Avoiding two cycles in Avoider--Enforcer games

Source abstract

We study the strict and monotone $(1:b)$ Avoider--Enforcer games on the edges of the complete graph $K_n$. We prove that, for integers $n\ge2$ and $b\ge6n$, Avoider can keep his graph a forest after every move, except possibly the last. Thus, his final graph contains at most one cycle. This answers Question~10 of Clemens, Ehrenmüller, Person, and Tran, which asks whether a bias linear in $n$ is sufficient.