surface SS and η η be a meromorphic two-form on SS satisfying f^* η= δ η f∗ η= δ η for
some δ ∈ C^* δ∈ C∗. We show that under a mild topological assumption on ff, there is a
birational change of domain ψ: X\dashrightarrow S ψ: X⤏ S such that ψ^* η ψ∗ η has no
zeros. In this context, we investigate the notion of algebraic stability for ff, proving that ff can
be made algebraically stable if and only if it acts nicely on the poles of η η. We illustrate this …