Abstract (EN):
Given a basis of pseudoidentities for a pseudovariety of ordered semigroups containing the 5-element aperiodic Brandt semigroup B-2, under the natural order, it is shown that the same basis, over the most general graph over which it can be read, defines the global. This is used to show that the global of the pseudovariety of level 3/2 of Straubing-Therien's concatenation hierarchy has infinite vertex rank.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica