Predicate Calculus Formula 1.Set of attributes and constants 2.Set of comparison operators:(e.g,<,≤，=，≠，>，≥) 3.Set of connectives:and (A),or (v),not ( 4.Implication(→)：x→y,if x if true,then y is true X→y≡nXVy 5.Set of quantifiers: p3t∈r(Q(t)=”there exists”a tuple in t in relation r such that predicate Q(t)is true Vt er(Q(t))=Q is true "for all"tuples t in relation r Database System Concepts-6th Edition 6.14 @Silberschatz,Korth and SudarshanDatabase System Concepts - 6 6.14 ©Silberschatz, Korth and Sudarshan th Edition Predicate Calculus Formula 1. Set of attributes and constants 2. Set of comparison operators: (e.g., , , =, , , ) 3. Set of connectives: and (), or (v)‚ not () 4. Implication (): x  y, if x if true, then y is true x  y  x v y 5. Set of quantifiers:   t  r (Q (t ))  ”there exists” a tuple in t in relation r such that predicate Q (t ) is true  t  r (Q (t ))  Q is true “for all” tuples t in relation r