An Algorithm for Pronominal Anaphora Resolution
Summary
The paper presents RAP (Resolution of Anaphora Procedure), a classic rule-based algorithm for resolving third-person pronouns (including reflexives and reciprocals) using syntactic information from a parser. Candidate antecedents are assigned a salience score built from weighted factors such as recency, grammatical role (subject, existential, direct object, indirect object/oblique), head-noun status and not being inside an adverbial phrase. Salience is halved for each sentence boundary crossed, and role parallelism and cataphora adjust the score. Syntactic filters (agreement and binding-style constraints on co-arguments) remove impossible candidates before the highest-scoring one is chosen. The authors evaluate RAP on technical manuals and compare it with Hobbs' syntactic search algorithm, reporting that the salience approach performs at least as well. The work became a standard reference point for knowledge-poor, transparent pronoun resolution.
How Mova uses it
- the development notes of
coref("What next") — the salience weights of this paper (recency 100, subject 80, existential 70, object 50, indirect object and oblique 40, head noun 80, non-adverbial 50; halving per sentence; parallelism +35, cataphora −175) are recorded as a candidate replacement or complement for the Hobbs-style candidate order used in thepronounsieve. - Not implemented yet; the current resolver orders candidates in a Hobbs-like breadth-first tree traversal.
Effectiveness in Mova
Not tried yet (the coref README marks it explicitly as "not tried"). Planned idea only; not measured.
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Library summary
Written for the Research library (claude-opus-5-5) from the paper text, in our own words: the license "CC BY-NC-SA 3.0 (ACL Anthology, before 2016)" does not allow redistributing the text itself. Original — aclanthology.org/J94-4002.pdf
Summary
Lappin and Leass tackle the task of linking third person pronouns, reflexives and reciprocals to their noun phrase antecedents, both within a sentence and across sentences. Their system, RAP (Resolution of Anaphora Procedure), is written in Prolog and runs on parses from McCord's Slot Grammar. It uses no semantic reasoning or world knowledge. Instead, it removes impossible candidates with syntactic and agreement filters, flags pleonastic "it", and binds lexical anaphors with a separate algorithm. The remaining candidates are ranked by salience scores. These scores combine grammatical role, role parallelism, frequency of mention, proximity and sentence recency, and they are updated as the discourse unfolds. In a blind test on computer manual text with 360 pronouns, RAP chose the correct antecedent in 86% of cases. This is 4 points better than a Slot Grammar reimplementation of Hobbs' algorithm. Adding Dagan's statistical lexical preferences improved accuracy by only about 2%. The study suggests that inexpensive structural and attentional cues do most of the work. Semantic knowledge can then serve as a secondary step for close calls.
Key points
- RAP operates on Slot Grammar clausal representations (ESG; a GSG version also exists). It keeps the four preceding sentences in memory and is integrated into the LMT English–German machine translation system to choose the gender of target-language pronouns.
- Its components are a six-condition syntactic non-coreference filter, morphological agreement checks, pattern-based detection of pleonastic "it" (modal adjectives, cognitive verbs), a binding algorithm for reflexives and reciprocals, and salience weighting computed over equivalence classes of coreferent NPs.
- The grammatical role hierarchy ranks subjects above other NPs, direct objects above other complements, arguments above adjuncts, and head nouns above their complements.
- Blind test: 360 pronoun occurrences, 86% accuracy, compared with a 4-point lower score for Hobbs' search procedure on the same sentences.
- The statistically enhanced variant (RAPSTAT, using Dagan 1992 lexical preferences) gained only about 2%. It mainly helped when the top salience scores were close and a less salient candidate had strong lexical support.
Cite
@misc{lappin1994algorithm,
title = {{An Algorithm for Pronominal Anaphora Resolution}},
author = {Lappin, Shalom and Leass, Herbert J.},
year = {1994},
doi = {10.5555/203987.203989},
url = {https://doi.org/10.5555/203987.203989}
}References
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