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Theorem xchbinxr 641
Description: Replacement of a subexpression by an equivalent one. (Contributed by Wolf Lammen, 27-Sep-2014.)
Hypotheses
Ref Expression
xchbinxr.1 (𝜑 ↔ ¬ 𝜓)
xchbinxr.2 (𝜒𝜓)
Assertion
Ref Expression
xchbinxr (𝜑 ↔ ¬ 𝜒)

Proof of Theorem xchbinxr
StepHypRef Expression
1 xchbinxr.1 . 2 (𝜑 ↔ ¬ 𝜓)
2 xchbinxr.2 . . 3 (𝜒𝜓)
32bicomi 130 . 2 (𝜓𝜒)
41, 3xchbinx 640 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:  xordc1  1325  sbnv  1811  ralnex  2363  difab  3249  disjsn  3472  iindif2m  3765  reldm0  4601
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