 Henry Prakken (Prakken 2010) has expanded Dung’s model by including support as well as attack relations between arguments. Bart Verheij’s DefLog system (Verheij 2003, 2005) makes use of a conditional to represent support and a negation operator to represent attack. Anthony Hunter, Sylwia Polberg, and Matthias Thimm (Hunter et al. 2020) have recently used epistemic graphs to represent both positive and negative interactions among arguments.