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Theorem neqned 2213
Description: If it is not the case that two classes are equal, they are unequal. Converse of neneqd 2226. One-way deduction form of df-ne 2206. (Contributed by David Moews, 28-Feb-2017.) Allow a shortening of necon3bi 2255. (Revised by Wolf Lammen, 22-Nov-2019.)
Hypothesis
Ref Expression
neqned.1 (𝜑 → ¬ 𝐴 = 𝐵)
Assertion
Ref Expression
neqned (𝜑𝐴𝐵)

Proof of Theorem neqned
StepHypRef Expression
1 neqned.1 . 2 (𝜑 → ¬ 𝐴 = 𝐵)
2 df-ne 2206 . 2 (𝐴𝐵 ↔ ¬ 𝐴 = 𝐵)
31, 2sylibr 137 1 (𝜑𝐴𝐵)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4   = wceq 1243  wne 2204
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101
This theorem depends on definitions:  df-bi 110  df-ne 2206
This theorem is referenced by:  neqne  2214  flqltnz  9129
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