Theorem dfac5 8834

Description: Equivalence of two versions of the Axiom of Choice. The right-hand side is Theorem 6M(4) of [Enderton] p. 151 and asserts that given a family of mutually disjoint nonempty sets, a set exists containing exactly one member from each set in the family. The proof does not depend on AC. (Contributed by NM, 11-Apr-2004.) (Revised by Mario Carneiro, 17-May-2015.)

Assertion

Ref	Expression
dfac5	⊢ (CHOICE ↔ ∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)))

Distinct variable group:   𝑥,𝑧,𝑦,𝑤,𝑣

Proof of Theorem dfac5

Dummy variables 𝑓 ℎ 𝑢 𝑡 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		dfac4 8828	. . 3 ⊢ (CHOICE ↔ ∀𝑥∃𝑓(𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤)))
2		neeq1 2844	. . . . . . . . . . . . 13 ⊢ (𝑧 = 𝑤 → (𝑧 ≠ ∅ ↔ 𝑤 ≠ ∅))
3	2	cbvralv 3147	. . . . . . . . . . . 12 ⊢ (∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ↔ ∀𝑤 ∈ 𝑥 𝑤 ≠ ∅)
4	3	anbi2i 726	. . . . . . . . . . 11 ⊢ ((∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ ∀𝑧 ∈ 𝑥 𝑧 ≠ ∅) ↔ (∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ ∀𝑤 ∈ 𝑥 𝑤 ≠ ∅))
5		r19.26 3046	. . . . . . . . . . 11 ⊢ (∀𝑤 ∈ 𝑥 ((𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑤 ≠ ∅) ↔ (∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ ∀𝑤 ∈ 𝑥 𝑤 ≠ ∅))
6	4, 5	bitr4i 266	. . . . . . . . . 10 ⊢ ((∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ ∀𝑧 ∈ 𝑥 𝑧 ≠ ∅) ↔ ∀𝑤 ∈ 𝑥 ((𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑤 ≠ ∅))
7		pm3.35 609	. . . . . . . . . . . 12 ⊢ ((𝑤 ≠ ∅ ∧ (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤)) → (𝑓‘𝑤) ∈ 𝑤)
8	7	ancoms 468	. . . . . . . . . . 11 ⊢ (((𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑤 ≠ ∅) → (𝑓‘𝑤) ∈ 𝑤)
9	8	ralimi 2936	. . . . . . . . . 10 ⊢ (∀𝑤 ∈ 𝑥 ((𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑤 ≠ ∅) → ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤)
10	6, 9	sylbi 206	. . . . . . . . 9 ⊢ ((∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ ∀𝑧 ∈ 𝑥 𝑧 ≠ ∅) → ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤)
11		r19.26 3046	. . . . . . . . . . . . . . . . . 18 ⊢ (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) ↔ (∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 ∧ ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)))
12		elin 3758	. . . . . . . . . . . . . . . . . . 19 ⊢ (𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ (𝑣 ∈ 𝑧 ∧ 𝑣 ∈ ran 𝑓))
13		fvelrnb 6153	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (𝑓 Fn 𝑥 → (𝑣 ∈ ran 𝑓 ↔ ∃𝑡 ∈ 𝑥 (𝑓‘𝑡) = 𝑣))
14	13	biimpac 502	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ ((𝑣 ∈ ran 𝑓 ∧ 𝑓 Fn 𝑥) → ∃𝑡 ∈ 𝑥 (𝑓‘𝑡) = 𝑣)
15		fveq2 6103	. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ⊢ (𝑤 = 𝑡 → (𝑓‘𝑤) = (𝑓‘𝑡))
16		id 22	. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ⊢ (𝑤 = 𝑡 → 𝑤 = 𝑡)
17	15, 16	eleq12d 2682	. . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ⊢ (𝑤 = 𝑡 → ((𝑓‘𝑤) ∈ 𝑤 ↔ (𝑓‘𝑡) ∈ 𝑡))
18		neeq2 2845	. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ⊢ (𝑤 = 𝑡 → (𝑧 ≠ 𝑤 ↔ 𝑧 ≠ 𝑡))
19		ineq2 3770	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 ⊢ (𝑤 = 𝑡 → (𝑧 ∩ 𝑤) = (𝑧 ∩ 𝑡))
20	19	eqeq1d 2612	. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ⊢ (𝑤 = 𝑡 → ((𝑧 ∩ 𝑤) = ∅ ↔ (𝑧 ∩ 𝑡) = ∅))
