Sowa introduced the conceptual graph (CG) theorywhich provides a knowledge representation frameworkconsisting of a form of logic with a graph notationandintegrating several features from semantic net and framerepresentations.

Relating diagrams to logic.- Representation, discourse, logic and truth: Situating knowledge technology.- Heterogeneous reasoning.- A comparison between conceptual graphs and KL-ONE.- The term definition operators of ontolingua and of the conceptual graph formalism: a comparison.- Implementing conceptual graphs in a RDBMS.- A conceptual graphs approach to conceptual schema integration.- Conceptual graphs for relational Databases.- Inducing a CG representation for basic-level categorization of verbs.- The representation of linguistic information in an approach used for modelling temporal knowledge in discourses.- Representing natural language causality in Conceptual Graphs: The Higher order conceptual relation problem.- Executable conceptual structures.- Inverting resolution with conceptual graphs.- Towards domain-independent machine intelligence.- Efficient retrieval from hierarchies of objects using lattice operations.- Characterization and algorithmic recognition of canonical conceptual graphs.- A conceptual semantics ontology for conceptual graphs.- Acquiring temporal knowledge from schedules.- Conceptual structures for modeling in CIM.- Elicitation of taxonomies based on the use of conceptual graph operators.- Presenting a peirce logic based inference engine and theorem prover for conceptual graphs.- Operations on conceptual structures and Peirce's system of existential graphs.- Modal logics for conceptual graphs.- Fuzzy conceptual graphs.