Shift spaces, Languages and Transfinite Induction

Abstract

This paper deals with an extension of the classical concept of shift space, which corresponds to any shift-invariant closed subset of the Cartesian product of a particular finite set (alphabet) endowed with the prodiscrete topology. In such an extended framework the notion of language is introduced and a characterization is shown. In order to do this, transfinite induction is required because the cardinality of the index set of the product may not be countable.