Theorem euxfr2dc 2915

Description: Transfer existential uniqueness from a variable 𝑥 to another variable 𝑦 contained in expression 𝐴. (Contributed by NM, 14-Nov-2004.)

Hypotheses

Ref	Expression
euxfr2dc.1	⊢ 𝐴 ∈ V
euxfr2dc.2	⊢ ∃*𝑦 𝑥 = 𝐴

Assertion

Ref	Expression
euxfr2dc	⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑) ↔ ∃!𝑦𝜑))

Distinct variable groups:   𝜑,𝑥   𝑥,𝐴

Allowed substitution hints:   𝜑(𝑦)   𝐴(𝑦)

Proof of Theorem euxfr2dc

Step	Hyp	Ref	Expression
1		euxfr2dc.2	. . . . . . 7 ⊢ ∃*𝑦 𝑥 = 𝐴
2	1	moani 2089	. . . . . 6 ⊢ ∃*𝑦(𝜑 ∧ 𝑥 = 𝐴)
3		ancom 264	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 = 𝐴) ↔ (𝑥 = 𝐴 ∧ 𝜑))
4	3	mobii 2056	. . . . . 6 ⊢ (∃*𝑦(𝜑 ∧ 𝑥 = 𝐴) ↔ ∃*𝑦(𝑥 = 𝐴 ∧ 𝜑))
5	2, 4	mpbi 144	. . . . 5 ⊢ ∃*𝑦(𝑥 = 𝐴 ∧ 𝜑)
6	5	ax-gen 1442	. . . 4 ⊢ ∀𝑥∃*𝑦(𝑥 = 𝐴 ∧ 𝜑)
7		excom 1657	. . . . . 6 ⊢ (∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) ↔ ∃𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑))
8	7	dcbii 835	. . . . 5 ⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) ↔ DECID ∃𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑))
9		2euswapdc 2110	. . . . 5 ⊢ (DECID ∃𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑) → (∀𝑥∃*𝑦(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑) → ∃!𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑))))
10	8, 9	sylbi 120	. . . 4 ⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∀𝑥∃*𝑦(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑) → ∃!𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑))))
11	6, 10	mpi 15	. . 3 ⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑) → ∃!𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑)))
12		moeq 2905	. . . . . . 7 ⊢ ∃*𝑥 𝑥 = 𝐴
13	12	moani 2089	. . . . . 6 ⊢ ∃*𝑥(𝜑 ∧ 𝑥 = 𝐴)
14	3	mobii 2056	. . . . . 6 ⊢ (∃*𝑥(𝜑 ∧ 𝑥 = 𝐴) ↔ ∃*𝑥(𝑥 = 𝐴 ∧ 𝜑))
15	13, 14	mpbi 144	. . . . 5 ⊢ ∃*𝑥(𝑥 = 𝐴 ∧ 𝜑)
16	15	ax-gen 1442	. . . 4 ⊢ ∀𝑦∃*𝑥(𝑥 = 𝐴 ∧ 𝜑)
17		2euswapdc 2110	. . . 4 ⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∀𝑦∃*𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → ∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑))))
18	16, 17	mpi 15	. . 3 ⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → ∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑)))
19	11, 18	impbid 128	. 2 ⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑) ↔ ∃!𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑)))
20		euxfr2dc.1	. . . 4 ⊢ 𝐴 ∈ V
21		biidd 171	. . . 4 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜑))
22	20, 21	ceqsexv 2769	. . 3 ⊢ (∃𝑥(𝑥 = 𝐴 ∧ 𝜑) ↔ 𝜑)
23	22	eubii 2028	. 2 ⊢ (∃!𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) ↔ ∃!𝑦𝜑)
24	19, 23	bitrdi 195	1 ⊢ (DECID ∃𝑦∃𝑥(𝑥 = 𝐴 ∧ 𝜑) → (∃!𝑥∃𝑦(𝑥 = 𝐴 ∧ 𝜑) ↔ ∃!𝑦𝜑))

Syntax hints:   → wi 4   ∧ wa 103   ↔ wb 104  DECID wdc 829  ∀wal 1346   = wceq 1348  ∃wex 1485  ∃!weu 2019  ∃*wmo 2020   ∈ wcel 2141  Vcvv 2730

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 609  ax-in2 610  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-dc 830  df-tru 1351  df-nf 1454  df-sb 1756  df-eu 2022  df-mo 2023  df-clab 2157  df-cleq 2163  df-clel 2166  df-v 2732

This theorem is referenced by:  euxfrdc  2916