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Theorem bj-con4iALT 31132
Description: Alternate proof of con4i 134. Probably the original proof. (Contributed by BJ, 29-Mar-2020.) (New usage is discouraged.) (Proof modification is discouraged.)
Hypothesis
Ref Expression
bj-con4iALT.1  |-  ( -. 
ph  ->  -.  ps )
Assertion
Ref Expression
bj-con4iALT  |-  ( ps 
->  ph )

Proof of Theorem bj-con4iALT
StepHypRef Expression
1 bj-con4iALT.1 . 2  |-  ( -. 
ph  ->  -.  ps )
2 ax-3 8 . 2  |-  ( ( -.  ph  ->  -.  ps )  ->  ( ps  ->  ph ) )
31, 2ax-mp 5 1  |-  ( ps 
->  ph )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4
This theorem was proved from axioms:  ax-mp 5  ax-3 8
This theorem is referenced by: (None)
  Copyright terms: Public domain W3C validator