This lecture is #5 in a series of 10 lectures:  Given an algebraic symplectic variety X with an action of a torus A preserving the symplectic form one can define, under rather relaxed hypotheses, a collection of maps from the equivariant cohomology of the fixed locus X^A to the equivariant cohomology of X. These maps are indexed by a certain chamber decomposition in the Lie algebra of A and change in an interesting fashion as we cross from one chamber to the next.