Extracting and Representating Causal Relations in Children’s Stories

Abstract

Stories are an essential part of knowledge and communication for humans. They are composed of a series of related concepts, such as events and states, which people use to share ideas to other members of society. Past researches have already tried to replicate the way humans produce or understand stories through creative­text generation systems. Unfortunately, there is a lack of data concerning relationships between events within and across sentences in a story because of lacking common sense knowledge. Therefore, a system called Eventure, which extracts instances of event relations within children’s stories, has been implemented. This system identifies concepts, as well as meta-data, in stories through the use of a third­party language processing tool that provides pre­processing capabilities like tokenization and POS ­tagging. With the concepts and meta-data collected, Eventure utilizes a pre­defined list of grammar templates and rules to extract instances of event relations and ultimately produces an ontology that stores them. The initial list grammar rules were collected from (Samson 2014) and were modified to accommodate meta-data of concepts. A new event relation between a causing state and a resulting event was also added. To validate the system’s accuracy, a gold standard of the extracted instances of event relations was created using ten children’s stories. The system yielded a precision of only 3.27%, a recall of 10.14%, and an F-­measure of 4.95%. This is due to the relatively generic extraction templates, complexity of the children’s stories, and inherent problems with the utilized POS tagger.

Keywords: causal relation, relation extraction, knowledge representation, lexical semantics

Introduction

A story is essentially a series of events. ...

In this paper, we describe our system, Eventure, that extracts event relations from children’s stories with the use of predefined extraction templates and rules, as well as concept indicators. Multiple word and sentence analysis tools such as morphological analyzers and transducers are also utilized. Section 2 describes an event relation and the representation of an event in Eventure’s ontology. This is followed by a discussion of the templates and rules used in the extraction process in Section 3. Section 4 presents an analysis of the quality of the extracted relations. The paper ends with a discussion of issues and recommendations for future work.

Knowledge Representation

some intro text...

Event Relations

An event relation is a form of binary semantic relation represented as common sense assertions of the form relation(concept1, concept2). This form was patterned after ConceptNet (cite) and is used to provide the storytelling knowledge needed by story generation systems (MakeBelieve, PB1, PB2).

A number of relations are used by ConceptNet to describe events, as shown in Table 1.

Table 1. Event Relations <INSERT TABLE 4.2 HERE>

Eventure’s Ontology

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