Resolving Ambiguities in Sentence Processing with Domination and Command

Department of Cognitive Science, The Johns Hopkins University 
Oct 7 1997

Abstract
--------
Sentence processing is almost always an effortless task.  This
seemingly banal observation becomes considerably more puzzling when
juxtaposed with the somewhat less obvious observation that natural
language syntax exhibits rampant (local) ambiguity.  That is to say,
in the processing of a given sentence there are likely to be many
points at which there are multiple analyses compatible with the input
seen thus far, but only one of these may turn out to be consistent
with the remainder of the utterance.  Many traditional models of
parsing deal with such ambiguity by exploiting some type of
parallelism, carrying a number of partial parses forward from the
point of ambiguity for further consideration.  Unfortunately, such a
proliferation of parses is bound to consume significant time and space
resources, rendering this type of approach inappropriate as a model
for human processing.

An alternative approach to the local ambiguity problem has been
suggested by Marcus, Hindle, and Fleck (1983) in their work on
D-theory.  In this work and in a significant number of papers that
have followed in this line of inquiry, the parser constructs an
underspecified description of a parse tree by positing domination (as
opposed to parent) relations among nodes in a phrase structure tree.
In this talk, I will suggest that certain empirical and conceptual
shortcomings of the D-theory approach to local ambiguity can be
overcome if the descriptive primitive is changed from domination to the
more abstract and linguistically ubiquitous relation of c-command.  I
will illustrate the advantages of c-command over domination with a
range of examples from English and Japanese.

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