Decidable Expansions of Labelled Linear Orderings
Alexis Bes, Alexander Rabinovich · Logical Methods in Computer Science · 2011
Consider a linear ordering equipped with a finite sequence of monadic predicates. If the ordering contains an interval of order type \omega or -\omega, and the monadic second-order theory of the combined structure is decidable, there exists a non-trivial expansion by a further monadic predicate that is still decidable.