cofidf2a - Mathbox for Zhi Wang

	Mathbox for Zhi Wang		< Previous Next > Nearby theorems
Mirrors > Home > MPE Home > Th. List > Mathboxes > cofidf2a		Structured version Visualization version GIF version

Theorem cofidf2a 49470

Description: If "𝐹 is a section of 𝐺 " in a category of small categories (in a universe), then the morphism part of 𝐹 is injective, and the morphism part of 𝐺 is surjective in the image of 𝐹. (Contributed by Zhi Wang, 15-Nov-2025.)

**Hypotheses**
Ref	Expression
cofidvala.i	⊢ 𝐼 = (id_func‘𝐷)
cofidvala.b	⊢ 𝐵 = (Base‘𝐷)
cofidvala.f	⊢ (𝜑 → 𝐹 ∈ (𝐷 Func 𝐸))
cofidvala.g	⊢ (𝜑 → 𝐺 ∈ (𝐸 Func 𝐷))
cofidvala.o	⊢ (𝜑 → (𝐺 ∘_func 𝐹) = 𝐼)
cofidvala.h	⊢ 𝐻 = (Hom ‘𝐷)
cofidf2a.j	⊢ 𝐽 = (Hom ‘𝐸)
cofidf2a.x	⊢ (𝜑 → 𝑋 ∈ 𝐵)
cofidf2a.y	⊢ (𝜑 → 𝑌 ∈ 𝐵)

**Assertion**
Ref	Expression
cofidf2a	⊢ (𝜑 → ((𝑋(2^nd ‘𝐹)𝑌):(𝑋𝐻𝑌)–1-1→(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌)) ∧ (((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)):(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌))–onto→(𝑋𝐻𝑌)))

