| Step | Hyp | Ref | Expression | 
						
							| 1 |  | xpsmnd0.t |  |-  T = ( R Xs. S ) | 
						
							| 2 |  | eqid |  |-  ( Base ` T ) = ( Base ` T ) | 
						
							| 3 |  | eqid |  |-  ( 0g ` T ) = ( 0g ` T ) | 
						
							| 4 |  | eqid |  |-  ( +g ` T ) = ( +g ` T ) | 
						
							| 5 |  | eqid |  |-  ( Base ` R ) = ( Base ` R ) | 
						
							| 6 |  | eqid |  |-  ( 0g ` R ) = ( 0g ` R ) | 
						
							| 7 | 5 6 | mndidcl |  |-  ( R e. Mnd -> ( 0g ` R ) e. ( Base ` R ) ) | 
						
							| 8 | 7 | adantr |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( 0g ` R ) e. ( Base ` R ) ) | 
						
							| 9 |  | eqid |  |-  ( Base ` S ) = ( Base ` S ) | 
						
							| 10 |  | eqid |  |-  ( 0g ` S ) = ( 0g ` S ) | 
						
							| 11 | 9 10 | mndidcl |  |-  ( S e. Mnd -> ( 0g ` S ) e. ( Base ` S ) ) | 
						
							| 12 | 11 | adantl |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( 0g ` S ) e. ( Base ` S ) ) | 
						
							| 13 | 8 12 | opelxpd |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> <. ( 0g ` R ) , ( 0g ` S ) >. e. ( ( Base ` R ) X. ( Base ` S ) ) ) | 
						
							| 14 |  | simpl |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> R e. Mnd ) | 
						
							| 15 |  | simpr |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> S e. Mnd ) | 
						
							| 16 | 1 5 9 14 15 | xpsbas |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( ( Base ` R ) X. ( Base ` S ) ) = ( Base ` T ) ) | 
						
							| 17 | 13 16 | eleqtrd |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> <. ( 0g ` R ) , ( 0g ` S ) >. e. ( Base ` T ) ) | 
						
							| 18 | 16 | eleq2d |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( x e. ( ( Base ` R ) X. ( Base ` S ) ) <-> x e. ( Base ` T ) ) ) | 
						
							| 19 |  | elxp2 |  |-  ( x e. ( ( Base ` R ) X. ( Base ` S ) ) <-> E. a e. ( Base ` R ) E. b e. ( Base ` S ) x = <. a , b >. ) | 
						
							| 20 | 14 | adantr |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> R e. Mnd ) | 
						
							| 21 | 15 | adantr |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> S e. Mnd ) | 
						
							| 22 | 8 | adantr |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( 0g ` R ) e. ( Base ` R ) ) | 
						
							| 23 | 12 | adantr |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( 0g ` S ) e. ( Base ` S ) ) | 
						
							| 24 |  | simpl |  |-  ( ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) -> a e. ( Base ` R ) ) | 
						
							| 25 | 24 | adantl |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> a e. ( Base ` R ) ) | 
						
							| 26 |  | simpr |  |-  ( ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) -> b e. ( Base ` S ) ) | 
						
							| 27 | 26 | adantl |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> b e. ( Base ` S ) ) | 
						
							| 28 |  | eqid |  |-  ( +g ` R ) = ( +g ` R ) | 
						
							| 29 | 5 28 | mndcl |  |-  ( ( R e. Mnd /\ ( 0g ` R ) e. ( Base ` R ) /\ a e. ( Base ` R ) ) -> ( ( 0g ` R ) ( +g ` R ) a ) e. ( Base ` R ) ) | 
						
							| 30 | 20 22 25 29 | syl3anc |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( ( 0g ` R ) ( +g ` R ) a ) e. ( Base ` R ) ) | 
						
							| 31 |  | eqid |  |-  ( +g ` S ) = ( +g ` S ) | 
						
							| 32 | 9 31 | mndcl |  |-  ( ( S e. Mnd /\ ( 0g ` S ) e. ( Base ` S ) /\ b e. ( Base ` S ) ) -> ( ( 0g ` S ) ( +g ` S ) b ) e. ( Base ` S ) ) | 
						
							| 33 | 21 23 27 32 | syl3anc |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( ( 0g ` S ) ( +g ` S ) b ) e. ( Base ` S ) ) | 
						
							| 34 | 1 5 9 20 21 22 23 25 27 30 33 28 31 4 | xpsadd |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) <. a , b >. ) = <. ( ( 0g ` R ) ( +g ` R ) a ) , ( ( 0g ` S ) ( +g ` S ) b ) >. ) | 
						
							| 35 | 5 28 6 | mndlid |  |-  ( ( R e. Mnd /\ a e. ( Base ` R ) ) -> ( ( 0g ` R ) ( +g ` R ) a ) = a ) | 
						
							| 36 | 14 24 35 | syl2an |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( ( 0g ` R ) ( +g ` R ) a ) = a ) | 
						
							| 37 | 9 31 10 | mndlid |  |-  ( ( S e. Mnd /\ b e. ( Base ` S ) ) -> ( ( 0g ` S ) ( +g ` S ) b ) = b ) | 
						
							| 38 | 15 26 37 | syl2an |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( ( 0g ` S ) ( +g ` S ) b ) = b ) | 
						
