 With gestures toward earlier work by Phan Minh Dung (1995), Gregor Betz constructs a model of belief change based on “dialectical structures” of linked arguments (Betz 2013). Sentences and their negations are represented as digits positive and negative, arguments as ordered sets of sentences, and two forms of links between arguments: an attack relation in which a conclusion of one argument contradicts a premise of another and support relations in which the conclusion of one argument is equivalent to the premise of another  (Figure 4).  A “position” on a dynamical structure, complete or partial, consists of an assignment of truth values T or F to the elements of the set of sentences involved. Consistent positions relative to a structure are those in which contradictory sentences are signed opposite truth values and every argument in which all premises are assigned T has a conclusion which is assigned T as well. Betz then maps the space of coherent positions for a given dialectical structure as an undirected network, with links between positions that differ in the truth-value of just one sentence of the set.