| Step | Hyp | Ref | Expression | 
						
							| 1 |  | df-nr |  |-  R. = ( ( P. X. P. ) /. ~R ) | 
						
							| 2 |  | breq1 |  |-  ( [ <. x , y >. ] ~R = f -> ( [ <. x , y >. ] ~R . ] ~R <-> f . ] ~R ) ) | 
						
							| 3 |  | eqeq1 |  |-  ( [ <. x , y >. ] ~R = f -> ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R <-> f = [ <. z , w >. ] ~R ) ) | 
						
							| 4 |  | breq2 |  |-  ( [ <. x , y >. ] ~R = f -> ( [ <. z , w >. ] ~R . ] ~R <-> [ <. z , w >. ] ~R  | 
						
							| 5 | 3 4 | orbi12d |  |-  ( [ <. x , y >. ] ~R = f -> ( ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R . ] ~R ) <-> ( f = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R  | 
						
							| 6 | 5 | notbid |  |-  ( [ <. x , y >. ] ~R = f -> ( -. ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R . ] ~R ) <-> -. ( f = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R  | 
						
							| 7 | 2 6 | bibi12d |  |-  ( [ <. x , y >. ] ~R = f -> ( ( [ <. x , y >. ] ~R . ] ~R <-> -. ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R . ] ~R ) ) <-> ( f . ] ~R <-> -. ( f = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R  | 
						
							| 8 |  | breq2 |  |-  ( [ <. z , w >. ] ~R = g -> ( f . ] ~R <-> f  | 
						
							| 9 |  | eqeq2 |  |-  ( [ <. z , w >. ] ~R = g -> ( f = [ <. z , w >. ] ~R <-> f = g ) ) | 
						
							| 10 |  | breq1 |  |-  ( [ <. z , w >. ] ~R = g -> ( [ <. z , w >. ] ~R  g  | 
						
							| 11 | 9 10 | orbi12d |  |-  ( [ <. z , w >. ] ~R = g -> ( ( f = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R  ( f = g \/ g  | 
						
							| 12 | 11 | notbid |  |-  ( [ <. z , w >. ] ~R = g -> ( -. ( f = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R  -. ( f = g \/ g  | 
						
							| 13 | 8 12 | bibi12d |  |-  ( [ <. z , w >. ] ~R = g -> ( ( f . ] ~R <-> -. ( f = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R  ( f  -. ( f = g \/ g  | 
						
							| 14 |  | ltsrpr |  |-  ( [ <. x , y >. ] ~R . ] ~R <-> ( x +P. w )  | 
						
							| 15 |  | addclpr |  |-  ( ( x e. P. /\ w e. P. ) -> ( x +P. w ) e. P. ) | 
						
							| 16 |  | addclpr |  |-  ( ( y e. P. /\ z e. P. ) -> ( y +P. z ) e. P. ) | 
						
							| 17 |  | ltsopr |  |-   | 
						
							| 18 |  | sotric |  |-  ( (  ( ( x +P. w )   -. ( ( x +P. w ) = ( y +P. z ) \/ ( y +P. z )  | 
						
							| 19 | 17 18 | mpan |  |-  ( ( ( x +P. w ) e. P. /\ ( y +P. z ) e. P. ) -> ( ( x +P. w )  -. ( ( x +P. w ) = ( y +P. z ) \/ ( y +P. z )  | 
						
							| 20 | 15 16 19 | syl2an |  |-  ( ( ( x e. P. /\ w e. P. ) /\ ( y e. P. /\ z e. P. ) ) -> ( ( x +P. w )  -. ( ( x +P. w ) = ( y +P. z ) \/ ( y +P. z )  | 
						
							| 21 | 20 | an42s |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) ) -> ( ( x +P. w )  -. ( ( x +P. w ) = ( y +P. z ) \/ ( y +P. z )  | 
						
							| 22 |  | enreceq |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) ) -> ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R <-> ( x +P. w ) = ( y +P. z ) ) ) | 
						
							| 23 |  | ltsrpr |  |-  ( [ <. z , w >. ] ~R . ] ~R <-> ( z +P. y )  | 
						
							| 24 |  | addcompr |  |-  ( z +P. y ) = ( y +P. z ) | 
						
							| 25 |  | addcompr |  |-  ( w +P. x ) = ( x +P. w ) | 
						
							| 26 | 24 25 | breq12i |  |-  ( ( z +P. y )  ( y +P. z )  | 
						
							| 27 | 23 26 | bitri |  |-  ( [ <. z , w >. ] ~R . ] ~R <-> ( y +P. z )  | 
						
							| 28 | 27 | a1i |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) ) -> ( [ <. z , w >. ] ~R . ] ~R <-> ( y +P. z )  | 
						
