| Step | Hyp | Ref | Expression | 
						
							| 1 |  | isdrngdOLD.b |  |-  ( ph -> B = ( Base ` R ) ) | 
						
							| 2 |  | isdrngdOLD.t |  |-  ( ph -> .x. = ( .r ` R ) ) | 
						
							| 3 |  | isdrngdOLD.z |  |-  ( ph -> .0. = ( 0g ` R ) ) | 
						
							| 4 |  | isdrngdOLD.u |  |-  ( ph -> .1. = ( 1r ` R ) ) | 
						
							| 5 |  | isdrngdOLD.r |  |-  ( ph -> R e. Ring ) | 
						
							| 6 |  | isdrngdOLD.n |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) /\ ( y e. B /\ y =/= .0. ) ) -> ( x .x. y ) =/= .0. ) | 
						
							| 7 |  | isdrngdOLD.o |  |-  ( ph -> .1. =/= .0. ) | 
						
							| 8 |  | isdrngdOLD.i |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) ) -> I e. B ) | 
						
							| 9 |  | isdrngdOLD.j |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) ) -> I =/= .0. ) | 
						
							| 10 |  | isdrngdOLD.k |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) ) -> ( I .x. x ) = .1. ) | 
						
							| 11 |  | difss |  |-  ( B \ { .0. } ) C_ B | 
						
							| 12 | 11 1 | sseqtrid |  |-  ( ph -> ( B \ { .0. } ) C_ ( Base ` R ) ) | 
						
							| 13 |  | eqid |  |-  ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) = ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) | 
						
							| 14 |  | eqid |  |-  ( mulGrp ` R ) = ( mulGrp ` R ) | 
						
							| 15 |  | eqid |  |-  ( Base ` R ) = ( Base ` R ) | 
						
							| 16 | 14 15 | mgpbas |  |-  ( Base ` R ) = ( Base ` ( mulGrp ` R ) ) | 
						
							| 17 | 13 16 | ressbas2 |  |-  ( ( B \ { .0. } ) C_ ( Base ` R ) -> ( B \ { .0. } ) = ( Base ` ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) ) ) | 
						
							| 18 | 12 17 | syl |  |-  ( ph -> ( B \ { .0. } ) = ( Base ` ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) ) ) | 
						
							| 19 |  | fvex |  |-  ( Base ` R ) e. _V | 
						
							| 20 | 1 19 | eqeltrdi |  |-  ( ph -> B e. _V ) | 
						
							| 21 |  | difexg |  |-  ( B e. _V -> ( B \ { .0. } ) e. _V ) | 
						
							| 22 |  | eqid |  |-  ( .r ` R ) = ( .r ` R ) | 
						
							| 23 | 14 22 | mgpplusg |  |-  ( .r ` R ) = ( +g ` ( mulGrp ` R ) ) | 
						
							| 24 | 13 23 | ressplusg |  |-  ( ( B \ { .0. } ) e. _V -> ( .r ` R ) = ( +g ` ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) ) ) | 
						
							| 25 | 20 21 24 | 3syl |  |-  ( ph -> ( .r ` R ) = ( +g ` ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) ) ) | 
						
							| 26 | 2 25 | eqtrd |  |-  ( ph -> .x. = ( +g ` ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) ) ) | 
						
							| 27 |  | eldifsn |  |-  ( x e. ( B \ { .0. } ) <-> ( x e. B /\ x =/= .0. ) ) | 
						
							| 28 |  | eldifsn |  |-  ( y e. ( B \ { .0. } ) <-> ( y e. B /\ y =/= .0. ) ) | 
						
							| 29 | 15 22 | ringcl |  |-  ( ( R e. Ring /\ x e. ( Base ` R ) /\ y e. ( Base ` R ) ) -> ( x ( .r ` R ) y ) e. ( Base ` R ) ) | 
						
							| 30 | 5 29 | syl3an1 |  |-  ( ( ph /\ x e. ( Base ` R ) /\ y e. ( Base ` R ) ) -> ( x ( .r ` R ) y ) e. ( Base ` R ) ) | 
						
