Abstract (EN):
A *-band is an algebra consisting of a band (idempotent semigroup) on which an involution * is defined satisfying an extra condition; in summary (xy)* = y*x*, x** = x, x = xx*x, (xy)z = x(yz), x2 = x. The lattice of all *-band varieties was determined by Adair who also provided a basis for the identities of each variety. Another system of bases was devised by Petrich. Defining certain operators on the free involutorial semigroup F on a nonempty set X, we construct a system of fully invariant congruences on F which is in bijection with the set of all proper *-band varieties, with the exception of normal *-band varieties which require a different treatment. The proof of this result is based on those evoked above and is broken into a long sequence of lemmas. © 2000 Heldermann Verlag.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica