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Theorem expt 582
Description: Exportation theorem expressed with primitive connectives. (Contributed by NM, 5-Aug-1993.)
Assertion
Ref Expression
expt ((¬ (φ → ¬ ψ) → χ) → (φ → (ψχ)))

Proof of Theorem expt
StepHypRef Expression
1 pm3.2im 565 . . 3 (φ → (ψ → ¬ (φ → ¬ ψ)))
21imim1d 69 . 2 (φ → ((¬ (φ → ¬ ψ) → χ) → (ψχ)))
32com12 27 1 ((¬ (φ → ¬ ψ) → χ) → (φ → (ψχ)))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-in1 544  ax-in2 545
This theorem is referenced by: (None)
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