Some classes of prolog programs inferable from positive data

In this paper, we study inferability of Prolog programs from positive examp les alone. The importance of studying inductive inference From positive dat a alone stems from the scarcity of negative information in practical applic ations. Starting with Shinohara's result on bounded finite thickness and in ductive inference from positive data, we investigate a broad spectrum of cl asses of Prolog programs inferable from positive data and the relationships between these classes. First we consider programs without local variables and show that a few classes of programs (without any bound on the length of clauses) are inferable from positive data. Then we consider programs with local variables and identify a very useful class of programs inferable from positive data, using mode annotations of predicates and linear predicate i nequalities. (C) 2000 Elsevier Science B.V. All rights reserved.