| Step | Hyp | Ref | Expression | 
						
							| 1 |  | issubrgd.s |  |-  ( ph -> S = ( I |`s D ) ) | 
						
							| 2 |  | issubrgd.z |  |-  ( ph -> .0. = ( 0g ` I ) ) | 
						
							| 3 |  | issubrgd.p |  |-  ( ph -> .+ = ( +g ` I ) ) | 
						
							| 4 |  | issubrgd.ss |  |-  ( ph -> D C_ ( Base ` I ) ) | 
						
							| 5 |  | issubrgd.zcl |  |-  ( ph -> .0. e. D ) | 
						
							| 6 |  | issubrgd.acl |  |-  ( ( ph /\ x e. D /\ y e. D ) -> ( x .+ y ) e. D ) | 
						
							| 7 |  | issubrgd.ncl |  |-  ( ( ph /\ x e. D ) -> ( ( invg ` I ) ` x ) e. D ) | 
						
							| 8 |  | issubrgd.o |  |-  ( ph -> .1. = ( 1r ` I ) ) | 
						
							| 9 |  | issubrgd.t |  |-  ( ph -> .x. = ( .r ` I ) ) | 
						
							| 10 |  | issubrgd.ocl |  |-  ( ph -> .1. e. D ) | 
						
							| 11 |  | issubrgd.tcl |  |-  ( ( ph /\ x e. D /\ y e. D ) -> ( x .x. y ) e. D ) | 
						
							| 12 |  | issubrgd.g |  |-  ( ph -> I e. Ring ) | 
						
							| 13 |  | ringgrp |  |-  ( I e. Ring -> I e. Grp ) | 
						
							| 14 | 12 13 | syl |  |-  ( ph -> I e. Grp ) | 
						
							| 15 | 1 2 3 4 5 6 7 14 | issubgrpd2 |  |-  ( ph -> D e. ( SubGrp ` I ) ) | 
						
							| 16 | 8 10 | eqeltrrd |  |-  ( ph -> ( 1r ` I ) e. D ) | 
						
							| 17 | 9 | oveqdr |  |-  ( ( ph /\ ( x e. D /\ y e. D ) ) -> ( x .x. y ) = ( x ( .r ` I ) y ) ) | 
						
							| 18 | 11 | 3expb |  |-  ( ( ph /\ ( x e. D /\ y e. D ) ) -> ( x .x. y ) e. D ) | 
						
							| 19 | 17 18 | eqeltrrd |  |-  ( ( ph /\ ( x e. D /\ y e. D ) ) -> ( x ( .r ` I ) y ) e. D ) | 
						
							| 20 | 19 | ralrimivva |  |-  ( ph -> A. x e. D A. y e. D ( x ( .r ` I ) y ) e. D ) | 
						
							| 21 |  | eqid |  |-  ( Base ` I ) = ( Base ` I ) | 
						
							| 22 |  | eqid |  |-  ( 1r ` I ) = ( 1r ` I ) | 
						
							| 23 |  | eqid |  |-  ( .r ` I ) = ( .r ` I ) | 
						
							| 24 | 21 22 23 | issubrg2 |  |-  ( I e. Ring -> ( D e. ( SubRing ` I ) <-> ( D e. ( SubGrp ` I ) /\ ( 1r ` I ) e. D /\ A. x e. D A. y e. D ( x ( .r ` I ) y ) e. D ) ) ) | 
						
							| 25 | 12 24 | syl |  |-  ( ph -> ( D e. ( SubRing ` I ) <-> ( D e. ( SubGrp ` I ) /\ ( 1r ` I ) e. D /\ A. x e. D A. y e. D ( x ( .r ` I ) y ) e. D ) ) ) | 
						
							| 26 | 15 16 20 25 | mpbir3and |  |-  ( ph -> D e. ( SubRing ` I ) ) |