A simplified version of a query processor has been implemented. Basic theory is well understood. System is partially implemented. There is a need to extend the theory and to complete implementation. We are currently involved in developing the theory that will allow such translations to be done easily.
Theory is under development.
However, we have pretty clear ideas of how to continue. There is a need to implement and test out preliminary results. They are especially prevelent in conjunction with data warehouses. We are currently studying issues relating to aggregate query optimization. We are interested both in characterizing equivalences and in rewriting aggregate queries with views.