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Theorem bj-bisym 32852
Description: This used to be in the main part. (Contributed by Wolf Lammen, 14-May-2013.) (Revised by BJ, 14-Jun-2019.)
Assertion
Ref Expression
bj-bisym (((𝜑𝜓) → (𝜒𝜃)) → (((𝜓𝜑) → (𝜃𝜒)) → ((𝜑𝜓) → (𝜒𝜃))))

Proof of Theorem bj-bisym
StepHypRef Expression
1 impbi 198 . 2 ((𝜒𝜃) → ((𝜃𝜒) → (𝜒𝜃)))
21bj-bi3ant 32851 1 (((𝜑𝜓) → (𝜒𝜃)) → (((𝜓𝜑) → (𝜃𝜒)) → ((𝜑𝜓) → (𝜒𝜃))))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 196
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 197
This theorem is referenced by: (None)
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