On Classes of Regular Languages Related to Monotone WQOs

Abstract

© 2019, IFIP International Federation for Information Processing. We study relationships of monotone well quasiorders to regular languages and ω-languages, concentrating on decidability of the lattices of upper sets on words and infinite words. We establish rather general sufficient conditions for decidability. Applying these conditions to concrete natural monotone WQOs, we obtain new decidability results and new proofs of some known results.