Theorem reusv2lem2 5398

Description: Lemma for reusv2 5402. (Contributed by NM, 27-Oct-2010.) (Proof shortened by Mario Carneiro, 19-Nov-2016.) (Proof shortened by JJ, 7-Aug-2021.)

Assertion

Ref	Expression
reusv2lem2	⊢ (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵)

Distinct variable groups:   𝑥,𝑦,𝐴   𝑥,𝐵

Allowed substitution hint:   𝐵(𝑦)

Proof of Theorem reusv2lem2

Dummy variable 𝑧 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		eunex 5389	. . . . 5 ⊢ (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃𝑥 ¬ ∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
2		exnal 1830	. . . . 5 ⊢ (∃𝑥 ¬ ∀𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ¬ ∀𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
3	1, 2	sylib 217	. . . 4 ⊢ (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ¬ ∀𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
4		rzal 4509	. . . . 5 ⊢ (𝐴 = ∅ → ∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
5	4	alrimiv 1931	. . . 4 ⊢ (𝐴 = ∅ → ∀𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
6	3, 5	nsyl3 138	. . 3 ⊢ (𝐴 = ∅ → ¬ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
7	6	pm2.21d 121	. 2 ⊢ (𝐴 = ∅ → (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵))
8		simpr 486	. . . 4 ⊢ ((𝐴 ≠ ∅ ∧ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵) → ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
9		nfra1 3282	. . . . . . . . . . 11 ⊢ Ⅎ𝑦∀𝑦 ∈ 𝐴 𝑧 = 𝐵
10		nfra1 3282	. . . . . . . . . . 11 ⊢ Ⅎ𝑦∀𝑦 ∈ 𝐴 𝑥 = 𝐵
11		simpr 486	. . . . . . . . . . . . . 14 ⊢ (((∀𝑦 ∈ 𝐴 𝑧 = 𝐵 ∧ 𝑦 ∈ 𝐴) ∧ 𝑥 = 𝐵) → 𝑥 = 𝐵)
12		rspa 3246	. . . . . . . . . . . . . . 15 ⊢ ((∀𝑦 ∈ 𝐴 𝑧 = 𝐵 ∧ 𝑦 ∈ 𝐴) → 𝑧 = 𝐵)
13	12	adantr 482	. . . . . . . . . . . . . 14 ⊢ (((∀𝑦 ∈ 𝐴 𝑧 = 𝐵 ∧ 𝑦 ∈ 𝐴) ∧ 𝑥 = 𝐵) → 𝑧 = 𝐵)
14	11, 13	eqtr4d 2776	. . . . . . . . . . . . 13 ⊢ (((∀𝑦 ∈ 𝐴 𝑧 = 𝐵 ∧ 𝑦 ∈ 𝐴) ∧ 𝑥 = 𝐵) → 𝑥 = 𝑧)
15		eqeq1 2737	. . . . . . . . . . . . . . . 16 ⊢ (𝑥 = 𝑧 → (𝑥 = 𝐵 ↔ 𝑧 = 𝐵))
16	15	ralbidv 3178	. . . . . . . . . . . . . . 15 ⊢ (𝑥 = 𝑧 → (∀𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∀𝑦 ∈ 𝐴 𝑧 = 𝐵))
17	16	biimprcd 249	. . . . . . . . . . . . . 14 ⊢ (∀𝑦 ∈ 𝐴 𝑧 = 𝐵 → (𝑥 = 𝑧 → ∀𝑦 ∈ 𝐴 𝑥 = 𝐵))
18	17	ad2antrr 725	. . . . . . . . . . . . 13 ⊢ (((∀𝑦 ∈ 𝐴 𝑧 = 𝐵 ∧ 𝑦 ∈ 𝐴) ∧ 𝑥 = 𝐵) → (𝑥 = 𝑧 → ∀𝑦 ∈ 𝐴 𝑥 = 𝐵))
19	14, 18	mpd 15	. . . . . . . . . . . 12 ⊢ (((∀𝑦 ∈ 𝐴 𝑧 = 𝐵 ∧ 𝑦 ∈ 𝐴) ∧ 𝑥 = 𝐵) → ∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
20	19	exp31 421	. . . . . . . . . . 11 ⊢ (∀𝑦 ∈ 𝐴 𝑧 = 𝐵 → (𝑦 ∈ 𝐴 → (𝑥 = 𝐵 → ∀𝑦 ∈ 𝐴 𝑥 = 𝐵)))
