A [[semantic net]] represents concepts (e.g. "house","door") as nodes and relations among concepts (e.g. "has-a") as links between the nodes. The first AI program to use a semantic net was written by [[Ross Quillian]]<ref>{{Harvnb|Crevier|1993|pp=79−83}}</ref> and the most successful (and controversial) version was [[Roger Schank]]'s [[Conceptual Dependency]].<ref>{{Harvnb|Crevier|1993|pp=164−172}}</ref>
During the 70's many programmers began to write 'conceptual ontologies', which structured real-word information into computer-understandable data:
During this time, many [[chatterbots]] were written including
