CHNIQUES

Apply derivation rules for propositional logic.

Use propositional logic to prove the validity of a

verbal argument.

AIN IDEAS

A valid argument can be represented by a wff of

the form $P_1^{{?}^{?}}{P}_2^{{?}^{?}}{P}_3^{{?}^{?}}dot{s}^{{?}^{?}}{P}_{n}Q$ that is a

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 argument

XERCISES $1\mathrm{.}2$

or Exercises $1-4,$ what inference rule is illustrated by the argument given?

If Martina is the author, then the book is fiction. But the book is nonfiction. Therefore Martina is not the

author.

If the business declares bankruptcy, then all assets must be confiscated. The business declared bankruptcy

It follows that all assets must be confiscated.