Theorem fcof1 5762

Description: An application is injective if a retraction exists. Proposition 8 of [BourbakiEns] p. E.II.18. (Contributed by FL, 11-Nov-2011.) (Revised by Mario Carneiro, 27-Dec-2014.)

Assertion

Ref	Expression
fcof1	|- ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) -> F : A -1-1-> B )

Proof of Theorem fcof1

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

Step	Hyp	Ref	Expression
1		simpl 108	. 2 |- ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) -> F : A --> B )
2		simprr 527	. . . . . . . 8 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( F ` x ) = ( F ` y ) )
3	2	fveq2d 5500	. . . . . . 7 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( R ` ( F ` x ) ) = ( R ` ( F ` y ) ) )
4		simpll 524	. . . . . . . 8 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> F : A --> B )
5		simprll 532	. . . . . . . 8 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> x e. A )
6		fvco3 5567	. . . . . . . 8 |- ( ( F : A --> B /\ x e. A ) -> ( ( R o. F ) ` x ) = ( R ` ( F ` x ) ) )
7	4, 5, 6	syl2anc 409	. . . . . . 7 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( R o. F ) ` x ) = ( R ` ( F ` x ) ) )
8		simprlr 533	. . . . . . . 8 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> y e. A )
9		fvco3 5567	. . . . . . . 8 |- ( ( F : A --> B /\ y e. A ) -> ( ( R o. F ) ` y ) = ( R ` ( F ` y ) ) )
10	4, 8, 9	syl2anc 409	. . . . . . 7 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( R o. F ) ` y ) = ( R ` ( F ` y ) ) )
11	3, 7, 10	3eqtr4d 2213	. . . . . 6 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( R o. F ) ` x ) = ( ( R o. F ) ` y ) )
12		simplr 525	. . . . . . 7 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( R o. F ) = ( _I |` A ) )
13	12	fveq1d 5498	. . . . . 6 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( R o. F ) ` x ) = ( ( _I |` A ) ` x ) )
14	12	fveq1d 5498	. . . . . 6 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( R o. F ) ` y ) = ( ( _I |` A ) ` y ) )
15	11, 13, 14	3eqtr3d 2211	. . . . 5 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( _I |` A ) ` x ) = ( ( _I |` A ) ` y ) )
16		fvresi 5689	. . . . . 6 |- ( x e. A -> ( ( _I |` A ) ` x ) = x )
17	5, 16	syl 14	. . . . 5 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( _I |` A ) ` x ) = x )
18		fvresi 5689	. . . . . 6 |- ( y e. A -> ( ( _I |` A ) ` y ) = y )
19	8, 18	syl 14	. . . . 5 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> ( ( _I |` A ) ` y ) = y )
20	15, 17, 19	3eqtr3d 2211	. . . 4 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( ( x e. A /\ y e. A ) /\ ( F ` x ) = ( F ` y ) ) ) -> x = y )
21	20	expr 373	. . 3 |- ( ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) /\ ( x e. A /\ y e. A ) ) -> ( ( F ` x ) = ( F ` y ) -> x = y ) )
22	21	ralrimivva 2552	. 2 |- ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) -> A. x e. A A. y e. A ( ( F ` x ) = ( F ` y ) -> x = y ) )
23		dff13 5747	. 2 |- ( F : A -1-1-> B <-> ( F : A --> B /\ A. x e. A A. y e. A ( ( F ` x ) = ( F ` y ) -> x = y ) ) )
24	1, 22, 23	sylanbrc 415	1 |- ( ( F : A --> B /\ ( R o. F ) = ( _I |` A ) ) -> F : A -1-1-> B )

Syntax hints:   -> wi 4   /\ wa 103   = wceq 1348   e. wcel 2141   A.wral 2448   _I cid 4273   |` cres 4613   o. ccom 4615   -->wf 5194   -1-1->wf1 5195   ` cfv 5198

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-14 2144  ax-ext 2152  ax-sep 4107  ax-pow 4160  ax-pr 4194

This theorem depends on definitions:  df-bi 116  df-3an 975  df-tru 1351  df-nf 1454  df-sb 1756  df-eu 2022  df-mo 2023  df-clab 2157  df-cleq 2163  df-clel 2166  df-nfc 2301  df-ral 2453  df-rex 2454  df-v 2732  df-sbc 2956  df-un 3125  df-in 3127  df-ss 3134  df-pw 3568  df-sn 3589  df-pr 3590  df-op 3592  df-uni 3797  df-br 3990  df-opab 4051  df-id 4278  df-xp 4617  df-rel 4618  df-cnv 4619  df-co 4620  df-dm 4621  df-rn 4622  df-res 4623  df-ima 4624  df-iota 5160  df-fun 5200  df-fn 5201  df-f 5202  df-f1 5203  df-fv 5206

This theorem is referenced by:  fcof1o  5768