Theorem dvelimalcasei 35044

Description: Eliminate a disjoint variable condition from a universally quantified statement using cases. Inference form of dvelimalcased 35043. (Contributed by BTernaryTau, 31-Jul-2025.)

Hypotheses

Ref	Expression
dvelimalcasei.1	⊢ (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑥𝜑)
dvelimalcasei.2	⊢ (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑧𝜒)
dvelimalcasei.3	⊢ (¬ ∀𝑥 𝑥 = 𝑦 → (𝑧 = 𝑥 → (𝜑 → 𝜒)))
dvelimalcasei.4	⊢ (∀𝑥 𝑥 = 𝑦 → (𝜓 → 𝜒))
dvelimalcasei.5	⊢ ∀𝑧𝜑
dvelimalcasei.6	⊢ ∀𝑥𝜓

Assertion

Ref	Expression
dvelimalcasei	⊢ ∀𝑥𝜒

Distinct variable groups:   𝑥,𝑧   𝑦,𝑧

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

Proof of Theorem dvelimalcasei

Step	Hyp	Ref	Expression
1		nftru 1802	. . 3 ⊢ Ⅎ𝑥⊤
2		nfvd 1914	. . 3 ⊢ (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑧⊤)
3		dvelimalcasei.1	. . . 4 ⊢ (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑥𝜑)
4	3	adantl 481	. . 3 ⊢ ((⊤ ∧ ¬ ∀𝑥 𝑥 = 𝑦) → Ⅎ𝑥𝜑)
5		dvelimalcasei.2	. . . 4 ⊢ (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑧𝜒)
6	5	adantl 481	. . 3 ⊢ ((⊤ ∧ ¬ ∀𝑥 𝑥 = 𝑦) → Ⅎ𝑧𝜒)
7		dvelimalcasei.3	. . . 4 ⊢ (¬ ∀𝑥 𝑥 = 𝑦 → (𝑧 = 𝑥 → (𝜑 → 𝜒)))
8	7	adantl 481	. . 3 ⊢ ((⊤ ∧ ¬ ∀𝑥 𝑥 = 𝑦) → (𝑧 = 𝑥 → (𝜑 → 𝜒)))
9		dvelimalcasei.4	. . . 4 ⊢ (∀𝑥 𝑥 = 𝑦 → (𝜓 → 𝜒))
10	9	adantl 481	. . 3 ⊢ ((⊤ ∧ ∀𝑥 𝑥 = 𝑦) → (𝜓 → 𝜒))
11		dvelimalcasei.5	. . . 4 ⊢ ∀𝑧𝜑
12	11	a1i 11	. . 3 ⊢ (⊤ → ∀𝑧𝜑)
13		dvelimalcasei.6	. . . 4 ⊢ ∀𝑥𝜓
14	13	a1i 11	. . 3 ⊢ (⊤ → ∀𝑥𝜓)
15	1, 2, 4, 6, 8, 10, 12, 14	dvelimalcased 35043	. 2 ⊢ (⊤ → ∀𝑥𝜒)
16	15	mptru 1544	1 ⊢ ∀𝑥𝜒

Syntax hints:  ¬ wn 3   → wi 4  ∀wal 1535  ⊤wtru 1538  Ⅎwnf 1781

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1967  ax-7 2007  ax-10 2136  ax-11 2153  ax-12 2173

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 847  df-tru 1540  df-ex 1778  df-nf 1782

This theorem is referenced by: (None)