a1 Department of Philosophy, The University of Melbourne, Victoria 3010, Australia, E-mail: firstname.lastname@example.org
a2 Dipartimento di Scienze Pedagogiche e Filosofiche, Università di Cagliari, Via Ls Mirrionis 1, 09123 Cagliari, Italy, E-mail: email@example.com
In this paper we introduce a new natural deduction system for the logic of lattices, and a number of extensions of lattice logic with different negation connectives. We provide the class of natural deduction proofs with both a standard inductive definition and a global graph-theoretical criterion for correctness, and we show how normalisation in this system corresponds to cut elimination in the sequent calculus for lattice logic. This natural deduction system is inspired both by Shoesmith and Smiley's multiple conclusion systems for classical logic and Girard's proofnets for linear logic.
(Received August 06 2004)
(Revised March 17 2005)