On Freese’s technique

Abstract

In this paper, we explore some applications of a certain technique (that we call Freese’ technique), which is a tool for identifying certain lattices as sublattices of the congruence lattice of a given algebra. In particular we will give sufficient conditions for two family of lattices (called the rods and the snakes) to be admissible as sublattices of a variety generated by a given algebra, extending an unpublished result of Freese and Lipparini.