| Step | Hyp | Ref | Expression | 
						
							| 1 |  | omeulem1 |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> E. x e. On E. y e. A ( ( A .o x ) +o y ) = B ) | 
						
							| 2 |  | opex |  |-  <. x , y >. e. _V | 
						
							| 3 | 2 | isseti |  |-  E. z z = <. x , y >. | 
						
							| 4 |  | 19.41v |  |-  ( E. z ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> ( E. z z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) | 
						
							| 5 | 3 4 | mpbiran |  |-  ( E. z ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> ( ( A .o x ) +o y ) = B ) | 
						
							| 6 | 5 | rexbii |  |-  ( E. y e. A E. z ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> E. y e. A ( ( A .o x ) +o y ) = B ) | 
						
							| 7 |  | rexcom4 |  |-  ( E. y e. A E. z ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> E. z E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) | 
						
							| 8 | 6 7 | bitr3i |  |-  ( E. y e. A ( ( A .o x ) +o y ) = B <-> E. z E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) | 
						
							| 9 | 8 | rexbii |  |-  ( E. x e. On E. y e. A ( ( A .o x ) +o y ) = B <-> E. x e. On E. z E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) | 
						
							| 10 |  | rexcom4 |  |-  ( E. x e. On E. z E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> E. z E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) | 
						
							| 11 | 9 10 | bitri |  |-  ( E. x e. On E. y e. A ( ( A .o x ) +o y ) = B <-> E. z E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) | 
						
							| 12 | 1 11 | sylib |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> E. z E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) | 
						
							| 13 |  | simp2rl |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> z = <. x , y >. ) | 
						
							| 14 |  | simp3rl |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> t = <. r , s >. ) | 
						
							| 15 |  | simp2rr |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> ( ( A .o x ) +o y ) = B ) | 
						
							| 16 |  | simp3rr |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> ( ( A .o r ) +o s ) = B ) | 
						
							| 17 | 15 16 | eqtr4d |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> ( ( A .o x ) +o y ) = ( ( A .o r ) +o s ) ) | 
						
							| 18 |  | simp11 |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> A e. On ) | 
						
							| 19 |  | simp13 |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> A =/= (/) ) | 
						
							| 20 |  | simp2ll |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> x e. On ) | 
						
							| 21 |  | simp2lr |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> y e. A ) | 
						
							| 22 |  | simp3ll |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> r e. On ) | 
						
							| 23 |  | simp3lr |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> s e. A ) | 
						
							| 24 |  | omopth2 |  |-  ( ( ( A e. On /\ A =/= (/) ) /\ ( x e. On /\ y e. A ) /\ ( r e. On /\ s e. A ) ) -> ( ( ( A .o x ) +o y ) = ( ( A .o r ) +o s ) <-> ( x = r /\ y = s ) ) ) | 
						
							| 25 | 18 19 20 21 22 23 24 | syl222anc |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> ( ( ( A .o x ) +o y ) = ( ( A .o r ) +o s ) <-> ( x = r /\ y = s ) ) ) | 
						
							| 26 | 17 25 | mpbid |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> ( x = r /\ y = s ) ) | 
						
							| 27 |  | opeq12 |  |-  ( ( x = r /\ y = s ) -> <. x , y >. = <. r , s >. ) | 
						
							| 28 | 26 27 | syl |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> <. x , y >. = <. r , s >. ) | 
						
							| 29 | 14 28 | eqtr4d |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> t = <. x , y >. ) | 
						
							| 30 | 13 29 | eqtr4d |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) /\ ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) -> z = t ) | 
						
							| 31 | 30 | 3expia |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) ) -> ( ( ( r e. On /\ s e. A ) /\ ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) -> z = t ) ) | 
						
							| 32 | 31 | exp4b |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> ( ( ( x e. On /\ y e. A ) /\ ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) -> ( ( r e. On /\ s e. A ) -> ( ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) -> z = t ) ) ) ) | 
						
