Hypersubstitutions and Colored Trees
by
Slavcho Shtrakov
South-West University, Blagoevgrad

Hypersubstitutions are homomorphisms between the sets of terms (trees) fully determined by their images of the set of operation symbols, considered as terms.

Multi hypersubstitutions work over so called n-colored trees in an analogous way. They are introduced and studied in two Ms. Theses of my students in 1999.

The discussion in the present paper is when a such multi hypersubstitution is an one-to-one mapping on the set of terms of a given type. The concept of expansible and contracting hypersubstitution is considered, too.

Date received: July 27, 2001