Theorem nf5di 2105

Description: Since the converse holds by a1i 11, this inference shows that we can represent a not-free hypothesis with either Ⅎ𝑥𝜑 (inference form) or (𝜑 → Ⅎ𝑥𝜑) (deduction form). (Contributed by NM, 17-Aug-2018.) (Proof shortened by Wolf Lammen, 10-Jul-2019.)

Hypothesis

Ref	Expression
nf5di.1	⊢ (𝜑 → Ⅎ𝑥𝜑)

Assertion

Ref	Expression
nf5di	⊢ Ⅎ𝑥𝜑

Proof of Theorem nf5di

Step	Hyp	Ref	Expression
1		nf5di.1	. . . 4 ⊢ (𝜑 → Ⅎ𝑥𝜑)
2	1	nf5rd 2054	. . 3 ⊢ (𝜑 → (𝜑 → ∀𝑥𝜑))
3	2	pm2.43i 50	. 2 ⊢ (𝜑 → ∀𝑥𝜑)
4	3	nf5i 2011	1 ⊢ Ⅎ𝑥𝜑

Syntax hints:   → wi 4  ∀wal 1473  Ⅎwnf 1699

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-10 2006  ax-12 2034

This theorem depends on definitions:  df-bi 196  df-ex 1696  df-nf 1701

This theorem is referenced by: (None)