							| 29 | 22 28 | orbi12d |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) ) -> ( ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R . ] ~R ) <-> ( ( x +P. w ) = ( y +P. z ) \/ ( y +P. z )  | 
						
							| 30 | 29 | notbid |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) ) -> ( -. ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R . ] ~R ) <-> -. ( ( x +P. w ) = ( y +P. z ) \/ ( y +P. z )  | 
						
							| 31 | 21 30 | bitr4d |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) ) -> ( ( x +P. w )  -. ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R . ] ~R ) ) ) | 
						
							| 32 | 14 31 | bitrid |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) ) -> ( [ <. x , y >. ] ~R . ] ~R <-> -. ( [ <. x , y >. ] ~R = [ <. z , w >. ] ~R \/ [ <. z , w >. ] ~R . ] ~R ) ) ) | 
						
							| 33 | 1 7 13 32 | 2ecoptocl |  |-  ( ( f e. R. /\ g e. R. ) -> ( f  -. ( f = g \/ g  | 
						
							| 34 | 2 | anbi1d |  |-  ( [ <. x , y >. ] ~R = f -> ( ( [ <. x , y >. ] ~R . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) <-> ( f . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) ) ) | 
						
							| 35 |  | breq1 |  |-  ( [ <. x , y >. ] ~R = f -> ( [ <. x , y >. ] ~R . ] ~R <-> f . ] ~R ) ) | 
						
							| 36 | 34 35 | imbi12d |  |-  ( [ <. x , y >. ] ~R = f -> ( ( ( [ <. x , y >. ] ~R . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) -> [ <. x , y >. ] ~R . ] ~R ) <-> ( ( f . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) -> f . ] ~R ) ) ) | 
						
							| 37 |  | breq1 |  |-  ( [ <. z , w >. ] ~R = g -> ( [ <. z , w >. ] ~R . ] ~R <-> g . ] ~R ) ) | 
						
							| 38 | 8 37 | anbi12d |  |-  ( [ <. z , w >. ] ~R = g -> ( ( f . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) <-> ( f . ] ~R ) ) ) | 
						
							| 39 | 38 | imbi1d |  |-  ( [ <. z , w >. ] ~R = g -> ( ( ( f . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) -> f . ] ~R ) <-> ( ( f . ] ~R ) -> f . ] ~R ) ) ) | 
						
							| 40 |  | breq2 |  |-  ( [ <. v , u >. ] ~R = h -> ( g . ] ~R <-> g  | 
						
							| 41 | 40 | anbi2d |  |-  ( [ <. v , u >. ] ~R = h -> ( ( f . ] ~R ) <-> ( f  | 
						
							| 42 |  | breq2 |  |-  ( [ <. v , u >. ] ~R = h -> ( f . ] ~R <-> f  | 
						
							| 43 | 41 42 | imbi12d |  |-  ( [ <. v , u >. ] ~R = h -> ( ( ( f . ] ~R ) -> f . ] ~R ) <-> ( ( f  f  | 
						
							| 44 |  | ovex |  |-  ( x +P. w ) e. _V | 
						
							| 45 |  | ovex |  |-  ( y +P. z ) e. _V | 
						
							| 46 |  | ltapr |  |-  ( h e. P. -> ( f  ( h +P. f )  | 
						
							| 47 |  | vex |  |-  u e. _V | 
						
							| 48 |  | addcompr |  |-  ( f +P. g ) = ( g +P. f ) | 
						
							| 49 | 44 45 46 47 48 | caovord2 |  |-  ( u e. P. -> ( ( x +P. w )  ( ( x +P. w ) +P. u )  | 
						
							| 50 |  | addasspr |  |-  ( ( x +P. w ) +P. u ) = ( x +P. ( w +P. u ) ) | 
						
							| 51 |  | addasspr |  |-  ( ( y +P. z ) +P. u ) = ( y +P. ( z +P. u ) ) | 
						
							| 52 | 50 51 | breq12i |  |-  ( ( ( x +P. w ) +P. u )  ( x +P. ( w +P. u ) )  | 
						
							| 53 | 49 52 | bitrdi |  |-  ( u e. P. -> ( ( x +P. w )  ( x +P. ( w +P. u ) )  | 
						
