simplenlg.aggregation

Class ForwardConjunctionReductionRule

java.lang.Object

simplenlg.aggregation.AggregationRule

simplenlg.aggregation.ForwardConjunctionReductionRule

public class ForwardConjunctionReductionRule
extends AggregationRule

Implementation of the forward conjunction rule. Given two sentences s1 and s2, this rule elides any constituent in the left periphery of s2 which is also in s1. The left periphery in simplenlg is roughly defined as the subjects, front modifiers and cue phrase of an SPhraseSpec.

This rule elides any constituent in the left periphery of s2 which is lemma-identical to a constituent with the same function in s1, that is, it is headed by the same lexical item, though possibly with different inflectional features and/or modifiers. Note that this means that the tall man and the man are counted as "identical" for the purposes of this rule. This is only justifiable insofar as the two NPs are co-referential. Since SimpleNLG does not make assumptions about the referentiality (or any part of the semantics) of phrases, it is up to the developer to ensure that this is always the case.

The current implementation is loosely based on the algorithm in Harbusch and Kempen (2009), which is described here: http://aclweb.org/anthology-new/W/W09/W09-0624.pdf

Implementation note: The current implementation only applies ellipsis to phrasal constituents (i.e. not to their component lexical items).

Note:: this rule can be used in conjunction with the BackwardConjunctionReductionRule in Aggregator.

Author:

agatt

Field Summary

Fields inherited from class simplenlg.aggregation.AggregationRule

factory

Constructor Summary

Constructors

Constructor and Description
ForwardConjunctionReductionRule() Creates a new ForwardConjunctionReduction.

Method Summary

Modifier and Type	Method and Description
NLGElement	apply(NLGElement previous, NLGElement next) Applies forward conjunction reduction to two NLGElements e1 and e2, succeeding only if they are clauses (that is, e1.getCategory() == e2.getCategory == PhraseCategory.CLAUSE) and the clauses are not passive.

Methods inherited from class simplenlg.aggregation.AggregationRule

apply, apply, getFactory, setFactory

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ForwardConjunctionReductionRule

public ForwardConjunctionReductionRule()

Creates a new ForwardConjunctionReduction.

Method Detail

apply

public NLGElement apply(NLGElement previous,
                        NLGElement next)

Applies forward conjunction reduction to two NLGElements e1 and e2, succeeding only if they are clauses (that is, e1.getCategory() == e2.getCategory == PhraseCategory.CLAUSE) and the clauses are not passive.

Specified by:

apply in class AggregationRule

Parameters:

previous - the first phrase

next - the second phrase

Returns:

a coordinate phrase if aggregation is successful, null otherwise