Rule-based Knowledge Representation Research Articles

Building an expert system for the preliminary design of ships

An expert system for the preliminary design of ships developed. The design process is understood as determining design variables and the relationships among design parameters. The relationships among the elements of design knowledge are represented by a network model. The object-oriented knowledge representations are introduced in the computer system to manipulate design variables such as the principle particulars of a ship in the network model. The expert system based on the above concept provides the following functions: (1) flexibility for building a model and easy modification of the model; (2) effective diagnosis of the design process by using rule-based knowledge representations; (3) hybrid function with both symbolic treatment of the design knowledge and numerical computations by coupling the systems programmed in LISP and FORTRAN and (4) a supporting method for determination of the design variables.Finally the system's validity and effectiveness is ascertained by applying it to the preliminary design of a bulk carrier ship.

Symmetric relations, intensional individuals, and variable binding

A symmetric relation such as ... are adjacent or ... are related is characterized by not distinguishing among two or more of its arguments. Such a relation may efficiently be represented as a relation that takes a set as its argument, or as one of its arguments. The semantics of such a representation is, in part, determined by the instantiation (matching or unification) rule used by the reasoning system operating on the representation. Two such rules are discussed. One interprets the relation to be reflexive, the other does not. Since many of these relations are not reflexive, we prefer the latter rule, which forbids two distinct variables from matching the same term. It is argued that this apparently strange restriction is actually reasonable if the rules of the system are interpreted as fully intensional. Under that interpretation, an even stronger version of the instantiation rule emerges, which we name the Unique Variable Binding Rule (UVBR). Considering the behavior of the UVBR when reasoning about reflexive relations and about nonreflexive relations used reflexively casts light on the implications of a fully intensional knowledge representation scheme. These ideas are illustrated by the output of an intensional, rule-based knowledge representation system that has been modified to allow the choice of using the UVBR instead of standard unification.