Terms and semiterms
The class of algebras in which weak independence is equivalent to direct sums independence
The free one-generated left distributive algebra: basics and a simplified proof of the division algorithm
The left distributive law is the law a· (b· c) = (a·b) · (a· c). Left distributive algebras have been classically used in the study of knots and braids, and more recently free left distributive algebras have been studied in connection with large cardinal axioms in set theory. We provide a survey of results on the free left distributive algebra on one generator, A, and a new, simplified proof of the existence of a normal form for terms in A. Topics included are: the confluence of A, the linearity...
The ordering of commutative terms
By a commutative term we mean an element of the free commutative groupoid of infinite rank. For two commutative terms , write if contains a subterm that is a substitution instance of . With respect to this relation, is a quasiordered set which becomes an ordered set after the appropriate factorization. We study definability in this ordered set. Among other things, we prove that every commutative term (or its block in the factor) is a definable element. Consequently, the ordered set has...
The order-sum in classes of partially ordered algebras.
The refinement of two isomorphic generalized lexicographic products
The variety generated by tournaments
Three-variable equations of posets
We find an independent base for three-variable equations of posets.
Two enumeration principles for free algebras