On Fri, Mar 23, 2012 at 01:14:00AM -0700, Frédéric Chapoton wrote:
> Trying to use inversions for elements of Weyl groups, I found that it
> exists, but does not work, and is badly documented and tested. In which
> patch is this located ?
sage: w.inversions??
Tells it is in sage/combinat/root_system/weyl_group.py. By
investigating:
> hg annotate sage/combinat/root_system/weyl_group.py
one finds:
16769: def inversions(self):
16769: """
16769: EXAMPLES:
16769: sage: G = WeylGroup(['A',3])
16769: sage: w = G.from_reduced_word([1,2,1])
16769: sage: w.inversions()
...
(the revision number might vary depending on the version of Sage, ...)
looking in
> hg log sage/combinat/root_system/weyl_group.py
one finds:
changeset: 16769:b178281a23c2
tag: coxeter3-mh.patch
I guess ``self.lattice()`` should be replaced by
``self.parent().lattice().
By the way, it should be possible to generalize this method to
infinite coxeter groups by running only through the set of inversions
and its frontier (in the root poset or something similar; I forgot the
details).
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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