Abstract: | Let R be a commutative ring with identity in which 2 is invertible. Let H denote a subgroup of the unitary group U(2n,R,Λ) with n≥4. H is normalized by EU(2n,J,ΓJ) for some form ideal (J,ΓJ) of the form ring (R,Λ). The purpose of the paper is to prove that H satisfies a “sandwich” property, i.e. there exists a form ideal (I,ΓI) such that EU(2n,IJ8ΓJ,Γ)⊆H⊆CU(2n,I,ΓI). |