Theorem tbw-ax2 1701

Description: The second of four axioms in the Tarski-Bernays-Wajsberg system. (Contributed by Anthony Hart, 13-Aug-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
tbw-ax2	⊢ (𝜑 → (𝜓 → 𝜑))

Proof of Theorem tbw-ax2

Step	Hyp	Ref	Expression
1		ax-1 6	1 ⊢ (𝜑 → (𝜓 → 𝜑))

Syntax hints:   → wi 4

This theorem was proved from axioms:  ax-1 6

This theorem is referenced by:  tbwlem1  1705  tbwlem3  1707  tbwlem5  1709  re1luk2  1711