On proper accretive extensions of positive linear relations

A linear relation S is called a proper extension of a symmetric linear relation S if S S S^*. As is well known, an arbitrary dissipative extension of a symmetric linear relation is proper. In the present paper, we establish criteria for an accretive extension of a given positive symmetric linear relation to be proper.Published in Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 6, pp. 723–730, June, 1995.