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Theorem nfnf1OLD 2306
Description: Obsolete proof of nfnf1 2180 as of 12-Oct-2021. (Contributed by Mario Carneiro, 11-Aug-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
nfnf1OLD 𝑥𝑥𝜑

Proof of Theorem nfnf1OLD
StepHypRef Expression
1 nf5 2263 . 2 (Ⅎ𝑥𝜑 ↔ ∀𝑥(𝜑 → ∀𝑥𝜑))
2 nfa1 2177 . 2 𝑥𝑥(𝜑 → ∀𝑥𝜑)
31, 2nfxfr 1928 1 𝑥𝑥𝜑
Colors of variables: wff setvar class
Syntax hints:  wi 4  wal 1630  wnf 1857
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1871  ax-4 1886  ax-5 1988  ax-6 2054  ax-7 2090  ax-10 2168  ax-12 2196
This theorem depends on definitions:  df-bi 197  df-or 384  df-ex 1854  df-nf 1859
This theorem is referenced by: (None)
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