Theorem eusvnf 4500

Description: Even if 𝑥 is free in 𝐴, it is effectively bound when 𝐴(𝑥) is single-valued. (Contributed by NM, 14-Oct-2010.) (Revised by Mario Carneiro, 14-Oct-2016.)

Assertion

Ref	Expression
eusvnf	⊢ (∃!𝑦∀𝑥 𝑦 = 𝐴 → Ⅎ𝑥𝐴)

Distinct variable groups:   𝑥,𝑦   𝑦,𝐴

Allowed substitution hint:   𝐴(𝑥)

Proof of Theorem eusvnf

Dummy variables 𝑧 𝑤 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		euex 2084	. 2 ⊢ (∃!𝑦∀𝑥 𝑦 = 𝐴 → ∃𝑦∀𝑥 𝑦 = 𝐴)
2		vex 2775	. . . . . . 7 ⊢ 𝑧 ∈ V
3		nfcv 2348	. . . . . . . 8 ⊢ Ⅎ𝑥𝑧
4		nfcsb1v 3126	. . . . . . . . 9 ⊢ Ⅎ𝑥⦋𝑧 / 𝑥⦌𝐴
5	4	nfeq2 2360	. . . . . . . 8 ⊢ Ⅎ𝑥 𝑦 = ⦋𝑧 / 𝑥⦌𝐴
6		csbeq1a 3102	. . . . . . . . 9 ⊢ (𝑥 = 𝑧 → 𝐴 = ⦋𝑧 / 𝑥⦌𝐴)
7	6	eqeq2d 2217	. . . . . . . 8 ⊢ (𝑥 = 𝑧 → (𝑦 = 𝐴 ↔ 𝑦 = ⦋𝑧 / 𝑥⦌𝐴))
8	3, 5, 7	spcgf 2855	. . . . . . 7 ⊢ (𝑧 ∈ V → (∀𝑥 𝑦 = 𝐴 → 𝑦 = ⦋𝑧 / 𝑥⦌𝐴))
9	2, 8	ax-mp 5	. . . . . 6 ⊢ (∀𝑥 𝑦 = 𝐴 → 𝑦 = ⦋𝑧 / 𝑥⦌𝐴)
10		vex 2775	. . . . . . 7 ⊢ 𝑤 ∈ V
11		nfcv 2348	. . . . . . . 8 ⊢ Ⅎ𝑥𝑤
12		nfcsb1v 3126	. . . . . . . . 9 ⊢ Ⅎ𝑥⦋𝑤 / 𝑥⦌𝐴
13	12	nfeq2 2360	. . . . . . . 8 ⊢ Ⅎ𝑥 𝑦 = ⦋𝑤 / 𝑥⦌𝐴
14		csbeq1a 3102	. . . . . . . . 9 ⊢ (𝑥 = 𝑤 → 𝐴 = ⦋𝑤 / 𝑥⦌𝐴)
15	14	eqeq2d 2217	. . . . . . . 8 ⊢ (𝑥 = 𝑤 → (𝑦 = 𝐴 ↔ 𝑦 = ⦋𝑤 / 𝑥⦌𝐴))
16	11, 13, 15	spcgf 2855	. . . . . . 7 ⊢ (𝑤 ∈ V → (∀𝑥 𝑦 = 𝐴 → 𝑦 = ⦋𝑤 / 𝑥⦌𝐴))
17	10, 16	ax-mp 5	. . . . . 6 ⊢ (∀𝑥 𝑦 = 𝐴 → 𝑦 = ⦋𝑤 / 𝑥⦌𝐴)
18	9, 17	eqtr3d 2240	. . . . 5 ⊢ (∀𝑥 𝑦 = 𝐴 → ⦋𝑧 / 𝑥⦌𝐴 = ⦋𝑤 / 𝑥⦌𝐴)
19	18	alrimivv 1898	. . . 4 ⊢ (∀𝑥 𝑦 = 𝐴 → ∀𝑧∀𝑤⦋𝑧 / 𝑥⦌𝐴 = ⦋𝑤 / 𝑥⦌𝐴)
20		sbnfc2 3154	. . . 4 ⊢ (Ⅎ𝑥𝐴 ↔ ∀𝑧∀𝑤⦋𝑧 / 𝑥⦌𝐴 = ⦋𝑤 / 𝑥⦌𝐴)
21	19, 20	sylibr 134	. . 3 ⊢ (∀𝑥 𝑦 = 𝐴 → Ⅎ𝑥𝐴)
22	21	exlimiv 1621	. 2 ⊢ (∃𝑦∀𝑥 𝑦 = 𝐴 → Ⅎ𝑥𝐴)
23	1, 22	syl 14	1 ⊢ (∃!𝑦∀𝑥 𝑦 = 𝐴 → Ⅎ𝑥𝐴)

Syntax hints:   → wi 4  ∀wal 1371   = wceq 1373  ∃wex 1515  ∃!weu 2054   ∈ wcel 2176  Ⅎwnfc 2335  Vcvv 2772  ⦋csb 3093

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 711  ax-5 1470  ax-7 1471  ax-gen 1472  ax-ie1 1516  ax-ie2 1517  ax-8 1527  ax-10 1528  ax-11 1529  ax-i12 1530  ax-bndl 1532  ax-4 1533  ax-17 1549  ax-i9 1553  ax-ial 1557  ax-i5r 1558  ax-ext 2187

This theorem depends on definitions:  df-bi 117  df-tru 1376  df-nf 1484  df-sb 1786  df-eu 2057  df-clab 2192  df-cleq 2198  df-clel 2201  df-nfc 2337  df-v 2774  df-sbc 2999  df-csb 3094

This theorem is referenced by:  eusvnfb  4501  eusv2i  4502