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Theorem anbi2 688
Description: Introduce a left conjunct to both sides of a logical equivalence. (Contributed by NM, 16-Nov-2013.)
Assertion
Ref Expression
anbi2 ((φψ) → ((χ φ) ↔ (χ ψ)))

Proof of Theorem anbi2
StepHypRef Expression
1 id 19 . 2 ((φψ) → (φψ))
21anbi2d 684 1 ((φψ) → ((χ φ) ↔ (χ ψ)))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 176   wa 358
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 177  df-an 360
This theorem is referenced by: (None)
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