| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dsmmsubg.p |  |-  P = ( S Xs_ R ) | 
						
							| 2 |  | dsmmsubg.h |  |-  H = ( Base ` ( S (+)m R ) ) | 
						
							| 3 |  | dsmmsubg.i |  |-  ( ph -> I e. W ) | 
						
							| 4 |  | dsmmsubg.s |  |-  ( ph -> S e. V ) | 
						
							| 5 |  | dsmmsubg.r |  |-  ( ph -> R : I --> Grp ) | 
						
							| 6 |  | eqidd |  |-  ( ph -> ( P |`s H ) = ( P |`s H ) ) | 
						
							| 7 |  | eqidd |  |-  ( ph -> ( 0g ` P ) = ( 0g ` P ) ) | 
						
							| 8 |  | eqidd |  |-  ( ph -> ( +g ` P ) = ( +g ` P ) ) | 
						
							| 9 | 5 3 | fexd |  |-  ( ph -> R e. _V ) | 
						
							| 10 |  | eqid |  |-  { a e. ( Base ` ( S Xs_ R ) ) | { b e. dom R | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin } = { a e. ( Base ` ( S Xs_ R ) ) | { b e. dom R | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin } | 
						
							| 11 | 10 | dsmmbase |  |-  ( R e. _V -> { a e. ( Base ` ( S Xs_ R ) ) | { b e. dom R | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin } = ( Base ` ( S (+)m R ) ) ) | 
						
							| 12 | 9 11 | syl |  |-  ( ph -> { a e. ( Base ` ( S Xs_ R ) ) | { b e. dom R | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin } = ( Base ` ( S (+)m R ) ) ) | 
						
							| 13 |  | ssrab2 |  |-  { a e. ( Base ` ( S Xs_ R ) ) | { b e. dom R | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin } C_ ( Base ` ( S Xs_ R ) ) | 
						
							| 14 | 12 13 | eqsstrrdi |  |-  ( ph -> ( Base ` ( S (+)m R ) ) C_ ( Base ` ( S Xs_ R ) ) ) | 
						
							| 15 | 1 | fveq2i |  |-  ( Base ` P ) = ( Base ` ( S Xs_ R ) ) | 
						
							| 16 | 14 2 15 | 3sstr4g |  |-  ( ph -> H C_ ( Base ` P ) ) | 
						
							| 17 |  | grpmnd |  |-  ( a e. Grp -> a e. Mnd ) | 
						
							| 18 | 17 | ssriv |  |-  Grp C_ Mnd | 
						
							| 19 |  | fss |  |-  ( ( R : I --> Grp /\ Grp C_ Mnd ) -> R : I --> Mnd ) | 
						
							| 20 | 5 18 19 | sylancl |  |-  ( ph -> R : I --> Mnd ) | 
						
							| 21 |  | eqid |  |-  ( 0g ` P ) = ( 0g ` P ) | 
						
							| 22 | 1 2 3 4 20 21 | dsmm0cl |  |-  ( ph -> ( 0g ` P ) e. H ) | 
						
							| 23 | 3 | 3ad2ant1 |  |-  ( ( ph /\ a e. H /\ b e. H ) -> I e. W ) | 
						
							| 24 | 4 | 3ad2ant1 |  |-  ( ( ph /\ a e. H /\ b e. H ) -> S e. V ) | 
						
							| 25 | 20 | 3ad2ant1 |  |-  ( ( ph /\ a e. H /\ b e. H ) -> R : I --> Mnd ) | 
						
							| 26 |  | simp2 |  |-  ( ( ph /\ a e. H /\ b e. H ) -> a e. H ) | 
						
							| 27 |  | simp3 |  |-  ( ( ph /\ a e. H /\ b e. H ) -> b e. H ) | 
						
							| 28 |  | eqid |  |-  ( +g ` P ) = ( +g ` P ) | 
						
							| 29 | 1 2 23 24 25 26 27 28 | dsmmacl |  |-  ( ( ph /\ a e. H /\ b e. H ) -> ( a ( +g ` P ) b ) e. H ) | 
						
							| 30 | 1 3 4 5 | prdsgrpd |  |-  ( ph -> P e. Grp ) | 
						
							| 31 | 30 | adantr |  |-  ( ( ph /\ a e. H ) -> P e. Grp ) | 
						
							| 32 | 16 | sselda |  |-  ( ( ph /\ a e. H ) -> a e. ( Base ` P ) ) | 
						
							| 33 |  | eqid |  |-  ( Base ` P ) = ( Base ` P ) | 
						
							| 34 |  | eqid |  |-  ( invg ` P ) = ( invg ` P ) | 
						
							| 35 | 33 34 | grpinvcl |  |-  ( ( P e. Grp /\ a e. ( Base ` P ) ) -> ( ( invg ` P ) ` a ) e. ( Base ` P ) ) | 
						
							| 36 | 31 32 35 | syl2anc |  |-  ( ( ph /\ a e. H ) -> ( ( invg ` P ) ` a ) e. ( Base ` P ) ) | 
						
							| 37 |  | simpr |  |-  ( ( ph /\ a e. H ) -> a e. H ) | 
						
							| 38 |  | eqid |  |-  ( S (+)m R ) = ( S (+)m R ) | 
						
							| 39 | 3 | adantr |  |-  ( ( ph /\ a e. H ) -> I e. W ) | 
						
							| 40 | 5 | ffnd |  |-  ( ph -> R Fn I ) | 
						
							| 41 | 40 | adantr |  |-  ( ( ph /\ a e. H ) -> R Fn I ) | 
						
							| 42 | 1 38 33 2 39 41 | dsmmelbas |  |-  ( ( ph /\ a e. H ) -> ( a e. H <-> ( a e. ( Base ` P ) /\ { b e. I | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin ) ) ) | 
						
