An automatic diacritization algorithm for undiacritized Arabic text

Modern Standard Arabic (MSA) is used today in most written and some spoken media. It is, however, not the native dialect of any country. Recently, the rate of the written dialectal Arabic text increased dramatically. Most of these texts have been written in the Egyptian dialectal, as it is considered the most widely used dialect and understandable throughout the Middle East. Like other Semitic languages, in written Arabic, short vowels are not written, but are represented by diacritic marks. Nonetheless, these marks are not used in most of the modern Arabic texts (for example books and newspapers). The absence of diacritic marks creates a huge ambiguity, as the un-diacritized word may correspond to more than one correct diacritization (vowelization) form. Hence, the aim of this research is to reduce the ambiguity of the absences of diacritic marks using hybrid algorithm with significantly higher accuracy than the state-of-the-art systems for MSA. Moreover, this research is to implement and evaluate the accuracy of the algorithm for dialectal Arabic text. The design of the proposed algorithm based on two main techniques as follows: statistical n-gram along with maximum likelihood estimation and morphological analyzer. Merging the word, morpheme, and letter levels with their sub-models together into one platform in order to improve the automatic diacritization accuracy is the proposition of this research. Moreover, by utilizing the feature of the case ending diacritization, which is ignoring the diacritic mark on the last letter of the word, shows a significant error improvement. The reason for this remarkable improvement is that the Arabic language prohibits adding diacritic marks over some letters. The hybrid algorithm demonstrated a good performance of 97.9% when applied to MSA corpora (Tashkeela), 97.1% when applied on LDC’s Arabic Treebank-Part 3 v1.0 and 91.8% when applied to Egyptian dialectal corpus (CallHome). The main contribution of this research is the hybrid algorithm for automatic diacritization of undiacritized MSA text and dialectal Arabic text. The proposed algorithm applied and evaluated on Egyptian colloquial dialect, the most widely dialect understood and used throughout the Arab world, which is considered as first time based on the literature review

Morphological, syntactic and diacritics rules for automatic diacritization of Arabic sentences

AbstractThe diacritical marks of Arabic language are characters other than letters and are in the majority of cases absent from Arab writings. This paper presents a hybrid system for automatic diacritization of Arabic sentences combining linguistic rules and statistical treatments. The used approach is based on four stages. The first phase consists of a morphological analysis using the second version of the morphological analyzer Alkhalil Morpho Sys. Morphosyntactic outputs from this step are used in the second phase to eliminate invalid word transitions according to the syntactic rules. Then, the system used in the third stage is a discrete hidden Markov model and Viterbi algorithm to determine the most probable diacritized sentence. The unseen transitions in the training corpus are processed using smoothing techniques. Finally, the last step deals with words not analyzed by Alkhalil analyzer, for which we use statistical treatments based on the letters. The word error rate of our system is around 2.58% if we ignore the diacritic of the last letter of the word and around 6.28% when this diacritic is taken into account

Combining Speech with textual methods for arabic diacritization

Master'sMASTER OF SCIENC

Construction of an ontology for intelligent Arabic QA systems leveraging the Conceptual Graphs representation

The last decade had known a great interest in Arabic Natural Language Processing (NLP) applications. This interest is due to the prominent importance of this 6th most wide-spread language in the world with more than 350 million native speakers. Currently, some basic Arabic language challenges related to the high inflection and derivation, Part-of-Speech (PoS) tagging, and diacritical ambiguity of Arabic text are practically tamed to a great extent. However, the development of high level and intelligent applications such as Question Answering (QA) systems is still obstructed by the lacks in terms of ontologies and other semantic resources. In this paper, we present the construction of a new Arabic ontology leveraging the contents of Arabic WordNet (AWN) and Arabic VerbNet (AVN). This new resource presents the advantage to combine the high lexical coverage and semantic relations between words existing in AWN together with the formal representation of syntactic and semantic frames corresponding to verbs in AVN. The Conceptual Graphs representation was adopted in the framework of a multi-layer platform dedicated to the development of intelligent and multi-agents systems. The built ontology is used to represent key concepts in questions and documents for further semantic comparison. Experiments conducted in the context of the QA task show a promising coverage with respect to the processed questions and passages. The obtained results also highlight an improvement in the performance of Arabic QA regarding the c@1 measure.The work of the last author was carried out in the framework of the WIQ-EI IRSES project (Grant No. 269180) within the FP 7 Marie Curie, the DIANA APPLICATIONS - Finding Hidden Knowledge in Texts: Applications (TIN2012-38603-C02-01) project, and the VLC/CAMPUS Microcluster on Multimodal Interaction in Intelligent Systems.Abouenour, L.; Nasri, M.; Bouzoubaa, K.; Kabbaj, A.; Rosso, P. (2014). Construction of an ontology for intelligent Arabic QA systems leveraging the Conceptual Graphs representation. Journal of Intelligent and Fuzzy Systems. 27(6):2869-2881. https://doi.org/10.3233/IFS-141248S2869288127

Conversational Arabic Automatic Speech Recognition

Colloquial Arabic (CA) is the set of spoken variants of modern Arabic that exist in the form of regional dialects and are considered generally to be mother-tongues in those regions. CA has limited textual resource because it exists only as a spoken language and without a standardised written form. Normally the modern standard Arabic (MSA) writing convention is employed that has limitations in phonetically representing CA. Without phonetic dictionaries the pronunciation of CA words is ambiguous, and can only be obtained through word and/or sentence context. Moreover, CA inherits the MSA complex word structure where words can be created from attaching affixes to a word. In automatic speech recognition (ASR), commonly used approaches to model acoustic, pronunciation and word variability are language independent. However, one can observe significant differences in performance between English and CA, with the latter yielding up to three times higher error rates. This thesis investigates the main issues for the under-performance of CA ASR systems. The work focuses on two directions: first, the impact of limited lexical coverage, and insufficient training data for written CA on language modelling is investigated; second, obtaining better models for the acoustics and pronunciations by learning to transfer between written and spoken forms. Several original contributions result from each direction. Using data-driven classes from decomposed text are shown to reduce out-of-vocabulary rate. A novel colloquialisation system to import additional data is introduced; automatic diacritisation to restore the missing short vowels was found to yield good performance; and a new acoustic set for describing CA was defined. Using the proposed methods improved the ASR performance in terms of word error rate in a CA conversational telephone speech ASR task