Information-relational Semantics of the Fifth System

This describes work in progress on the semantics of Fifth, a declarative programming language which obtains efficiency without relying on domain-specific assumptions by means of an adaptive evaluation strategy. The adaptive evaluation strategy demands a consistent way of measuring the progress of a computation in terms of the information yielded by different control paths explored in the course of attempting to evaluate it. The Fifth system’s semantics are situated at the intersection of Icon, Prolog, Radul’s and Sussman’s information propagation networks and Codd’s relational model as developed by Date et. al. which in turn places it somewhere between abstract execution systems for program analysis and existing logic programming tools, and promises to enrich declarative programming with the semantics of relations on answer sets, and may through the consistent use of relations achieve the combination of expressivity and efficiency characteristic of the APL family and its consistent reliance on arrays.