On logically defined recognizable tree languages

Abstract

We provide an algebraic characterization of the expressive power of various naturally defined logics on finite trees. These logics are described in terms of Lindström quantifiers, and particular cases include first-order logic and modular logic. The algebraic characterization we give is expressed in terms of a new algebraic structure, finitary preclones, and uses a generalization of the block product operation. © Springer-Verlag Berlin Heidelberg 2003.