A step towards the cluster positivity conjecture
arXiv:1103.2726
Abstract
We prove a conjecture of Kontsevich, which asserts that the iterations of the noncommutative rational map are given by noncommutative Laurent polynomials with nonnegative integer coefficients.
Comments welcome, v2:16 pages. introduction expanded. section 4 added in order to compare with the known formula when r=2. references added. thank you list added. definitions clarified. This paper is superseded by a joint paper with Ralf Schiffler (http://arxiv.org/abs/1109.5130)