Research

My research focuses on the logical foundations of grammar formalisms and the mathematical properties of language (more accurately, the properties of the sets of structures that Linguists use to model languages). The majority of my research falls in the area known as Model-Theoretic Syntax.

For the last few years, working with various collaborators and my undergraduate research group, I have been focusing primarily on descriptive characterizations of classes of stringsets (sets of strings) that are weaker than the Regular stringsets. These classes turn out to be useful in a number of areas:

• Exploring the minimal capabilities of cognitive mechanisms that can recognize whether a sequence meets various types of constraints
• Designing and evaluating experiments comparing the ability of human and non-human animals to distinguish aural and visual patterns
• Classifying the phonological patterns that occur in human languages
• As a foundation for stochastic models of human languages and human language learning.

I have done a great deal of work on descriptive characterizations of classes of sets of more complicated structures, including Context-Free (CF) sets of strings and trees and a variety of generalizations of CF sets including those mildly context-sensitive sets that are licensed by Tree-Adjoining Grammars (TAGs) and Wier's Control Grammars. These classes are useful in, inter alia:

• Reasoning about linguistic structure independently of assumptions about potential mechanisms for processing.
• Identifying the abstract principles embodied in linguistic theories that have been expressed in grammar- or automata-theoretic terms.
• Comparing linguistic theories expressed in terms of disparate formalisms.
• Specifying CFGs, TAGs, etc., in terms of the principles they are intended to capture via logical formulae which can be compiled into grammars in the traditional form.
• Verifying that CFGs, TAGS, etc., enforce or are consistent with various linguistic principles.
• Determining the independence of sets of linguistic principles.

My doctoral studies were carried out in the Computer and Information Sciences Department at the University Delaware under K. Vijay-Shanker. Copies of my dissertation Studies in the Logic of Trees with Applications to Grammar Formalisms are available from the Univ. of Delaware as Technical Report No. 95-04, email requests to dasaro@cis.udel.edu This is not available electronically, although an abstract is available here.