An extendible language for database schema refinement transformations

The paper presents a formal language for specifying database schema transformations. This language consists of a set of primitive operations and a compositiono perator.Each of the primitive operators has associated the conditions under which it can be applied. A rule is given for generating the applicability conditions of a composed transformation from those of the components transformations. The paper shows how the language can be exploited for supportingn a flexible and correct data base schema design also when other transformational frameworks ar used.