Text Databases

A text is any sequence of symbols (or characters) drawn from an alphabet. A large portion of the information available worldwide in electronic form is actually in text form (other popular forms are structured and multimedia information). Some examples are natural language text (e.g., books, journals, newspapers, jurisprudence databases, corporate information, the Web), biological sequences (e.g., ADN and protein sequences), continuous signals (e.g., audio and video sequence descriptions, time functions), and so on. Recently, due to the increasing complexity of applications, text and structured data are being merged into so-called semistructured data, which is expressed and manipulated in formats such as XML (out of the scope of this review).