# The Effect of Preprocessing on Arabic Document Categorization
## 3 Overview of Arabic Language Structure  
The Arabic language is a semantic language with a complicated morphology, which is significantly different from the most popular languages, such as English, Spanish, French, and Chinese. The Arabic language is a native language of the Arab states and the secondary language in a number of other countries [19]. More than 422 million people are able to speak Arabic, which makes this language the fifth most spoken language in the world, according to [14]. The alphabet of the Arabic language consists of 28 letters:  
The Arabic language is classified into three forms: Classical Arabic (CA), Colloquial Arabic Dialects (CAD), and Modern Standard Arabic (MSA). CA is fully vowelized and includes classical historical liturgical text and old literature texts. CAD includes predominantly spoken vernaculars, and each Arab country has its dialect. MSA is the official language and includes news, media, and official documents [3]. The direction of writing in the Arabic language is from right to left. The Arabic language has two genders, feminine (\(\triangle\)\(\  
Arabic is a challenging language in comparison with other languages such as English for a number of reasons:  
* The Arabic language has a rich and complex morphology in comparison with English. Its richness is attributed to the fact that one root can generate several hundreds of words having different meanings. Table 3 presents different morphological forms of root study (). * In English, prefixes and suffixes are added to the beginning or end of the root to create new words. In Arabic, in addition to the prefixes and suffixes there are infixes that can be added inside the word to create new words that have the same meaning. For example, in English, the word write is the root of word writer. In Arabic, the word writer () is derived from the root write () by adding the letter Alef () inside the root. In these cases, it is difficult to distinguish between infix letters and the root letters. * Some Arabic words have different meanings based on their appearance in the context. Especially when diacritics are not used, the proper meaning of the Arabic word can be determined based on the context. For instance, the word () could be Science (), Teach () or Flag () depending on the diacritics [23]. * Another challenge of automatic Arabic text processing is that proper nouns in Arabic do not start with a capital letter as in English, and Arabic letters do not have lower and upper case, which makes identifying proper names, acronyms, and abbreviations difficult. * There are several free benchmarking English datasets used for document categorization, such as 20 Newsgroup, which contains around 20,000 documents distributed almost evenly into 20 classes; Reuters 21,578, which contains 21,578 documents belonging to 17 classes; and RCV1 (Reuters Corpus Volume 1), which contains 806,791 documents classified into four main classes. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \(\hat{\mathbf{\omega}}\) & \(\hat{\mathbf{\omega}}\) & \(\hat{\mathbf{\omega}}\) & \(\hat{\mathbf{\omega}}\) & \(\hat{\mathbf{\omega}}\) & \(\hat{\mathbf{\omega}}\) & \(\hat{\mathbf{\omega}}\) \\ \hline /s/ & /sun/ / /sin/ / / /san/ / /ssa/ / /ssu/ / /sss/ / /si/ /ssa/ / /su/ \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Presents different pronunciations of the letter (Sad) (). Unfortunately, there is no free benchmarking dataset for Arabic document classification. In this work, to overcome this issue, we have used an in-house dataset collected from several published papers for Arabic document classification and from scanning the well-known and reputable Arabic websites. * In the Arabic language, the problem of synonyms and broken plural forms are widespread.