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Theorem bian1d 32484
Description: Adding a superfluous conjunct in a biconditional. (Contributed by Thierry Arnoux, 26-Feb-2017.) (Proof shortened by Hongxiu Chen, 29-Jun-2025.)
Hypothesis
Ref Expression
bian1d.1 (𝜑 → (𝜓 ↔ (𝜒𝜃)))
Assertion
Ref Expression
bian1d (𝜑 → ((𝜒𝜓) ↔ (𝜒𝜃)))

Proof of Theorem bian1d
StepHypRef Expression
1 bian1d.1 . . . 4 (𝜑 → (𝜓 ↔ (𝜒𝜃)))
2 ibar 528 . . . . 5 (𝜒 → (𝜃 ↔ (𝜒𝜃)))
32bicomd 223 . . . 4 (𝜒 → ((𝜒𝜃) ↔ 𝜃))
41, 3sylan9bb 509 . . 3 ((𝜑𝜒) → (𝜓𝜃))
54ex 412 . 2 (𝜑 → (𝜒 → (𝜓𝜃)))
65pm5.32d 576 1 (𝜑 → ((𝜒𝜓) ↔ (𝜒𝜃)))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 206  wa 395
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 207  df-an 396
This theorem is referenced by:  funcnvmpt  32685
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