| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ecopopr.1 |  |-  .~ = { <. x , y >. | ( ( x e. ( S X. S ) /\ y e. ( S X. S ) ) /\ E. z E. w E. v E. u ( ( x = <. z , w >. /\ y = <. v , u >. ) /\ ( z .+ u ) = ( w .+ v ) ) ) } | 
						
							| 2 |  | ecopopr.com |  |-  ( x .+ y ) = ( y .+ x ) | 
						
							| 3 |  | ecopopr.cl |  |-  ( ( x e. S /\ y e. S ) -> ( x .+ y ) e. S ) | 
						
							| 4 |  | ecopopr.ass |  |-  ( ( x .+ y ) .+ z ) = ( x .+ ( y .+ z ) ) | 
						
							| 5 |  | ecopopr.can |  |-  ( ( x e. S /\ y e. S ) -> ( ( x .+ y ) = ( x .+ z ) -> y = z ) ) | 
						
							| 6 |  | opabssxp |  |-  { <. x , y >. | ( ( x e. ( S X. S ) /\ y e. ( S X. S ) ) /\ E. z E. w E. v E. u ( ( x = <. z , w >. /\ y = <. v , u >. ) /\ ( z .+ u ) = ( w .+ v ) ) ) } C_ ( ( S X. S ) X. ( S X. S ) ) | 
						
							| 7 | 1 6 | eqsstri |  |-  .~ C_ ( ( S X. S ) X. ( S X. S ) ) | 
						
							| 8 | 7 | brel |  |-  ( A .~ B -> ( A e. ( S X. S ) /\ B e. ( S X. S ) ) ) | 
						
							| 9 | 8 | simpld |  |-  ( A .~ B -> A e. ( S X. S ) ) | 
						
							| 10 | 7 | brel |  |-  ( B .~ C -> ( B e. ( S X. S ) /\ C e. ( S X. S ) ) ) | 
						
							| 11 | 9 10 | anim12i |  |-  ( ( A .~ B /\ B .~ C ) -> ( A e. ( S X. S ) /\ ( B e. ( S X. S ) /\ C e. ( S X. S ) ) ) ) | 
						
							| 12 |  | 3anass |  |-  ( ( A e. ( S X. S ) /\ B e. ( S X. S ) /\ C e. ( S X. S ) ) <-> ( A e. ( S X. S ) /\ ( B e. ( S X. S ) /\ C e. ( S X. S ) ) ) ) | 
						
							| 13 | 11 12 | sylibr |  |-  ( ( A .~ B /\ B .~ C ) -> ( A e. ( S X. S ) /\ B e. ( S X. S ) /\ C e. ( S X. S ) ) ) | 
						
							| 14 |  | eqid |  |-  ( S X. S ) = ( S X. S ) | 
						
							| 15 |  | breq1 |  |-  ( <. f , g >. = A -> ( <. f , g >. .~ <. h , t >. <-> A .~ <. h , t >. ) ) | 
						
							| 16 | 15 | anbi1d |  |-  ( <. f , g >. = A -> ( ( <. f , g >. .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) <-> ( A .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) ) ) | 
						
							| 17 |  | breq1 |  |-  ( <. f , g >. = A -> ( <. f , g >. .~ <. s , r >. <-> A .~ <. s , r >. ) ) | 
						
							| 18 | 16 17 | imbi12d |  |-  ( <. f , g >. = A -> ( ( ( <. f , g >. .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) -> <. f , g >. .~ <. s , r >. ) <-> ( ( A .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) -> A .~ <. s , r >. ) ) ) | 
						
							| 19 |  | breq2 |  |-  ( <. h , t >. = B -> ( A .~ <. h , t >. <-> A .~ B ) ) | 
						
							| 20 |  | breq1 |  |-  ( <. h , t >. = B -> ( <. h , t >. .~ <. s , r >. <-> B .~ <. s , r >. ) ) | 
						
							| 21 | 19 20 | anbi12d |  |-  ( <. h , t >. = B -> ( ( A .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) <-> ( A .~ B /\ B .~ <. s , r >. ) ) ) | 
						
							| 22 | 21 | imbi1d |  |-  ( <. h , t >. = B -> ( ( ( A .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) -> A .~ <. s , r >. ) <-> ( ( A .~ B /\ B .~ <. s , r >. ) -> A .~ <. s , r >. ) ) ) | 
						
							| 23 |  | breq2 |  |-  ( <. s , r >. = C -> ( B .~ <. s , r >. <-> B .~ C ) ) | 
						
							| 24 | 23 | anbi2d |  |-  ( <. s , r >. = C -> ( ( A .~ B /\ B .~ <. s , r >. ) <-> ( A .~ B /\ B .~ C ) ) ) | 
						
							| 25 |  | breq2 |  |-  ( <. s , r >. = C -> ( A .~ <. s , r >. <-> A .~ C ) ) | 
						
							| 26 | 24 25 | imbi12d |  |-  ( <. s , r >. = C -> ( ( ( A .~ B /\ B .~ <. s , r >. ) -> A .~ <. s , r >. ) <-> ( ( A .~ B /\ B .~ C ) -> A .~ C ) ) ) | 
						
