Transcription of Predicate Logic - Stanford University
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CHAPTER14FF FFPredicateLogicWe now turn our attention to a generalization of propositional Logic , called predi-cate, or first-order, Logic . predicates are functions ofzero or more variables thatreturn Boolean values. Thus predicates can be true sometimes and false sometimes,depending on the values of their arguments. For example, we shall find in predicatelogic atomic operands such ascsg(C, S, G). Here,csgis the Predicate name, andC,S, andGare arguments. We can think of this expression as a representationin Logic of the database relation Course-Student-Grade of Fig.
and G, that student S took course C and got grade G. Put another way, when we substitute constants c for C, s for S, and g for G, the value of csg(c,s,g) is TRUEif and only if student s took course c and got grade g. We can also express the particular facts (i.e., tuples) in the relation as ground atomic formulas, by using constants as arguments.
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