Theorem pm2.61 191

Description: Theorem *2.61 of [WhiteheadRussell] p. 107. Useful for eliminating an antecedent. (Contributed by NM, 4-Jan-1993.) (Proof shortened by Wolf Lammen, 22-Sep-2013.)

Assertion

Ref	Expression
pm2.61	⊢ ((𝜑 → 𝜓) → ((¬ 𝜑 → 𝜓) → 𝜓))

Proof of Theorem pm2.61

Step	Hyp	Ref	Expression
1		pm2.6 190	. 2 ⊢ ((¬ 𝜑 → 𝜓) → ((𝜑 → 𝜓) → 𝜓))
2	1	com12 32	1 ⊢ ((𝜑 → 𝜓) → ((¬ 𝜑 → 𝜓) → 𝜓))

Syntax hints:  ¬ wn 3   → wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem is referenced by:  bnj1109  32766  jath  33672  isltrn2N  38134  ltrnid  38149  ltrneq  38163  onfrALT  42169  onfrALTVD  42511