| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 1onn |  |-  1o e. _om | 
						
							| 2 |  | 1on |  |-  1o e. On | 
						
							| 3 | 2 | onirri |  |-  -. 1o e. 1o | 
						
							| 4 |  | eldif |  |-  ( 1o e. ( _om \ 1o ) <-> ( 1o e. _om /\ -. 1o e. 1o ) ) | 
						
							| 5 | 1 3 4 | mpbir2an |  |-  1o e. ( _om \ 1o ) | 
						
							| 6 |  | vex |  |-  x e. _V | 
						
							| 7 |  | vex |  |-  y e. _V | 
						
							| 8 | 6 7 | ifex |  |-  if ( m = (/) , x , y ) e. _V | 
						
							| 9 |  | eqid |  |-  ( m e. suc 1o |-> if ( m = (/) , x , y ) ) = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) | 
						
							| 10 | 8 9 | fnmpti |  |-  ( m e. suc 1o |-> if ( m = (/) , x , y ) ) Fn suc 1o | 
						
							| 11 |  | eqid |  |-  x = x | 
						
							| 12 |  | eqid |  |-  y = y | 
						
							| 13 | 11 12 | pm3.2i |  |-  ( x = x /\ y = y ) | 
						
							| 14 |  | 1oex |  |-  1o e. _V | 
						
							| 15 | 14 | sucex |  |-  suc 1o e. _V | 
						
							| 16 | 15 | mptex |  |-  ( m e. suc 1o |-> if ( m = (/) , x , y ) ) e. _V | 
						
							| 17 |  | fneq1 |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( f Fn suc 1o <-> ( m e. suc 1o |-> if ( m = (/) , x , y ) ) Fn suc 1o ) ) | 
						
							| 18 |  | fveq1 |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( f ` (/) ) = ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) ` (/) ) ) | 
						
							| 19 | 2 | onordi |  |-  Ord 1o | 
						
							| 20 |  | 0elsuc |  |-  ( Ord 1o -> (/) e. suc 1o ) | 
						
							| 21 | 19 20 | ax-mp |  |-  (/) e. suc 1o | 
						
							| 22 |  | iftrue |  |-  ( m = (/) -> if ( m = (/) , x , y ) = x ) | 
						
							| 23 | 22 9 6 | fvmpt |  |-  ( (/) e. suc 1o -> ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) ` (/) ) = x ) | 
						
							| 24 | 21 23 | ax-mp |  |-  ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) ` (/) ) = x | 
						
							| 25 | 18 24 | eqtrdi |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( f ` (/) ) = x ) | 
						
							| 26 | 25 | eqeq1d |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( ( f ` (/) ) = x <-> x = x ) ) | 
						
							| 27 |  | fveq1 |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( f ` 1o ) = ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) ` 1o ) ) | 
						
							| 28 | 14 | sucid |  |-  1o e. suc 1o | 
						
							| 29 |  | eqeq1 |  |-  ( m = 1o -> ( m = (/) <-> 1o = (/) ) ) | 
						
							| 30 | 29 | ifbid |  |-  ( m = 1o -> if ( m = (/) , x , y ) = if ( 1o = (/) , x , y ) ) | 
						
							| 31 |  | 1n0 |  |-  1o =/= (/) | 
						
							| 32 | 31 | neii |  |-  -. 1o = (/) | 
						
							| 33 | 32 | iffalsei |  |-  if ( 1o = (/) , x , y ) = y | 
						
							| 34 | 33 7 | eqeltri |  |-  if ( 1o = (/) , x , y ) e. _V | 
						
							| 35 | 30 9 34 | fvmpt |  |-  ( 1o e. suc 1o -> ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) ` 1o ) = if ( 1o = (/) , x , y ) ) | 
						
							| 36 | 28 35 | ax-mp |  |-  ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) ` 1o ) = if ( 1o = (/) , x , y ) | 
						
							| 37 | 36 33 | eqtri |  |-  ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) ` 1o ) = y | 
						
							| 38 | 27 37 | eqtrdi |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( f ` 1o ) = y ) | 
						
							| 39 | 38 | eqeq1d |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( ( f ` 1o ) = y <-> y = y ) ) | 
						
							| 40 | 26 39 | anbi12d |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) <-> ( x = x /\ y = y ) ) ) | 
						
							| 41 | 25 38 | breq12d |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( ( f ` (/) ) R ( f ` 1o ) <-> x R y ) ) | 
						
							| 42 | 17 40 41 | 3anbi123d |  |-  ( f = ( m e. suc 1o |-> if ( m = (/) , x , y ) ) -> ( ( f Fn suc 1o /\ ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) /\ ( f ` (/) ) R ( f ` 1o ) ) <-> ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) Fn suc 1o /\ ( x = x /\ y = y ) /\ x R y ) ) ) | 
						
							| 43 | 16 42 | spcev |  |-  ( ( ( m e. suc 1o |-> if ( m = (/) , x , y ) ) Fn suc 1o /\ ( x = x /\ y = y ) /\ x R y ) -> E. f ( f Fn suc 1o /\ ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) /\ ( f ` (/) ) R ( f ` 1o ) ) ) | 
						
							| 44 | 10 13 43 | mp3an12 |  |-  ( x R y -> E. f ( f Fn suc 1o /\ ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) /\ ( f ` (/) ) R ( f ` 1o ) ) ) | 
						
