Theorem funopsn 7167

Description: If a function is an ordered pair then it is a singleton of an ordered pair. (Contributed by AV, 20-Sep-2020.) (Proof shortened by AV, 15-Jul-2021.) A function is a class of ordered pairs, so the fact that an ordered pair may sometimes be itself a function is an "accident" depending on the specific encoding of ordered pairs as classes (in set.mm, the Kuratowski encoding). A more meaningful statement is funsng 6616, as relsnopg 5812 is to relop 5860. (New usage is discouraged.)

Hypotheses

Ref	Expression
funopsn.x	⊢ 𝑋 ∈ V
funopsn.y	⊢ 𝑌 ∈ V

Assertion

Ref	Expression
funopsn	⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → ∃𝑎(𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩}))

Distinct variable groups:   𝐹,𝑎   𝑋,𝑎   𝑌,𝑎

Proof of Theorem funopsn

Dummy variable 𝑥 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		funiun 7166	. 2 ⊢ (Fun 𝐹 → 𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩})
2		eqeq1 2740	. . . . . . 7 ⊢ (𝐹 = ⟨𝑋, 𝑌⟩ → (𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} ↔ ⟨𝑋, 𝑌⟩ = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩}))
3		eqcom 2743	. . . . . . 7 ⊢ (⟨𝑋, 𝑌⟩ = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} ↔ ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = ⟨𝑋, 𝑌⟩)
4	2, 3	bitrdi 287	. . . . . 6 ⊢ (𝐹 = ⟨𝑋, 𝑌⟩ → (𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} ↔ ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = ⟨𝑋, 𝑌⟩))
5	4	adantl 481	. . . . 5 ⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → (𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} ↔ ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = ⟨𝑋, 𝑌⟩))
6		funopsn.x	. . . . . . . 8 ⊢ 𝑋 ∈ V
7		funopsn.y	. . . . . . . 8 ⊢ 𝑌 ∈ V
8	6, 7	opnzi 5478	. . . . . . 7 ⊢ ⟨𝑋, 𝑌⟩ ≠ ∅
9		neeq1 3002	. . . . . . . . . . 11 ⊢ (⟨𝑋, 𝑌⟩ = 𝐹 → (⟨𝑋, 𝑌⟩ ≠ ∅ ↔ 𝐹 ≠ ∅))
10	9	eqcoms 2744	. . . . . . . . . 10 ⊢ (𝐹 = ⟨𝑋, 𝑌⟩ → (⟨𝑋, 𝑌⟩ ≠ ∅ ↔ 𝐹 ≠ ∅))
11		funrel 6582	. . . . . . . . . . . . . 14 ⊢ (Fun 𝐹 → Rel 𝐹)
12		reldm0 5937	. . . . . . . . . . . . . 14 ⊢ (Rel 𝐹 → (𝐹 = ∅ ↔ dom 𝐹 = ∅))
13	11, 12	syl 17	. . . . . . . . . . . . 13 ⊢ (Fun 𝐹 → (𝐹 = ∅ ↔ dom 𝐹 = ∅))
14	13	biimprd 248	. . . . . . . . . . . 12 ⊢ (Fun 𝐹 → (dom 𝐹 = ∅ → 𝐹 = ∅))
15	14	necon3d 2960	. . . . . . . . . . 11 ⊢ (Fun 𝐹 → (𝐹 ≠ ∅ → dom 𝐹 ≠ ∅))
16	15	com12 32	. . . . . . . . . 10 ⊢ (𝐹 ≠ ∅ → (Fun 𝐹 → dom 𝐹 ≠ ∅))
17	10, 16	biimtrdi 253	. . . . . . . . 9 ⊢ (𝐹 = ⟨𝑋, 𝑌⟩ → (⟨𝑋, 𝑌⟩ ≠ ∅ → (Fun 𝐹 → dom 𝐹 ≠ ∅)))
18	17	com3l 89	. . . . . . . 8 ⊢ (⟨𝑋, 𝑌⟩ ≠ ∅ → (Fun 𝐹 → (𝐹 = ⟨𝑋, 𝑌⟩ → dom 𝐹 ≠ ∅)))
19	18	impd 410	. . . . . . 7 ⊢ (⟨𝑋, 𝑌⟩ ≠ ∅ → ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → dom 𝐹 ≠ ∅))
20	8, 19	ax-mp 5	. . . . . 6 ⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → dom 𝐹 ≠ ∅)
21		fvex 6918	. . . . . . 7 ⊢ (𝐹‘𝑥) ∈ V
22	21, 6, 7	iunopeqop 5525	. . . . . 6 ⊢ (dom 𝐹 ≠ ∅ → (∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = ⟨𝑋, 𝑌⟩ → ∃𝑎dom 𝐹 = {𝑎}))
23	20, 22	syl 17	. . . . 5 ⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → (∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = ⟨𝑋, 𝑌⟩ → ∃𝑎dom 𝐹 = {𝑎}))
24	5, 23	sylbid 240	. . . 4 ⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → (𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} → ∃𝑎dom 𝐹 = {𝑎}))
25	24	imp 406	. . 3 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩}) → ∃𝑎dom 𝐹 = {𝑎})
26		iuneq1 5007	. . . . . . . . 9 ⊢ (dom 𝐹 = {𝑎} → ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = ∪ 𝑥 ∈ {𝑎} {⟨𝑥, (𝐹‘𝑥)⟩})
27		vex 3483	. . . . . . . . . 10 ⊢ 𝑎 ∈ V
28		id 22	. . . . . . . . . . . 12 ⊢ (𝑥 = 𝑎 → 𝑥 = 𝑎)
29		fveq2 6905	. . . . . . . . . . . 12 ⊢ (𝑥 = 𝑎 → (𝐹‘𝑥) = (𝐹‘𝑎))
30	28, 29	opeq12d 4880	. . . . . . . . . . 11 ⊢ (𝑥 = 𝑎 → ⟨𝑥, (𝐹‘𝑥)⟩ = ⟨𝑎, (𝐹‘𝑎)⟩)
31	30	sneqd 4637	. . . . . . . . . 10 ⊢ (𝑥 = 𝑎 → {⟨𝑥, (𝐹‘𝑥)⟩} = {⟨𝑎, (𝐹‘𝑎)⟩})
32	27, 31	iunxsn 5090	. . . . . . . . 9 ⊢ ∪ 𝑥 ∈ {𝑎} {⟨𝑥, (𝐹‘𝑥)⟩} = {⟨𝑎, (𝐹‘𝑎)⟩}
33	26, 32	eqtrdi 2792	. . . . . . . 8 ⊢ (dom 𝐹 = {𝑎} → ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = {⟨𝑎, (𝐹‘𝑎)⟩})
34	33	adantl 481	. . . . . . 7 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ dom 𝐹 = {𝑎}) → ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} = {⟨𝑎, (𝐹‘𝑎)⟩})
