ISSN:
1432-2137
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mathematics
Notes:
S is said to be efficient if it can be defined by a presentation (A | R) with |R| -|A|=rank(H 2(S)). In this paper we demonstrate certain infinite classes of both efficient and inefficient semigroups. Thus, finite abelian groups, dihedral groups D 2 n with n even, and finite rectangular bands are efficient semigroups. By way of contrast we show that finite zero semigroups and free semilattices are never efficient. These results are compared with some well-known results on the efficiency of groups.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002339910016