#14107: Expose quantum Littlewood-Richardson coefficients from lrcalc
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Reporter: nthiery | Owner: sage-combinat
Type: enhancement | Status: new
Priority: major | Milestone: sage-5.8
Component: combinatorics | Keywords: days45, lrcalc
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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Beside Littlewood-Richardson coefficient calculations and fusion
products, Anders Buch's lrcalc C library implements quantum products,
using the rim-hook rewriting rule (this corresponds to cup products in
the cohomology of quantum Grassmanian variety). The latter
functionality needs to be exposed in Sage's interface to lrcalc.
Roadmap:
Change mult to accept a "quantum" argument:
{{{
def mult(part1, part2, maxrows=None, level=None, quantum=None):
"""
...
- ``quantum`` -- an element of a ring
...
EXAMPLES::
sage: var('q')
sage: mult([1],[2,1],2,2, quantum=q)
{[2, 2]: 1, []: q}
sage: mult([2,1],[2,1],2,2, quantum=q)
{[2]: q, [1,1]: q}
"""
}}}
If {{{quantum}}} is set, then {{{maxrows}}} and {{{level}}} should be
set. Looking at <lrcalc>src/mult.c one would just need to call the
quantum_reduce function function on the result of lrcalc's
{{{mult_c}}}. The result is a list of hash tables, each giving one
homogeneous pieces of the result w.r.t. {{{q}}}.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14107>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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