presenter : jian-ren chen authors : gonenc ercan , ilyas cicekli * 2007.ipm

Intelligent Database Systems Lab

Presenter : JIAN-REN CHEN

Authors : GONENC ERCAN, ILYAS CICEKLI *

2007.IPM

Using lexical chains for keyword extraction

Intelligent Database Systems Lab

OutlinesMotivationObjectivesMethodologyExperimentsConclusionsComments

Intelligent Database Systems Lab

MotivationIt is a hard and time consuming task to assign keywords to

documents.

The automatic keyphrase extraction algorithms are limited with

phrases that appear in the text.

Intelligent Database Systems Lab

Objectives

• We present a keyword extraction method such that it uses the features based on lexical chains in the selection of keywords for a text.

Intelligent Database Systems Lab

Methodology

1. first occurrence position2. frequency3. last occurrence position

Intelligent Database Systems Lab

Methodology – Lexical chains

• WordNet - synonym、 hyponym/hypernym1) more than one relationship2) up to 3 levels of depth3) identify nouns4) only consider individual words

Intelligent Database Systems Lab

Methodology – lexical chains

1. Lexical chain score of a word: 2. Direct Lexical chain score of a word:3. Lexical chain span score of a word:4. Direct lexical chain span score of a word:

59 (=7 · 7 + 10)

28 (=4 · 7)

Intelligent Database Systems Lab

Experiments - Datasets

Corpus Name Texts in corpusNumber of

Training Documents

Number of Testing

Documents

Total Number of Documents

Journal Articles full texts 55 20 75

Global corpus abstracts 110 45 155

- extract 1, 5, 10, 15 keywords for each document

Intelligent Database Systems Lab

Experiments

1. Lexical chain score of a word: 2. Direct Lexical chain score of a word:3. Lexical chain span score of a word:4. Direct lexical chain span score of a word:

Intelligent Database Systems Lab

Experiments

Intelligent Database Systems Lab

Experiments

Intelligent Database Systems Lab

Conclusions

According to the results that are obtained, the lexical chain features improve the precision significantly in the keyword extraction process.

Intelligent Database Systems Lab

Comments• Advantages

– Lexical chains will more consider the semantic relationships

• Applications– keyword extraction