Theorem jarr 91

Description: Elimination of a nested antecedent as a kind of reversal of inference ja 153. (Contributed by Wolf Lammen, 9-May-2013.)

Assertion

Ref	Expression
jarr	⊢ (((φ → ψ) → χ) → (ψ → χ))

Proof of Theorem jarr

Step	Hyp	Ref	Expression
1		ax-1 6	. 2 ⊢ (ψ → (φ → ψ))
2	1	imim1i 54	1 ⊢ (((φ → ψ) → χ) → (ψ → χ))

Syntax hints:   → wi 4

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

This theorem is referenced by:  loolinALT  95  loowoz  96