Graph, RDF, default theory, GCFL, clausal form logic.

The aim describes the idea of graph-based representation of clauses. This ap-proach follows the Richards idea of graph-based clausal form knowledge repre-sentation. Moreover, it enabled to build up the graph-based formal system GCFL (Graph-based Clausal Form Logic) that cannot only illustrate knowledge bases graphically, but also allows us to obtain consequents of a knowledge base in a special graph-based way. The article continues the idea by creation of a graph-based formal system of generating revisable theories following the known Reiter's default principle of building non-monotonic theories.