L. N. Shevrin posed such an important open problem in the theory of semigroups: Is a semigroup of which the proper subsemigroups are all nilpotent itself nilpotent? It is still an unsolved problem. L. N. Shevrin prove...L. N. Shevrin posed such an important open problem in the theory of semigroups: Is a semigroup of which the proper subsemigroups are all nilpotent itself nilpotent? It is still an unsolved problem. L. N. Shevrin proved that for commutative semigroups the展开更多
文摘L. N. Shevrin posed such an important open problem in the theory of semigroups: Is a semigroup of which the proper subsemigroups are all nilpotent itself nilpotent? It is still an unsolved problem. L. N. Shevrin proved that for commutative semigroups the