Reading is one of the four basic skills for humans to acquire knowledge all over the world. In the modern days, billions of the texts can be read, including comprehensive and incomprehensible documents. It is not simple to select texts suitable for those at certain levels to read and understand, as a result a lot of studies on how to match a text to a group of readers has been done. Finding out whether a given text is suitable for a group of readers consists of the two major factors: the reader’s ability and the text’s difficulty itself. On the one hand, the readers’ ability factor is related to their prior knowledge (how much they know about the subject before reading the text), their reading skill, his interest in the subject, and his motivation on reading the text. On the other hand, the text factor is related to its content (how the ideas are expressed), the style of expression and level of readability, the way it is designed (including layout and typography), its organization and navigational aids .
Readability is one of the directions of the research on matching documents to readers. According to Alan Bailin, Ann Grafstein , readability is the degree to which a text is easy or difficult to read and understand. Readability is influenced largely on linguistic elements of written texts such as the way the words, phrases and sentences are used, the style of the text…
Researches on text readability have begun since the early years of the 20th century, most of them are for English and some common languages like Arabic, Italian, French, Chinese, Japanese and so on. In Vietnamese language, there are few studies about text readability have done. This has motivated us to do further researches on Readability assessment for Vietnamese texts.
We are focusing on three sub-problems of Readability assessment:
- Construct large and reliable corpora for Vietnamese text readability examination.
- Examine and evaluate valid features for assessing readability for Vietnamese texts [3, 4, 5].
- Building a precise and accurate model for assessing Vietnamese text readability.
 DuBay, W. H. (2007). Unlocking language: The classic readability studies. Costa Mesa, CA: Impact Information.
 Bailin, A., & Grafstein, A. (2016). Readability: Text and context. Basingstoke: Palgrave Macmillan.
 An-Vinh Luong, Diep Nguyen, Dien Dinh (2017). Examining the Text-length Factor in Evaluating the Readability of Literary Texts in Vietnamese Textbooks, Knowledge and Systems Engineering (KSE). 2017 Ninth International Conference on, Hue Province, 2017.
 Nguyen Thi Nhu Diep, Luong An Vinh, Dinh Dien (2017). Investigating some elements affecting the readability of Vietnamese texts – Primary level (in comparision to English ones). The 3rd international conference on Vietnamese studies, Vung Tau province, 08/2017.
 Luong An Vinh, Nguyen Thi Nhu Diep, Truong Thi Hong , Dinh Dien (2017). Examining the Readability of proses in the literature textbooks for Vietnamese students at primary and secondary schools. The 3rd international conference on Vietnamese studies, Vung Tau province, 08/2017.