In order to exactly describe logic relations among objects of discrete event control systems and write programs, a rule-based language, logic rule Description language (LRDL) is put forward.

Derive is written in Lisp, a common programming language that is especially suited for the kind of rule-based processing necessary for transforming one abstract mathematical expression into another.

The fuzzy control based on the control rule described by the fuzzy language, has been successfully used in the industry control process and has an extensive foreground of application.