#12930: Poset of Alternating sign matrices
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Reporter: aschilling | Owner:
sage-combinat
Type: enhancement | Status:
needs_review
Priority: major | Milestone:
sage-5.1
Component: combinatorics | Resolution:
Keywords: alternating sign matrices, posets, days38 | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Frédéric Chapoton | Merged in:
Dependencies: | Stopgaps:
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Comment (by PierreCagne):
Sorry for the delay, I didn't have the time lately.
But as Anne said, I implemented it (with the help of Luis Serrano) and I
used the occasion to do some cleaning in the file
alternating_sign_matrix.py.
In fact, there was some obsolete uses (like CombinatorialClass) that I
changed. I settled a factory pattern based on classes instead of functions
to allow some 'isinstance'. An other issue was the lack of documentation
about contre-tableaux : except Sage's documentation, I was unable to find
anything about them, even a definition ! So this new implementation uses
monotone triangles, that are pretty well referenced on the web. I kept the
default definition through contre-tableaux, but consider it obsolete and
recommend to work with monotone triangles (by putting the keyword
'use_monotone_triangles' as True when declaring the object, see
documentation).
To get the lattice, just use the 'lattice' method of your object of type
AlternatingSignMatrices or MonotoneTriangles. (I got round the non-
hashability of the lists for the monotone triangles by making them
tuples.)
Regards.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12930#comment:4>
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