Semigroups of high rank II doubly noble semigroups
Emília Giraldes · Proceedings of the Edinburgh Mathematical Society · 1985
This paper is a sequel to [2]. By asemigroup of high rankwe mean a semigroup such that for s1≠s2, 〈S\{s1,s2}〉⊂S(properly). Semigroups of high rank such that 〈S\{s}〉⊂S(royal semigroups) were classified in [2], where it was also shown that for anoble semigroup(i.e. a semigroup of high rank such that there exists a superfluous elementzinSfor which 〈S\{z}〉S) there exists eithere exactly one superfluous element or exactly two superfluous elements [2, Theorem 3.7].