[sage-combinat-devel] promotion operator

2011-03-22 Thread Anne Schilling

Hi again!

Is the promotion operator on arbitrary tableaux already in sage?
I think I once implemented the promotion operator on rectangular tableaux as

sage: t = Tableau([[1,2],[2,3]])
sage: t.promotion(2)
[[1, 2], [3, 3]]
sage: t
[[1, 2], [2, 3]]

There is also a strange promotion_operator which seems to add boxes to a 
tableau,
but there is no explanation what it does. Perhaps it is a misnomer?

def promotion_operator(self, i):

EXAMPLES::

sage: t = Tableau([[1,2],[3]])
sage: t.promotion_operator(1)
[[[1, 2], [3], [4]], [[1, 2], [3, 4]], [[1, 2, 4], [3]]]
sage: t.promotion_operator(2)
[[[1, 1], [2, 3], [4]],
 [[1, 1, 2], [3], [4]],
 [[1, 1, 4], [2, 3]],
 [[1, 1, 2, 4], [3]]]
sage: Tableau([[1]]).promotion_operator(2)
[[[1, 1], [2]], [[1, 1, 2]]]
sage: Tableau([[1,1],[2]]).promotion_operator(3)
[[[1, 1, 1], [2, 2], [3]],
 [[1, 1, 1, 2], [2], [3]],
 [[1, 1, 1, 3], [2, 2]],
 [[1, 1, 1, 2, 3], [2]]]

TESTS::

sage: Tableau([]).promotion_operator(2)
[[[1, 1]]]
sage: Tableau([]).promotion_operator(1)
[[[1]]]

Best,

Anne

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Re: [sage-combinat-devel] promotion operator

2011-03-22 Thread Anne Schilling

There is also a strange promotion_operator which seems to add boxes to a
tableau,
but there is no explanation what it does. Perhaps it is a misnomer?


This is part of the combinatorial definition of k-Schur functions. I
believe what it does is add a horizontal i-strip in all possible ways,
and then uses the symmetric group action on each of the resulting
tableaux so that they all have partition weight. I do not know why it is
called promotion.


Yes, this is a misnomer!

Best,

Anne

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