A preferred extension of an argument structure is a maximal admissible set of the structure. Every structure possesses at least one preferred extension. A stable extension of a structure is a conflict-free set \(S\) that attacks each argument that does not belong to \(S\). Every stable extension is a preferred extension, but not vice versa. Some structures do not have stable extensions. Leendert van der Torre and Srdjan Vesic (van der Torre and Vesic 2018) outline the full range of definitions of extensions, along with the principles of rationality they embody.