Symplectic resolutions, Lefschetz property and formality.

Abstract

We introduce a method to resolve a symplectic orbifold (M, omega) into a smooth symplectic manifold ((M) over tilde,(omega) over tilde). Then we study how the formality and the Lefschetz property of ((M) over tilde,(omega) over tilde) are compared with that of (M, omega). We also study the formality of the symplectic blow-up of (M, omega) along symplectic submanifolds disjoint from the orbifold singularities. This allows us to construct the first example of a simply connected compact symplectic manifold of dimension 8 which satisfies the Lefschetz property but is not formal, therefore giving a counter-example to a conjecture of Babenko and Taimanov.