The paper describes a formal theory for the dependency approach to syntax. The formalism is able to deal with long-distance dependencies, involved in function sharing and extractions. The distinctive aspects of the approach are the use of non lexical categories and a GPSG-style treatment of long-distance dependencies. The formalism is applied to a number of coordination phenomena, that are well-known in the literature. Mots Clefs - Keywords: Dependency grammar, Long-distance dependencies, Coordination, Non-lexical units * Dipartimento di Scienze e Tecnologie Avanzate, Universit del Piemonte Orientale "A. Avogadro", c.so Borsalino 54, 15100 Alessandria, Italy , vincenzo@mfn.unipmn.it. ** Dipartimento di Informatica and Centro di Scienza Cognitiva, Universit di Torino, c.so Svizzera 185, 10149 Torino, Italy, {vincenzo, lesmo}@di.unito.it. - 2 - 1. INTRODUCTION Dependency syntax has had a long tradition in European linguistics since (Tesniere L. 1959): formal descriptions o...