@INPROCEEDINGS{AntoyHanus09PPDP,
author = "Antoy, S. and Hanus, M.",
title = "Set Functions for Functional Logic Programming",
year = "2009",
pages = "73-82",
publisher = "ACM Press",
booktitle = "Proc.\ of the 11th International ACM SIGPLAN Conference on
             Principle and Practice of Declarative Programming (PPDP'09)"
abstract = {
We propose a novel approach to encapsulate non-deterministic
computations in functional logic programs.  Our approach is based on
set functions that return the set of all the results of a
corresponding ordinary operation.  A characteristic feature of our
approach is the complete separation between a
usually-non-deterministic operation and its possibly-non-deterministic
arguments.  This separation leads to the first provably
order-independent approach to computing the set of values of
non-deterministic expressions.  The proof is provided within the
framework of graph rewriting in constructor-based systems.  We propose
an abstract implementation of our approach and prove its independence
of the order of evaluation.  Our approach solves easily and naturally
problems mishandled by current implementations of functional logic
languages.
}
}