ABA_PLUS

ABA+ (Čyras and Toni 2016): flat ABA with preferences between assumptions, sup(Stronger, Weaker), an attack by an argument resting on a weaker assumption reversed (see the extension abaPref). The theory satisfies Weak Contraposition (Axiom 4 of Čyras and Toni), and is refused otherwise: without it, the semantics of ABA+ are those of sets of assumptions, which the arguments do not capture.