A simple proof of associativity and commutativity of LR-coefficients (or the hive ring)
arXiv:math/0409447
Abstract
We give a simple bijective proof of associativity and commutativity of the Littlewood-Richardson coefficients or the hive ring. Specifically, we establish existence a polarized polymatroidal discretely concave functions on the tetrahedron with given boundary values at two adjoint faces.
18 pages, 9 figures