| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fpar.1 |  |-  H = ( ( `' ( 1st |` ( _V X. _V ) ) o. ( F o. ( 1st |` ( _V X. _V ) ) ) ) i^i ( `' ( 2nd |` ( _V X. _V ) ) o. ( G o. ( 2nd |` ( _V X. _V ) ) ) ) ) | 
						
							| 2 |  | fparlem3 |  |-  ( F Fn A -> ( `' ( 1st |` ( _V X. _V ) ) o. ( F o. ( 1st |` ( _V X. _V ) ) ) ) = U_ x e. A ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) ) | 
						
							| 3 |  | fparlem4 |  |-  ( G Fn B -> ( `' ( 2nd |` ( _V X. _V ) ) o. ( G o. ( 2nd |` ( _V X. _V ) ) ) ) = U_ y e. B ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) | 
						
							| 4 | 2 3 | ineqan12d |  |-  ( ( F Fn A /\ G Fn B ) -> ( ( `' ( 1st |` ( _V X. _V ) ) o. ( F o. ( 1st |` ( _V X. _V ) ) ) ) i^i ( `' ( 2nd |` ( _V X. _V ) ) o. ( G o. ( 2nd |` ( _V X. _V ) ) ) ) ) = ( U_ x e. A ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i U_ y e. B ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) ) | 
						
							| 5 |  | opex |  |-  <. ( F ` x ) , ( G ` y ) >. e. _V | 
						
							| 6 | 5 | dfmpo |  |-  ( x e. A , y e. B |-> <. ( F ` x ) , ( G ` y ) >. ) = U_ x e. A U_ y e. B { <. <. x , y >. , <. ( F ` x ) , ( G ` y ) >. >. } | 
						
							| 7 |  | inxp |  |-  ( ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) = ( ( ( { x } X. _V ) i^i ( _V X. { y } ) ) X. ( ( { ( F ` x ) } X. _V ) i^i ( _V X. { ( G ` y ) } ) ) ) | 
						
							| 8 |  | inxp |  |-  ( ( { x } X. _V ) i^i ( _V X. { y } ) ) = ( ( { x } i^i _V ) X. ( _V i^i { y } ) ) | 
						
							| 9 |  | inv1 |  |-  ( { x } i^i _V ) = { x } | 
						
							| 10 |  | incom |  |-  ( _V i^i { y } ) = ( { y } i^i _V ) | 
						
							| 11 |  | inv1 |  |-  ( { y } i^i _V ) = { y } | 
						
							| 12 | 10 11 | eqtri |  |-  ( _V i^i { y } ) = { y } | 
						
							| 13 | 9 12 | xpeq12i |  |-  ( ( { x } i^i _V ) X. ( _V i^i { y } ) ) = ( { x } X. { y } ) | 
						
							| 14 |  | vex |  |-  x e. _V | 
						
							| 15 |  | vex |  |-  y e. _V | 
						
							| 16 | 14 15 | xpsn |  |-  ( { x } X. { y } ) = { <. x , y >. } | 
						
							| 17 | 8 13 16 | 3eqtri |  |-  ( ( { x } X. _V ) i^i ( _V X. { y } ) ) = { <. x , y >. } | 
						
							| 18 |  | inxp |  |-  ( ( { ( F ` x ) } X. _V ) i^i ( _V X. { ( G ` y ) } ) ) = ( ( { ( F ` x ) } i^i _V ) X. ( _V i^i { ( G ` y ) } ) ) | 
						
							| 19 |  | inv1 |  |-  ( { ( F ` x ) } i^i _V ) = { ( F ` x ) } | 
						
							| 20 |  | incom |  |-  ( _V i^i { ( G ` y ) } ) = ( { ( G ` y ) } i^i _V ) | 
						
							| 21 |  | inv1 |  |-  ( { ( G ` y ) } i^i _V ) = { ( G ` y ) } | 
						
							| 22 | 20 21 | eqtri |  |-  ( _V i^i { ( G ` y ) } ) = { ( G ` y ) } | 
						
							| 23 | 19 22 | xpeq12i |  |-  ( ( { ( F ` x ) } i^i _V ) X. ( _V i^i { ( G ` y ) } ) ) = ( { ( F ` x ) } X. { ( G ` y ) } ) | 
						
							| 24 |  | fvex |  |-  ( F ` x ) e. _V | 
						
							| 25 |  | fvex |  |-  ( G ` y ) e. _V | 
						
							| 26 | 24 25 | xpsn |  |-  ( { ( F ` x ) } X. { ( G ` y ) } ) = { <. ( F ` x ) , ( G ` y ) >. } | 
						
							| 27 | 18 23 26 | 3eqtri |  |-  ( ( { ( F ` x ) } X. _V ) i^i ( _V X. { ( G ` y ) } ) ) = { <. ( F ` x ) , ( G ` y ) >. } | 
						
							| 28 | 17 27 | xpeq12i |  |-  ( ( ( { x } X. _V ) i^i ( _V X. { y } ) ) X. ( ( { ( F ` x ) } X. _V ) i^i ( _V X. { ( G ` y ) } ) ) ) = ( { <. x , y >. } X. { <. ( F ` x ) , ( G ` y ) >. } ) | 
						
							| 29 |  | opex |  |-  <. x , y >. e. _V | 
						
							| 30 | 29 5 | xpsn |  |-  ( { <. x , y >. } X. { <. ( F ` x ) , ( G ` y ) >. } ) = { <. <. x , y >. , <. ( F ` x ) , ( G ` y ) >. >. } | 
						
							| 31 | 7 28 30 | 3eqtri |  |-  ( ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) = { <. <. x , y >. , <. ( F ` x ) , ( G ` y ) >. >. } | 
						
							| 32 | 31 | a1i |  |-  ( y e. B -> ( ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) = { <. <. x , y >. , <. ( F ` x ) , ( G ` y ) >. >. } ) | 
						
							| 33 | 32 | iuneq2i |  |-  U_ y e. B ( ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) = U_ y e. B { <. <. x , y >. , <. ( F ` x ) , ( G ` y ) >. >. } | 
						
							| 34 | 33 | a1i |  |-  ( x e. A -> U_ y e. B ( ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) = U_ y e. B { <. <. x , y >. , <. ( F ` x ) , ( G ` y ) >. >. } ) | 
						
							| 35 | 34 | iuneq2i |  |-  U_ x e. A U_ y e. B ( ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) = U_ x e. A U_ y e. B { <. <. x , y >. , <. ( F ` x ) , ( G ` y ) >. >. } | 
						
							| 36 |  | 2iunin |  |-  U_ x e. A U_ y e. B ( ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) = ( U_ x e. A ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i U_ y e. B ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) | 
						
							| 37 | 6 35 36 | 3eqtr2i |  |-  ( x e. A , y e. B |-> <. ( F ` x ) , ( G ` y ) >. ) = ( U_ x e. A ( ( { x } X. _V ) X. ( { ( F ` x ) } X. _V ) ) i^i U_ y e. B ( ( _V X. { y } ) X. ( _V X. { ( G ` y ) } ) ) ) | 
						
							| 38 | 4 1 37 | 3eqtr4g |  |-  ( ( F Fn A /\ G Fn B ) -> H = ( x e. A , y e. B |-> <. ( F ` x ) , ( G ` y ) >. ) ) |