Hi Martin, hi Vincent,
On Thu, Mar 15, 2012 at 08:43:47AM +0100, Martin Rubey wrote:
> I was using lrcalc, and noticed that supplying the weight keyword does
> not work, not even the doctest: (this is on sage 4.8)
>
> lrcalc.lrskew([3,2,1], [2], weight=[3,1])
>
> gives "1 not in alphabet".
>
> I found that the problem is that the row_word of a skew tableau expects
> its entries to be from ZZ, while lrcalc uses int's.
>
> If this is not known, how should it be fixed? Should we convert the
> entries of the tableau returned by lrcalc to ZZ's or only when computing
> the row_word?
For the record, this only appears when alphabet-vd.patch is
applied. Without it, the doctest pass (4.8, 5.0):
sage: import sage.libs.lrcalc.lrcalc
sage: sage.libs.lrcalc.lrcalc.lrskew([3,2,1], [2], weight=[3,1])
[[[None, None, 1], [1, 1], [2]]]
That being said, internally, this tableau indeed contains ints:
sage: t = sage.libs.lrcalc.lrcalc.lrskew([3,2,1], [2], weight=[3,1])[0]
sage: type(t[2][0])
<type 'int'>
Whereas the same tableau build from the command line would be filled
with Integers::
sage: t2 = SkewTableau([[None, None, 1], [1, 1], [2]])
sage: type(t2[2][0])
<type 'sage.rings.integer.Integer'>
Well, at least, those two tableaux are equal:
sage: t == t2
True
I let the tableau fans decide whether we want to enforce that all
entries of a (skew) tableau are Integers, and if yes to write a patch
on lrcalc to convert the ints to Integers. We could throw this in the
ticket #12284 which will make lrcalc a standard Sage package.
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <[email protected]>
http://Nicolas.Thiery.name/
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