On odd unitary Steinberg group

Abstract

Let $R$ be a ring with pseudo-involution, $\mathfrak L$ be an odd form parameter, $\mathrm U(2n,\,R,\,\mathfrak L)$ be an odd hyperbolic unitary group, $\mathrm{EU}(2n,\,R,\,\mathfrak L)$ be it elementary subgroup and $\mathrm{StU}(2n,\,R,\,\mathfrak L)$ be an odd unitary Steinberg group. We compute the Schur multipliers of $\mathrm{StU}(2n,\,R,\,\mathfrak L)$ and $\mathrm{EU}(R,\,\mathfrak L)$.