The articles assembled in this issue of the Canadian Journal of Linguistics/Revue canadienne de linguistique contribute to our understanding of the role of asymmetric relations at the interfaces. Asymmetric relations have privileged status in the syntactic, phonological, and morphological derivation of linguistic expressions (see for example the articles in Di Sciullo 2003).

Interfaces are representations that must meet legibility conditions imposed by external systems. According to the Strong Minimalist Thesis (Chomsky 2001), language is an optimal solution to interface conditions, in that language is an optimal way to link sound and meaning. Questions arise regarding the properties of the interface representations that make them optimally legible by external systems. These properties could very well be abstract, and remote from the perceptual systems, and could bear on the form of interface representations, rather than on the interpretation of their parts. A strong hypothesis in this regard is that asymmetric relations are core properties of the relations derived by the grammar (Chomsky 1981, 1995, 2001; Kayne 1994; Moro 2000; Di Sciullo 2005; Zwart 2006). From this perspective, asymmetry is a pervasive property of derivations and interface representations; it is thus expected to be a property of different structural relations, such as the relation between a displaced constituent and its copy, the relation between an anaphor and its antecedent, the relation between a head and its dependent, and more generally, the relation between the constituents of a configuration.