The functional side of logic programming

In this paper we study the relationships between logic programming and functional programming, trying to rmswer the following basic question: to what extent is logic programming just functional programming in disguise?We develop a theory to formally express this correspondence, and exhibit a class that can by right be considered as the functional core of logic programming.Moreover, since the functional meaning of each program in this class is provided constructively, via a transformation from logic to functional mo~rams.we show how the obtained theoretical results are .V, useful also in the study of languages integration, termination issues, and practical implementations.