| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mgpress.1 |  |-  S = ( R |`s A ) | 
						
							| 2 |  | mgpress.2 |  |-  M = ( mulGrp ` R ) | 
						
							| 3 |  | simpr |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> ( Base ` R ) C_ A ) | 
						
							| 4 | 2 | fvexi |  |-  M e. _V | 
						
							| 5 | 4 | a1i |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> M e. _V ) | 
						
							| 6 |  | simplr |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> A e. W ) | 
						
							| 7 |  | eqid |  |-  ( M |`s A ) = ( M |`s A ) | 
						
							| 8 |  | eqid |  |-  ( Base ` R ) = ( Base ` R ) | 
						
							| 9 | 2 8 | mgpbas |  |-  ( Base ` R ) = ( Base ` M ) | 
						
							| 10 | 7 9 | ressid2 |  |-  ( ( ( Base ` R ) C_ A /\ M e. _V /\ A e. W ) -> ( M |`s A ) = M ) | 
						
							| 11 | 3 5 6 10 | syl3anc |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> ( M |`s A ) = M ) | 
						
							| 12 |  | simpll |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> R e. V ) | 
						
							| 13 | 1 8 | ressid2 |  |-  ( ( ( Base ` R ) C_ A /\ R e. V /\ A e. W ) -> S = R ) | 
						
							| 14 | 3 12 6 13 | syl3anc |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> S = R ) | 
						
							| 15 | 14 | fveq2d |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> ( mulGrp ` S ) = ( mulGrp ` R ) ) | 
						
							| 16 | 2 11 15 | 3eqtr4a |  |-  ( ( ( R e. V /\ A e. W ) /\ ( Base ` R ) C_ A ) -> ( M |`s A ) = ( mulGrp ` S ) ) | 
						
							| 17 |  | eqid |  |-  ( .r ` R ) = ( .r ` R ) | 
						
							| 18 | 2 17 | mgpval |  |-  M = ( R sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) | 
						
							| 19 | 18 | oveq1i |  |-  ( M sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) = ( ( R sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) | 
						
							| 20 |  | simpr |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> -. ( Base ` R ) C_ A ) | 
						
							| 21 | 4 | a1i |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> M e. _V ) | 
						
							| 22 |  | simplr |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> A e. W ) | 
						
							| 23 | 7 9 | ressval2 |  |-  ( ( -. ( Base ` R ) C_ A /\ M e. _V /\ A e. W ) -> ( M |`s A ) = ( M sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) ) | 
						
							| 24 | 20 21 22 23 | syl3anc |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> ( M |`s A ) = ( M sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) ) | 
						
							| 25 |  | eqid |  |-  ( mulGrp ` S ) = ( mulGrp ` S ) | 
						
							| 26 |  | eqid |  |-  ( .r ` S ) = ( .r ` S ) | 
						
							| 27 | 25 26 | mgpval |  |-  ( mulGrp ` S ) = ( S sSet <. ( +g ` ndx ) , ( .r ` S ) >. ) | 
						
							| 28 |  | simpll |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> R e. V ) | 
						
							| 29 | 1 8 | ressval2 |  |-  ( ( -. ( Base ` R ) C_ A /\ R e. V /\ A e. W ) -> S = ( R sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) ) | 
						
							| 30 | 20 28 22 29 | syl3anc |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> S = ( R sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) ) | 
						
							| 31 | 1 17 | ressmulr |  |-  ( A e. W -> ( .r ` R ) = ( .r ` S ) ) | 
						
							| 32 | 31 | eqcomd |  |-  ( A e. W -> ( .r ` S ) = ( .r ` R ) ) | 
						
							| 33 | 32 | ad2antlr |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> ( .r ` S ) = ( .r ` R ) ) | 
						
							| 34 | 33 | opeq2d |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> <. ( +g ` ndx ) , ( .r ` S ) >. = <. ( +g ` ndx ) , ( .r ` R ) >. ) | 
						
							| 35 | 30 34 | oveq12d |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> ( S sSet <. ( +g ` ndx ) , ( .r ` S ) >. ) = ( ( R sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) ) | 
						
							| 36 | 27 35 | eqtrid |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> ( mulGrp ` S ) = ( ( R sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) ) | 
						
							| 37 |  | basendxnplusgndx |  |-  ( Base ` ndx ) =/= ( +g ` ndx ) | 
						
							| 38 | 37 | necomi |  |-  ( +g ` ndx ) =/= ( Base ` ndx ) | 
						
							| 39 |  | fvex |  |-  ( .r ` R ) e. _V | 
						
							| 40 |  | fvex |  |-  ( Base ` R ) e. _V | 
						
							| 41 | 40 | inex2 |  |-  ( A i^i ( Base ` R ) ) e. _V | 
						
							| 42 |  | fvex |  |-  ( +g ` ndx ) e. _V | 
						
							| 43 |  | fvex |  |-  ( Base ` ndx ) e. _V | 
						
							| 44 | 42 43 | setscom |  |-  ( ( ( R e. V /\ ( +g ` ndx ) =/= ( Base ` ndx ) ) /\ ( ( .r ` R ) e. _V /\ ( A i^i ( Base ` R ) ) e. _V ) ) -> ( ( R sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) = ( ( R sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) ) | 
						
							| 45 | 39 41 44 | mpanr12 |  |-  ( ( R e. V /\ ( +g ` ndx ) =/= ( Base ` ndx ) ) -> ( ( R sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) = ( ( R sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) ) | 
						
							| 46 | 28 38 45 | sylancl |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> ( ( R sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) = ( ( R sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) ) | 
						
							| 47 | 36 46 | eqtr4d |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> ( mulGrp ` S ) = ( ( R sSet <. ( +g ` ndx ) , ( .r ` R ) >. ) sSet <. ( Base ` ndx ) , ( A i^i ( Base ` R ) ) >. ) ) | 
						
							| 48 | 19 24 47 | 3eqtr4a |  |-  ( ( ( R e. V /\ A e. W ) /\ -. ( Base ` R ) C_ A ) -> ( M |`s A ) = ( mulGrp ` S ) ) | 
						
							| 49 | 16 48 | pm2.61dan |  |-  ( ( R e. V /\ A e. W ) -> ( M |`s A ) = ( mulGrp ` S ) ) |