F-invariant and E-invariant

Abstract

$F$-invariant for a pair of good elements (e.g. cluster monomials) in cluster algebras is introduced by the author in a previous work. A key feature of $F$-invariant is that it is a coordinate-free invariant, that is, it is mutation invariant under the initial seed mutations. $E$-invariant for a pair of decorated representations of quivers with potentials is introduced by Derksen, Weyman and Zelevinsky, which is also a coordinate-free invariant. The strategies used to show the mutation-invariance of $F$-invariant and $E$-invariant are totally different. In this paper, we give a new proof of the mutation-invariance of $F$-invariant following the strategy used by Derksen, Weyman and Zelevinsky. As a result, we prove that $F$-invariant coincides with $E$-invariant on cluster monomials. We also give a proof of Reading's conjecture, which says that the non-compatible cluster variables in cluster algebras can be separated by the sign-coherence of $g$-vectors.

11 pages