21	18, 20	imbi12d 333	. . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ⊢ (𝑤 = 𝑡 → ((𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) ↔ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)))
22	17, 21	anbi12d 743	. . . . . . . . . . . . . . . . . . . . . . . . . . 27 ⊢ (𝑤 = 𝑡 → (((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) ↔ ((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅))))
23	22	rspcv 3278	. . . . . . . . . . . . . . . . . . . . . . . . . 26 ⊢ (𝑡 ∈ 𝑥 → (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅))))
24		eleq1 2676	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 ⊢ ((𝑓‘𝑡) = 𝑣 → ((𝑓‘𝑡) ∈ 𝑧 ↔ 𝑣 ∈ 𝑧))
25	24	biimpar 501	. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ⊢ (((𝑓‘𝑡) = 𝑣 ∧ 𝑣 ∈ 𝑧) → (𝑓‘𝑡) ∈ 𝑧)
26		minel 3985	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 ⊢ (((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ∩ 𝑡) = ∅) → ¬ (𝑓‘𝑡) ∈ 𝑧)
27	26	ex 449	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 ⊢ ((𝑓‘𝑡) ∈ 𝑡 → ((𝑧 ∩ 𝑡) = ∅ → ¬ (𝑓‘𝑡) ∈ 𝑧))
28	27	imim2d 55	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 ⊢ ((𝑓‘𝑡) ∈ 𝑡 → ((𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅) → (𝑧 ≠ 𝑡 → ¬ (𝑓‘𝑡) ∈ 𝑧)))
29	28	imp 444	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 ⊢ (((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)) → (𝑧 ≠ 𝑡 → ¬ (𝑓‘𝑡) ∈ 𝑧))
30	29	necon4ad 2801	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 ⊢ (((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)) → ((𝑓‘𝑡) ∈ 𝑧 → 𝑧 = 𝑡))
31	30	imp 444	. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ⊢ ((((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)) ∧ (𝑓‘𝑡) ∈ 𝑧) → 𝑧 = 𝑡)
32	25, 31	sylan2 490	. . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ⊢ ((((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)) ∧ ((𝑓‘𝑡) = 𝑣 ∧ 𝑣 ∈ 𝑧)) → 𝑧 = 𝑡)
33		fveq2 6103	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 ⊢ (𝑧 = 𝑡 → (𝑓‘𝑧) = (𝑓‘𝑡))
34		eqeq2 2621	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 ⊢ ((𝑓‘𝑡) = 𝑣 → ((𝑓‘𝑧) = (𝑓‘𝑡) ↔ (𝑓‘𝑧) = 𝑣))
35		eqcom 2617	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 ⊢ ((𝑓‘𝑧) = 𝑣 ↔ 𝑣 = (𝑓‘𝑧))
36	34, 35	syl6bb 275	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 ⊢ ((𝑓‘𝑡) = 𝑣 → ((𝑓‘𝑧) = (𝑓‘𝑡) ↔ 𝑣 = (𝑓‘𝑧)))
37	33, 36	syl5ib 233	. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ⊢ ((𝑓‘𝑡) = 𝑣 → (𝑧 = 𝑡 → 𝑣 = (𝑓‘𝑧)))
38	37	ad2antrl 760	. . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ⊢ ((((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)) ∧ ((𝑓‘𝑡) = 𝑣 ∧ 𝑣 ∈ 𝑧)) → (𝑧 = 𝑡 → 𝑣 = (𝑓‘𝑧)))
39	32, 38	mpd 15	. . . . . . . . . . . . . . . . . . . . . . . . . . 27 ⊢ ((((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)) ∧ ((𝑓‘𝑡) = 𝑣 ∧ 𝑣 ∈ 𝑧)) → 𝑣 = (𝑓‘𝑧))
40	39	exp32 629	. . . . . . . . . . . . . . . . . . . . . . . . . 26 ⊢ (((𝑓‘𝑡) ∈ 𝑡 ∧ (𝑧 ≠ 𝑡 → (𝑧 ∩ 𝑡) = ∅)) → ((𝑓‘𝑡) = 𝑣 → (𝑣 ∈ 𝑧 → 𝑣 = (𝑓‘𝑧))))
41	23, 40	syl6com 36	. . . . . . . . . . . . . . . . . . . . . . . . 25 ⊢ (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → (𝑡 ∈ 𝑥 → ((𝑓‘𝑡) = 𝑣 → (𝑣 ∈ 𝑧 → 𝑣 = (𝑓‘𝑧)))))
42	41	com14 94	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (𝑣 ∈ 𝑧 → (𝑡 ∈ 𝑥 → ((𝑓‘𝑡) = 𝑣 → (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → 𝑣 = (𝑓‘𝑧)))))
43	42	rexlimdv 3012	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝑣 ∈ 𝑧 → (∃𝑡 ∈ 𝑥 (𝑓‘𝑡) = 𝑣 → (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → 𝑣 = (𝑓‘𝑧))))
