Generalized Earley Deduction and Its Correctness

This paper describes a deduction method that works both top-down and bottom-up. The method can be viewed as an extension of a well-known approach—Earley deduction—to handle negation-as-failure. We show that with respect to the stratified model theory of [1] the method is sound, that it is strongly complete (terminating) for function-free programs with negation, and complete for programs without negation if function symbols are allowed.