35	34	eqeq2d 2747	. . . . . 6 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ dom 𝐹 = {𝑎}) → (𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} ↔ 𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩}))
36		eqeq1 2740	. . . . . . . . . . 11 ⊢ (𝐹 = ⟨𝑋, 𝑌⟩ → (𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} ↔ ⟨𝑋, 𝑌⟩ = {⟨𝑎, (𝐹‘𝑎)⟩}))
37	36	adantl 481	. . . . . . . . . 10 ⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → (𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} ↔ ⟨𝑋, 𝑌⟩ = {⟨𝑎, (𝐹‘𝑎)⟩}))
38		eqcom 2743	. . . . . . . . . . 11 ⊢ (⟨𝑋, 𝑌⟩ = {⟨𝑎, (𝐹‘𝑎)⟩} ↔ {⟨𝑎, (𝐹‘𝑎)⟩} = ⟨𝑋, 𝑌⟩)
39		fvex 6918	. . . . . . . . . . . 12 ⊢ (𝐹‘𝑎) ∈ V
40	27, 39	snopeqop 5510	. . . . . . . . . . 11 ⊢ ({⟨𝑎, (𝐹‘𝑎)⟩} = ⟨𝑋, 𝑌⟩ ↔ (𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}))
41	38, 40	sylbb 219	. . . . . . . . . 10 ⊢ (⟨𝑋, 𝑌⟩ = {⟨𝑎, (𝐹‘𝑎)⟩} → (𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}))
42	37, 41	biimtrdi 253	. . . . . . . . 9 ⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → (𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} → (𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎})))
43	42	imp 406	. . . . . . . 8 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩}) → (𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}))
44		simpr3 1196	. . . . . . . . . . . 12 ⊢ ((𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} ∧ (𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎})) → 𝑋 = {𝑎})
45		simp1 1136	. . . . . . . . . . . . . . . . 17 ⊢ ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → 𝑎 = (𝐹‘𝑎))
46	45	eqcomd 2742	. . . . . . . . . . . . . . . 16 ⊢ ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → (𝐹‘𝑎) = 𝑎)
47	46	opeq2d 4879	. . . . . . . . . . . . . . 15 ⊢ ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → ⟨𝑎, (𝐹‘𝑎)⟩ = ⟨𝑎, 𝑎⟩)
48	47	sneqd 4637	. . . . . . . . . . . . . 14 ⊢ ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → {⟨𝑎, (𝐹‘𝑎)⟩} = {⟨𝑎, 𝑎⟩})
49	48	eqeq2d 2747	. . . . . . . . . . . . 13 ⊢ ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → (𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} ↔ 𝐹 = {⟨𝑎, 𝑎⟩}))
50	49	biimpac 478	. . . . . . . . . . . 12 ⊢ ((𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} ∧ (𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎})) → 𝐹 = {⟨𝑎, 𝑎⟩})
51	44, 50	jca 511	. . . . . . . . . . 11 ⊢ ((𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} ∧ (𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎})) → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩}))
52	51	ex 412	. . . . . . . . . 10 ⊢ (𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} → ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩})))
53	52	adantl 481	. . . . . . . . 9 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩}) → ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩})))
54	53	a1dd 50	. . . . . . . 8 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩}) → ((𝑎 = (𝐹‘𝑎) ∧ 𝑋 = 𝑌 ∧ 𝑋 = {𝑎}) → (dom 𝐹 = {𝑎} → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩}))))
55	43, 54	mpd 15	. . . . . . 7 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩}) → (dom 𝐹 = {𝑎} → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩})))
56	55	impancom 451	. . . . . 6 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ dom 𝐹 = {𝑎}) → (𝐹 = {⟨𝑎, (𝐹‘𝑎)⟩} → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩})))
57	35, 56	sylbid 240	. . . . 5 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ dom 𝐹 = {𝑎}) → (𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩} → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩})))
58	57	impancom 451	. . . 4 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩}) → (dom 𝐹 = {𝑎} → (𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩})))
59	58	eximdv 1916	. . 3 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩}) → (∃𝑎dom 𝐹 = {𝑎} → ∃𝑎(𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩})))
60	25, 59	mpd 15	. 2 ⊢ (((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) ∧ 𝐹 = ∪ 𝑥 ∈ dom 𝐹{⟨𝑥, (𝐹‘𝑥)⟩}) → ∃𝑎(𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩}))
61	1, 60	mpidan 689	1 ⊢ ((Fun 𝐹 ∧ 𝐹 = ⟨𝑋, 𝑌⟩) → ∃𝑎(𝑋 = {𝑎} ∧ 𝐹 = {⟨𝑎, 𝑎⟩}))

