number 2

SECTION 1.2 REVIEW TECHNIQUES W Apply derivation rules for propositional logic. W Use propositional logic to prove the validity of a verbal argument. A proof sequence in a formal logic system is a se- quence of wffs that are either hypotheses or derived from earlier wffs in the sequence by the derivation rules of the system The propositional logic system is complete and correct; valid arguments and only valid arguments are provable. MAIN IDEAS A valid argument can be represented by a wff of the form P, AP, APA... AP, Q that is a tautology. EXERCISES 1.2 For Exercises 1-4, what inference rule is illustrated by the argument given? 1. If Martina is the author, then the book is fiction. But the book is nonfiction. Therefore Martina is not the author. 2. If the business declares bankruptcy, then all assets must be confiscated. The business declared bankruptcy. It follows that all assets must be confiscated