GroundedFixpoint

groundedFixpoint: extends the IN/OUT labelling of the active context to the grounded fixpoint, labelling UND the arguments left. Each round labels IN the arguments whose attackers are all OUT, then OUT the arguments attacked by an IN one; the context is read once and only the new labels are asserted.

Each argument keeps the number of its attackers not OUT: a round only looks at the arguments the previous one changed (those attacked by the arguments just labelled), rather than at all the unlabelled ones, which made a chain of attacks quadratic. The labels of a round are asserted in the order of the arguments.