							| 31 | 30 | 3expib |  |-  ( ph -> ( ( x e. ( Base ` R ) /\ y e. ( Base ` R ) ) -> ( x ( .r ` R ) y ) e. ( Base ` R ) ) ) | 
						
							| 32 | 1 | eleq2d |  |-  ( ph -> ( x e. B <-> x e. ( Base ` R ) ) ) | 
						
							| 33 | 1 | eleq2d |  |-  ( ph -> ( y e. B <-> y e. ( Base ` R ) ) ) | 
						
							| 34 | 32 33 | anbi12d |  |-  ( ph -> ( ( x e. B /\ y e. B ) <-> ( x e. ( Base ` R ) /\ y e. ( Base ` R ) ) ) ) | 
						
							| 35 | 2 | oveqd |  |-  ( ph -> ( x .x. y ) = ( x ( .r ` R ) y ) ) | 
						
							| 36 | 35 1 | eleq12d |  |-  ( ph -> ( ( x .x. y ) e. B <-> ( x ( .r ` R ) y ) e. ( Base ` R ) ) ) | 
						
							| 37 | 31 34 36 | 3imtr4d |  |-  ( ph -> ( ( x e. B /\ y e. B ) -> ( x .x. y ) e. B ) ) | 
						
							| 38 | 37 | 3impib |  |-  ( ( ph /\ x e. B /\ y e. B ) -> ( x .x. y ) e. B ) | 
						
							| 39 | 38 | 3adant2r |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) /\ y e. B ) -> ( x .x. y ) e. B ) | 
						
							| 40 | 39 | 3adant3r |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) /\ ( y e. B /\ y =/= .0. ) ) -> ( x .x. y ) e. B ) | 
						
							| 41 |  | eldifsn |  |-  ( ( x .x. y ) e. ( B \ { .0. } ) <-> ( ( x .x. y ) e. B /\ ( x .x. y ) =/= .0. ) ) | 
						
							| 42 | 40 6 41 | sylanbrc |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) /\ ( y e. B /\ y =/= .0. ) ) -> ( x .x. y ) e. ( B \ { .0. } ) ) | 
						
							| 43 | 28 42 | syl3an3b |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) /\ y e. ( B \ { .0. } ) ) -> ( x .x. y ) e. ( B \ { .0. } ) ) | 
						
							| 44 | 27 43 | syl3an2b |  |-  ( ( ph /\ x e. ( B \ { .0. } ) /\ y e. ( B \ { .0. } ) ) -> ( x .x. y ) e. ( B \ { .0. } ) ) | 
						
							| 45 | 15 22 | ringass |  |-  ( ( R e. Ring /\ ( x e. ( Base ` R ) /\ y e. ( Base ` R ) /\ z e. ( Base ` R ) ) ) -> ( ( x ( .r ` R ) y ) ( .r ` R ) z ) = ( x ( .r ` R ) ( y ( .r ` R ) z ) ) ) | 
						
							| 46 | 45 | ex |  |-  ( R e. Ring -> ( ( x e. ( Base ` R ) /\ y e. ( Base ` R ) /\ z e. ( Base ` R ) ) -> ( ( x ( .r ` R ) y ) ( .r ` R ) z ) = ( x ( .r ` R ) ( y ( .r ` R ) z ) ) ) ) | 
						
							| 47 | 5 46 | syl |  |-  ( ph -> ( ( x e. ( Base ` R ) /\ y e. ( Base ` R ) /\ z e. ( Base ` R ) ) -> ( ( x ( .r ` R ) y ) ( .r ` R ) z ) = ( x ( .r ` R ) ( y ( .r ` R ) z ) ) ) ) | 
						
