Published online by Cambridge University Press: 20 November 2018
Let $M$ be the product of two compact Hamiltonian
$T$-spaces
$X$ and
$Y$. We present a formula for evaluating integrals on the symplectic reduction of
$M$ by the diagonal
$T$ action. At every regular value of the moment map for
$X\,\times \,Y$, the integral is the convolution of two distributions associated to the symplectic reductions of
$X$ by
$T$ and of
$Y$ by
$T$. Several examples illustrate the computational strength of this relationship. We also prove a linear analogue which can be used to find cohomology pairings on toric orbifolds.