Knowledge Engineering Environment (KEE) is aframe-based development tool forexpert systems.^[1] It was developed and sold byIntelliCorp, and was first released in 1983. It ran onLisp machines, and was later ported to LucidCommon Lisp with the CLXlibrary, anX Window System (X11) interface for Common Lisp. This version was available on several different UNIXworkstations.

On KEE, several extensions were offered:

• Simkit, a frame-based simulation library^[2][3]
• KEEconnection,database connection between the frame system andrelational databases^[4]

In KEE, frames are calledunits. Units are used for both individual instances and classes. Frames haveslots and slots havefacets. Facets can describe, for example, a slot's expected values, its working value, or its inheritance rule. Slots can have multiple values. Behavior can be implemented using amessage passing model.

KEE provides an extensivegraphical user interface (GUI) to create, browse, and manipulate frames.

KEE also includes a frame-basedrule system. In the KEE knowledge base, rules are frames. Bothforward chaining andbackward chaininginference are available.

KEE supports non-monotonic reasoning through the concepts ofworlds. Worlds allow providing alternative slot-values of frames. Through an assumption-based truth orreason maintenance system, inconsistencies can be detected and analyzed.^[5]

ActiveImages allows graphical displays to be attached to slots of Units. Typical examples are buttons, dials, graphs, and histograms. The graphics are also implemented as Units viaKEEPictures, a frame-based graphics library.

• Expert system
• Frame language
• Inference engine
• IntelliCorp (software)
• Knowledge base
• Knowledge-based system
• Knowledge representation

• An Assessment of Tools for Building Large Knowledge-Based Systems

• Knowledge engineering
• Knowledge representation
• Common Lisp (programming language) software

• Use dmy dates from October 2017