On power semigroups of groups
摘要
The monoid of non-empty subsets of a group, with respect to the natural multiplication of subsets, is called the power semigroup of the group. We prove that every semigroup embeds in the power semigroup of a free group, while not every semigroup—even a periodic one—is embeddable in the power semigroup of a periodic group. We provide some necessary and some sufficient conditions for the embeddability in the power semigroup of a periodic group.