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D.15.8.3 LRskew
Procedure from library lrcalc.lib (see lrcalc_lib).
- Usage:
- LRskew(z, x [,s, r]); z, x lists of integers (partitions)
s string equal to 'r', r non-negative integer
- Return:
- list of lists
- Purpose:
- computes the partitions y for which the Littlewood-Richardson
coefficient c^z_{x,y} is non-zero together with that coefficient;
only partitions up to length r are computed
if the optional parameters age given
- Note:
Example:
| | LIB "lrcalc.lib";
// Compute the partitions y for which the Littlewood-Richardson coefficient
// c^z_{x,y} is non-zero together with that coefficient
// for z= (3, 2, 1), x=(2, 1)
list z = 3, 2, 1;
list x = 2, 1;
LRskew(z, x);
==> [1]:
==> [1]:
==> 1
==> [2]:
==> [1]:
==> 3
==> [2]:
==> [1]:
==> 2
==> [2]:
==> [1]:
==> 2
==> [2]:
==> 1
==> [3]:
==> [1]:
==> 1
==> [2]:
==> [1]:
==> 1
==> [2]:
==> 1
==> [3]:
==> 1
// Now compute only the partitions with at most 2 entries
LRskew(z, x, "r", 2);
==> [1]:
==> [1]:
==> 1
==> [2]:
==> [1]:
==> 3
==> [2]:
==> [1]:
==> 2
==> [2]:
==> [1]:
==> 2
==> [2]:
==> 1
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