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arXiv · 2006.10087

Positivity among P-partition generating functions

Nathan R. T. Lesnevich·Peter R. W. McNamara
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Abstract

We seek simple conditions on a pair of labeled posets that determine when the difference of their $(P,\omega)$-partition enumerators is $F$-positive, i.e., positive in Gessel's fundamental basis. This is a quasisymmetric analogue of the extensively studied problem of finding conditions on a pair of skew shapes that determine when the difference of their skew Schur functions is Schur-positive. We determine necessary conditions and separate sufficient conditions for $F$-positivity, and show that a broad operation for combining posets preserves positivity properties. We conclude with classes of posets for which we have conditions that are both necessary and sufficient.

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Nathan R. T. Lesnevich, Peter R. W. McNamara. 2020-06-17. Positivity among P-partition generating functions. https://doi.org/10.1007/s00026-021-00563-2

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