							| 48 | 1 | eleq2d |  |-  ( ph -> ( z e. B <-> z e. ( Base ` R ) ) ) | 
						
							| 49 | 32 33 48 | 3anbi123d |  |-  ( ph -> ( ( x e. B /\ y e. B /\ z e. B ) <-> ( x e. ( Base ` R ) /\ y e. ( Base ` R ) /\ z e. ( Base ` R ) ) ) ) | 
						
							| 50 |  | eqidd |  |-  ( ph -> z = z ) | 
						
							| 51 | 2 35 50 | oveq123d |  |-  ( ph -> ( ( x .x. y ) .x. z ) = ( ( x ( .r ` R ) y ) ( .r ` R ) z ) ) | 
						
							| 52 |  | eqidd |  |-  ( ph -> x = x ) | 
						
							| 53 | 2 | oveqd |  |-  ( ph -> ( y .x. z ) = ( y ( .r ` R ) z ) ) | 
						
							| 54 | 2 52 53 | oveq123d |  |-  ( ph -> ( x .x. ( y .x. z ) ) = ( x ( .r ` R ) ( y ( .r ` R ) z ) ) ) | 
						
							| 55 | 51 54 | eqeq12d |  |-  ( ph -> ( ( ( x .x. y ) .x. z ) = ( x .x. ( y .x. z ) ) <-> ( ( x ( .r ` R ) y ) ( .r ` R ) z ) = ( x ( .r ` R ) ( y ( .r ` R ) z ) ) ) ) | 
						
							| 56 | 47 49 55 | 3imtr4d |  |-  ( ph -> ( ( x e. B /\ y e. B /\ z e. B ) -> ( ( x .x. y ) .x. z ) = ( x .x. ( y .x. z ) ) ) ) | 
						
							| 57 |  | eldifi |  |-  ( x e. ( B \ { .0. } ) -> x e. B ) | 
						
							| 58 |  | eldifi |  |-  ( y e. ( B \ { .0. } ) -> y e. B ) | 
						
							| 59 |  | eldifi |  |-  ( z e. ( B \ { .0. } ) -> z e. B ) | 
						
							| 60 | 57 58 59 | 3anim123i |  |-  ( ( x e. ( B \ { .0. } ) /\ y e. ( B \ { .0. } ) /\ z e. ( B \ { .0. } ) ) -> ( x e. B /\ y e. B /\ z e. B ) ) | 
						
							| 61 | 56 60 | impel |  |-  ( ( ph /\ ( x e. ( B \ { .0. } ) /\ y e. ( B \ { .0. } ) /\ z e. ( B \ { .0. } ) ) ) -> ( ( x .x. y ) .x. z ) = ( x .x. ( y .x. z ) ) ) | 
						
							| 62 |  | eqid |  |-  ( 1r ` R ) = ( 1r ` R ) | 
						
							| 63 | 15 62 | ringidcl |  |-  ( R e. Ring -> ( 1r ` R ) e. ( Base ` R ) ) | 
						
							| 64 | 5 63 | syl |  |-  ( ph -> ( 1r ` R ) e. ( Base ` R ) ) | 
						
							| 65 | 64 4 1 | 3eltr4d |  |-  ( ph -> .1. e. B ) | 
						
							| 66 |  | eldifsn |  |-  ( .1. e. ( B \ { .0. } ) <-> ( .1. e. B /\ .1. =/= .0. ) ) | 
						
							| 67 | 65 7 66 | sylanbrc |  |-  ( ph -> .1. e. ( B \ { .0. } ) ) | 
						
							| 68 | 15 22 62 | ringlidm |  |-  ( ( R e. Ring /\ x e. ( Base ` R ) ) -> ( ( 1r ` R ) ( .r ` R ) x ) = x ) | 
						
							| 69 | 68 | ex |  |-  ( R e. Ring -> ( x e. ( Base ` R ) -> ( ( 1r ` R ) ( .r ` R ) x ) = x ) ) | 
						
							| 70 | 5 69 | syl |  |-  ( ph -> ( x e. ( Base ` R ) -> ( ( 1r ` R ) ( .r ` R ) x ) = x ) ) | 
						
