Two Formulas for -Polynomials
arXiv:2112.11839 · doi:10.1093/imrn/rnad074
Abstract
We discuss a product formula for -polynomials in cluster algebras, and provide two proofs. One proof is inductive and uses only the mutation rule for -polynomials. The other is based on the Fock-Goncharov decomposition of mutations. We conclude by expanding this product formula as a sum and illustrate applications. This expansion provides an explicit combinatorial computation of -polynomials in a given seed that depends only on the -vectors and -vectors along a finite sequence of mutations from the initial seed to the given seed.