							| 33 | 32 | expd |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> ( ( x e. On /\ y e. A ) -> ( ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) -> ( ( r e. On /\ s e. A ) -> ( ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) -> z = t ) ) ) ) ) | 
						
							| 34 | 33 | rexlimdvv |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> ( E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) -> ( ( r e. On /\ s e. A ) -> ( ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) -> z = t ) ) ) ) | 
						
							| 35 | 34 | imp |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) -> ( ( r e. On /\ s e. A ) -> ( ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) -> z = t ) ) ) | 
						
							| 36 | 35 | rexlimdvv |  |-  ( ( ( A e. On /\ B e. On /\ A =/= (/) ) /\ E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) -> ( E. r e. On E. s e. A ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) -> z = t ) ) | 
						
							| 37 | 36 | expimpd |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> ( ( E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) /\ E. r e. On E. s e. A ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) -> z = t ) ) | 
						
							| 38 | 37 | alrimivv |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> A. z A. t ( ( E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) /\ E. r e. On E. s e. A ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) -> z = t ) ) | 
						
							| 39 |  | opeq1 |  |-  ( x = r -> <. x , y >. = <. r , y >. ) | 
						
							| 40 | 39 | eqeq2d |  |-  ( x = r -> ( z = <. x , y >. <-> z = <. r , y >. ) ) | 
						
							| 41 |  | oveq2 |  |-  ( x = r -> ( A .o x ) = ( A .o r ) ) | 
						
							| 42 | 41 | oveq1d |  |-  ( x = r -> ( ( A .o x ) +o y ) = ( ( A .o r ) +o y ) ) | 
						
							| 43 | 42 | eqeq1d |  |-  ( x = r -> ( ( ( A .o x ) +o y ) = B <-> ( ( A .o r ) +o y ) = B ) ) | 
						
							| 44 | 40 43 | anbi12d |  |-  ( x = r -> ( ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> ( z = <. r , y >. /\ ( ( A .o r ) +o y ) = B ) ) ) | 
						
							| 45 |  | opeq2 |  |-  ( y = s -> <. r , y >. = <. r , s >. ) | 
						
							| 46 | 45 | eqeq2d |  |-  ( y = s -> ( z = <. r , y >. <-> z = <. r , s >. ) ) | 
						
							| 47 |  | oveq2 |  |-  ( y = s -> ( ( A .o r ) +o y ) = ( ( A .o r ) +o s ) ) | 
						
							| 48 | 47 | eqeq1d |  |-  ( y = s -> ( ( ( A .o r ) +o y ) = B <-> ( ( A .o r ) +o s ) = B ) ) | 
						
							| 49 | 46 48 | anbi12d |  |-  ( y = s -> ( ( z = <. r , y >. /\ ( ( A .o r ) +o y ) = B ) <-> ( z = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) | 
						
							| 50 | 44 49 | cbvrex2vw |  |-  ( E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> E. r e. On E. s e. A ( z = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) | 
						
							| 51 |  | eqeq1 |  |-  ( z = t -> ( z = <. r , s >. <-> t = <. r , s >. ) ) | 
						
							| 52 | 51 | anbi1d |  |-  ( z = t -> ( ( z = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) <-> ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) | 
						
							| 53 | 52 | 2rexbidv |  |-  ( z = t -> ( E. r e. On E. s e. A ( z = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) <-> E. r e. On E. s e. A ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) | 
						
							| 54 | 50 53 | bitrid |  |-  ( z = t -> ( E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> E. r e. On E. s e. A ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) ) | 
						
							| 55 | 54 | eu4 |  |-  ( E! z E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) <-> ( E. z E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) /\ A. z A. t ( ( E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) /\ E. r e. On E. s e. A ( t = <. r , s >. /\ ( ( A .o r ) +o s ) = B ) ) -> z = t ) ) ) | 
						
							| 56 | 12 38 55 | sylanbrc |  |-  ( ( A e. On /\ B e. On /\ A =/= (/) ) -> E! z E. x e. On E. y e. A ( z = <. x , y >. /\ ( ( A .o x ) +o y ) = B ) ) |