| Step | Hyp | Ref | Expression | 
						
							| 1 |  | xpcomf1o.1 |  |-  F = ( x e. ( A X. B ) |-> U. `' { x } ) | 
						
							| 2 |  | xpcomco.1 |  |-  G = ( y e. B , z e. A |-> C ) | 
						
							| 3 | 1 | xpcomf1o |  |-  F : ( A X. B ) -1-1-onto-> ( B X. A ) | 
						
							| 4 |  | f1ofun |  |-  ( F : ( A X. B ) -1-1-onto-> ( B X. A ) -> Fun F ) | 
						
							| 5 |  | funbrfv2b |  |-  ( Fun F -> ( u F w <-> ( u e. dom F /\ ( F ` u ) = w ) ) ) | 
						
							| 6 | 3 4 5 | mp2b |  |-  ( u F w <-> ( u e. dom F /\ ( F ` u ) = w ) ) | 
						
							| 7 |  | ancom |  |-  ( ( u e. dom F /\ ( F ` u ) = w ) <-> ( ( F ` u ) = w /\ u e. dom F ) ) | 
						
							| 8 |  | eqcom |  |-  ( ( F ` u ) = w <-> w = ( F ` u ) ) | 
						
							| 9 |  | f1odm |  |-  ( F : ( A X. B ) -1-1-onto-> ( B X. A ) -> dom F = ( A X. B ) ) | 
						
							| 10 | 3 9 | ax-mp |  |-  dom F = ( A X. B ) | 
						
							| 11 | 10 | eleq2i |  |-  ( u e. dom F <-> u e. ( A X. B ) ) | 
						
							| 12 | 8 11 | anbi12i |  |-  ( ( ( F ` u ) = w /\ u e. dom F ) <-> ( w = ( F ` u ) /\ u e. ( A X. B ) ) ) | 
						
							| 13 | 6 7 12 | 3bitri |  |-  ( u F w <-> ( w = ( F ` u ) /\ u e. ( A X. B ) ) ) | 
						
							| 14 | 13 | anbi1i |  |-  ( ( u F w /\ w G v ) <-> ( ( w = ( F ` u ) /\ u e. ( A X. B ) ) /\ w G v ) ) | 
						
							| 15 |  | anass |  |-  ( ( ( w = ( F ` u ) /\ u e. ( A X. B ) ) /\ w G v ) <-> ( w = ( F ` u ) /\ ( u e. ( A X. B ) /\ w G v ) ) ) | 
						
							| 16 | 14 15 | bitri |  |-  ( ( u F w /\ w G v ) <-> ( w = ( F ` u ) /\ ( u e. ( A X. B ) /\ w G v ) ) ) | 
						
							| 17 | 16 | exbii |  |-  ( E. w ( u F w /\ w G v ) <-> E. w ( w = ( F ` u ) /\ ( u e. ( A X. B ) /\ w G v ) ) ) | 
						
							| 18 |  | fvex |  |-  ( F ` u ) e. _V | 
						
							| 19 |  | breq1 |  |-  ( w = ( F ` u ) -> ( w G v <-> ( F ` u ) G v ) ) | 
						
							| 20 | 19 | anbi2d |  |-  ( w = ( F ` u ) -> ( ( u e. ( A X. B ) /\ w G v ) <-> ( u e. ( A X. B ) /\ ( F ` u ) G v ) ) ) | 
						
							| 21 | 18 20 | ceqsexv |  |-  ( E. w ( w = ( F ` u ) /\ ( u e. ( A X. B ) /\ w G v ) ) <-> ( u e. ( A X. B ) /\ ( F ` u ) G v ) ) | 
						
							| 22 |  | elxp |  |-  ( u e. ( A X. B ) <-> E. z E. y ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) ) | 
						
							| 23 | 22 | anbi1i |  |-  ( ( u e. ( A X. B ) /\ ( F ` u ) G v ) <-> ( E. z E. y ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) ) | 
						
							| 24 |  | nfcv |  |-  F/_ z ( F ` u ) | 
						
							| 25 |  | nfmpo2 |  |-  F/_ z ( y e. B , z e. A |-> C ) | 
						
							| 26 | 2 25 | nfcxfr |  |-  F/_ z G | 
						
							| 27 |  | nfcv |  |-  F/_ z v | 
						
							| 28 | 24 26 27 | nfbr |  |-  F/ z ( F ` u ) G v | 
						
							| 29 | 28 | 19.41 |  |-  ( E. z ( E. y ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) <-> ( E. z E. y ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) ) | 
						
							| 30 |  | nfcv |  |-  F/_ y ( F ` u ) | 
						
							| 31 |  | nfmpo1 |  |-  F/_ y ( y e. B , z e. A |-> C ) | 
						
							| 32 | 2 31 | nfcxfr |  |-  F/_ y G | 
						
							| 33 |  | nfcv |  |-  F/_ y v | 
						
							| 34 | 30 32 33 | nfbr |  |-  F/ y ( F ` u ) G v | 
						
							| 35 | 34 | 19.41 |  |-  ( E. y ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) <-> ( E. y ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) ) | 
						
							| 36 |  | anass |  |-  ( ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) <-> ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ ( F ` u ) G v ) ) ) | 
						
