Theorem dvelimv 2463

Description: Similar to dvelim 2462 with first hypothesis replaced by a distinct variable condition. Usage of this theorem is discouraged because it depends on ax-13 2379. Check out dvelimhw 2355 for a version requiring fewer axioms. (Contributed by NM, 25-Jul-2015.) (Proof shortened by Wolf Lammen, 30-Apr-2018.) (New usage is discouraged.)

Hypothesis

Ref	Expression
dvelimv.1	⊢ (𝑧 = 𝑦 → (𝜑 ↔ 𝜓))

Assertion

Ref	Expression
dvelimv	⊢ (¬ ∀𝑥 𝑥 = 𝑦 → (𝜓 → ∀𝑥𝜓))

Distinct variable groups:   𝜑,𝑥   𝜓,𝑧

Allowed substitution hints:   𝜑(𝑦,𝑧)   𝜓(𝑥,𝑦)

Proof of Theorem dvelimv

Step	Hyp	Ref	Expression
1		ax-5 1911	. 2 ⊢ (𝜑 → ∀𝑥𝜑)
2		dvelimv.1	. 2 ⊢ (𝑧 = 𝑦 → (𝜑 ↔ 𝜓))
3	1, 2	dvelim 2462	1 ⊢ (¬ ∀𝑥 𝑥 = 𝑦 → (𝜓 → ∀𝑥𝜓))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 209  ∀wal 1536

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-10 2142  ax-11 2158  ax-12 2175  ax-13 2379

This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-tru 1541  df-ex 1782  df-nf 1786

This theorem is referenced by:  dveeq2ALT  2465  dveel1  2473  dveel2  2474  rgen2a  3193