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	|- (((ph -> ps) -> ch) -> (ps -> ch))

Proof of Theorem jarr

Step	Hyp	Ref	Expression
1		ax-1 6	. 2 |- (ps -> (ph -> ps))
2	1	imim1i 54	1 |- (((ph -> ps) -> ch) -> (ps -> ch))

This proof depends on syntax axioms:   -> wi 4

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

This theorem is used by:  loolinALT  95  loowoz  96