Monadic representability of certain binary relations
Lloyd Humberstone · Bulletin of the Australian Mathematical Society · 1984
Call a relation R⊆A2 (A some non-empty set) monadically representable when there exist F, G⊆A such that R = {(x, y) | x ∈ F ∘ y ∈ G} for some truth-functional connective ∘. This note finds a first-order condition on R which is necessary and sufficient for R to be monadically representable.