© 2003 by Oxford University Press
Original Article |
Order-Based Inference in Natural Logic
1 Computer Science Faculty, Technion - IIT, Haifa, Israel. E-mail: yaroslav{at}cs.technion.ac.il 2 Computer Science Faculty, Technion - IIT, Haifa, Israel. E-mail: winter{at}cs.technion.ac.il 3 Computer Science Faculty, Technion - IIT, Haifa, Israel. E-mail: francez{at}cs.technion.ac.il
This paper develops a version of Natural Logic an inference system that works directly on natural language syntactic representations, with no intermediate translation to logical formulae. Following work by Sánchez, we develop a small fragment that computes semantic order relations between derivation trees in Categorial Grammar. The proposed system has the following new characteristics: (i) It uses orderings between derivation trees as purely syntactic units, derivable by a formal calculus. (ii) The system is extended for conjunctive phenomena like coordination and relative clauses. This allows a simple account of non-monotonic expressions that are reducible to conjunctions of monotonic ones. (iii) A decision procedure for provability is developed for a fragment of Natural Logic.
Key Words: inference, monotonicity, natural logic, order, semantics
Received 15 January 2001.