12、Natural Language Index Term Selection: A Comprehensive Guide

Natural Language Index Term Selection: A Comprehensive Guide

1. Introduction to Index Term Metrics

In the realm of natural language processing, selecting appropriate index terms is crucial for effective text representation and retrieval. Several metrics are used to evaluate the significance of index terms, each offering unique insights into the content of a text.

1.1 Term Frequency (tf)

The term frequency ($tfi$) of an index term $i$ is defined as the frequency of its occurrence in the text. High term frequency often indicates that a term is important for representing the text’s content, especially in long texts or those containing many significant or technical terms. However, in short texts, term frequency information may be negligible or