Orbits of groups generated by transvections over $\FF_2$

Abstract

Let V be a finite dimensional vector space over the two element field. We compute orbits for the linear action of groups generated by transvections with respect to a certain class of bilinear forms on V. In particular, we compute orbits that are in bijection with connected components of real double Bruhat cells in semisimple groups, extending results of M.Gekhtman, B. Shapiro, M. Shapiro, A.Vainshtein and A. Zelevinsky.