Contextual Urdu Lemmatization Using Recurrent Neural Network Models

Rabab Hafeez, Muhammad Waqas Anwar, Muhammad Hasan Jamal, Tayyaba Fatima, Julio César Martínez Espinosa, Luis Alonso Dzul López, Ernesto Bautista Thompson and Imran Ashraf ()
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Rabab Hafeez: Department of Computer Science, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan
Muhammad Waqas Anwar: Department of Computer Science, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan
Muhammad Hasan Jamal: Department of Computer Science, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan
Tayyaba Fatima: Department of Computer Science, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan
Julio César Martínez Espinosa: Higher Polytechnic School, Universidad Europea del Atlántico, Isabel Torres 21, 39011 Santander, Spain
Luis Alonso Dzul López: Higher Polytechnic School, Universidad Europea del Atlántico, Isabel Torres 21, 39011 Santander, Spain
Ernesto Bautista Thompson: Higher Polytechnic School, Universidad Europea del Atlántico, Isabel Torres 21, 39011 Santander, Spain
Imran Ashraf: Department of Information and Communication Engineering, Yeungnam University, Gyeongsan 38541, Republic of Korea

Mathematics, 2023, vol. 11, issue 2, 1-20

Abstract: In the field of natural language processing, machine translation is a colossally developing research area that helps humans communicate more effectively by bridging the linguistic gap. In machine translation, normalization and morphological analyses are the first and perhaps the most important modules for information retrieval (IR). To build a morphological analyzer, or to complete the normalization process, it is important to extract the correct root out of different words. Stemming and lemmatization are techniques commonly used to find the correct root words in a language. However, a few studies on IR systems for the Urdu language have shown that lemmatization is more effective than stemming due to infixes found in Urdu words. This paper presents a lemmatization algorithm based on recurrent neural network models for the Urdu language. However, lemmatization techniques for resource-scarce languages such as Urdu are not very common. The proposed model is trained and tested on two datasets, namely, the Urdu Monolingual Corpus (UMC) and the Universal Dependencies Corpus of Urdu (UDU). The datasets are lemmatized with the help of recurrent neural network models. The Word2Vec model and edit trees are used to generate semantic and syntactic embedding. Bidirectional long short-term memory (BiLSTM), bidirectional gated recurrent unit (BiGRU), bidirectional gated recurrent neural network (BiGRNN), and attention-free encoder–decoder (AFED) models are trained under defined hyperparameters. Experimental results show that the attention-free encoder-decoder model achieves an accuracy, precision, recall, and F-score of 0.96, 0.95, 0.95, and 0.95, respectively, and outperforms existing models.

Keywords: neural networks; natural language processing; inflectional morphology; derivational morphology (search for similar items in EconPapers)
JEL-codes: C (search for similar items in EconPapers)
Date: 2023
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