| Step | Hyp | Ref | Expression | 
						
							| 1 |  | prproropf1o.o |  |-  O = ( R i^i ( V X. V ) ) | 
						
							| 2 |  | prproropf1o.p |  |-  P = { p e. ~P V | ( # ` p ) = 2 } | 
						
							| 3 |  | prproropf1o.f |  |-  F = ( p e. P |-> <. inf ( p , V , R ) , sup ( p , V , R ) >. ) | 
						
							| 4 |  | infeq1 |  |-  ( p = { ( 1st ` W ) , ( 2nd ` W ) } -> inf ( p , V , R ) = inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) ) | 
						
							| 5 |  | supeq1 |  |-  ( p = { ( 1st ` W ) , ( 2nd ` W ) } -> sup ( p , V , R ) = sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) ) | 
						
							| 6 | 4 5 | opeq12d |  |-  ( p = { ( 1st ` W ) , ( 2nd ` W ) } -> <. inf ( p , V , R ) , sup ( p , V , R ) >. = <. inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) , sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) >. ) | 
						
							| 7 | 1 | prproropf1olem0 |  |-  ( W e. O <-> ( W = <. ( 1st ` W ) , ( 2nd ` W ) >. /\ ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) | 
						
							| 8 |  | simpl |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> R Or V ) | 
						
							| 9 |  | simprll |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> ( 1st ` W ) e. V ) | 
						
							| 10 |  | simprlr |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> ( 2nd ` W ) e. V ) | 
						
							| 11 |  | infpr |  |-  ( ( R Or V /\ ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) -> inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) = if ( ( 1st ` W ) R ( 2nd ` W ) , ( 1st ` W ) , ( 2nd ` W ) ) ) | 
						
							| 12 | 8 9 10 11 | syl3anc |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) = if ( ( 1st ` W ) R ( 2nd ` W ) , ( 1st ` W ) , ( 2nd ` W ) ) ) | 
						
							| 13 |  | iftrue |  |-  ( ( 1st ` W ) R ( 2nd ` W ) -> if ( ( 1st ` W ) R ( 2nd ` W ) , ( 1st ` W ) , ( 2nd ` W ) ) = ( 1st ` W ) ) | 
						
							| 14 | 13 | ad2antll |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> if ( ( 1st ` W ) R ( 2nd ` W ) , ( 1st ` W ) , ( 2nd ` W ) ) = ( 1st ` W ) ) | 
						
							| 15 | 12 14 | eqtrd |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) = ( 1st ` W ) ) | 
						
							| 16 |  | suppr |  |-  ( ( R Or V /\ ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) -> sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) = if ( ( 2nd ` W ) R ( 1st ` W ) , ( 1st ` W ) , ( 2nd ` W ) ) ) | 
						
							| 17 | 8 9 10 16 | syl3anc |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) = if ( ( 2nd ` W ) R ( 1st ` W ) , ( 1st ` W ) , ( 2nd ` W ) ) ) | 
						
							| 18 |  | soasym |  |-  ( ( R Or V /\ ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) ) -> ( ( 1st ` W ) R ( 2nd ` W ) -> -. ( 2nd ` W ) R ( 1st ` W ) ) ) | 
						
							| 19 | 18 | impr |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> -. ( 2nd ` W ) R ( 1st ` W ) ) | 
						
							| 20 | 19 | iffalsed |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> if ( ( 2nd ` W ) R ( 1st ` W ) , ( 1st ` W ) , ( 2nd ` W ) ) = ( 2nd ` W ) ) | 
						
							| 21 | 17 20 | eqtrd |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) = ( 2nd ` W ) ) | 
						
							| 22 | 15 21 | opeq12d |  |-  ( ( R Or V /\ ( ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> <. inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) , sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) >. = <. ( 1st ` W ) , ( 2nd ` W ) >. ) | 
						
							| 23 | 22 | 3adantr1 |  |-  ( ( R Or V /\ ( W = <. ( 1st ` W ) , ( 2nd ` W ) >. /\ ( ( 1st ` W ) e. V /\ ( 2nd ` W ) e. V ) /\ ( 1st ` W ) R ( 2nd ` W ) ) ) -> <. inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) , sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) >. = <. ( 1st ` W ) , ( 2nd ` W ) >. ) | 
						
							| 24 | 7 23 | sylan2b |  |-  ( ( R Or V /\ W e. O ) -> <. inf ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) , sup ( { ( 1st ` W ) , ( 2nd ` W ) } , V , R ) >. = <. ( 1st ` W ) , ( 2nd ` W ) >. ) | 
						
							| 25 | 6 24 | sylan9eqr |  |-  ( ( ( R Or V /\ W e. O ) /\ p = { ( 1st ` W ) , ( 2nd ` W ) } ) -> <. inf ( p , V , R ) , sup ( p , V , R ) >. = <. ( 1st ` W ) , ( 2nd ` W ) >. ) | 
						
							| 26 | 1 2 | prproropf1olem1 |  |-  ( ( R Or V /\ W e. O ) -> { ( 1st ` W ) , ( 2nd ` W ) } e. P ) | 
						
							| 27 |  | opex |  |-  <. ( 1st ` W ) , ( 2nd ` W ) >. e. _V | 
						
							| 28 | 27 | a1i |  |-  ( ( R Or V /\ W e. O ) -> <. ( 1st ` W ) , ( 2nd ` W ) >. e. _V ) | 
						
							| 29 | 3 25 26 28 | fvmptd2 |  |-  ( ( R Or V /\ W e. O ) -> ( F ` { ( 1st ` W ) , ( 2nd ` W ) } ) = <. ( 1st ` W ) , ( 2nd ` W ) >. ) |