scholarly journals On a problem of M. P. Schützenberger

1980 ◽  
Vol 23 (3) ◽  
pp. 243-247 ◽  
Author(s):  
D. B. McAlister

A class of finite semigroups is called a genus if it is closed under homomorphic images, subsemigroups and finite direct products. During a talk at the Symposium on Semigroups held at the University of St Andrews, in 1976, M. P. Schützenberger posed the problem of characterising the smallest genus which contains finite groups and finite semigroups, all of whose subgroups are trivial.

2006 ◽  
Vol 86 (6) ◽  
pp. 481-489 ◽  
Author(s):  
J. N. S. Bidwell ◽  
M. J. Curran ◽  
D. J. McCaughan

2010 ◽  
Vol 95 (3) ◽  
pp. 201-206 ◽  
Author(s):  
Martino Garonzi ◽  
Andrea Lucchini

2008 ◽  
Vol 91 (2) ◽  
pp. 111-121 ◽  
Author(s):  
J. N. S. Bidwell

2012 ◽  
Vol 85 (2) ◽  
pp. 217-231
Author(s):  
CARLO CASOLO ◽  
ELISA MARIA TOMBARI

AbstractWe consider finite groups in which, for all primes p, the p-part of the length of any conjugacy class is trivial or fixed. We obtain a full description in the case in which for each prime divisor p of the order of the group there exists a noncentral conjugacy class of p-power size.


1999 ◽  
Vol 60 (2) ◽  
pp. 177-189 ◽  
Author(s):  
K.W. Gruenberg ◽  
L.G. Kovács

Let G be a finite group, F a free group of finite rank, R the kernel of a homomorphism φ of F onto G, and let [R, F], [R, R] denote mutual commutator subgroups. Conjugation in F yields a G-module structure on R/[R, R] let dg(R/[R, R]) be the number of elements required to generate this module. Define d(R/[R, F]) similarly. By an earlier result of the first author, for a fixed G, the difference dG(R/[R, R]) − d(R/[R, F]) is independent of the choice of F and φ; here it is called the proficiency gap of G. If this gap is 0, then G is said to be proficient. It has been more usual to consider dF(R), the number of elements required to generate R as normal subgroup of F: the group G has been called efficient if F and φ can be chosen so that dF(R) = dG(R/[R, F]). An efficient group is necessarily proficient; but (though usually expressed in different terms) the converse has been an open question for some time.


1997 ◽  
Vol 25 (1) ◽  
pp. 243-246 ◽  
Author(s):  
Joseph Kirtland

2003 ◽  
Vol 02 (02) ◽  
pp. 137-163 ◽  
Author(s):  
J. ALMEIDA ◽  
M. V. VOLKOV

We introduce a series of new polynomially computable implicit operations on the class of all finite semigroups. These new operations enable us to construct a finite pro-identity basis for the pseudovariety [Formula: see text] of all finite semigroups whose subgroups belong to a given finitely based pseudovariety H of finite groups.


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