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Uncertainty-Valued Horn Clauses

Victoria Hall
DFKI, DFKI Technical Memos (TM), Vol. 94-03, 1994.


There are many forms of uncertainty, each usually again having more than one theoretical model.

Therefore, a very flexible kind of uncertainty-valued Horn clauses is introduced in RELFUN in section 1. They have a head, several premises and an uncertainty factor, which represents the uncertainty of the clause. The premises are all 'functional' in the sense that their returne d value is again an uncertainty value. These premises and the uncertainty factor of an uncertainty rule become embedded into the arguments of a combination function when translating uncertainty clauses into footed clauses (non-ground, non-deterministic functions in RELFUN, which can then be compiled as usual). The combination funct ion can be modified by the user. It may be a built-in or a user-defined function, either of which may be computed as the value of a higher-order function. In section 2, an application of uncertainty clauses to the uncertain concept of a 'pet holder', according to German law, is described. This and another example are then fully demonstrated in appendix A. Finally, appendix B gives a listing of the complete uncertainty translator in LISP.