Simplification of the Computation of D* We can simplify the computation of the closure of D by using the following rules(proved using rules 1-8). Multivalued union rule.If a>B holds and a>>y holds,then -→>βy holds. · Intersection rule.If a>B holds and a>>y holds,then a>>By holds. ·Difference rule..lfa→>B holds and a->>y holds,then a>>β-y holds and>>y-阝holds. Database System Concepts-7th Edition 28.5 @Silberschatz,Korth and SudarshanDatabase System Concepts - 7 28.5 ©Silberschatz, Korth and Sudarshan th Edition Simplification of the Computation of D+ ▪ We can simplify the computation of the closure of D by using the following rules (proved using rules 1-8). • Multivalued union rule. If   holds and   holds, then   holds. • Intersection rule. If   holds and   holds, then     holds. • Difference rule. If   holds and   holds, then   –  holds and   –  holds