DR-irreducibility of monounary algebras
by
Danica Jakubíková-Studenovská
Dept. of Geom. and Algebra, Safarik University, Jesenná 5, Kosice, SK--041 54, Slovakia

For an algebra A let R(A) be the class of all algebras which are isomorphic to a retract of A. Next, A is said to be irreducible in the sense of Duffus and Rival (DR-irreducible) if, whenever A in R(\prod_{i in I} B_i) and B_i in R(A) for each i in I, then there is j in I such that A in R(B_j). We describe all connected monounary algebras which are DR-irreducible.

Date received: May 24, 2000