Linkage principle for ortho-symplectic supergroups

The purpose of the paper is to derive linkage principle for modular representations of ortho-symplectic supergroups. We follow the approach of Doty and investigate in detail the representation theory of the ortho-symplectic group SpO(2|1) and that of its Frobenius thickening. Using the description of flags and adjacent Borel supersubgroups we derive first the strong linkage for the Frobenius thickening G_rT of the ortho-symplectic supergroup G of type SpO(2m|2n+1) and SpO(2m|2n). Based on this, we derive the linkage principle for ortho-symplectic supergroups SpO(2m|2n+1) and SpO(2m|2n).