Both Common Lisp and Prolog code for FOIDL is available via anonymous ftp. See the README files here for details. Pointers to papers on FOIDL can be found on our ILP research page. Below is the standard reference (click on the open book image).
Journal of Artificial Intelligence Research, 3 (1995) pp. 1-24.
This paper presents a method for inducing logic programs from examples that
learns a new class of concepts called first-order decision lists, defined
as ordered lists of clauses each ending in a cut. The method, called FOIDL,
is based on FOIL but employs intensional background knowledge and avoids
the need for explicit negative examples. It is particularly useful for
problems that involve rules with specific exceptions, such as learning the
past-tense of English verbs, a task widely studied in the context of the
symbolic/connectionist debate. FOIDL is able to learn concise, accurate
programs for this problem from significantly fewer examples than previous
methods (both connectionist and symbolic).