The Thai language belongs to a class of non-segmented
languages, the sentences of which consist of a string of symbols
without explicit word delimiters. Words in the Thai language
are not naturally separated by any word-delimiting symbols.
Due to this characteristic, indexing Thai text documents is a
challenging task and has become one of the research focuses
in the area of Thai information retrieval. Many techniques
have been proposed to index Thai text documents, including
n-gram inverted index [3], word inverted index and suffix
array approaches [4].