Theorem funfocofob 47538

Description: If the domain of a function 𝐺 is a subset of the range of a function 𝐹, then the composition (𝐺 ∘ 𝐹) is surjective iff 𝐺 is surjective. (Contributed by GL and AV, 29-Sep-2024.)

Assertion

Ref	Expression
funfocofob	⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → ((𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵 ↔ 𝐺:𝐴–onto→𝐵))

Proof of Theorem funfocofob

Step	Hyp	Ref	Expression
1		fdmrn 6693	. . . . . . . 8 ⊢ (Fun 𝐹 ↔ 𝐹:dom 𝐹⟶ran 𝐹)
2	1	biimpi 216	. . . . . . 7 ⊢ (Fun 𝐹 → 𝐹:dom 𝐹⟶ran 𝐹)
3	2	3ad2ant1 1134	. . . . . 6 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → 𝐹:dom 𝐹⟶ran 𝐹)
4	3	adantr 480	. . . . 5 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵) → 𝐹:dom 𝐹⟶ran 𝐹)
5		eqid 2737	. . . . 5 ⊢ (ran 𝐹 ∩ 𝐴) = (ran 𝐹 ∩ 𝐴)
6		eqid 2737	. . . . 5 ⊢ (◡𝐹 “ 𝐴) = (◡𝐹 “ 𝐴)
7		eqid 2737	. . . . 5 ⊢ (𝐹 ↾ (◡𝐹 “ 𝐴)) = (𝐹 ↾ (◡𝐹 “ 𝐴))
8		simp2 1138	. . . . . 6 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → 𝐺:𝐴⟶𝐵)
9	8	adantr 480	. . . . 5 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵) → 𝐺:𝐴⟶𝐵)
10		eqid 2737	. . . . 5 ⊢ (𝐺 ↾ (ran 𝐹 ∩ 𝐴)) = (𝐺 ↾ (ran 𝐹 ∩ 𝐴))
11		simpr 484	. . . . 5 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵) → (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵)
12	4, 5, 6, 7, 9, 10, 11	fcoresfo 47531	. . . 4 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵) → (𝐺 ↾ (ran 𝐹 ∩ 𝐴)):(ran 𝐹 ∩ 𝐴)–onto→𝐵)
13	12	ex 412	. . 3 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → ((𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵 → (𝐺 ↾ (ran 𝐹 ∩ 𝐴)):(ran 𝐹 ∩ 𝐴)–onto→𝐵))
14		sseqin2 4164	. . . . . . . . 9 ⊢ (𝐴 ⊆ ran 𝐹 ↔ (ran 𝐹 ∩ 𝐴) = 𝐴)
15	14	biimpi 216	. . . . . . . 8 ⊢ (𝐴 ⊆ ran 𝐹 → (ran 𝐹 ∩ 𝐴) = 𝐴)
16	15	3ad2ant3 1136	. . . . . . 7 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → (ran 𝐹 ∩ 𝐴) = 𝐴)
17	8	fdmd 6672	. . . . . . 7 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → dom 𝐺 = 𝐴)
18	16, 17	eqtr4d 2775	. . . . . 6 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → (ran 𝐹 ∩ 𝐴) = dom 𝐺)
19	18	reseq2d 5938	. . . . 5 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → (𝐺 ↾ (ran 𝐹 ∩ 𝐴)) = (𝐺 ↾ dom 𝐺))
20	8	freld 6668	. . . . . 6 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → Rel 𝐺)
21		resdm 5985	. . . . . 6 ⊢ (Rel 𝐺 → (𝐺 ↾ dom 𝐺) = 𝐺)
22	20, 21	syl 17	. . . . 5 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → (𝐺 ↾ dom 𝐺) = 𝐺)
23	19, 22	eqtrd 2772	. . . 4 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → (𝐺 ↾ (ran 𝐹 ∩ 𝐴)) = 𝐺)
24		eqidd 2738	. . . 4 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → 𝐵 = 𝐵)
25	23, 16, 24	foeq123d 6767	. . 3 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → ((𝐺 ↾ (ran 𝐹 ∩ 𝐴)):(ran 𝐹 ∩ 𝐴)–onto→𝐵 ↔ 𝐺:𝐴–onto→𝐵))
26	13, 25	sylibd 239	. 2 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → ((𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵 → 𝐺:𝐴–onto→𝐵))
27		simpr 484	. . . 4 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ 𝐺:𝐴–onto→𝐵) → 𝐺:𝐴–onto→𝐵)
28		simpl1 1193	. . . 4 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ 𝐺:𝐴–onto→𝐵) → Fun 𝐹)
29		simpl3 1195	. . . 4 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ 𝐺:𝐴–onto→𝐵) → 𝐴 ⊆ ran 𝐹)
30		focofo 6759	. . . 4 ⊢ ((𝐺:𝐴–onto→𝐵 ∧ Fun 𝐹 ∧ 𝐴 ⊆ ran 𝐹) → (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵)
31	27, 28, 29, 30	syl3anc 1374	. . 3 ⊢ (((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) ∧ 𝐺:𝐴–onto→𝐵) → (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵)
32	31	ex 412	. 2 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → (𝐺:𝐴–onto→𝐵 → (𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵))
33	26, 32	impbid 212	1 ⊢ ((Fun 𝐹 ∧ 𝐺:𝐴⟶𝐵 ∧ 𝐴 ⊆ ran 𝐹) → ((𝐺 ∘ 𝐹):(◡𝐹 “ 𝐴)–onto→𝐵 ↔ 𝐺:𝐴–onto→𝐵))

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   ∧ w3a 1087   = wceq 1542   ∩ cin 3889   ⊆ wss 3890  ^◡ccnv 5623  dom cdm 5624  ran crn 5625   ↾ cres 5626   “ cima 5627   ∘ ccom 5628  Rel wrel 5629  Fun wfun 6486  ⟶wf 6488  –onto→wfo 6490

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1969  ax-7 2010  ax-8 2116  ax-9 2124  ax-10 2147  ax-11 2163  ax-12 2185  ax-ext 2709  ax-sep 5231  ax-nul 5241  ax-pr 5370

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 849  df-3an 1089  df-tru 1545  df-fal 1555  df-ex 1782  df-nf 1786  df-sb 2069  df-mo 2540  df-eu 2570  df-clab 2716  df-cleq 2729  df-clel 2812  df-nfc 2886  df-ne 2934  df-ral 3053  df-rex 3063  df-rab 3391  df-v 3432  df-sbc 3730  df-csb 3839  df-dif 3893  df-un 3895  df-in 3897  df-ss 3907  df-nul 4275  df-if 4468  df-sn 4569  df-pr 4571  df-op 4575  df-uni 4852  df-br 5087  df-opab 5149  df-mpt 5168  df-id 5519  df-xp 5630  df-rel 5631  df-cnv 5632  df-co 5633  df-dm 5634  df-rn 5635  df-res 5636  df-ima 5637  df-iota 6448  df-fun 6494  df-fn 6495  df-f 6496  df-fo 6498  df-fv 6500

This theorem is referenced by:  fnfocofob  47539