Theorem fsn 6989

Description: A function maps a singleton to a singleton iff it is the singleton of an ordered pair. (Contributed by NM, 10-Dec-2003.)

Hypotheses

Ref	Expression
fsn.1	⊢ 𝐴 ∈ V
fsn.2	⊢ 𝐵 ∈ V

Assertion

Ref	Expression
fsn	⊢ (𝐹:{𝐴}⟶{𝐵} ↔ 𝐹 = {⟨𝐴, 𝐵⟩})

Proof of Theorem fsn

Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		opelf 6619	. . . . . . . 8 ⊢ ((𝐹:{𝐴}⟶{𝐵} ∧ ⟨𝑥, 𝑦⟩ ∈ 𝐹) → (𝑥 ∈ {𝐴} ∧ 𝑦 ∈ {𝐵}))
2		velsn 4574	. . . . . . . . 9 ⊢ (𝑥 ∈ {𝐴} ↔ 𝑥 = 𝐴)
3		velsn 4574	. . . . . . . . 9 ⊢ (𝑦 ∈ {𝐵} ↔ 𝑦 = 𝐵)
4	2, 3	anbi12i 626	. . . . . . . 8 ⊢ ((𝑥 ∈ {𝐴} ∧ 𝑦 ∈ {𝐵}) ↔ (𝑥 = 𝐴 ∧ 𝑦 = 𝐵))
5	1, 4	sylib 217	. . . . . . 7 ⊢ ((𝐹:{𝐴}⟶{𝐵} ∧ ⟨𝑥, 𝑦⟩ ∈ 𝐹) → (𝑥 = 𝐴 ∧ 𝑦 = 𝐵))
6	5	ex 412	. . . . . 6 ⊢ (𝐹:{𝐴}⟶{𝐵} → (⟨𝑥, 𝑦⟩ ∈ 𝐹 → (𝑥 = 𝐴 ∧ 𝑦 = 𝐵)))
7		fsn.1	. . . . . . . . . 10 ⊢ 𝐴 ∈ V
8	7	snid 4594	. . . . . . . . 9 ⊢ 𝐴 ∈ {𝐴}
9		feu 6634	. . . . . . . . 9 ⊢ ((𝐹:{𝐴}⟶{𝐵} ∧ 𝐴 ∈ {𝐴}) → ∃!𝑦 ∈ {𝐵}⟨𝐴, 𝑦⟩ ∈ 𝐹)
10	8, 9	mpan2 687	. . . . . . . 8 ⊢ (𝐹:{𝐴}⟶{𝐵} → ∃!𝑦 ∈ {𝐵}⟨𝐴, 𝑦⟩ ∈ 𝐹)
11	3	anbi1i 623	. . . . . . . . . . 11 ⊢ ((𝑦 ∈ {𝐵} ∧ ⟨𝐴, 𝑦⟩ ∈ 𝐹) ↔ (𝑦 = 𝐵 ∧ ⟨𝐴, 𝑦⟩ ∈ 𝐹))
12		opeq2 4802	. . . . . . . . . . . . . 14 ⊢ (𝑦 = 𝐵 → ⟨𝐴, 𝑦⟩ = ⟨𝐴, 𝐵⟩)
13	12	eleq1d 2823	. . . . . . . . . . . . 13 ⊢ (𝑦 = 𝐵 → (⟨𝐴, 𝑦⟩ ∈ 𝐹 ↔ ⟨𝐴, 𝐵⟩ ∈ 𝐹))
14	13	pm5.32i 574	. . . . . . . . . . . 12 ⊢ ((𝑦 = 𝐵 ∧ ⟨𝐴, 𝑦⟩ ∈ 𝐹) ↔ (𝑦 = 𝐵 ∧ ⟨𝐴, 𝐵⟩ ∈ 𝐹))
15	14	biancomi 462	. . . . . . . . . . 11 ⊢ ((𝑦 = 𝐵 ∧ ⟨𝐴, 𝑦⟩ ∈ 𝐹) ↔ (⟨𝐴, 𝐵⟩ ∈ 𝐹 ∧ 𝑦 = 𝐵))
16	11, 15	bitr2i 275	. . . . . . . . . 10 ⊢ ((⟨𝐴, 𝐵⟩ ∈ 𝐹 ∧ 𝑦 = 𝐵) ↔ (𝑦 ∈ {𝐵} ∧ ⟨𝐴, 𝑦⟩ ∈ 𝐹))
17	16	eubii 2585	. . . . . . . . 9 ⊢ (∃!𝑦(⟨𝐴, 𝐵⟩ ∈ 𝐹 ∧ 𝑦 = 𝐵) ↔ ∃!𝑦(𝑦 ∈ {𝐵} ∧ ⟨𝐴, 𝑦⟩ ∈ 𝐹))
18		fsn.2	. . . . . . . . . . . 12 ⊢ 𝐵 ∈ V
19	18	eueqi 3639	. . . . . . . . . . 11 ⊢ ∃!𝑦 𝑦 = 𝐵
20	19	biantru 529	. . . . . . . . . 10 ⊢ (⟨𝐴, 𝐵⟩ ∈ 𝐹 ↔ (⟨𝐴, 𝐵⟩ ∈ 𝐹 ∧ ∃!𝑦 𝑦 = 𝐵))
21		euanv 2626	. . . . . . . . . 10 ⊢ (∃!𝑦(⟨𝐴, 𝐵⟩ ∈ 𝐹 ∧ 𝑦 = 𝐵) ↔ (⟨𝐴, 𝐵⟩ ∈ 𝐹 ∧ ∃!𝑦 𝑦 = 𝐵))
