Summary form only given. The manual design of data warehouse and data mart schemes can be a tedious, error-prone, and time-consuming task. In addition, it is a highly complex engineering task that calls for methodological support. This paper lays the grounds for an automatic generation approach of multidimensional schemes. It first defines a tabular format for OLAP requirements. Secondly, it presents a set of algebraic operators used to transform automatically the OLAP requirements, specified in the tabular format, to data mart modelled either as star or constellation schemes. Our approach is illustrated with an example.