44	14, 43	syl5 33	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ (𝑣 ∈ 𝑧 → ((𝑣 ∈ ran 𝑓 ∧ 𝑓 Fn 𝑥) → (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → 𝑣 = (𝑓‘𝑧))))
45	44	expd 451	. . . . . . . . . . . . . . . . . . . . 21 ⊢ (𝑣 ∈ 𝑧 → (𝑣 ∈ ran 𝑓 → (𝑓 Fn 𝑥 → (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → 𝑣 = (𝑓‘𝑧)))))
46	45	com4t 91	. . . . . . . . . . . . . . . . . . . 20 ⊢ (𝑓 Fn 𝑥 → (∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → (𝑣 ∈ 𝑧 → (𝑣 ∈ ran 𝑓 → 𝑣 = (𝑓‘𝑧)))))
47	46	imp4b 611	. . . . . . . . . . . . . . . . . . 19 ⊢ ((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅))) → ((𝑣 ∈ 𝑧 ∧ 𝑣 ∈ ran 𝑓) → 𝑣 = (𝑓‘𝑧)))
48	12, 47	syl5bi 231	. . . . . . . . . . . . . . . . . 18 ⊢ ((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 ((𝑓‘𝑤) ∈ 𝑤 ∧ (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅))) → (𝑣 ∈ (𝑧 ∩ ran 𝑓) → 𝑣 = (𝑓‘𝑧)))
49	11, 48	sylan2br 492	. . . . . . . . . . . . . . . . 17 ⊢ ((𝑓 Fn 𝑥 ∧ (∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 ∧ ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅))) → (𝑣 ∈ (𝑧 ∩ ran 𝑓) → 𝑣 = (𝑓‘𝑧)))
50	49	anassrs 678	. . . . . . . . . . . . . . . 16 ⊢ (((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → (𝑣 ∈ (𝑧 ∩ ran 𝑓) → 𝑣 = (𝑓‘𝑧)))
51	50	adantlr 747	. . . . . . . . . . . . . . 15 ⊢ ((((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) ∧ ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → (𝑣 ∈ (𝑧 ∩ ran 𝑓) → 𝑣 = (𝑓‘𝑧)))
52		fveq2 6103	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (𝑤 = 𝑧 → (𝑓‘𝑤) = (𝑓‘𝑧))
53		id 22	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (𝑤 = 𝑧 → 𝑤 = 𝑧)
54	52, 53	eleq12d 2682	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝑤 = 𝑧 → ((𝑓‘𝑤) ∈ 𝑤 ↔ (𝑓‘𝑧) ∈ 𝑧))
55	54	rspcv 3278	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ (𝑧 ∈ 𝑥 → (∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 → (𝑓‘𝑧) ∈ 𝑧))
56		fnfvelrn 6264	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ ((𝑓 Fn 𝑥 ∧ 𝑧 ∈ 𝑥) → (𝑓‘𝑧) ∈ ran 𝑓)
57	56	expcom 450	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ (𝑧 ∈ 𝑥 → (𝑓 Fn 𝑥 → (𝑓‘𝑧) ∈ ran 𝑓))
58	55, 57	anim12d 584	. . . . . . . . . . . . . . . . . . . . 21 ⊢ (𝑧 ∈ 𝑥 → ((∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 ∧ 𝑓 Fn 𝑥) → ((𝑓‘𝑧) ∈ 𝑧 ∧ (𝑓‘𝑧) ∈ ran 𝑓)))
59		elin 3758	. . . . . . . . . . . . . . . . . . . . 21 ⊢ ((𝑓‘𝑧) ∈ (𝑧 ∩ ran 𝑓) ↔ ((𝑓‘𝑧) ∈ 𝑧 ∧ (𝑓‘𝑧) ∈ ran 𝑓))
60	58, 59	syl6ibr 241	. . . . . . . . . . . . . . . . . . . 20 ⊢ (𝑧 ∈ 𝑥 → ((∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 ∧ 𝑓 Fn 𝑥) → (𝑓‘𝑧) ∈ (𝑧 ∩ ran 𝑓)))
61	60	expd 451	. . . . . . . . . . . . . . . . . . 19 ⊢ (𝑧 ∈ 𝑥 → (∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 → (𝑓 Fn 𝑥 → (𝑓‘𝑧) ∈ (𝑧 ∩ ran 𝑓))))
62	61	com13 86	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓 Fn 𝑥 → (∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 → (𝑧 ∈ 𝑥 → (𝑓‘𝑧) ∈ (𝑧 ∩ ran 𝑓))))
63	62	imp31 447	. . . . . . . . . . . . . . . . 17 ⊢ (((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) → (𝑓‘𝑧) ∈ (𝑧 ∩ ran 𝑓))
64		eleq1 2676	. . . . . . . . . . . . . . . . 17 ⊢ (𝑣 = (𝑓‘𝑧) → (𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ (𝑓‘𝑧) ∈ (𝑧 ∩ ran 𝑓)))
65	63, 64	syl5ibrcom 236	. . . . . . . . . . . . . . . 16 ⊢ (((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) → (𝑣 = (𝑓‘𝑧) → 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