22	20, 21	bitr4i 277	. . . . . . . . 9 ⊢ (⟨𝐴, 𝐵⟩ ∈ 𝐹 ↔ ∃!𝑦(⟨𝐴, 𝐵⟩ ∈ 𝐹 ∧ 𝑦 = 𝐵))
23		df-reu 3070	. . . . . . . . 9 ⊢ (∃!𝑦 ∈ {𝐵}⟨𝐴, 𝑦⟩ ∈ 𝐹 ↔ ∃!𝑦(𝑦 ∈ {𝐵} ∧ ⟨𝐴, 𝑦⟩ ∈ 𝐹))
24	17, 22, 23	3bitr4i 302	. . . . . . . 8 ⊢ (⟨𝐴, 𝐵⟩ ∈ 𝐹 ↔ ∃!𝑦 ∈ {𝐵}⟨𝐴, 𝑦⟩ ∈ 𝐹)
25	10, 24	sylibr 233	. . . . . . 7 ⊢ (𝐹:{𝐴}⟶{𝐵} → ⟨𝐴, 𝐵⟩ ∈ 𝐹)
26		opeq12 4803	. . . . . . . 8 ⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → ⟨𝑥, 𝑦⟩ = ⟨𝐴, 𝐵⟩)
27	26	eleq1d 2823	. . . . . . 7 ⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → (⟨𝑥, 𝑦⟩ ∈ 𝐹 ↔ ⟨𝐴, 𝐵⟩ ∈ 𝐹))
28	25, 27	syl5ibrcom 246	. . . . . 6 ⊢ (𝐹:{𝐴}⟶{𝐵} → ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → ⟨𝑥, 𝑦⟩ ∈ 𝐹))
29	6, 28	impbid 211	. . . . 5 ⊢ (𝐹:{𝐴}⟶{𝐵} → (⟨𝑥, 𝑦⟩ ∈ 𝐹 ↔ (𝑥 = 𝐴 ∧ 𝑦 = 𝐵)))
30		opex 5373	. . . . . . 7 ⊢ ⟨𝑥, 𝑦⟩ ∈ V
31	30	elsn 4573	. . . . . 6 ⊢ (⟨𝑥, 𝑦⟩ ∈ {⟨𝐴, 𝐵⟩} ↔ ⟨𝑥, 𝑦⟩ = ⟨𝐴, 𝐵⟩)
32	7, 18	opth2 5389	. . . . . 6 ⊢ (⟨𝑥, 𝑦⟩ = ⟨𝐴, 𝐵⟩ ↔ (𝑥 = 𝐴 ∧ 𝑦 = 𝐵))
33	31, 32	bitr2i 275	. . . . 5 ⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) ↔ ⟨𝑥, 𝑦⟩ ∈ {⟨𝐴, 𝐵⟩})
34	29, 33	bitrdi 286	. . . 4 ⊢ (𝐹:{𝐴}⟶{𝐵} → (⟨𝑥, 𝑦⟩ ∈ 𝐹 ↔ ⟨𝑥, 𝑦⟩ ∈ {⟨𝐴, 𝐵⟩}))
35	34	alrimivv 1932	. . 3 ⊢ (𝐹:{𝐴}⟶{𝐵} → ∀𝑥∀𝑦(⟨𝑥, 𝑦⟩ ∈ 𝐹 ↔ ⟨𝑥, 𝑦⟩ ∈ {⟨𝐴, 𝐵⟩}))
36		frel 6589	. . . 4 ⊢ (𝐹:{𝐴}⟶{𝐵} → Rel 𝐹)
37	7, 18	relsnop 5704	. . . 4 ⊢ Rel {⟨𝐴, 𝐵⟩}
38		eqrel 5684	. . . 4 ⊢ ((Rel 𝐹 ∧ Rel {⟨𝐴, 𝐵⟩}) → (𝐹 = {⟨𝐴, 𝐵⟩} ↔ ∀𝑥∀𝑦(⟨𝑥, 𝑦⟩ ∈ 𝐹 ↔ ⟨𝑥, 𝑦⟩ ∈ {⟨𝐴, 𝐵⟩})))
39	36, 37, 38	sylancl 585	. . 3 ⊢ (𝐹:{𝐴}⟶{𝐵} → (𝐹 = {⟨𝐴, 𝐵⟩} ↔ ∀𝑥∀𝑦(⟨𝑥, 𝑦⟩ ∈ 𝐹 ↔ ⟨𝑥, 𝑦⟩ ∈ {⟨𝐴, 𝐵⟩})))
40	35, 39	mpbird 256	. 2 ⊢ (𝐹:{𝐴}⟶{𝐵} → 𝐹 = {⟨𝐴, 𝐵⟩})
41	7, 18	f1osn 6739	. . . 4 ⊢ {⟨𝐴, 𝐵⟩}:{𝐴}–1-1-onto→{𝐵}
42		f1oeq1 6688	. . . 4 ⊢ (𝐹 = {⟨𝐴, 𝐵⟩} → (𝐹:{𝐴}–1-1-onto→{𝐵} ↔ {⟨𝐴, 𝐵⟩}:{𝐴}–1-1-onto→{𝐵}))
43	41, 42	mpbiri 257	. . 3 ⊢ (𝐹 = {⟨𝐴, 𝐵⟩} → 𝐹:{𝐴}–1-1-onto→{𝐵})
44		f1of 6700	. . 3 ⊢ (𝐹:{𝐴}–1-1-onto→{𝐵} → 𝐹:{𝐴}⟶{𝐵})
45	43, 44	syl 17	. 2 ⊢ (𝐹 = {⟨𝐴, 𝐵⟩} → 𝐹:{𝐴}⟶{𝐵})
46	40, 45	impbii 208	1 ⊢ (𝐹:{𝐴}⟶{𝐵} ↔ 𝐹 = {⟨𝐴, 𝐵⟩})

