INTERMEDIATE SUBGROUPS OF CHEVALLEY GROUPS OVER A FIELD OF FRACTIONS OF A RING OF PRINCIPAL IDEALS

Let K be a field of fractions of a principal ideal ring R and Gk be a Chevalley group (of normal type) over K. For each subring P< K, denote by Gp a subgroup of all elements of GK with coefficients in P. Let M be intermediate between GR and GK, i, e., GR< M < Gk. We prove that M = Gp for some intermediate subring P (R C P C K).