Fundamental Lemma

A semantics σ\sigma satisfies the Fundamental Lemma iff E∈σ(F)E \in \sigma(F) and EE defends aa imply E∪{a}∈σ(F)E \cup \{a\} \in \sigma(F), generalising Dung's fundamental lemma for admissible sets.

Reference

Baumann, R., Brewka, G. & Ulbricht, M. (2020). Revisiting the Foundations of Abstract Argumentation - Semantics Based on Weak Admissibility and Weak Defense. In: Proceedings of the 34th AAAI Conference on Artificial Intelligence (AAAI 2020), pp. 2742–2749. AAAI Press.