As with object classes, Frames were organized in subsumption hierarchies. Classifiers focus on the subsumption relations in a knowledge base rather than rules. This lattice is called the subsumption lattice. Also the type values are part of a "subsumption hierarchy" including some "basic level values". Georg Henrik von Wright, another critic, named the totality "subsumption theory". This corresponds to logical subsumption and DL "concept inclusion" notated formula 4. This concept is also known as subsumption or subtype polymorphism. Apparently, the subsumption lattice was first investigated by Gordon D. Plotkin, in 1970. The following is a small list of robots that utilize the subsumption architecture. The method used is called Cross-Sentence Information Subsumption (CSIS). In the late 1980s, Brooks and his team introduced Allen, a robot using subsumption architecture. In the seventh step, a "subsumption" mechanism is typically applied. Subsumption has been widely influential in autonomous robotics and elsewhere in real-time AI.