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Theorem elnelall 2454
Description: A contradiction concerning membership implies anything. (Contributed by Alexander van der Vekens, 25-Jan-2018.)
Assertion
Ref Expression
elnelall (𝐴𝐵 → (𝐴𝐵𝜑))

Proof of Theorem elnelall
StepHypRef Expression
1 df-nel 2443 . 2 (𝐴𝐵 ↔ ¬ 𝐴𝐵)
2 pm2.24 621 . 2 (𝐴𝐵 → (¬ 𝐴𝐵𝜑))
31, 2biimtrid 152 1 (𝐴𝐵 → (𝐴𝐵𝜑))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wcel 2148  wnel 2442
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-in2 615
This theorem depends on definitions:  df-bi 117  df-nel 2443
This theorem is referenced by:  xnn0lenn0nn0  9849
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