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Theorem bj-nfnnfTEMP 34940
Description: New nonfreeness is equivalent to old nonfreeness on core FOL axioms plus sp 2176. (Contributed by BJ, 28-Jul-2023.) The proof should not rely on df-nf 1787 except via df-nf 1787 directly. (Proof modification is discouraged.)
Assertion
Ref Expression
bj-nfnnfTEMP (Ⅎ'𝑥𝜑 ↔ Ⅎ𝑥𝜑)

Proof of Theorem bj-nfnnfTEMP
StepHypRef Expression
1 bj-dfnnf3 34939 . 2 (Ⅎ'𝑥𝜑 ↔ (∃𝑥𝜑 → ∀𝑥𝜑))
2 df-nf 1787 . 2 (Ⅎ𝑥𝜑 ↔ (∃𝑥𝜑 → ∀𝑥𝜑))
31, 2bitr4i 277 1 (Ⅎ'𝑥𝜑 ↔ Ⅎ𝑥𝜑)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 205  wal 1537  wex 1782  wnf 1786  Ⅎ'wnnf 34905
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1913  ax-6 1971  ax-7 2011  ax-12 2171
This theorem depends on definitions:  df-bi 206  df-an 397  df-ex 1783  df-nf 1787  df-bj-nnf 34906
This theorem is referenced by: (None)
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