Cross-disciplinary influences
Argumentation theory
Notions such as counterargument and reinstatement have been formally studied (e.g., Vreeswijk, 1991, 1993; Verheij, 1995a, b, c).
Dialectics
Several game-like formalisms have been proposed in which two parties are disputing an issue (e.g., Gordon, 1993a, 1993b, 1995; Brewka, 1994; Hage et al., 1994; Lodder and Herczog, 1995).