| Step | Hyp | Ref | Expression | 
						
							| 1 |  | relcnv |  |-  Rel `' dom F | 
						
							| 2 |  | dmtpos |  |-  ( Rel dom F -> dom tpos F = `' dom F ) | 
						
							| 3 | 2 | releqd |  |-  ( Rel dom F -> ( Rel dom tpos F <-> Rel `' dom F ) ) | 
						
							| 4 | 1 3 | mpbiri |  |-  ( Rel dom F -> Rel dom tpos F ) | 
						
							| 5 |  | reltpos |  |-  Rel tpos F | 
						
							| 6 | 4 5 | jctil |  |-  ( Rel dom F -> ( Rel tpos F /\ Rel dom tpos F ) ) | 
						
							| 7 |  | relrelss |  |-  ( ( Rel tpos F /\ Rel dom tpos F ) <-> tpos F C_ ( ( _V X. _V ) X. _V ) ) | 
						
							| 8 | 6 7 | sylib |  |-  ( Rel dom F -> tpos F C_ ( ( _V X. _V ) X. _V ) ) | 
						
							| 9 | 8 | sseld |  |-  ( Rel dom F -> ( w e. tpos F -> w e. ( ( _V X. _V ) X. _V ) ) ) | 
						
							| 10 |  | elvvv |  |-  ( w e. ( ( _V X. _V ) X. _V ) <-> E. x E. y E. z w = <. <. x , y >. , z >. ) | 
						
							| 11 | 9 10 | imbitrdi |  |-  ( Rel dom F -> ( w e. tpos F -> E. x E. y E. z w = <. <. x , y >. , z >. ) ) | 
						
							| 12 | 11 | pm4.71rd |  |-  ( Rel dom F -> ( w e. tpos F <-> ( E. x E. y E. z w = <. <. x , y >. , z >. /\ w e. tpos F ) ) ) | 
						
							| 13 |  | 19.41vvv |  |-  ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ w e. tpos F ) <-> ( E. x E. y E. z w = <. <. x , y >. , z >. /\ w e. tpos F ) ) | 
						
							| 14 |  | eleq1 |  |-  ( w = <. <. x , y >. , z >. -> ( w e. tpos F <-> <. <. x , y >. , z >. e. tpos F ) ) | 
						
							| 15 |  | df-br |  |-  ( <. x , y >. tpos F z <-> <. <. x , y >. , z >. e. tpos F ) | 
						
							| 16 |  | brtpos |  |-  ( z e. _V -> ( <. x , y >. tpos F z <-> <. y , x >. F z ) ) | 
						
							| 17 | 16 | elv |  |-  ( <. x , y >. tpos F z <-> <. y , x >. F z ) | 
						
							| 18 | 15 17 | bitr3i |  |-  ( <. <. x , y >. , z >. e. tpos F <-> <. y , x >. F z ) | 
						
							| 19 | 14 18 | bitrdi |  |-  ( w = <. <. x , y >. , z >. -> ( w e. tpos F <-> <. y , x >. F z ) ) | 
						
							| 20 | 19 | pm5.32i |  |-  ( ( w = <. <. x , y >. , z >. /\ w e. tpos F ) <-> ( w = <. <. x , y >. , z >. /\ <. y , x >. F z ) ) | 
						
							| 21 | 20 | 3exbii |  |-  ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ w e. tpos F ) <-> E. x E. y E. z ( w = <. <. x , y >. , z >. /\ <. y , x >. F z ) ) | 
						
							| 22 | 13 21 | bitr3i |  |-  ( ( E. x E. y E. z w = <. <. x , y >. , z >. /\ w e. tpos F ) <-> E. x E. y E. z ( w = <. <. x , y >. , z >. /\ <. y , x >. F z ) ) | 
						
							| 23 | 12 22 | bitrdi |  |-  ( Rel dom F -> ( w e. tpos F <-> E. x E. y E. z ( w = <. <. x , y >. , z >. /\ <. y , x >. F z ) ) ) | 
						
							| 24 | 23 | eqabdv |  |-  ( Rel dom F -> tpos F = { w | E. x E. y E. z ( w = <. <. x , y >. , z >. /\ <. y , x >. F z ) } ) | 
						
							| 25 |  | df-oprab |  |-  { <. <. x , y >. , z >. | <. y , x >. F z } = { w | E. x E. y E. z ( w = <. <. x , y >. , z >. /\ <. y , x >. F z ) } | 
						
							| 26 | 24 25 | eqtr4di |  |-  ( Rel dom F -> tpos F = { <. <. x , y >. , z >. | <. y , x >. F z } ) |