A Deterministic Co-reference System with Rich Syntactic Features and Semantic Knowledge Heeyoung Lee & Sudarshan Rangarajan Collaborators : Karthik Raghunathan under the guidance of Mihai Surdeanu, Nate Chambers & Dan Jurafsky 1

The Problem boolean isCoreferent(Mention A, Mention B) isCoreferent(‘Sony’, ‘The Japanese Company’) : TRUE isCoreferent(‘Sony’, ‘it’) : TRUE isCoreferent(‘The Japanese Company’, ‘it’) : TRUE isCoreferent(‘it’, ‘camcorder market’) : FALSE isCoreferent(‘it’, ‘RCA’) : FALSE 2 ‘More important to the future of 8mm is Sony's success in the $2.3 billion camcorder market. The Japanese company already has 12% of the total camcorder market, ranking it third behind the RCA and Panasonic brands.’

Baseline System Simple Co-reference Resolution with Rich Syntactic and Semantic Features, by Aria Haghighi & Dan Klein (EMNLP 2009) Deterministic, single-pass, constraint-based system Included Syntactic salience & Agreement constraint checking. Lack of Semantic Knowledge in decision making. 3 ‘President Bush and his colleague had different opinions. However, the person who has the right to make the final decision is the president.’

Preliminary Error Analysis Corpora for Error Analysis : MUC-6 (Train Set); and for Experiments : MUC-6 & ACE 4

Simple Knowledge Extraction System (SKES) Seed & Mention Pairs Yield Semantic Patterns Yield Metrics used to refine pattern yield 5

Construct passes 6 Sort decision features – Highest precision first.

Multi-pass Coreference System Deterministic, multi-pass, constraint based system. Decisions based on more confident mention pairs first. Further decisions based on previously accumulated knowledge about mentions. 7 ‘President Bush and his colleague had different opinions. However, the person who has the right to make the final decision is the president.’

Result 8 Multi-pass system is more sensitive to error propagation -> need high precision passes. Higher precision, but lower recall and F1. Needs more passes to increase recall -> Future work ( & Co-reference decision Re-ranker)

Questions? Thank You! 9