							| 45 |  | suceq |  |-  ( n = 1o -> suc n = suc 1o ) | 
						
							| 46 | 45 | fneq2d |  |-  ( n = 1o -> ( f Fn suc n <-> f Fn suc 1o ) ) | 
						
							| 47 |  | fveqeq2 |  |-  ( n = 1o -> ( ( f ` n ) = y <-> ( f ` 1o ) = y ) ) | 
						
							| 48 | 47 | anbi2d |  |-  ( n = 1o -> ( ( ( f ` (/) ) = x /\ ( f ` n ) = y ) <-> ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) ) ) | 
						
							| 49 |  | raleq |  |-  ( n = 1o -> ( A. m e. n ( f ` m ) R ( f ` suc m ) <-> A. m e. 1o ( f ` m ) R ( f ` suc m ) ) ) | 
						
							| 50 |  | df1o2 |  |-  1o = { (/) } | 
						
							| 51 | 50 | raleqi |  |-  ( A. m e. 1o ( f ` m ) R ( f ` suc m ) <-> A. m e. { (/) } ( f ` m ) R ( f ` suc m ) ) | 
						
							| 52 |  | 0ex |  |-  (/) e. _V | 
						
							| 53 |  | fveq2 |  |-  ( m = (/) -> ( f ` m ) = ( f ` (/) ) ) | 
						
							| 54 |  | suceq |  |-  ( m = (/) -> suc m = suc (/) ) | 
						
							| 55 |  | df-1o |  |-  1o = suc (/) | 
						
							| 56 | 54 55 | eqtr4di |  |-  ( m = (/) -> suc m = 1o ) | 
						
							| 57 | 56 | fveq2d |  |-  ( m = (/) -> ( f ` suc m ) = ( f ` 1o ) ) | 
						
							| 58 | 53 57 | breq12d |  |-  ( m = (/) -> ( ( f ` m ) R ( f ` suc m ) <-> ( f ` (/) ) R ( f ` 1o ) ) ) | 
						
							| 59 | 52 58 | ralsn |  |-  ( A. m e. { (/) } ( f ` m ) R ( f ` suc m ) <-> ( f ` (/) ) R ( f ` 1o ) ) | 
						
							| 60 | 51 59 | bitri |  |-  ( A. m e. 1o ( f ` m ) R ( f ` suc m ) <-> ( f ` (/) ) R ( f ` 1o ) ) | 
						
							| 61 | 49 60 | bitrdi |  |-  ( n = 1o -> ( A. m e. n ( f ` m ) R ( f ` suc m ) <-> ( f ` (/) ) R ( f ` 1o ) ) ) | 
						
							| 62 | 46 48 61 | 3anbi123d |  |-  ( n = 1o -> ( ( f Fn suc n /\ ( ( f ` (/) ) = x /\ ( f ` n ) = y ) /\ A. m e. n ( f ` m ) R ( f ` suc m ) ) <-> ( f Fn suc 1o /\ ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) /\ ( f ` (/) ) R ( f ` 1o ) ) ) ) | 
						
							| 63 | 62 | exbidv |  |-  ( n = 1o -> ( E. f ( f Fn suc n /\ ( ( f ` (/) ) = x /\ ( f ` n ) = y ) /\ A. m e. n ( f ` m ) R ( f ` suc m ) ) <-> E. f ( f Fn suc 1o /\ ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) /\ ( f ` (/) ) R ( f ` 1o ) ) ) ) | 
						
							| 64 | 63 | rspcev |  |-  ( ( 1o e. ( _om \ 1o ) /\ E. f ( f Fn suc 1o /\ ( ( f ` (/) ) = x /\ ( f ` 1o ) = y ) /\ ( f ` (/) ) R ( f ` 1o ) ) ) -> E. n e. ( _om \ 1o ) E. f ( f Fn suc n /\ ( ( f ` (/) ) = x /\ ( f ` n ) = y ) /\ A. m e. n ( f ` m ) R ( f ` suc m ) ) ) | 
						
							| 65 | 5 44 64 | sylancr |  |-  ( x R y -> E. n e. ( _om \ 1o ) E. f ( f Fn suc n /\ ( ( f ` (/) ) = x /\ ( f ` n ) = y ) /\ A. m e. n ( f ` m ) R ( f ` suc m ) ) ) | 
						
							| 66 |  | df-br |  |-  ( x R y <-> <. x , y >. e. R ) | 
						
							| 67 |  | brttrcl |  |-  ( x t++ R y <-> E. n e. ( _om \ 1o ) E. f ( f Fn suc n /\ ( ( f ` (/) ) = x /\ ( f ` n ) = y ) /\ A. m e. n ( f ` m ) R ( f ` suc m ) ) ) | 
						
							| 68 |  | df-br |  |-  ( x t++ R y <-> <. x , y >. e. t++ R ) | 
						
							| 69 | 67 68 | bitr3i |  |-  ( E. n e. ( _om \ 1o ) E. f ( f Fn suc n /\ ( ( f ` (/) ) = x /\ ( f ` n ) = y ) /\ A. m e. n ( f ` m ) R ( f ` suc m ) ) <-> <. x , y >. e. t++ R ) | 
						
							| 70 | 65 66 69 | 3imtr3i |  |-  ( <. x , y >. e. R -> <. x , y >. e. t++ R ) | 
						
							| 71 | 70 | gen2 |  |-  A. x A. y ( <. x , y >. e. R -> <. x , y >. e. t++ R ) | 
						
							| 72 |  | ssrel |  |-  ( Rel R -> ( R C_ t++ R <-> A. x A. y ( <. x , y >. e. R -> <. x , y >. e. t++ R ) ) ) | 
						
							| 73 | 71 72 | mpbiri |  |-  ( Rel R -> R C_ t++ R ) |