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   ∧ w3a 1086   = wceq 1539  ∃wex 1778   ∈ wcel 2107   ≠ wne 2939  Vcvv 3479  ∅c0 4332  {csn 4625  ⟨cop 4631  ∪ ciun 4990  dom cdm 5684  Rel wrel 5689  Fun wfun 6554  ‘cfv 6560

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1794  ax-4 1808  ax-5 1909  ax-6 1966  ax-7 2006  ax-8 2109  ax-9 2117  ax-10 2140  ax-11 2156  ax-12 2176  ax-ext 2707  ax-sep 5295  ax-nul 5305  ax-pr 5431

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1542  df-fal 1552  df-ex 1779  df-nf 1783  df-sb 2064  df-mo 2539  df-eu 2568  df-clab 2714  df-cleq 2728  df-clel 2815  df-nfc 2891  df-ne 2940  df-ral 3061  df-rex 3070  df-reu 3380  df-rab 3436  df-v 3481  df-sbc 3788  df-csb 3899  df-dif 3953  df-un 3955  df-in 3957  df-ss 3967  df-nul 4333  df-if 4525  df-sn 4626  df-pr 4628  df-op 4632  df-uni 4907  df-iun 4992  df-br 5143  df-opab 5205  df-mpt 5225  df-id 5577  df-xp 5690  df-rel 5691  df-cnv 5692  df-co 5693  df-dm 5694  df-rn 5695  df-iota 6513  df-fun 6562  df-fn 6563  df-f 6564  df-f1 6565  df-fo 6566  df-f1o 6567  df-fv 6568

This theorem is referenced by:  funop  7168  funop1  47300