On incomparable abstract family of languages (AFL)

摘要

Given an abstract family of languages (AFL) ℒ the question is considered if there exists an AFL incomparable with ℒ. In case there is an AFL ℒ′ incomparable with ℒ the paper considers if there exists a largest AFL incomparable with ℒ, and if there is a maximal AFL containing ℒ′ incomparable with ℒ. The main results characterize those full AFL ℒ′ having a largest full incomparable AFL ℒ′ and relate properties of ℒ to properties of ℒ′.