Abdulmohsen Al-Thubaity, Sakhar Alkhereyf, Hanan Murayshid, Nouf Alshalawi, Maha Omirah, Raghad Alateeq, Rawabi Almutairi, Razan Alsuwailem, Manal Alhassoun, Imaan Alkhanen. Proceedings of ArabicNLP 2023. 2023.

In this paper, we propose an Arabic word segmentation technique based on a bi-directional long short-term memory deep neural network. Our work addresses the two tasks of word segmentation only and word segmentation for nine cases of rewrite. Word segmentation with rewrite concerns inferring letters that are dropped or changed when the main word unit is attached to another unit, and it writes these letters back when the two units are separated as a result of segmentation. We only use binary labels as indicators of segmentation positions. Therefore, label 1 is an indicator of the start of a new word (split) in a sequence of symbols not including whitespace, and label 0 is an indicator for any other case (no-split). This is different from the mainstream feature representation for word segmentation in which multi-valued labeling is used to mark the sequence symbols: beginning, inside and outside. We used Arabic Treebank data and its clitics segmentation scheme in our experiments. The trained model without the help of any additional language resources, such as dictionaries, morphological analyzers, or rules, achieved a high F1 value for the Arabic word segmentation only (98.03%) and Arabic word segmentation with rewrite (more than 99% for frequent rewrite cases). We also compared our model with four state-of-the-art Arabic word segmenters. It performed better than the other segmenters on a modern standard Arabic text, and it was the best among the segmenters that do not use any additional language resources in another test using classical Arabic text.

Arabic diacritics play a significant role in distinguishing words with the same orthography but different meanings, pronunciations, and syntactic functions. The presence of Arabic diacritics can be useful in many natural language processing applications, such as text-to-speech tasks, machine translation, and part-of-speech tagging. This paper discusses the use of bidirectional long short-term memory neural networks with conditional random fields for Arabic diacritization. This approach requires no morphological analyzers, dictionary, or feature engineering, but rather uses a sequence-to-sequence schema. The input is a sequence of characters that constitute the sentence, and the output consists of the corresponding diacritic(s) for each character in that sentence. The performance of the proposed approach was examined using four datasets with different sizes and genres, namely, the King Abdulaziz City for Science and Technology text-to-speech (KACST TTS) dataset, the Holy Quran, Sahih Al-Bukhary, and the Penn Arabic Treebank (ATB). For training, 60% of the sentences were randomly selected from each dataset, 20% were selected for validation, and 20% were selected for testing. The trained models achieved diacritic error rates of 3.41%, 1.34%, 1.57%, and 2.13% and word error rates of 14.46%, 4.92%, 5.65%, and 8.43% on the KACST TTS, Holy Quran, Sahih Al-Bukhary, and ATB datasets, respectively. Comparison of the proposed method with those used in other studies and existing systems revealed that its results are comparable to or better than those of the state-of-the-art methods.