableau_class.__div__, Partition_class.__div__ are checking domination
when they should check inclusion
-----------------------------+----------------------------------------------
Reporter: hthomas | Owner: sage-combinat
Type: defect | Status: new
Priority: major | Milestone: sage-5.1
Component: combinatorics | Keywords: tableau
Work issues: | Report Upstream: N/A
Reviewers: | Authors: Hugh Thomas
Merged in: | Dependencies:
Stopgaps: |
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If rho and mu are partitions, rho/mu is supposed to return the skew
partition rho/mu. It tries to check that mu is of the right shape for it
to be able to do this, but it does this check using the dominates()
method, which tests dominance order not inclusion order. This is not so
serious, in that if rho contains mu, then it does also dominate mu, so it
will always let correct calculations go through. The error is then caught
by SkewPartition, which realizes it's been handed invalid data. So this
is not actually so bad.
However, the same thing happens when T is a tableau and you calculate
T/mu, and there, it causes a "list index out of range".
{{{
sage: rho = Partition((3,2,1))
sage: mu = Partition((2,1,1,1))
sage: rho/mu
ValueError: invalid skew partition: [[3, 2, 1], [2, 1, 1, 1]]
sage: t=Tableau([[1,2,3],[4,5],[6]])
sage: t/mu
IndexError: list index out of range
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12943>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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