| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nfimdetndef.d |  |-  D = ( N maDet R ) | 
						
							| 2 |  | eqid |  |-  ( N Mat R ) = ( N Mat R ) | 
						
							| 3 |  | eqid |  |-  ( Base ` ( N Mat R ) ) = ( Base ` ( N Mat R ) ) | 
						
							| 4 |  | eqid |  |-  ( Base ` ( SymGrp ` N ) ) = ( Base ` ( SymGrp ` N ) ) | 
						
							| 5 |  | eqid |  |-  ( ZRHom ` R ) = ( ZRHom ` R ) | 
						
							| 6 |  | eqid |  |-  ( pmSgn ` N ) = ( pmSgn ` N ) | 
						
							| 7 |  | eqid |  |-  ( .r ` R ) = ( .r ` R ) | 
						
							| 8 |  | eqid |  |-  ( mulGrp ` R ) = ( mulGrp ` R ) | 
						
							| 9 | 1 2 3 4 5 6 7 8 | mdetfval |  |-  D = ( m e. ( Base ` ( N Mat R ) ) |-> ( R gsum ( p e. ( Base ` ( SymGrp ` N ) ) |-> ( ( ( ( ZRHom ` R ) o. ( pmSgn ` N ) ) ` p ) ( .r ` R ) ( ( mulGrp ` R ) gsum ( x e. N |-> ( ( p ` x ) m x ) ) ) ) ) ) ) | 
						
							| 10 |  | df-nel |  |-  ( N e/ Fin <-> -. N e. Fin ) | 
						
							| 11 | 10 | biimpi |  |-  ( N e/ Fin -> -. N e. Fin ) | 
						
							| 12 | 11 | intnanrd |  |-  ( N e/ Fin -> -. ( N e. Fin /\ R e. _V ) ) | 
						
							| 13 |  | matbas0 |  |-  ( -. ( N e. Fin /\ R e. _V ) -> ( Base ` ( N Mat R ) ) = (/) ) | 
						
							| 14 | 12 13 | syl |  |-  ( N e/ Fin -> ( Base ` ( N Mat R ) ) = (/) ) | 
						
							| 15 | 14 | mpteq1d |  |-  ( N e/ Fin -> ( m e. ( Base ` ( N Mat R ) ) |-> ( R gsum ( p e. ( Base ` ( SymGrp ` N ) ) |-> ( ( ( ( ZRHom ` R ) o. ( pmSgn ` N ) ) ` p ) ( .r ` R ) ( ( mulGrp ` R ) gsum ( x e. N |-> ( ( p ` x ) m x ) ) ) ) ) ) ) = ( m e. (/) |-> ( R gsum ( p e. ( Base ` ( SymGrp ` N ) ) |-> ( ( ( ( ZRHom ` R ) o. ( pmSgn ` N ) ) ` p ) ( .r ` R ) ( ( mulGrp ` R ) gsum ( x e. N |-> ( ( p ` x ) m x ) ) ) ) ) ) ) ) | 
						
							| 16 |  | mpt0 |  |-  ( m e. (/) |-> ( R gsum ( p e. ( Base ` ( SymGrp ` N ) ) |-> ( ( ( ( ZRHom ` R ) o. ( pmSgn ` N ) ) ` p ) ( .r ` R ) ( ( mulGrp ` R ) gsum ( x e. N |-> ( ( p ` x ) m x ) ) ) ) ) ) ) = (/) | 
						
							| 17 | 15 16 | eqtrdi |  |-  ( N e/ Fin -> ( m e. ( Base ` ( N Mat R ) ) |-> ( R gsum ( p e. ( Base ` ( SymGrp ` N ) ) |-> ( ( ( ( ZRHom ` R ) o. ( pmSgn ` N ) ) ` p ) ( .r ` R ) ( ( mulGrp ` R ) gsum ( x e. N |-> ( ( p ` x ) m x ) ) ) ) ) ) ) = (/) ) | 
						
							| 18 | 9 17 | eqtrid |  |-  ( N e/ Fin -> D = (/) ) |