Reasoning with Type Definitions

This article presents an extension of the basic model of conceptual graphs: the introduction of type definitions. We choose to consider definitions as sufficient and necessary conditions to belong to a type. We extend the specialization/generalization relation on conceptual graphs to take advantage of these definitions. Type contractions and type expansions are clearly defined. We establish the correspondence with projection by use of the atomic form of conceptual graphs. Finally, we give a logical interpretation of type definitions and prove than the correspondence between logical deduction and generalization relation is maintained.