21	9, 10, 20	rexlimd 3264	. . . . . . . . . 10 ⊢ (∀𝑦 ∈ 𝐴 𝑧 = 𝐵 → (∃𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∀𝑦 ∈ 𝐴 𝑥 = 𝐵))
22	21	adantl 483	. . . . . . . . 9 ⊢ ((𝐴 ≠ ∅ ∧ ∀𝑦 ∈ 𝐴 𝑧 = 𝐵) → (∃𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∀𝑦 ∈ 𝐴 𝑥 = 𝐵))
23		r19.2z 4495	. . . . . . . . . . 11 ⊢ ((𝐴 ≠ ∅ ∧ ∀𝑦 ∈ 𝐴 𝑥 = 𝐵) → ∃𝑦 ∈ 𝐴 𝑥 = 𝐵)
24	23	ex 414	. . . . . . . . . 10 ⊢ (𝐴 ≠ ∅ → (∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃𝑦 ∈ 𝐴 𝑥 = 𝐵))
25	24	adantr 482	. . . . . . . . 9 ⊢ ((𝐴 ≠ ∅ ∧ ∀𝑦 ∈ 𝐴 𝑧 = 𝐵) → (∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃𝑦 ∈ 𝐴 𝑥 = 𝐵))
26	22, 25	impbid 211	. . . . . . . 8 ⊢ ((𝐴 ≠ ∅ ∧ ∀𝑦 ∈ 𝐴 𝑧 = 𝐵) → (∃𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∀𝑦 ∈ 𝐴 𝑥 = 𝐵))
27	26	eubidv 2581	. . . . . . 7 ⊢ ((𝐴 ≠ ∅ ∧ ∀𝑦 ∈ 𝐴 𝑧 = 𝐵) → (∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵))
28	27	ex 414	. . . . . 6 ⊢ (𝐴 ≠ ∅ → (∀𝑦 ∈ 𝐴 𝑧 = 𝐵 → (∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)))
29	28	exlimdv 1937	. . . . 5 ⊢ (𝐴 ≠ ∅ → (∃𝑧∀𝑦 ∈ 𝐴 𝑧 = 𝐵 → (∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)))
30		euex 2572	. . . . . 6 ⊢ (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)
31	16	cbvexvw 2041	. . . . . 6 ⊢ (∃𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∃𝑧∀𝑦 ∈ 𝐴 𝑧 = 𝐵)
32	30, 31	sylib 217	. . . . 5 ⊢ (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃𝑧∀𝑦 ∈ 𝐴 𝑧 = 𝐵)
33	29, 32	impel 507	. . . 4 ⊢ ((𝐴 ≠ ∅ ∧ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵) → (∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵))
34	8, 33	mpbird 257	. . 3 ⊢ ((𝐴 ≠ ∅ ∧ ∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵) → ∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵)
35	34	ex 414	. 2 ⊢ (𝐴 ≠ ∅ → (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵))
36	7, 35	pm2.61ine 3026	1 ⊢ (∃!𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵 → ∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 205   ∧ wa 397  ∀wal 1540   = wceq 1542  ∃wex 1782   ∈ wcel 2107  ∃!weu 2563   ≠ wne 2941  ∀wral 3062  ∃wrex 3071  ∅c0 4323

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2109  ax-9 2117  ax-10 2138  ax-12 2172  ax-ext 2704  ax-nul 5307  ax-pow 5364

This theorem depends on definitions:  df-bi 206  df-an 398  df-or 847  df-tru 1545  df-fal 1555  df-ex 1783  df-nf 1787  df-sb 2069  df-mo 2535  df-eu 2564  df-clab 2711  df-cleq 2725  df-ne 2942  df-ral 3063  df-rex 3072  df-dif 3952  df-nul 4324

This theorem is referenced by:  reusv2lem3  5399