Higher Level Meta Programming in Qu-Prolog 3: 0

For representing high level knowledge, such as the mathematical knowledge used in interactive theorem provers and veriication systems, it is desirable to extend Prolog's concept of data object. A basic reason is that Prolog data objects | Herbrand objects | are terms of a minimal object language, which does not include its own object variables, or quantiication over those variables. Qu-Prolog (Quantiier Prolog) is an extended logic programming concept which takes as its data objects, object terms which may include object level variables, free or bound, and arbitrary quantiiers to bind those variables. Qu-Prolog is unique in allowing its data objects to include free occurrences of object variables. This paper describes Qu-Prolog's data objects and its facilities for computing on those objects. The Qu-Prolog uniication algorithm uniies Qu-Prolog terms up to changes of bound variables. The power of Qu-Prolog uniication is greatly increased by the inclusion in the language of an evalu-able substitution operator which correctly substitutes at uniication time for free occurrences of object variables. Some related Qu-Prolog facilities for implementing theorem proving algorithms are described, including a new method for persisting data across queries. Qu-Prolog 3.0 is a compiled implementation which is in experimental use, supporting the development of interactive reasoning systems.