							| 27 | 1 | ecopoveq |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) ) -> ( <. f , g >. .~ <. h , t >. <-> ( f .+ t ) = ( g .+ h ) ) ) | 
						
							| 28 | 27 | 3adant3 |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( <. f , g >. .~ <. h , t >. <-> ( f .+ t ) = ( g .+ h ) ) ) | 
						
							| 29 | 1 | ecopoveq |  |-  ( ( ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( <. h , t >. .~ <. s , r >. <-> ( h .+ r ) = ( t .+ s ) ) ) | 
						
							| 30 | 29 | 3adant1 |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( <. h , t >. .~ <. s , r >. <-> ( h .+ r ) = ( t .+ s ) ) ) | 
						
							| 31 | 28 30 | anbi12d |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( ( <. f , g >. .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) <-> ( ( f .+ t ) = ( g .+ h ) /\ ( h .+ r ) = ( t .+ s ) ) ) ) | 
						
							| 32 |  | oveq12 |  |-  ( ( ( f .+ t ) = ( g .+ h ) /\ ( h .+ r ) = ( t .+ s ) ) -> ( ( f .+ t ) .+ ( h .+ r ) ) = ( ( g .+ h ) .+ ( t .+ s ) ) ) | 
						
							| 33 |  | vex |  |-  h e. _V | 
						
							| 34 |  | vex |  |-  t e. _V | 
						
							| 35 |  | vex |  |-  f e. _V | 
						
							| 36 |  | vex |  |-  r e. _V | 
						
							| 37 | 33 34 35 2 4 36 | caov411 |  |-  ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( f .+ t ) .+ ( h .+ r ) ) | 
						
							| 38 |  | vex |  |-  g e. _V | 
						
							| 39 |  | vex |  |-  s e. _V | 
						
							| 40 | 38 34 33 2 4 39 | caov411 |  |-  ( ( g .+ t ) .+ ( h .+ s ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) | 
						
							| 41 | 38 34 33 2 4 39 | caov4 |  |-  ( ( g .+ t ) .+ ( h .+ s ) ) = ( ( g .+ h ) .+ ( t .+ s ) ) | 
						
							| 42 | 40 41 | eqtr3i |  |-  ( ( h .+ t ) .+ ( g .+ s ) ) = ( ( g .+ h ) .+ ( t .+ s ) ) | 
						
							| 43 | 32 37 42 | 3eqtr4g |  |-  ( ( ( f .+ t ) = ( g .+ h ) /\ ( h .+ r ) = ( t .+ s ) ) -> ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) ) | 
						
							| 44 | 31 43 | biimtrdi |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( ( <. f , g >. .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) -> ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) ) ) | 
						
							| 45 | 3 | caovcl |  |-  ( ( h e. S /\ t e. S ) -> ( h .+ t ) e. S ) | 
						
							| 46 | 3 | caovcl |  |-  ( ( f e. S /\ r e. S ) -> ( f .+ r ) e. S ) | 
						
							| 47 |  | ovex |  |-  ( g .+ s ) e. _V | 
						
							| 48 | 47 5 | caovcan |  |-  ( ( ( h .+ t ) e. S /\ ( f .+ r ) e. S ) -> ( ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) -> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 49 | 45 46 48 | syl2an |  |-  ( ( ( h e. S /\ t e. S ) /\ ( f e. S /\ r e. S ) ) -> ( ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) -> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 50 | 49 | 3impb |  |-  ( ( ( h e. S /\ t e. S ) /\ f e. S /\ r e. S ) -> ( ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) -> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 51 | 50 | 3com12 |  |-  ( ( f e. S /\ ( h e. S /\ t e. S ) /\ r e. S ) -> ( ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) -> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 52 | 51 | 3adant3l |  |-  ( ( f e. S /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) -> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 53 | 52 | 3adant1r |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( ( ( h .+ t ) .+ ( f .+ r ) ) = ( ( h .+ t ) .+ ( g .+ s ) ) -> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 54 | 44 53 | syld |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( ( <. f , g >. .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) -> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 55 | 1 | ecopoveq |  |-  ( ( ( f e. S /\ g e. S ) /\ ( s e. S /\ r e. S ) ) -> ( <. f , g >. .~ <. s , r >. <-> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 56 | 55 | 3adant2 |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( <. f , g >. .~ <. s , r >. <-> ( f .+ r ) = ( g .+ s ) ) ) | 
						
							| 57 | 54 56 | sylibrd |  |-  ( ( ( f e. S /\ g e. S ) /\ ( h e. S /\ t e. S ) /\ ( s e. S /\ r e. S ) ) -> ( ( <. f , g >. .~ <. h , t >. /\ <. h , t >. .~ <. s , r >. ) -> <. f , g >. .~ <. s , r >. ) ) | 
						
							| 58 | 14 18 22 26 57 | 3optocl |  |-  ( ( A e. ( S X. S ) /\ B e. ( S X. S ) /\ C e. ( S X. S ) ) -> ( ( A .~ B /\ B .~ C ) -> A .~ C ) ) | 
						
							| 59 | 13 58 | mpcom |  |-  ( ( A .~ B /\ B .~ C ) -> A .~ C ) |