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          International Workshop on Reduction Strategies 
              in Rewriting and Programming (WRS 2001)

                 held in conjunction with RTA 2001
              in Utrecht, The Netherlands, May 26, 2001

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                         INVITED TALK


     Evaluation Strategies for Functional Logic Programming

                       by Sergio Antoy
                    Portland State University 
                    Dept. of Computer Science 


                          Abstract

   Recent advances in the foundations and the development of
   functional logic programming languages originate from
   far-reaching results on narrowing evaluation strategies.
   Narrowing is a computation similar to rewriting which yields
   substitutions in addition to values.  The classes of rewrite
   systems to which narrowing is applied are, for the most part,
   subclasses of the constructor-based, possibly conditional,
   rewrite systems.  Many interesting narrowing strategies,
   particularly for the smallest subclasses of the constructor
   based rewrite systems, are generalizations of well-known
   rewrite strategies.  However, some strategies for larger
   non-confluents subclasses have been developed just for
   functional logic computations.
   
   In this talk, I will discuss the elements that play a relevant
   role in evaluation strategies for functional logic programming.
   I will describe some important classes of rewrite systems that
   model functional logic programs.  I will show on examples the
   differences in expressiveness provided by these classes.  And I
   will review narrowing and, in particular, the characteristics
   of the various strategies proposed for each class of rewrite
   systems.

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