Theorem tsor1

Description: A Tseitin axiom for logical disjunction, in deduction form. (Contributed by Giovanni Mascellani, 25-Mar-2018)

	Ref	Expression
Assertion	tsor1	⊢ ( 𝜃 → ( ( 𝜑 ∨ 𝜓 ) ∨ ¬ ( 𝜑 ∨ 𝜓 ) ) )

Proof

Step	Hyp	Ref	Expression
1		exmidd	⊢ ( 𝜃 → ( ( 𝜑 ∨ 𝜓 ) ∨ ¬ ( 𝜑 ∨ 𝜓 ) ) )