Semantics for a Higher-Order Functional Language with Logic Variables Radha Jagadeesan Imperial College, London, UK SW7 2BZ. Keshav Pingali Cornell University, Ithaca, NY 14853. Although there is considerable experience in using languages that combine the functional and logic programmingparadigms,the problemofprovidingan adequate semantic foundation for such languages has remained open. In an earlier paper, we solved this problem for rst-order languages by reducing the problem to that of solving simultaneous xpoint equations involvingclosure operators over a Scott domain and showing that the resulting sewas fully abstract with respect to the operational semantics 4]. These results showed that the rst-order fragment could be viewed as a language of incremental de nition of data structures through constraint intersection. The problem for higher-order languages remained open, in part because higher-order functions can interact with logic variables in complicated ways to give rise to beha...