							| 37 |  | fveq2 |  |-  ( u = <. z , y >. -> ( F ` u ) = ( F ` <. z , y >. ) ) | 
						
							| 38 |  | opelxpi |  |-  ( ( z e. A /\ y e. B ) -> <. z , y >. e. ( A X. B ) ) | 
						
							| 39 |  | sneq |  |-  ( x = <. z , y >. -> { x } = { <. z , y >. } ) | 
						
							| 40 | 39 | cnveqd |  |-  ( x = <. z , y >. -> `' { x } = `' { <. z , y >. } ) | 
						
							| 41 | 40 | unieqd |  |-  ( x = <. z , y >. -> U. `' { x } = U. `' { <. z , y >. } ) | 
						
							| 42 |  | opswap |  |-  U. `' { <. z , y >. } = <. y , z >. | 
						
							| 43 | 41 42 | eqtrdi |  |-  ( x = <. z , y >. -> U. `' { x } = <. y , z >. ) | 
						
							| 44 |  | opex |  |-  <. y , z >. e. _V | 
						
							| 45 | 43 1 44 | fvmpt |  |-  ( <. z , y >. e. ( A X. B ) -> ( F ` <. z , y >. ) = <. y , z >. ) | 
						
							| 46 | 38 45 | syl |  |-  ( ( z e. A /\ y e. B ) -> ( F ` <. z , y >. ) = <. y , z >. ) | 
						
							| 47 | 37 46 | sylan9eq |  |-  ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) -> ( F ` u ) = <. y , z >. ) | 
						
							| 48 | 47 | breq1d |  |-  ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) -> ( ( F ` u ) G v <-> <. y , z >. G v ) ) | 
						
							| 49 |  | df-br |  |-  ( <. y , z >. G v <-> <. <. y , z >. , v >. e. G ) | 
						
							| 50 |  | df-mpo |  |-  ( y e. B , z e. A |-> C ) = { <. <. y , z >. , v >. | ( ( y e. B /\ z e. A ) /\ v = C ) } | 
						
							| 51 | 2 50 | eqtri |  |-  G = { <. <. y , z >. , v >. | ( ( y e. B /\ z e. A ) /\ v = C ) } | 
						
							| 52 | 51 | eleq2i |  |-  ( <. <. y , z >. , v >. e. G <-> <. <. y , z >. , v >. e. { <. <. y , z >. , v >. | ( ( y e. B /\ z e. A ) /\ v = C ) } ) | 
						
							| 53 |  | oprabidw |  |-  ( <. <. y , z >. , v >. e. { <. <. y , z >. , v >. | ( ( y e. B /\ z e. A ) /\ v = C ) } <-> ( ( y e. B /\ z e. A ) /\ v = C ) ) | 
						
							| 54 | 49 52 53 | 3bitri |  |-  ( <. y , z >. G v <-> ( ( y e. B /\ z e. A ) /\ v = C ) ) | 
						
							| 55 | 54 | baib |  |-  ( ( y e. B /\ z e. A ) -> ( <. y , z >. G v <-> v = C ) ) | 
						
							| 56 | 55 | ancoms |  |-  ( ( z e. A /\ y e. B ) -> ( <. y , z >. G v <-> v = C ) ) | 
						
							| 57 | 56 | adantl |  |-  ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) -> ( <. y , z >. G v <-> v = C ) ) | 
						
							| 58 | 48 57 | bitrd |  |-  ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) -> ( ( F ` u ) G v <-> v = C ) ) | 
						
							| 59 | 58 | pm5.32da |  |-  ( u = <. z , y >. -> ( ( ( z e. A /\ y e. B ) /\ ( F ` u ) G v ) <-> ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 60 | 59 | pm5.32i |  |-  ( ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ ( F ` u ) G v ) ) <-> ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 61 | 36 60 | bitri |  |-  ( ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) <-> ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 62 | 61 | exbii |  |-  ( E. y ( ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) <-> E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 63 | 35 62 | bitr3i |  |-  ( ( E. y ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) <-> E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 64 | 63 | exbii |  |-  ( E. z ( E. y ( u = <. z , y >. /\ ( z e. A /\ y e. B ) ) /\ ( F ` u ) G v ) <-> E. z E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 65 | 23 29 64 | 3bitr2i |  |-  ( ( u e. ( A X. B ) /\ ( F ` u ) G v ) <-> E. z E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 66 | 17 21 65 | 3bitri |  |-  ( E. w ( u F w /\ w G v ) <-> E. z E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) ) | 
						
							| 67 | 66 | opabbii |  |-  { <. u , v >. | E. w ( u F w /\ w G v ) } = { <. u , v >. | E. z E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) } | 
						
							| 68 |  | df-co |  |-  ( G o. F ) = { <. u , v >. | E. w ( u F w /\ w G v ) } | 
						
							| 69 |  | df-mpo |  |-  ( z e. A , y e. B |-> C ) = { <. <. z , y >. , v >. | ( ( z e. A /\ y e. B ) /\ v = C ) } | 
						
							| 70 |  | dfoprab2 |  |-  { <. <. z , y >. , v >. | ( ( z e. A /\ y e. B ) /\ v = C ) } = { <. u , v >. | E. z E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) } | 
						
							| 71 | 69 70 | eqtri |  |-  ( z e. A , y e. B |-> C ) = { <. u , v >. | E. z E. y ( u = <. z , y >. /\ ( ( z e. A /\ y e. B ) /\ v = C ) ) } | 
						
							| 72 | 67 68 71 | 3eqtr4i |  |-  ( G o. F ) = ( z e. A , y e. B |-> C ) |