Correlation functions in massive Landau-Ginzburg orbifolds and tests of dualities

In this paper we discuss correlation function computations in massive topological Landau-Ginzburg orbifolds, extending old results of Vafa. We then apply these computations to provide further tests of the nonabelian mirrors proposal and two-dimensional Hori-Seiberg dualities with $(S)O_{\pm }$ gauge groups and their mirrors.