Constraints for improving the generation of intentional answers in a deductive database

It is shown how intentional answers can be generated as logical consequences of the query and of deduction rules and how integrity constraints can filter out inadequate answers and produce simpler and more informative answers. An efficient organization for the combination of answers and constraints is presented. The authors focus on the design of mechanisms for controlling the generation of intentional answers using integrity constraints. The assertions specified by constraints bear not only on the database but also on queries and intentional answers, since the latter specify sets of values from the database