Lagrangian fibration structure on the cotangent bundle of a del Pezzo surface of degree 4

Abstract

In this paper, we show that there is a natural Lagrangian fibration structure on the map $\Phi$ from the cotangent bundle of a del Pezzo surface $X$ of degree 4 to ${\mathbb{C}}^2$. Moreover, we describe explicitly all level surfaces of the above natural map $\Phi$.

24 pages; Remark 2.8 is modified and references are added