| Step | Hyp | Ref | Expression | 
						
							| 1 |  | submateq.a |  |-  A = ( ( 1 ... N ) Mat R ) | 
						
							| 2 |  | submateq.b |  |-  B = ( Base ` A ) | 
						
							| 3 |  | submateq.n |  |-  ( ph -> N e. NN ) | 
						
							| 4 |  | submateq.i |  |-  ( ph -> I e. ( 1 ... N ) ) | 
						
							| 5 |  | submateq.j |  |-  ( ph -> J e. ( 1 ... N ) ) | 
						
							| 6 |  | submatminr1.r |  |-  ( ph -> R e. Ring ) | 
						
							| 7 |  | submatminr1.m |  |-  ( ph -> M e. B ) | 
						
							| 8 |  | submatminr1.e |  |-  E = ( I ( ( ( 1 ... N ) minMatR1 R ) ` M ) J ) | 
						
							| 9 |  | eqid |  |-  ( 1r ` R ) = ( 1r ` R ) | 
						
							| 10 | 1 2 9 | minmar1marrep |  |-  ( ( R e. Ring /\ M e. B ) -> ( ( ( 1 ... N ) minMatR1 R ) ` M ) = ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) ) | 
						
							| 11 | 6 7 10 | syl2anc |  |-  ( ph -> ( ( ( 1 ... N ) minMatR1 R ) ` M ) = ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) ) | 
						
							| 12 | 11 | oveqd |  |-  ( ph -> ( I ( ( ( 1 ... N ) minMatR1 R ) ` M ) J ) = ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) ) | 
						
							| 13 | 8 12 | eqtrid |  |-  ( ph -> E = ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) ) | 
						
							| 14 |  | eqid |  |-  ( Base ` R ) = ( Base ` R ) | 
						
							| 15 | 14 9 | ringidcl |  |-  ( R e. Ring -> ( 1r ` R ) e. ( Base ` R ) ) | 
						
							| 16 | 6 15 | syl |  |-  ( ph -> ( 1r ` R ) e. ( Base ` R ) ) | 
						
							| 17 | 1 2 | marrepcl |  |-  ( ( ( R e. Ring /\ M e. B /\ ( 1r ` R ) e. ( Base ` R ) ) /\ ( I e. ( 1 ... N ) /\ J e. ( 1 ... N ) ) ) -> ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) e. B ) | 
						
							| 18 | 6 7 16 4 5 17 | syl32anc |  |-  ( ph -> ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) e. B ) | 
						
							| 19 | 13 18 | eqeltrd |  |-  ( ph -> E e. B ) | 
						
							| 20 | 13 | 3ad2ant1 |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> E = ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) ) | 
						
							| 21 | 20 | oveqd |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> ( i E j ) = ( i ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) j ) ) | 
						
							| 22 | 7 | 3ad2ant1 |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> M e. B ) | 
						
							| 23 | 16 | 3ad2ant1 |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> ( 1r ` R ) e. ( Base ` R ) ) | 
						
							| 24 | 4 | 3ad2ant1 |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> I e. ( 1 ... N ) ) | 
						
							| 25 | 5 | 3ad2ant1 |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> J e. ( 1 ... N ) ) | 
						
							| 26 |  | simp2 |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> i e. ( ( 1 ... N ) \ { I } ) ) | 
						
							| 27 | 26 | eldifad |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> i e. ( 1 ... N ) ) | 
						
							| 28 |  | simp3 |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> j e. ( ( 1 ... N ) \ { J } ) ) | 
						
							| 29 | 28 | eldifad |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> j e. ( 1 ... N ) ) | 
						
							| 30 |  | eqid |  |-  ( ( 1 ... N ) matRRep R ) = ( ( 1 ... N ) matRRep R ) | 
						
							| 31 |  | eqid |  |-  ( 0g ` R ) = ( 0g ` R ) | 
						
							| 32 | 1 2 30 31 | marrepeval |  |-  ( ( ( M e. B /\ ( 1r ` R ) e. ( Base ` R ) ) /\ ( I e. ( 1 ... N ) /\ J e. ( 1 ... N ) ) /\ ( i e. ( 1 ... N ) /\ j e. ( 1 ... N ) ) ) -> ( i ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) j ) = if ( i = I , if ( j = J , ( 1r ` R ) , ( 0g ` R ) ) , ( i M j ) ) ) | 
						
							| 33 | 22 23 24 25 27 29 32 | syl222anc |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> ( i ( I ( M ( ( 1 ... N ) matRRep R ) ( 1r ` R ) ) J ) j ) = if ( i = I , if ( j = J , ( 1r ` R ) , ( 0g ` R ) ) , ( i M j ) ) ) | 
						
							| 34 |  | eldifsn |  |-  ( i e. ( ( 1 ... N ) \ { I } ) <-> ( i e. ( 1 ... N ) /\ i =/= I ) ) | 
						
							| 35 | 26 34 | sylib |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> ( i e. ( 1 ... N ) /\ i =/= I ) ) | 
						
							| 36 | 35 | simprd |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> i =/= I ) | 
						
							| 37 | 36 | neneqd |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> -. i = I ) | 
						
							| 38 | 37 | iffalsed |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> if ( i = I , if ( j = J , ( 1r ` R ) , ( 0g ` R ) ) , ( i M j ) ) = ( i M j ) ) | 
						
							| 39 | 21 33 38 | 3eqtrrd |  |-  ( ( ph /\ i e. ( ( 1 ... N ) \ { I } ) /\ j e. ( ( 1 ... N ) \ { J } ) ) -> ( i M j ) = ( i E j ) ) | 
						
							| 40 | 1 2 3 4 5 7 19 39 | submateq |  |-  ( ph -> ( I ( subMat1 ` M ) J ) = ( I ( subMat1 ` E ) J ) ) |