Lance Ramshaw (with Ralph Weischedel)

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Lance Ramshaw(with Ralph Weischedel)

• BBN

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Ontobank Coreference

• Part of the multi-site Ontobank effort
• Intended to combine with word-sense and
  propositional structure to capture lexical
  semantics
• Target coreference types
• Names, nominals, pronouns
• Attributes not corefed (Bush is the president.)
• Generic or underspecified nominals are not
  corefed, though pronouns may still refer to them
• Appositives
• These can then be treated like copulas
• Temporal expressions
• Definite references to events
• Intended for broad coverage
• Initial testing being done on Penn Treebank data

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Examples

• Names/Nominals/Pronouns
• Elco Industries Inc. said it expects net income
  in the year ending June 30 , 1990 , to fall below
  a recent analyst 's estimate of 1.65 a share .
  The Rockford , Ill. maker of fasteners also said
  it expects to post sales in the current fiscal
  year that are slightly above '' fiscal 1989
  sales of 155 million .
• Appositive constructions Heads and attributes in
• the PhacoFlex intraocular lens ltHEADgt, the first
  foldable silicone lens available for cataract
  surgery ltATTRIBgt
• Events/Verbs
• Sales of passenger cars grew 22. The strong
  growth followed year-to-year increases.
• Temporal expressions
• John spent three years in jail. In that time

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Results

• Corpus WSJ
• Mention extents extracted automatically from the
  Treebank trees
• Annotated so far 300K words (4 annotators)
• Annotation speed 4500 words / hour
• Double-annotation and adjudication of 100K words
  60 hours
• Interannotator agreement (using MUC coref
  measure)
• Coreference
• 84 measured between annotators
• 90 between annotator and the adjudicated
  version
• Apposition
• 90 measured between annotators
• 94 between annotator and the adjudicated
  version