The Hamilton space of pseudorandom graphs

Abstract

We show that if n is odd and $p\ge C\log n/n$, then with high probability Hamilton cycles in $G(n,p)$ span its cycle space. More generally, we show this holds for a class of graphs satisfying certain natural pseudorandom properties. The proof is based on a novel idea of parity-switchers, which can be thought of as analogues of absorbers in the context of cycle spaces. As another application of our method, we show that Hamilton cycles in a near-Dirac graph G, that is, a graph G with odd n vertices and minimum degree $n/2+C$ for sufficiently large constant C, span its cycle space.