1.

Determine whether the following propositions is a Tautology or a contradiction or neither. (i) (p ∧ q) ∧ ~p (ii) [~p ∧ (p ∨ q)] (iii) (p ∧ q) → (p ∨ q) (iv) (p ∧ q) →p (v) ~ p ∧ ~q

Answer»

(i) (p ∧ q) ∧~p

pqp ∧ q~p(p ∧ q) ∧~p
TTTFF
TFFFF
FTFTF
FFFTF

From last column we conclude that it is a contradiction

(ii) [~p ∧ (p ∨ q)]

p~pqp ∨ q~p ∧ (p ∨ q)
TFTTF
TFFTF
FTTTT
FTFFF

From last column we conclude it is neither tautology nor a contradiction

(iii) (p ∧ q) → (p ∨ q)

pqp ∧ qp ∨ q(p ∧ q) → (p ∨ q)
TTTTT
TFFTT
FTFTT
FFFFT

From last column we conclude it is a tautology

(iv) (p ∧ q) → p

pqp ∧ q(p ∧ q) → p
TTTT
TFFT
FTFT
FFFT

From last column we conclude that it is a tautology

(v) ~ p ∧ ~q

pq~ p~q~ p ∧ ~q
TTFFF
TFFTF
FTTFF
FFTTT

It is neither tautology nor contradiction



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