A bird's-eye view of LISPLOG : The LISP/PROLOG integration with initial-cut tools

Abstract

A combined LISP/PROLOG system was designed, implemented and tested, via stepwise refinement of Kenneth M. Kahn’s operational LISP semantics for pure PROLOG. LISPLOG.1 utilizes the representation of PROLOG terms as LISP-S-expressions for two generalizations of Edinburgh PROLOG: varying length structures, and goals with predicate variables. On the other hand, a goto>while-like spezialization is studied in this language: the cut>initial cut restriction, which improves both readability and parallelization of PROLOG programs. For accessing LISP from PROLOG, we permit LISP predicates as goals, and LISP functions as right-hand sides of the is-predicate. In the other direction, the first n PROLOG solutions can be returned as a LISP list.

LISPLOG.2 augments the trace and break tools already available in LISPLOG.1 by an (initial) ´cut-indicator´/´manual cutter´ for making the cuts in the search tree observable and interactive.

For improving efficiency, the originally recursive interpreter is reformulated iteratively, the binding environment is represented as an array structure, and the database is indexed by predicates and arguments. As the main application, LISPLOG runs a knowledge-based system, μ-UNIXPERT, for diagnosing printing problems.