Discrete Mathematics & Theoretical Computer Science (Sep 2021)
The undecidability of joint embedding for 3-dimensional permutation classes
Abstract
As a step towards resolving a question of Ru\v{s}kuc on the decidability of joint embedding for hereditary classes of permutations, which may be viewed as structures in a language of 2 linear orders, we show the corresponding problem is undecidable for hereditary classes of structures in a language of 3 linear orders.
Keywords