Computer Science Notes

Notes From CS Undergrad Courses FSU

This project is maintained by awa03

Truth Table

p q r p ∧ q q ⊕ r (p ∧ q)∨ r (q ⊕ r) ∧ p P
T T T T F T F F
T T F T T T T T
T F T F T T T T
T F F F F F F T
F T F F T F F T
F F T F T F F F
F F F F F F F T
								               LHS of P            RHS of P
LHS RHS LHS->RHS
T T T
T F F
F T T
F F T

The premise is true ∧ the conclusion is false -- if then is false

Logical Analysis

The only time P: LHS -> RHS is false (F) is when LHS ∧ RHS are F Logically analyze the problem ∧ see what is needed based on the above statement.

Logical Equivelence

P = ¬(LHS) ∨ (RHS) = [¬(p ∧ q) ∧ (¬ r)] ∨ [((q ∧ (¬ r)) ∨ (¬ q ∧ r)) ∨ p] = [(¬ p) ∨ (¬ q) ∧ (¬ r)] ∨ [(q ∧ (¬ r) ∧ p) ∨ (¬ q ∧ r) ∧ p] = [¬ p ∧ ¬ r] ∨ [¬ q ∧ ¬ r] ∨ [q ∧ ¬ r ∧ p] ∨ [¬ q ∧ r ∧ p]

This leads to the same result as the above table, similar to algebra f∨ f∨mal logic

Compound propositions P ∧ Q are described in terms of atomic propositions p, q, r, ... are logically equivalent. This is written as

$P ≡ Q (∨ P <==> Q)$

if P ∧ Q has identical truth values this means...

Definition

A proposition R is a tautology if it is always T, i.e., no matter the truth values of the atomic proposition R is T - p ∨ ¬ p - (p ∧ q) -> p - p -> p ∨ q