Theorem fo2ndf 6467

Description: The 2^nd (second component of an ordered pair) function restricted to a function 𝐹 is a function from 𝐹 onto the range of 𝐹. (Contributed by Alexander van der Vekens, 4-Feb-2018.)

Assertion

Ref	Expression
fo2ndf	⊢ (𝐹:𝐴⟶𝐵 → (2nd ↾ 𝐹):𝐹–onto→ran 𝐹)

Proof of Theorem fo2ndf

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

Step	Hyp	Ref	Expression
1		ffn 5536	. . . 4 ⊢ (𝐹:𝐴⟶𝐵 → 𝐹 Fn 𝐴)
2		dffn3 5547	. . . 4 ⊢ (𝐹 Fn 𝐴 ↔ 𝐹:𝐴⟶ran 𝐹)
3	1, 2	sylib 122	. . 3 ⊢ (𝐹:𝐴⟶𝐵 → 𝐹:𝐴⟶ran 𝐹)
4		f2ndf 6466	. . 3 ⊢ (𝐹:𝐴⟶ran 𝐹 → (2nd ↾ 𝐹):𝐹⟶ran 𝐹)
5	3, 4	syl 14	. 2 ⊢ (𝐹:𝐴⟶𝐵 → (2nd ↾ 𝐹):𝐹⟶ran 𝐹)
6	2, 4	sylbi 121	. . . . 5 ⊢ (𝐹 Fn 𝐴 → (2nd ↾ 𝐹):𝐹⟶ran 𝐹)
7	1, 6	syl 14	. . . 4 ⊢ (𝐹:𝐴⟶𝐵 → (2nd ↾ 𝐹):𝐹⟶ran 𝐹)
8		frn 5545	. . . 4 ⊢ ((2nd ↾ 𝐹):𝐹⟶ran 𝐹 → ran (2nd ↾ 𝐹) ⊆ ran 𝐹)
9	7, 8	syl 14	. . 3 ⊢ (𝐹:𝐴⟶𝐵 → ran (2nd ↾ 𝐹) ⊆ ran 𝐹)
10		elrn2g 4972	. . . . . 6 ⊢ (𝑦 ∈ ran 𝐹 → (𝑦 ∈ ran 𝐹 ↔ ∃𝑥⟨𝑥, 𝑦⟩ ∈ 𝐹))
11	10	ibi 176	. . . . 5 ⊢ (𝑦 ∈ ran 𝐹 → ∃𝑥⟨𝑥, 𝑦⟩ ∈ 𝐹)
12		fvres 5722	. . . . . . . . . 10 ⊢ (⟨𝑥, 𝑦⟩ ∈ 𝐹 → ((2nd ↾ 𝐹)‘⟨𝑥, 𝑦⟩) = (2nd ‘⟨𝑥, 𝑦⟩))
13	12	adantl 277	. . . . . . . . 9 ⊢ ((𝐹:𝐴⟶𝐵 ∧ ⟨𝑥, 𝑦⟩ ∈ 𝐹) → ((2nd ↾ 𝐹)‘⟨𝑥, 𝑦⟩) = (2nd ‘⟨𝑥, 𝑦⟩))
14		vex 2824	. . . . . . . . . 10 ⊢ 𝑥 ∈ V
15		vex 2824	. . . . . . . . . 10 ⊢ 𝑦 ∈ V
16	14, 15	op2nd 6385	. . . . . . . . 9 ⊢ (2nd ‘⟨𝑥, 𝑦⟩) = 𝑦
17	13, 16	eqtr2di 2288	. . . . . . . 8 ⊢ ((𝐹:𝐴⟶𝐵 ∧ ⟨𝑥, 𝑦⟩ ∈ 𝐹) → 𝑦 = ((2nd ↾ 𝐹)‘⟨𝑥, 𝑦⟩))
18		f2ndf 6466	. . . . . . . . . 10 ⊢ (𝐹:𝐴⟶𝐵 → (2nd ↾ 𝐹):𝐹⟶𝐵)
19		ffn 5536	. . . . . . . . . 10 ⊢ ((2nd ↾ 𝐹):𝐹⟶𝐵 → (2nd ↾ 𝐹) Fn 𝐹)
20	18, 19	syl 14	. . . . . . . . 9 ⊢ (𝐹:𝐴⟶𝐵 → (2nd ↾ 𝐹) Fn 𝐹)
21		fnfvelrn 5843	. . . . . . . . 9 ⊢ (((2nd ↾ 𝐹) Fn 𝐹 ∧ ⟨𝑥, 𝑦⟩ ∈ 𝐹) → ((2nd ↾ 𝐹)‘⟨𝑥, 𝑦⟩) ∈ ran (2nd ↾ 𝐹))
22	20, 21	sylan 283	. . . . . . . 8 ⊢ ((𝐹:𝐴⟶𝐵 ∧ ⟨𝑥, 𝑦⟩ ∈ 𝐹) → ((2nd ↾ 𝐹)‘⟨𝑥, 𝑦⟩) ∈ ran (2nd ↾ 𝐹))
23	17, 22	eqeltrd 2315	. . . . . . 7 ⊢ ((𝐹:𝐴⟶𝐵 ∧ ⟨𝑥, 𝑦⟩ ∈ 𝐹) → 𝑦 ∈ ran (2nd ↾ 𝐹))
24	23	ex 115	. . . . . 6 ⊢ (𝐹:𝐴⟶𝐵 → (⟨𝑥, 𝑦⟩ ∈ 𝐹 → 𝑦 ∈ ran (2nd ↾ 𝐹)))
25	24	exlimdv 1872	. . . . 5 ⊢ (𝐹:𝐴⟶𝐵 → (∃𝑥⟨𝑥, 𝑦⟩ ∈ 𝐹 → 𝑦 ∈ ran (2nd ↾ 𝐹)))
26	11, 25	syl5 32	. . . 4 ⊢ (𝐹:𝐴⟶𝐵 → (𝑦 ∈ ran 𝐹 → 𝑦 ∈ ran (2nd ↾ 𝐹)))
27	26	ssrdv 3254	. . 3 ⊢ (𝐹:𝐴⟶𝐵 → ran 𝐹 ⊆ ran (2nd ↾ 𝐹))
28	9, 27	eqssd 3265	. 2 ⊢ (𝐹:𝐴⟶𝐵 → ran (2nd ↾ 𝐹) = ran 𝐹)
29		dffo2 5622	. 2 ⊢ ((2nd ↾ 𝐹):𝐹–onto→ran 𝐹 ↔ ((2nd ↾ 𝐹):𝐹⟶ran 𝐹 ∧ ran (2nd ↾ 𝐹) = ran 𝐹))
30	5, 28, 29	sylanbrc 421	1 ⊢ (𝐹:𝐴⟶𝐵 → (2nd ↾ 𝐹):𝐹–onto→ran 𝐹)