							| 71 | 2 4 52 | oveq123d |  |-  ( ph -> ( .1. .x. x ) = ( ( 1r ` R ) ( .r ` R ) x ) ) | 
						
							| 72 | 71 | eqeq1d |  |-  ( ph -> ( ( .1. .x. x ) = x <-> ( ( 1r ` R ) ( .r ` R ) x ) = x ) ) | 
						
							| 73 | 70 32 72 | 3imtr4d |  |-  ( ph -> ( x e. B -> ( .1. .x. x ) = x ) ) | 
						
							| 74 | 73 | imp |  |-  ( ( ph /\ x e. B ) -> ( .1. .x. x ) = x ) | 
						
							| 75 | 74 | adantrr |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) ) -> ( .1. .x. x ) = x ) | 
						
							| 76 | 27 75 | sylan2b |  |-  ( ( ph /\ x e. ( B \ { .0. } ) ) -> ( .1. .x. x ) = x ) | 
						
							| 77 |  | eldifsn |  |-  ( I e. ( B \ { .0. } ) <-> ( I e. B /\ I =/= .0. ) ) | 
						
							| 78 | 8 9 77 | sylanbrc |  |-  ( ( ph /\ ( x e. B /\ x =/= .0. ) ) -> I e. ( B \ { .0. } ) ) | 
						
							| 79 | 27 78 | sylan2b |  |-  ( ( ph /\ x e. ( B \ { .0. } ) ) -> I e. ( B \ { .0. } ) ) | 
						
							| 80 | 27 10 | sylan2b |  |-  ( ( ph /\ x e. ( B \ { .0. } ) ) -> ( I .x. x ) = .1. ) | 
						
							| 81 | 18 26 44 61 67 76 79 80 | isgrpd |  |-  ( ph -> ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) e. Grp ) | 
						
							| 82 | 3 | sneqd |  |-  ( ph -> { .0. } = { ( 0g ` R ) } ) | 
						
							| 83 | 1 82 | difeq12d |  |-  ( ph -> ( B \ { .0. } ) = ( ( Base ` R ) \ { ( 0g ` R ) } ) ) | 
						
							| 84 | 83 | oveq2d |  |-  ( ph -> ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) = ( ( mulGrp ` R ) |`s ( ( Base ` R ) \ { ( 0g ` R ) } ) ) ) | 
						
							| 85 | 84 | eleq1d |  |-  ( ph -> ( ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) e. Grp <-> ( ( mulGrp ` R ) |`s ( ( Base ` R ) \ { ( 0g ` R ) } ) ) e. Grp ) ) | 
						
							| 86 | 85 | anbi2d |  |-  ( ph -> ( ( R e. Ring /\ ( ( mulGrp ` R ) |`s ( B \ { .0. } ) ) e. Grp ) <-> ( R e. Ring /\ ( ( mulGrp ` R ) |`s ( ( Base ` R ) \ { ( 0g ` R ) } ) ) e. Grp ) ) ) | 
						
							| 87 | 5 81 86 | mpbi2and |  |-  ( ph -> ( R e. Ring /\ ( ( mulGrp ` R ) |`s ( ( Base ` R ) \ { ( 0g ` R ) } ) ) e. Grp ) ) | 
						
							| 88 |  | eqid |  |-  ( 0g ` R ) = ( 0g ` R ) | 
						
							| 89 |  | eqid |  |-  ( ( mulGrp ` R ) |`s ( ( Base ` R ) \ { ( 0g ` R ) } ) ) = ( ( mulGrp ` R ) |`s ( ( Base ` R ) \ { ( 0g ` R ) } ) ) | 
						
							| 90 | 15 88 89 | isdrng2 |  |-  ( R e. DivRing <-> ( R e. Ring /\ ( ( mulGrp ` R ) |`s ( ( Base ` R ) \ { ( 0g ` R ) } ) ) e. Grp ) ) | 
						
							| 91 | 87 90 | sylibr |  |-  ( ph -> R e. DivRing ) |