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≡XVy 5.Set of quantifiers: 3ter(Q(t))="there exists"a tuple in t in relation r such that predicate Q(t)is true ∀ter(Q(t)≡Q is true“for all"tuples t in relation r Database System Concepts-5th Edition,July 8,2005 5.4 @Silberschatz,Korth and SudarshanDatabase System Concepts - 5 5.4 ©Silberschatz, Korth and Sudarshan th Edition, July 8, 2005 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