This proof depends on syntax axioms:   → wi 4   ∧ wa 104   = wceq 1402  ∃wex 1545   ∈ wcel 2209   ⊆ wss 3220  ⟨cop 3712  ran crn 4777   ↾ cres 4778   Fn wfn 5375  ⟶wf 5376  –onto→wfo 5378  ‘cfv 5380  2^nd c2nd 6377

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 721  ax-5 1500  ax-7 1501  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-10 1558  ax-11 1559  ax-i12 1560  ax-bndl 1562  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-i5r 1588  ax-14 2212  ax-ext 2220  ax-sep 4251  ax-pow 4313  ax-pr 4348  ax-un 4580

This proof depends on definitions:  df-bi 117  df-3an 1011  df-tru 1405  df-nf 1514  df-sb 1816  df-eu 2089  df-mo 2090  df-clab 2225  df-cleq 2231  df-clel 2234  df-nfc 2381  df-ral 2533  df-rex 2534  df-rab 2537  df-v 2823  df-sbc 3052  df-csb 3148  df-un 3224  df-in 3226  df-ss 3233  df-pw 3690  df-sn 3715  df-pr 3716  df-op 3718  df-uni 3936  df-iun 4014  df-br 4132  df-opab 4194  df-mpt 4195  df-id 4440  df-xp 4782  df-rel 4783  df-cnv 4784  df-co 4785  df-dm 4786  df-rn 4787  df-res 4788  df-ima 4789  df-iota 5340  df-fun 5382  df-fn 5383  df-f 5384  df-fo 5386  df-fv 5388  df-2nd 6379

This theorem is used by:  f1o2ndf1  6468