Ann Copestake
University of Cambridge

Wednesday, 5/13 1-2pm
EEB 403

Slacker semantics: why superficiality, dependency and avoidance of
commitment can be the right way to go.


Standard linguistic approaches to compositional semantics need
adaptation for use in broad-coverage computational processing. I'll
argue that an ideal compositional semantic representation should
capture all and only the information available from syntax and
productive morphology, allowing for shallow as well as deep syntactic
analysis and avoiding over-commitment when ambiguity cannot be
resolved. This leads to `surfacy' semantic representations which must
nevertheless allow for enrichment by deeper analysis (including
lexical semantics and anaphora resolution), support (robust) inference
and have a logically-sound interpretation. Other desiderata are
compatibility with generation, statistical ranking of
analyses/realisations and distributional semantics, ease of use for
consumers of the representation and for human annotators, and
cross-linguistic adequacy.

Several current approaches to computational compositional semantics
meet at least some of these goals, but in this talk I'll concentrate
on work within the DELPH-IN community using Minimal Recursion
Semantics (MRS) and Robust MRS (RMRS). I'll give a brief overview and
I'll then try to illustrate how the slacker perspective applies in the
grammars by talking about argument labelling (in contrast to semantic
role assignment). I'll then describe some new work on formalism and
show that, under certain assumptions about the grammar, an
interconversion is possible between MRS and a variable-free semantic
dependency notation (DMRS), which removes redundancy, supports
additional forms of underspecification and makes the representation
easier for humans and machine learning algorithms to process. Like
RMRS, DMRS output can be produced from fast, shallow(er) parsers
technology, and if time permits, I'll briefly discuss planned work on
its application to Web-scale parsing.

-- Main.ebender - 14 May 2009

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pdfpdf eaclslides.pdf manage 867.9 K 2009-05-14 - 22:04 UnknownUser Slides from Ann Copestake's talk
Topic revision: r1 - 2009-05-14 - 22:04:04 - ebender

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