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Theorem xchbinx 640
Description: Replacement of a subexpression by an equivalent one. (Contributed by Wolf Lammen, 27-Sep-2014.)
Hypotheses
Ref Expression
xchbinx.1 (𝜑 ↔ ¬ 𝜓)
xchbinx.2 (𝜓𝜒)
Assertion
Ref Expression
xchbinx (𝜑 ↔ ¬ 𝜒)

Proof of Theorem xchbinx
StepHypRef Expression
1 xchbinx.1 . 2 (𝜑 ↔ ¬ 𝜓)
2 xchbinx.2 . . 3 (𝜓𝜒)
32notbii 627 . 2 𝜓 ↔ ¬ 𝜒)
41, 3bitri 182 1 (𝜑 ↔ ¬ 𝜒)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wb 103
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 577  ax-in2 578
This theorem depends on definitions:  df-bi 115
This theorem is referenced by:  xchbinxr  641  necon3abii  2285  elirr  4312  en2lp  4325  dm0rn0  4600
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