Nothing is gained in CDG by having a word modify itself. Next the unary constraints are applied to all of the role values in the constraint network. A role value is incompatible with a unary constraint if and only if it satisfies the antecedent, but not the consequent. When a role value violates a unary constraint, node consistency eliminates those role values from their role because they can never participate in a parse for the sentence. Next, binary constraints are applied.
Binary constraints determine which pairs of role values can legally coexist.
To keep track of pairs of role values, arcs are constructed connecting each role to all other roles in the network, and each arc has an associated arc matrix , whose row and column indices are the role values associated with the two roles it connects. This is indicated by replacing the entry of 1 with 0 . Following the binary constraints, the roles of the constraint network can still contain role values which are incompatible with the parse for the sentence. Role values that are not supported by the binary constraints can be eliminated by achieving arc consistency. For example, det-3 for the is not supported by the remaining role value for eats and is thus deleted from the role.