摘要
In this paper, we discuss the groups and semigroups of D<MK> operators, where D<MK> indicates either D<MK>（R2） or D<MK> （R）. As a special case, we also consider the semigroups of generalized scalar operators and those of scalar operators. One of the main conditions given in A. R. Sourour’s and E. Berkson’s papers has been omitted.
