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Theorem bj-nnclavius 12950
Description: Clavius law with doubly negated consequent. (Contributed by BJ, 4-Dec-2023.)
Assertion
Ref Expression
bj-nnclavius  |-  ( ( -.  ph  ->  ph )  ->  -.  -.  ph )

Proof of Theorem bj-nnclavius
StepHypRef Expression
1 con3 631 . 2  |-  ( ( -.  ph  ->  ph )  ->  ( -.  ph  ->  -. 
-.  ph ) )
21pm2.01d 607 1  |-  ( ( -.  ph  ->  ph )  ->  -.  -.  ph )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-in1 603  ax-in2 604
This theorem is referenced by:  bj-pm2.18st  12958
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