J. Haglund ; K. Luoto ; S. Mason ; S. van Willigenburg
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Refinements of the Littlewood-Richardson rule
dmtcs:2744 -
Discrete Mathematics & Theoretical Computer Science,
January 1, 2009,
DMTCS Proceedings vol. AK, 21st International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2009)
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https://doi.org/10.46298/dmtcs.2744
Refinements of the Littlewood-Richardson ruleArticle
Authors: J. Haglund 1; K. Luoto 2; S. Mason 3; S. van Willigenburg 4
We refine the classical Littlewood-Richardson rule in several different settings. We begin with a combinatorial rule for the product of a Demazure atom and a Schur function. Building on this, we also describe the product of a quasisymmetric Schur function and a Schur function as a positive sum of quasisymmetric Schur functions. Finally, we provide a combinatorial formula for the product of a Demazure character and a Schur function as a positive sum of Demazure characters. This last rule implies the classical Littlewood-Richardson rule for the multiplication of two Schur functions.