							| 39 | 36 38 | opeq12d |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> <. ( ( 0g ` R ) ( +g ` R ) a ) , ( ( 0g ` S ) ( +g ` S ) b ) >. = <. a , b >. ) | 
						
							| 40 | 34 39 | eqtrd |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) <. a , b >. ) = <. a , b >. ) | 
						
							| 41 |  | oveq2 |  |-  ( x = <. a , b >. -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) x ) = ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) <. a , b >. ) ) | 
						
							| 42 |  | id |  |-  ( x = <. a , b >. -> x = <. a , b >. ) | 
						
							| 43 | 41 42 | eqeq12d |  |-  ( x = <. a , b >. -> ( ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) x ) = x <-> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) <. a , b >. ) = <. a , b >. ) ) | 
						
							| 44 | 40 43 | syl5ibrcom |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( x = <. a , b >. -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) x ) = x ) ) | 
						
							| 45 | 44 | rexlimdvva |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( E. a e. ( Base ` R ) E. b e. ( Base ` S ) x = <. a , b >. -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) x ) = x ) ) | 
						
							| 46 | 19 45 | biimtrid |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( x e. ( ( Base ` R ) X. ( Base ` S ) ) -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) x ) = x ) ) | 
						
							| 47 | 18 46 | sylbird |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( x e. ( Base ` T ) -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) x ) = x ) ) | 
						
							| 48 | 47 | imp |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ x e. ( Base ` T ) ) -> ( <. ( 0g ` R ) , ( 0g ` S ) >. ( +g ` T ) x ) = x ) | 
						
							| 49 | 5 28 | mndcl |  |-  ( ( R e. Mnd /\ a e. ( Base ` R ) /\ ( 0g ` R ) e. ( Base ` R ) ) -> ( a ( +g ` R ) ( 0g ` R ) ) e. ( Base ` R ) ) | 
						
							| 50 | 20 25 22 49 | syl3anc |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( a ( +g ` R ) ( 0g ` R ) ) e. ( Base ` R ) ) | 
						
							| 51 | 9 31 | mndcl |  |-  ( ( S e. Mnd /\ b e. ( Base ` S ) /\ ( 0g ` S ) e. ( Base ` S ) ) -> ( b ( +g ` S ) ( 0g ` S ) ) e. ( Base ` S ) ) | 
						
							| 52 | 21 27 23 51 | syl3anc |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( b ( +g ` S ) ( 0g ` S ) ) e. ( Base ` S ) ) | 
						
							| 53 | 1 5 9 20 21 25 27 22 23 50 52 28 31 4 | xpsadd |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( <. a , b >. ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = <. ( a ( +g ` R ) ( 0g ` R ) ) , ( b ( +g ` S ) ( 0g ` S ) ) >. ) | 
						
							| 54 | 5 28 6 | mndrid |  |-  ( ( R e. Mnd /\ a e. ( Base ` R ) ) -> ( a ( +g ` R ) ( 0g ` R ) ) = a ) | 
						
							| 55 | 14 24 54 | syl2an |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( a ( +g ` R ) ( 0g ` R ) ) = a ) | 
						
							| 56 | 9 31 10 | mndrid |  |-  ( ( S e. Mnd /\ b e. ( Base ` S ) ) -> ( b ( +g ` S ) ( 0g ` S ) ) = b ) | 
						
							| 57 | 15 26 56 | syl2an |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( b ( +g ` S ) ( 0g ` S ) ) = b ) | 
						
							| 58 | 55 57 | opeq12d |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> <. ( a ( +g ` R ) ( 0g ` R ) ) , ( b ( +g ` S ) ( 0g ` S ) ) >. = <. a , b >. ) | 
						
							| 59 | 53 58 | eqtrd |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( <. a , b >. ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = <. a , b >. ) | 
						
							| 60 |  | oveq1 |  |-  ( x = <. a , b >. -> ( x ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = ( <. a , b >. ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) ) | 
						
							| 61 | 60 42 | eqeq12d |  |-  ( x = <. a , b >. -> ( ( x ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = x <-> ( <. a , b >. ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = <. a , b >. ) ) | 
						
							| 62 | 59 61 | syl5ibrcom |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ ( a e. ( Base ` R ) /\ b e. ( Base ` S ) ) ) -> ( x = <. a , b >. -> ( x ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = x ) ) | 
						
							| 63 | 62 | rexlimdvva |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( E. a e. ( Base ` R ) E. b e. ( Base ` S ) x = <. a , b >. -> ( x ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = x ) ) | 
						
							| 64 | 19 63 | biimtrid |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( x e. ( ( Base ` R ) X. ( Base ` S ) ) -> ( x ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = x ) ) | 
						
							| 65 | 18 64 | sylbird |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( x e. ( Base ` T ) -> ( x ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = x ) ) | 
						
							| 66 | 65 | imp |  |-  ( ( ( R e. Mnd /\ S e. Mnd ) /\ x e. ( Base ` T ) ) -> ( x ( +g ` T ) <. ( 0g ` R ) , ( 0g ` S ) >. ) = x ) | 
						
							| 67 | 2 3 4 17 48 66 | ismgmid2 |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> <. ( 0g ` R ) , ( 0g ` S ) >. = ( 0g ` T ) ) | 
						
							| 68 | 67 | eqcomd |  |-  ( ( R e. Mnd /\ S e. Mnd ) -> ( 0g ` T ) = <. ( 0g ` R ) , ( 0g ` S ) >. ) |