Theorem tsor1

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

	Ref	Expression
Assertion	tsor1	$$⊢\theta \to \left(\left(\phi \vee \psi \right)\vee \neg \left(\phi \vee \psi \right)\right)$$

Proof

Step	Hyp	Ref	Expression
1		exmidd	$$⊢\theta \to \left(\left(\phi \vee \psi \right)\vee \neg \left(\phi \vee \psi \right)\right)$$