66	65	adantr 480	. . . . . . . . . . . . . . 15 ⊢ ((((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) ∧ ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → (𝑣 = (𝑓‘𝑧) → 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
67	51, 66	impbid 201	. . . . . . . . . . . . . 14 ⊢ ((((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) ∧ ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → (𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = (𝑓‘𝑧)))
68	67	ex 449	. . . . . . . . . . . . 13 ⊢ (((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) → (∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) → (𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = (𝑓‘𝑧))))
69	68	alrimdv 1844	. . . . . . . . . . . 12 ⊢ (((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) → (∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) → ∀𝑣(𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = (𝑓‘𝑧))))
70		fvex 6113	. . . . . . . . . . . . . 14 ⊢ (𝑓‘𝑧) ∈ V
71		eqeq2 2621	. . . . . . . . . . . . . . . 16 ⊢ (ℎ = (𝑓‘𝑧) → (𝑣 = ℎ ↔ 𝑣 = (𝑓‘𝑧)))
72	71	bibi2d 331	. . . . . . . . . . . . . . 15 ⊢ (ℎ = (𝑓‘𝑧) → ((𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = ℎ) ↔ (𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = (𝑓‘𝑧))))
73	72	albidv 1836	. . . . . . . . . . . . . 14 ⊢ (ℎ = (𝑓‘𝑧) → (∀𝑣(𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = ℎ) ↔ ∀𝑣(𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = (𝑓‘𝑧))))
74	70, 73	spcev 3273	. . . . . . . . . . . . 13 ⊢ (∀𝑣(𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = (𝑓‘𝑧)) → ∃ℎ∀𝑣(𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = ℎ))
75		df-eu 2462	. . . . . . . . . . . . 13 ⊢ (∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ ∃ℎ∀𝑣(𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = ℎ))
76	74, 75	sylibr 223	. . . . . . . . . . . 12 ⊢ (∀𝑣(𝑣 ∈ (𝑧 ∩ ran 𝑓) ↔ 𝑣 = (𝑓‘𝑧)) → ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓))
77	69, 76	syl6 34	. . . . . . . . . . 11 ⊢ (((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) ∧ 𝑧 ∈ 𝑥) → (∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) → ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
78	77	ralimdva 2945	. . . . . . . . . 10 ⊢ ((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤) → (∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) → ∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
79	78	ex 449	. . . . . . . . 9 ⊢ (𝑓 Fn 𝑥 → (∀𝑤 ∈ 𝑥 (𝑓‘𝑤) ∈ 𝑤 → (∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) → ∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓))))
80	10, 79	syl5 33	. . . . . . . 8 ⊢ (𝑓 Fn 𝑥 → ((∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) ∧ ∀𝑧 ∈ 𝑥 𝑧 ≠ ∅) → (∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) → ∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓))))
81	80	expd 451	. . . . . . 7 ⊢ (𝑓 Fn 𝑥 → (∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤) → (∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ → (∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅) → ∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓)))))
82	81	imp4b 611	. . . . . 6 ⊢ ((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤)) → ((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
