Theorem axtco1from2 36930

Description: Strong form axtco1 36928 of the Axiom of Transitive Containment, derived from the weak form axtco2 36929. See ax-tco 36927 for more information. As written, the proof uses ax-pr 5404 via el 5419, but we could alternatively use ax-pow 5336 via elALT2 5340. Use axtco1 36928 instead. (Contributed by Matthew House, 6-Apr-2026.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
axtco1from2	⊢ ∃𝑦(𝑥 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))

Distinct variable groups:   𝑥,𝑦   𝑦,𝑤,𝑧

Proof of Theorem axtco1from2

Dummy variables 𝑣 𝑢 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		elequ1 2148	. . . 4 ⊢ (𝑣 = 𝑥 → (𝑣 ∈ 𝑦 ↔ 𝑥 ∈ 𝑦))
2	1	anbi1d 642	. . 3 ⊢ (𝑣 = 𝑥 → ((𝑣 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦))) ↔ (𝑥 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))))
3	2	exbidv 1949	. 2 ⊢ (𝑣 = 𝑥 → (∃𝑦(𝑣 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦))) ↔ ∃𝑦(𝑥 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))))
4		axtco2 36929	. . . 4 ⊢ ∃𝑦∀𝑧((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦))
5		orc 880	. . . . . . . . 9 ⊢ (𝑧 = 𝑢 → (𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦))
6		elequ2 2156	. . . . . . . . . . 11 ⊢ (𝑧 = 𝑢 → (𝑣 ∈ 𝑧 ↔ 𝑣 ∈ 𝑢))
7	6	biimprd 251	. . . . . . . . . 10 ⊢ (𝑧 = 𝑢 → (𝑣 ∈ 𝑢 → 𝑣 ∈ 𝑧))
8		elequ1 2148	. . . . . . . . . . . 12 ⊢ (𝑤 = 𝑣 → (𝑤 ∈ 𝑧 ↔ 𝑣 ∈ 𝑧))
9		elequ1 2148	. . . . . . . . . . . 12 ⊢ (𝑤 = 𝑣 → (𝑤 ∈ 𝑦 ↔ 𝑣 ∈ 𝑦))
10	8, 9	imbi12d 347	. . . . . . . . . . 11 ⊢ (𝑤 = 𝑣 → ((𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦) ↔ (𝑣 ∈ 𝑧 → 𝑣 ∈ 𝑦)))
11	10	spvv 2016	. . . . . . . . . 10 ⊢ (∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦) → (𝑣 ∈ 𝑧 → 𝑣 ∈ 𝑦))
12	7, 11	syl9 78	. . . . . . . . 9 ⊢ (𝑧 = 𝑢 → (∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦) → (𝑣 ∈ 𝑢 → 𝑣 ∈ 𝑦)))
13	5, 12	embantd 60	. . . . . . . 8 ⊢ (𝑧 = 𝑢 → (((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)) → (𝑣 ∈ 𝑢 → 𝑣 ∈ 𝑦)))
14	13	spimvw 2014	. . . . . . 7 ⊢ (∀𝑧((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)) → (𝑣 ∈ 𝑢 → 𝑣 ∈ 𝑦))
15	14	com12 33	. . . . . 6 ⊢ (𝑣 ∈ 𝑢 → (∀𝑧((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)) → 𝑣 ∈ 𝑦))
16		olc 881	. . . . . . . 8 ⊢ (𝑧 ∈ 𝑦 → (𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦))
17	16	imim1i 64	. . . . . . 7 ⊢ (((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)) → (𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))
18	17	alimi 1839	. . . . . 6 ⊢ (∀𝑧((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)) → ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))
19	15, 18	jca2 522	. . . . 5 ⊢ (𝑣 ∈ 𝑢 → (∀𝑧((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)) → (𝑣 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))))
20	19	eximdv 1945	. . . 4 ⊢ (𝑣 ∈ 𝑢 → (∃𝑦∀𝑧((𝑧 = 𝑢 ∨ 𝑧 ∈ 𝑦) → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)) → ∃𝑦(𝑣 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))))
21	4, 20	mpi 21	. . 3 ⊢ (𝑣 ∈ 𝑢 → ∃𝑦(𝑣 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦))))
22		el 5419	. . 3 ⊢ ∃𝑢 𝑣 ∈ 𝑢
23	21, 22	exlimiiv 1959	. 2 ⊢ ∃𝑦(𝑣 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))
24	3, 23	chvarvv 2017	1 ⊢ ∃𝑦(𝑥 ∈ 𝑦 ∧ ∀𝑧(𝑧 ∈ 𝑦 → ∀𝑤(𝑤 ∈ 𝑧 → 𝑤 ∈ 𝑦)))

Syntax hints:   → wi 4   ∧ wa 400   ∨ wo 860  ∀wal 1566  ∃wex 1807

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1823  ax-4 1837  ax-5 1938  ax-6 1995  ax-7 2036  ax-8 2143  ax-9 2151  ax-pr 5404  ax-tco 36927

This theorem depends on definitions:  df-bi 210  df-an 401  df-or 861  df-ex 1808

This theorem is referenced by: (None)