This paper describes a LISP program, called PCDB, for storage and retrieval in a data base of predicate calculus (PC) formulas. The PCDB pacxage uses standardized representations of PC formulas, where ground unit clauses are stored efficiently, e.g. on the property-lists of their arguments, and other clauses have other representation. The major part of the PCDB package is a function generator, which accepts declarations of PC relations and functions, and Which also accepts "rules" (= non-ground

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... axioms intended for use in deduction) Declarations and rules are used to generate efficient code for storage and retrieval of "facts" (usually = ground unit clauses) in and from the data base. This generation process may be characterized as a "compilation" of the rules (from predicate calculus to LISP).