Math Problem Statement

Consider the propositional formula ( NOT ( P ) IFF Q ) IMPLIES R and the formula ( P AND Q ) OR ( NOT ( P ) AND NOT ( Q ) ) OR R .Prove that the two formulas are equivalent, using logical rules.

Solution

We are tasked with proving that the two formulas are logically equivalent. The two formulas are:

  1. (¬P    Q)    R( \neg P \iff Q ) \implies R
  2. (PQ)(¬P¬Q)R( P \land Q ) \lor ( \neg P \land \neg Q ) \lor R

To show that these two are equivalent, we will simplify both formulas step by step using logical rules.

Formula 1: (¬P    Q)    R( \neg P \iff Q ) \implies R

Step 1: Expand the biconditional (IFF)

The biconditional ¬P    Q\neg P \iff Q means (¬P    Q)(Q    ¬P)(\neg P \implies Q) \land (Q \implies \neg P). So, the first formula becomes:

((¬P    Q)(Q    ¬P))    R( (\neg P \implies Q) \land (Q \implies \neg P) ) \implies R

Step 2: Express implications in terms of disjunction

Using the implication rule (A    B)(¬AB)(A \implies B) \equiv (\neg A \lor B), we rewrite both implications:

  • ¬P    QPQ\neg P \implies Q \equiv P \lor Q
  • Q    ¬P¬Q¬PQ \implies \neg P \equiv \neg Q \lor \neg P

Thus, the formula becomes:

((PQ)(¬Q¬P))    R((P \lor Q) \land (\neg Q \lor \neg P)) \implies R

Step 3: Simplify the conjunction

Let's analyze the conjunction (PQ)(¬Q¬P)(P \lor Q) \land (\neg Q \lor \neg P). This is a form of the exclusive OR (PQP \oplus Q), because it says that either PP is true and QQ is false,

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Math Problem Analysis

Mathematical Concepts

Propositional Logic
Logical Equivalences
Biconditional (IFF)
Implication (IMPLIES)

Formulas

(¬P IFF Q) IMPLIES R
(P ∧ Q) ∨ (¬P ∧ ¬Q) ∨ R
(A IFF B) ≡ ((A → B) ∧ (B → A))
(A → B) ≡ (¬A ∨ B)

Theorems

Biconditional (IFF) Expansion
Implication (IMPLIES) as Disjunction
De Morgan's Laws
Exclusive OR (XOR) Concept

Suitable Grade Level

Undergraduate Level (Discrete Mathematics/Logic)