**Proof of Theorem cofidf2a**
Step	Hyp	Ref	Expression
1		cofidvala.b	. . . 4 ⊢ 𝐵 = (Base‘𝐷)
2		cofidvala.h	. . . 4 ⊢ 𝐻 = (Hom ‘𝐷)
3		cofidf2a.j	. . . 4 ⊢ 𝐽 = (Hom ‘𝐸)
4		cofidvala.f	. . . . 5 ⊢ (𝜑 → 𝐹 ∈ (𝐷 Func 𝐸))
5	4	func1st2nd 49429	. . . 4 ⊢ (𝜑 → (1^st ‘𝐹)(𝐷 Func 𝐸)(2^nd ‘𝐹))
6		cofidf2a.x	. . . 4 ⊢ (𝜑 → 𝑋 ∈ 𝐵)
7		cofidf2a.y	. . . 4 ⊢ (𝜑 → 𝑌 ∈ 𝐵)
8	1, 2, 3, 5, 6, 7	funcf2 17804	. . 3 ⊢ (𝜑 → (𝑋(2^nd ‘𝐹)𝑌):(𝑋𝐻𝑌)⟶(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌)))
9		cofidvala.o	. . . . . 6 ⊢ (𝜑 → (𝐺 ∘_func 𝐹) = 𝐼)
10	9	fveq2d 6846	. . . . 5 ⊢ (𝜑 → (2^nd ‘(𝐺 ∘_func 𝐹)) = (2^nd ‘𝐼))
11	10	oveqd 7385	. . . 4 ⊢ (𝜑 → (𝑋(2^nd ‘(𝐺 ∘_func 𝐹))𝑌) = (𝑋(2^nd ‘𝐼)𝑌))
12		cofidvala.g	. . . . 5 ⊢ (𝜑 → 𝐺 ∈ (𝐸 Func 𝐷))
13	1, 4, 12, 6, 7	cofu2nd 17821	. . . 4 ⊢ (𝜑 → (𝑋(2^nd ‘(𝐺 ∘_func 𝐹))𝑌) = ((((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)) ∘ (𝑋(2^nd ‘𝐹)𝑌)))
14		cofidvala.i	. . . . 5 ⊢ 𝐼 = (id_func‘𝐷)
15	5	funcrcl2 49432	. . . . 5 ⊢ (𝜑 → 𝐷 ∈ Cat)
16	14, 1, 15, 2, 6, 7	idfu2nd 17813	. . . 4 ⊢ (𝜑 → (𝑋(2^nd ‘𝐼)𝑌) = ( I ↾ (𝑋𝐻𝑌)))
17	11, 13, 16	3eqtr3d 2780	. . 3 ⊢ (𝜑 → ((((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)) ∘ (𝑋(2^nd ‘𝐹)𝑌)) = ( I ↾ (𝑋𝐻𝑌)))
18		fcof1 7243	. . 3 ⊢ (((𝑋(2^nd ‘𝐹)𝑌):(𝑋𝐻𝑌)⟶(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌)) ∧ ((((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)) ∘ (𝑋(2^nd ‘𝐹)𝑌)) = ( I ↾ (𝑋𝐻𝑌))) → (𝑋(2^nd ‘𝐹)𝑌):(𝑋𝐻𝑌)–1-1→(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌)))
19	8, 17, 18	syl2anc 585	. 2 ⊢ (𝜑 → (𝑋(2^nd ‘𝐹)𝑌):(𝑋𝐻𝑌)–1-1→(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌)))
20	14, 1, 6, 4, 12, 9	cofid1a 49465	. . . . 5 ⊢ (𝜑 → ((1^st ‘𝐺)‘((1^st ‘𝐹)‘𝑋)) = 𝑋)
21	14, 1, 7, 4, 12, 9	cofid1a 49465	. . . . 5 ⊢ (𝜑 → ((1^st ‘𝐺)‘((1^st ‘𝐹)‘𝑌)) = 𝑌)
22	20, 21	oveq12d 7386	. . . 4 ⊢ (𝜑 → (((1^st ‘𝐺)‘((1^st ‘𝐹)‘𝑋))𝐻((1^st ‘𝐺)‘((1^st ‘𝐹)‘𝑌))) = (𝑋𝐻𝑌))
23		eqid 2737	. . . . 5 ⊢ (Base‘𝐸) = (Base‘𝐸)
24	12	func1st2nd 49429	. . . . 5 ⊢ (𝜑 → (1^st ‘𝐺)(𝐸 Func 𝐷)(2^nd ‘𝐺))
25	1, 23, 5	funcf1 17802	. . . . . 6 ⊢ (𝜑 → (1^st ‘𝐹):𝐵⟶(Base‘𝐸))
26	25, 6	ffvelcdmd 7039	. . . . 5 ⊢ (𝜑 → ((1^st ‘𝐹)‘𝑋) ∈ (Base‘𝐸))
27	25, 7	ffvelcdmd 7039	. . . . 5 ⊢ (𝜑 → ((1^st ‘𝐹)‘𝑌) ∈ (Base‘𝐸))
28	23, 3, 2, 24, 26, 27	funcf2 17804	. . . 4 ⊢ (𝜑 → (((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)):(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌))⟶(((1^st ‘𝐺)‘((1^st ‘𝐹)‘𝑋))𝐻((1^st ‘𝐺)‘((1^st ‘𝐹)‘𝑌))))
29	22, 28	feq3dd 6657	. . 3 ⊢ (𝜑 → (((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)):(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌))⟶(𝑋𝐻𝑌))
30		fcofo 7244	. . 3 ⊢ (((((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)):(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌))⟶(𝑋𝐻𝑌) ∧ (𝑋(2^nd ‘𝐹)𝑌):(𝑋𝐻𝑌)⟶(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌)) ∧ ((((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)) ∘ (𝑋(2^nd ‘𝐹)𝑌)) = ( I ↾ (𝑋𝐻𝑌))) → (((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)):(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌))–onto→(𝑋𝐻𝑌))
31	29, 8, 17, 30	syl3anc 1374	. 2 ⊢ (𝜑 → (((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)):(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌))–onto→(𝑋𝐻𝑌))
32	19, 31	jca 511	1 ⊢ (𝜑 → ((𝑋(2^nd ‘𝐹)𝑌):(𝑋𝐻𝑌)–1-1→(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌)) ∧ (((1^st ‘𝐹)‘𝑋)(2^nd ‘𝐺)((1^st ‘𝐹)‘𝑌)):(((1^st ‘𝐹)‘𝑋)𝐽((1^st ‘𝐹)‘𝑌))–onto→(𝑋𝐻𝑌)))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ∧ wa 395 = wceq 1542 ∈ wcel 2114 I cid 5526 ↾ cres 5634 ∘ ccom 5636 ⟶wf 6496 –1-1→wf1 6497 –onto→wfo 6498 ‘cfv 6500 (class class class)co 7368 1^st c1st 7941 2^nd c2nd 7942 Basecbs 17148 Hom chom 17200 Func cfunc 17790 id_funccidfu 17791 ∘_func ccofu 17792

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-rep 5226 ax-sep 5243 ax-nul 5253 ax-pow 5312 ax-pr 5379 ax-un 7690

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-reu 3353 df-rab 3402 df-v 3444 df-sbc 3743 df-csb 3852 df-dif 3906 df-un 3908 df-in 3910 df-ss 3920 df-nul 4288 df-if 4482 df-pw 4558 df-sn 4583 df-pr 4585 df-op 4589 df-uni 4866 df-iun 4950 df-br 5101 df-opab 5163 df-mpt 5182 df-id 5527 df-xp 5638 df-rel 5639 df-cnv 5640 df-co 5641 df-dm 5642 df-rn 5643 df-res 5644 df-ima 5645 df-iota 6456 df-fun 6502 df-fn 6503 df-f 6504 df-f1 6505 df-fo 6506 df-f1o 6507 df-fv 6508 df-ov 7371 df-oprab 7372 df-mpo 7373 df-1st 7943 df-2nd 7944 df-map 8777 df-ixp 8848 df-func 17794 df-idfu 17795 df-cofu 17796

This theorem is referenced by: cofidf2 49473

W3C validator