Prime exceptional divisors on holomorphic symplectic varieties and monodromy-reflections

Understand

Let X be a projective irreducible holomorphic symplectic manifold.

• The second integral cohomology of X is a lattice with respect to the Beauville-Bogomolov pairing.
• A divisor E on X is called a prime exceptional divisor, if E is reduced and irreducible and of negative Beauville-Bogomolov degree.
• Let E be a prime exceptional divisor on X.