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Frames

A FRS organizes knowledge in an ``object-oriented'' manner, which means that facts are associated with the objects mentioned in the facts. A frame is an object with which facts are associated. Frames have the required property of being named; that is, the FRS maintains a mapping from names to frame objects. These frame objects denote entities in the conceptual world, in the usual sense of a symbol denoting an object in the universe of discourse. In some languages one may denote an object by an expression rather than a symbol. For example, the expression (+ 2 3) denotes the integer 5. However, in the Generic Frame Protocol, a frame is accessed by a name which is a Lisp symbol, and each frame has a unique identifying name. When a frame is renamed all of the facts associated with the previous name are then associated with the new name. Operationally, then, it does not matter whether a renamed frame is the ``same'' frame or a new one with all the same associations.

A frame exists in the finite storage of a knowledge base. Whether the entity denoted by the frame exists in the world is an orthogonal question. The existence of a frame in a knowledge base is determined by the functions that map from names to frames. There is no assumption about how the information associated with frames is stored in Lisp memory.



  • Peter Karp