							| 43 | 37 42 | mpbid |  |-  ( ( ph /\ a e. H ) -> ( a e. ( Base ` P ) /\ { b e. I | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin ) ) | 
						
							| 44 | 43 | simprd |  |-  ( ( ph /\ a e. H ) -> { b e. I | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin ) | 
						
							| 45 | 3 | ad2antrr |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> I e. W ) | 
						
							| 46 | 4 | ad2antrr |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> S e. V ) | 
						
							| 47 | 5 | ad2antrr |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> R : I --> Grp ) | 
						
							| 48 | 32 | adantr |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> a e. ( Base ` P ) ) | 
						
							| 49 |  | simpr |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> b e. I ) | 
						
							| 50 | 1 45 46 47 33 34 48 49 | prdsinvgd2 |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> ( ( ( invg ` P ) ` a ) ` b ) = ( ( invg ` ( R ` b ) ) ` ( a ` b ) ) ) | 
						
							| 51 | 50 | adantrr |  |-  ( ( ( ph /\ a e. H ) /\ ( b e. I /\ ( a ` b ) = ( 0g ` ( R ` b ) ) ) ) -> ( ( ( invg ` P ) ` a ) ` b ) = ( ( invg ` ( R ` b ) ) ` ( a ` b ) ) ) | 
						
							| 52 |  | fveq2 |  |-  ( ( a ` b ) = ( 0g ` ( R ` b ) ) -> ( ( invg ` ( R ` b ) ) ` ( a ` b ) ) = ( ( invg ` ( R ` b ) ) ` ( 0g ` ( R ` b ) ) ) ) | 
						
							| 53 | 52 | ad2antll |  |-  ( ( ( ph /\ a e. H ) /\ ( b e. I /\ ( a ` b ) = ( 0g ` ( R ` b ) ) ) ) -> ( ( invg ` ( R ` b ) ) ` ( a ` b ) ) = ( ( invg ` ( R ` b ) ) ` ( 0g ` ( R ` b ) ) ) ) | 
						
							| 54 | 5 | ffvelcdmda |  |-  ( ( ph /\ b e. I ) -> ( R ` b ) e. Grp ) | 
						
							| 55 | 54 | adantlr |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> ( R ` b ) e. Grp ) | 
						
							| 56 |  | eqid |  |-  ( 0g ` ( R ` b ) ) = ( 0g ` ( R ` b ) ) | 
						
							| 57 |  | eqid |  |-  ( invg ` ( R ` b ) ) = ( invg ` ( R ` b ) ) | 
						
							| 58 | 56 57 | grpinvid |  |-  ( ( R ` b ) e. Grp -> ( ( invg ` ( R ` b ) ) ` ( 0g ` ( R ` b ) ) ) = ( 0g ` ( R ` b ) ) ) | 
						
							| 59 | 55 58 | syl |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> ( ( invg ` ( R ` b ) ) ` ( 0g ` ( R ` b ) ) ) = ( 0g ` ( R ` b ) ) ) | 
						
							| 60 | 59 | adantrr |  |-  ( ( ( ph /\ a e. H ) /\ ( b e. I /\ ( a ` b ) = ( 0g ` ( R ` b ) ) ) ) -> ( ( invg ` ( R ` b ) ) ` ( 0g ` ( R ` b ) ) ) = ( 0g ` ( R ` b ) ) ) | 
						
							| 61 | 51 53 60 | 3eqtrd |  |-  ( ( ( ph /\ a e. H ) /\ ( b e. I /\ ( a ` b ) = ( 0g ` ( R ` b ) ) ) ) -> ( ( ( invg ` P ) ` a ) ` b ) = ( 0g ` ( R ` b ) ) ) | 
						
							| 62 | 61 | expr |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> ( ( a ` b ) = ( 0g ` ( R ` b ) ) -> ( ( ( invg ` P ) ` a ) ` b ) = ( 0g ` ( R ` b ) ) ) ) | 
						
							| 63 | 62 | necon3d |  |-  ( ( ( ph /\ a e. H ) /\ b e. I ) -> ( ( ( ( invg ` P ) ` a ) ` b ) =/= ( 0g ` ( R ` b ) ) -> ( a ` b ) =/= ( 0g ` ( R ` b ) ) ) ) | 
						
							| 64 | 63 | ss2rabdv |  |-  ( ( ph /\ a e. H ) -> { b e. I | ( ( ( invg ` P ) ` a ) ` b ) =/= ( 0g ` ( R ` b ) ) } C_ { b e. I | ( a ` b ) =/= ( 0g ` ( R ` b ) ) } ) | 
						
							| 65 | 44 64 | ssfid |  |-  ( ( ph /\ a e. H ) -> { b e. I | ( ( ( invg ` P ) ` a ) ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin ) | 
						
							| 66 | 1 38 33 2 39 41 | dsmmelbas |  |-  ( ( ph /\ a e. H ) -> ( ( ( invg ` P ) ` a ) e. H <-> ( ( ( invg ` P ) ` a ) e. ( Base ` P ) /\ { b e. I | ( ( ( invg ` P ) ` a ) ` b ) =/= ( 0g ` ( R ` b ) ) } e. Fin ) ) ) | 
						
							| 67 | 36 65 66 | mpbir2and |  |-  ( ( ph /\ a e. H ) -> ( ( invg ` P ) ` a ) e. H ) | 
						
							| 68 | 6 7 8 16 22 29 67 30 | issubgrpd2 |  |-  ( ph -> H e. ( SubGrp ` P ) ) |