83		vex 3176	. . . . . . . 8 ⊢ 𝑓 ∈ V
84	83	rnex 6992	. . . . . . 7 ⊢ ran 𝑓 ∈ V
85		ineq2 3770	. . . . . . . . . 10 ⊢ (𝑦 = ran 𝑓 → (𝑧 ∩ 𝑦) = (𝑧 ∩ ran 𝑓))
86	85	eleq2d 2673	. . . . . . . . 9 ⊢ (𝑦 = ran 𝑓 → (𝑣 ∈ (𝑧 ∩ 𝑦) ↔ 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
87	86	eubidv 2478	. . . . . . . 8 ⊢ (𝑦 = ran 𝑓 → (∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦) ↔ ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
88	87	ralbidv 2969	. . . . . . 7 ⊢ (𝑦 = ran 𝑓 → (∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦) ↔ ∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓)))
89	84, 88	spcev 3273	. . . . . 6 ⊢ (∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ ran 𝑓) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦))
90	82, 89	syl6 34	. . . . 5 ⊢ ((𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤)) → ((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)))
91	90	exlimiv 1845	. . . 4 ⊢ (∃𝑓(𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤)) → ((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)))
92	91	alimi 1730	. . 3 ⊢ (∀𝑥∃𝑓(𝑓 Fn 𝑥 ∧ ∀𝑤 ∈ 𝑥 (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤)) → ∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)))
93	1, 92	sylbi 206	. 2 ⊢ (CHOICE → ∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)))
94		eqid 2610	. . . . 5 ⊢ {𝑢 ∣ (𝑢 ≠ ∅ ∧ ∃𝑡 ∈ ℎ 𝑢 = ({𝑡} × 𝑡))} = {𝑢 ∣ (𝑢 ≠ ∅ ∧ ∃𝑡 ∈ ℎ 𝑢 = ({𝑡} × 𝑡))}
95		eqid 2610	. . . . 5 ⊢ (∪ {𝑢 ∣ (𝑢 ≠ ∅ ∧ ∃𝑡 ∈ ℎ 𝑢 = ({𝑡} × 𝑡))} ∩ 𝑦) = (∪ {𝑢 ∣ (𝑢 ≠ ∅ ∧ ∃𝑡 ∈ ℎ 𝑢 = ({𝑡} × 𝑡))} ∩ 𝑦)
96		biid 250	. . . . 5 ⊢ (∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)) ↔ ∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)))
97	94, 95, 96	dfac5lem5 8833	. . . 4 ⊢ (∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)) → ∃𝑓∀𝑤 ∈ ℎ (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤))
98	97	alrimiv 1842	. . 3 ⊢ (∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)) → ∀ℎ∃𝑓∀𝑤 ∈ ℎ (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤))
99		dfac3 8827	. . 3 ⊢ (CHOICE ↔ ∀ℎ∃𝑓∀𝑤 ∈ ℎ (𝑤 ≠ ∅ → (𝑓‘𝑤) ∈ 𝑤))
100	98, 99	sylibr 223	. 2 ⊢ (∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)) → CHOICE)
101	93, 100	impbii 198	1 ⊢ (CHOICE ↔ ∀𝑥((∀𝑧 ∈ 𝑥 𝑧 ≠ ∅ ∧ ∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑥 (𝑧 ≠ 𝑤 → (𝑧 ∩ 𝑤) = ∅)) → ∃𝑦∀𝑧 ∈ 𝑥 ∃!𝑣 𝑣 ∈ (𝑧 ∩ 𝑦)))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 195   ∧ wa 383  ∀wal 1473   = wceq 1475  ∃wex 1695   ∈ wcel 1977  ∃!weu 2458  {cab 2596   ≠ wne 2780  ∀wral 2896  ∃wrex 2897   ∩ cin 3539  ∅c0 3874  {csn 4125  ∪ cuni 4372   × cxp 5036  ran crn 5039   Fn wfn 5799  ‘cfv 5804  CHOICEwac 8821

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-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833  ax-un 6847

This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ne 2782  df-ral 2901  df-rex 2902  df-rab 2905  df-v 3175  df-sbc 3403  df-csb 3500  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-if 4037  df-pw 4110  df-sn 4126  df-pr 4128  df-op 4132  df-uni 4373  df-br 4584  df-opab 4644  df-mpt 4645  df-id 4953  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-rn 5049  df-res 5050  df-ima 5051  df-iota 5768  df-fun 5806  df-fn 5807  df-f 5808  df-fv 5812  df-ac 8822

This theorem is referenced by:  dfackm  8871  ac8  9197