An infinite cardinal-valued Krull dimension for rings

Abstract

We define and study two generalizations of the Krull dimension for rings, which can assume cardinal number values of arbitrary size. The first, which we call the "cardinal Krull dimension," is the supremum of the cardinalities of chains of prime ideals in the ring. The second, which we call the "strong cardinal Krull dimension," is a slight strengthening of the first. Our main objective is to address the following question: for which cardinal pairs (K,L) does there exist a ring of cardinality K and (strong) cardinal Krull dimension L? Relying on results from the literature, we answer this question completely in the case where K>L or K=L. We also give several constructions, utilizing valuation rings, polynomial rings, and Leavitt path algebras, of rings having cardinality K and (strong) cardinal Krull dimension L>K. The exact values of K and L that occur in this situation depend on set-theoretic assumptions.