Syntax hints:   ↔ wb 205   ∧ wa 395  ∀wal 1537   = wceq 1539   ∈ wcel 2108  ∃!weu 2568  ∃!wreu 3065  Vcvv 3422  {csn 4558  ⟨cop 4564  Rel wrel 5585  ⟶wf 6414  –1-1-onto→wf1o 6417

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2110  ax-9 2118  ax-10 2139  ax-11 2156  ax-12 2173  ax-ext 2709  ax-sep 5218  ax-nul 5225  ax-pr 5347

This theorem depends on definitions:  df-bi 206  df-an 396  df-or 844  df-3an 1087  df-tru 1542  df-fal 1552  df-ex 1784  df-nf 1788  df-sb 2069  df-mo 2540  df-eu 2569  df-clab 2716  df-cleq 2730  df-clel 2817  df-nfc 2888  df-ral 3068  df-rex 3069  df-reu 3070  df-rab 3072  df-v 3424  df-dif 3886  df-un 3888  df-in 3890  df-ss 3900  df-nul 4254  df-if 4457  df-sn 4559  df-pr 4561  df-op 4565  df-br 5071  df-opab 5133  df-id 5480  df-xp 5586  df-rel 5587  df-cnv 5588  df-co 5589  df-dm 5590  df-rn 5591  df-fun 6420  df-fn 6421  df-f 6422  df-f1 6423  df-fo 6424  df-f1o 6425

This theorem is referenced by:  fsn2  6990  fsng  6991  axlowdimlem7  27219  poimirlem3  35707  poimirlem9  35713  fdc  35830