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Theorem nd5 1806
Description: A lemma for proving conditionless ZFC axioms. (Contributed by NM, 8-Jan-2002.)
Assertion
Ref Expression
nd5 (¬ ∀𝑦 𝑦 = 𝑥 → (𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦))
Distinct variable group:   𝑥,𝑧

Proof of Theorem nd5
StepHypRef Expression
1 dveeq2 1803 . 2 (¬ ∀𝑥 𝑥 = 𝑦 → (𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦))
21nalequcoms 1505 1 (¬ ∀𝑦 𝑦 = 𝑥 → (𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wal 1341   = wceq 1343
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605  ax-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522
This theorem depends on definitions:  df-bi 116  df-nf 1449  df-sb 1751
This theorem is referenced by: (None)
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