Theorem retbwax4 1748

Description: tbw-ax4 1736 rederived from merco1 1746. (Contributed by Anthony Hart, 17-Sep-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
retbwax4	⊢ (⊥ → 𝜑)

Proof of Theorem retbwax4

Step	Hyp	Ref	Expression
1		merco1lem1 1747	. 2 ⊢ (𝜑 → (⊥ → 𝜑))
2		merco1lem1 1747	. 2 ⊢ ((𝜑 → (⊥ → 𝜑)) → (⊥ → 𝜑))
3	1, 2	ax-mp 5	1 ⊢ (⊥ → 𝜑)

This proof depends on syntax axioms:   → wi 4  ⊥wfal 1582

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 210  df-tru 1573  df-fal 1583

This theorem is used by: (None)