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Theorem xchnxbir 616
Description: Replacement of a subexpression by an equivalent one. (Contributed by Wolf Lammen, 27-Sep-2014.)
Hypotheses
Ref Expression
xchnxbir.1 𝜑𝜓)
xchnxbir.2 (𝜒𝜑)
Assertion
Ref Expression
xchnxbir 𝜒𝜓)

Proof of Theorem xchnxbir
StepHypRef Expression
1 xchnxbir.1 . 2 𝜑𝜓)
2 xchnxbir.2 . . 3 (𝜒𝜑)
32bicomi 127 . 2 (𝜑𝜒)
41, 3xchnxbi 615 1 𝜒𝜓)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wb 102
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-in1 554  ax-in2 555
This theorem depends on definitions:  df-bi 114
This theorem is referenced by:  3ioran  911  truxortru  1326  truxorfal  1327  falxortru  1328  falxorfal  1329  nsspssun  3198  intirr  4739
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