An inclusion theorem for defeasible logics

Defeasible reasoning is a computationally simple nonmonotonic reasoning approach that has attracted
significant theoretical and practical attention. It comprises a family of logics that capture
different intuitions, among them ambiguity propagation versus ambiguity blocking, and the adoption or rejection of team defeat. This article provides a compact presentation of the defeasible logic variants, and derives an inclusion theorem which shows that different notions of provability in defeasible logic form a chain of levels of proof.