In: Advanced Math
problem 10 :
Explain why ∃xP(x) ∨ ∃xQ(x) ≡ ∃x(P(x) ∨ Q(x)). You need not formally prove it, but you should give a convincing explanation for why it is true?
Use the fact established in the problem that ∃xP(x) ∨ ∃xQ(x) ≡
∃x(P(x) ∨ Q(x)) to prove that ∀xP(x) ∧ ∀xQ(x) ≡ ∀x(P(x) ∧
Q(x)).
Use Problem 10 above to prove that ∀xP(x) → ∃xP(x) ≡ T