							| 54 | 14 53 | bitrid |  |-  ( u e. P. -> ( [ <. x , y >. ] ~R . ] ~R <-> ( x +P. ( w +P. u ) )  | 
						
							| 55 |  | ltsrpr |  |-  ( [ <. z , w >. ] ~R . ] ~R <-> ( z +P. u )  | 
						
							| 56 |  | ltapr |  |-  ( y e. P. -> ( ( z +P. u )  ( y +P. ( z +P. u ) )  | 
						
							| 57 | 55 56 | bitrid |  |-  ( y e. P. -> ( [ <. z , w >. ] ~R . ] ~R <-> ( y +P. ( z +P. u ) )  | 
						
							| 58 | 54 57 | bi2anan9r |  |-  ( ( y e. P. /\ u e. P. ) -> ( ( [ <. x , y >. ] ~R . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) <-> ( ( x +P. ( w +P. u ) )  | 
						
							| 59 |  | ltrelpr |  |-   | 
						
							| 60 | 17 59 | sotri |  |-  ( ( ( x +P. ( w +P. u ) )  ( x +P. ( w +P. u ) )  | 
						
							| 61 |  | dmplp |  |-  dom +P. = ( P. X. P. ) | 
						
							| 62 |  | 0npr |  |-  -. (/) e. P. | 
						
							| 63 |  | ltapr |  |-  ( w e. P. -> ( ( x +P. u )  ( w +P. ( x +P. u ) )  | 
						
							| 64 | 61 59 62 63 | ndmovordi |  |-  ( ( w +P. ( x +P. u ) )  ( x +P. u )  | 
						
							| 65 |  | vex |  |-  x e. _V | 
						
							| 66 |  | vex |  |-  w e. _V | 
						
							| 67 |  | addasspr |  |-  ( ( f +P. g ) +P. h ) = ( f +P. ( g +P. h ) ) | 
						
							| 68 | 65 66 47 48 67 | caov12 |  |-  ( x +P. ( w +P. u ) ) = ( w +P. ( x +P. u ) ) | 
						
							| 69 |  | vex |  |-  y e. _V | 
						
							| 70 |  | vex |  |-  v e. _V | 
						
							| 71 | 69 66 70 48 67 | caov12 |  |-  ( y +P. ( w +P. v ) ) = ( w +P. ( y +P. v ) ) | 
						
							| 72 | 68 71 | breq12i |  |-  ( ( x +P. ( w +P. u ) )  ( w +P. ( x +P. u ) )  | 
						
							| 73 |  | ltsrpr |  |-  ( [ <. x , y >. ] ~R . ] ~R <-> ( x +P. u )  | 
						
							| 74 | 64 72 73 | 3imtr4i |  |-  ( ( x +P. ( w +P. u ) )  [ <. x , y >. ] ~R . ] ~R ) | 
						
							| 75 | 60 74 | syl |  |-  ( ( ( x +P. ( w +P. u ) )  [ <. x , y >. ] ~R . ] ~R ) | 
						
							| 76 | 58 75 | biimtrdi |  |-  ( ( y e. P. /\ u e. P. ) -> ( ( [ <. x , y >. ] ~R . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) -> [ <. x , y >. ] ~R . ] ~R ) ) | 
						
							| 77 | 76 | ad2ant2l |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( v e. P. /\ u e. P. ) ) -> ( ( [ <. x , y >. ] ~R . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) -> [ <. x , y >. ] ~R . ] ~R ) ) | 
						
							| 78 | 77 | 3adant2 |  |-  ( ( ( x e. P. /\ y e. P. ) /\ ( z e. P. /\ w e. P. ) /\ ( v e. P. /\ u e. P. ) ) -> ( ( [ <. x , y >. ] ~R . ] ~R /\ [ <. z , w >. ] ~R . ] ~R ) -> [ <. x , y >. ] ~R . ] ~R ) ) | 
						
							| 79 | 1 36 39 43 78 | 3ecoptocl |  |-  ( ( f e. R. /\ g e. R. /\ h e. R. ) -> ( ( f  f  | 
						
							| 80 | 33 79 | isso2i |  |-   |