There is a wide variety of formalisms that draw on the entity-relationship model while representing the information in a network form: they are called semantic networks.

**Existential graphs**: In 1909, C.S.Peirce developed the first graphs, called existential, provided with an interpretation and logical heuristics. In 1959, Tesnière’s research in the field of linguistics led to the definition of a graphic formalism whose form is better adapted to the requirements of natural language, although the expressiveness remains similar to that of Peirce’s graphs.**Frames**: In the field of artificial intelligence in 1966, R. Quillian began a work on semantic networks with the objective of modeling the capabilities of human memory. In 1975, frames and scripts appeared (Minsky, 75) which are a more formal notation of semantic networks and which will later lead to the definition of description logics.**UML**: Let us also mention the UML formalism (ISO standard), allowing an illustrated representation of information, and commonly used in the industrial sector. It is used to model the specification of an architecture or the needs of a project.**Conceptual Graphs**: 1984, J. F. Sowa defined the formalism of conceptual graphs (conceptually closed to Peirce’s graphs) and provided it with a logical semantics (similar to existential graphs). This formalism is based on graph theory and the elementary reasoning operation called*projection*is a mapping between graph vertices.