Page 197 - DLIS402_INFORMATION_ANALYSIS_AND_REPACKAGING

Information Analysis and Repackaging Seema Sharma, Lovely Professional University

Notes
Unit 11: Indexing Language: Types and Characteristics

CONTENTS

Objectives
Introduction

11.1 Indexing Language

11.2 Types of Indexing Languages
11.3 Vocabulary Control

11.4 Vocabulary Tools
11.5 Construction of an IR Thesaurus

11.6 Structure of an IR Thesaurus
11.7 Automatic Indexing

11.8 Summary

11.9 Keywords
11.10 Review Questions

11.11 Further Readings

Objectives

After studying this unit, you will be able to:
• Define indexing language
• Describe vocabulary control and vocabulary tools
• Explain construction and structure of an IR thesaurus
• Define automatic indexing.

Introduction

Indexed languages are a class of formal languages discovered by Alfred Aho; they are described by
indexed grammars and can be recognized by nested stack automatons.
Indexed languages are a proper subset of context-sensitive languages. They qualify as an abstract
family of languages and hence satisfy many closure properties. However, they are not closed under
intersection or complement. Gerald Gazdar has characterized the mildly context-sensitive languages
in terms of linear indexed grammars.

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