A grammar-based approach towards unifying hierarchical data models
Marc Gyssens, Jan Paredaens, Dirk Van Gucht · ACM SIGMOD Record · 1989
A simple model for representing the hierarchical structure of information is proposed. This model, called the grammatical model, is based on trees that are generated by grammars; the grammars describe the hierarchy of the information represented by the trees. Two transformation languages, an algebra and a calculus, are presented and shown to be equally expressive.