John Sowa (1940-now) is an American computer scientist best known for his contributions to conceptual graphs. Tawan Banchuen said,
"Sowa (1992) observed that various kinds of semantics networks had been developed for multiple purposes, ranging from modeling human cognitive mechanisms to optimizing computational efficiency. He commented that computational motivations had occasionally produced the same network as psychological purposes." (The Geographical Analog Engine, 2008)Computer scientist Jeffrey Schiffel said,
"Among the formal graphical methods are Frege's (1879) Begriffsschrift, Pierce's (1909) existential graphs, and Sowa's (1984) conceptual graphs. These three are based in first-order predicate logic." (Improving Knowledge Management Programs Using Marginal Utility in a Metric Space Generated by Conceptual Graphs, 2008)The rest of this post is a some quotes from Sowa.
Conceptual graphs
"A conceptual graph is a finite connected bipartite graph which consists of concepts and conceptual relations. Every conceptual relation has one or more arcs each of which is linked to a concept." (Conceptual Structures, 1984)
"We define a semantic network as 'the collection of all the relationships that concepts have to other concepts, to percepts, to procedures, and to the motor mechanisms' of the knowledge." (Conceptual Structures, 1984)
"The purpose of [conceptual graphs] is to express meaning in a form that is logically precise, humanly readable and computationally tractable. With their direct mapping to language, conceptual graphs can serve as an intermediate language for translating computer oriented formalism to and from natural languages." (Conceptual graphs for knowledge representation, 1993)