Ranks for Families of Theories and Their Spectra

Abstract

We define ranks and degrees for families of theories, similar to Morley rank and degree, as well as Cantor–Bendixson rank and degree, and the notion of totally transcendental family of theories. Bounds for $$e$$ -spectra with respect to ranks and degrees are found. It is shown that the ranks and the degrees are preserved under $$E$$ -closures and values for the ranks and the degrees are characterized. Criteria for totally transcendental families in terms of cardinality of $$E$$ -closure and of the $$e$$ -spectrum value, for a countable language, are proved.