Explorations of a domain of locality

Aravind Joshi (University of Pennsylvania)

A grammar formalism explicitly or implicitly specifies a domain of
locality, i.e., a domain over which various kinds of dependencies can
be specified. It is of interest to figure out how the various
syntactic, semantic, computational (including psycholinguistic)
properties follow from this initial specification of the domain of
locality. A particular example is the lexicalized tree-adjoining
grammar (LTAG) in which the domains of locality are represented by the
structures (trees) representing `extended' projections of lexical
items, encapsulating syntactic/semantic arguments of the lexical
anchor. These structures are minimal in the sense that all and only
the syntactic/semantic arguments are encapsulated and further, all
recursion is factored away. This factoring of recursion is what leads
to the trees being extended projections or extended domains of

In the past several years the syntactic, semantic and computational properties of this domain of locality have been investigated, including how these notions can be possibly transplanted into other frameworks, in particular categorial grammars. I will present an overview of the key results, which together, I believe, constitute an interesting case study, with potential relevance to other formal systems.