| Step | Hyp | Ref | Expression | 
						
							| 1 |  | psgnval.g |  |-  G = ( SymGrp ` D ) | 
						
							| 2 |  | psgnval.t |  |-  T = ran ( pmTrsp ` D ) | 
						
							| 3 |  | psgnval.n |  |-  N = ( pmSgn ` D ) | 
						
							| 4 |  | eqid |  |-  ( Base ` G ) = ( Base ` G ) | 
						
							| 5 |  | eqid |  |-  { p e. ( Base ` G ) | dom ( p \ _I ) e. Fin } = { p e. ( Base ` G ) | dom ( p \ _I ) e. Fin } | 
						
							| 6 | 1 4 5 3 | psgnfn |  |-  N Fn { p e. ( Base ` G ) | dom ( p \ _I ) e. Fin } | 
						
							| 7 | 6 | fndmi |  |-  dom N = { p e. ( Base ` G ) | dom ( p \ _I ) e. Fin } | 
						
							| 8 |  | eqid |  |-  ( mrCls ` ( SubMnd ` G ) ) = ( mrCls ` ( SubMnd ` G ) ) | 
						
							| 9 | 2 1 4 8 | symggen |  |-  ( D e. V -> ( ( mrCls ` ( SubMnd ` G ) ) ` T ) = { p e. ( Base ` G ) | dom ( p \ _I ) e. Fin } ) | 
						
							| 10 | 1 | symggrp |  |-  ( D e. V -> G e. Grp ) | 
						
							| 11 | 10 | grpmndd |  |-  ( D e. V -> G e. Mnd ) | 
						
							| 12 | 2 1 4 | symgtrf |  |-  T C_ ( Base ` G ) | 
						
							| 13 | 4 8 | gsumwspan |  |-  ( ( G e. Mnd /\ T C_ ( Base ` G ) ) -> ( ( mrCls ` ( SubMnd ` G ) ) ` T ) = ran ( w e. Word T |-> ( G gsum w ) ) ) | 
						
							| 14 | 11 12 13 | sylancl |  |-  ( D e. V -> ( ( mrCls ` ( SubMnd ` G ) ) ` T ) = ran ( w e. Word T |-> ( G gsum w ) ) ) | 
						
							| 15 | 9 14 | eqtr3d |  |-  ( D e. V -> { p e. ( Base ` G ) | dom ( p \ _I ) e. Fin } = ran ( w e. Word T |-> ( G gsum w ) ) ) | 
						
							| 16 | 7 15 | eqtrid |  |-  ( D e. V -> dom N = ran ( w e. Word T |-> ( G gsum w ) ) ) | 
						
							| 17 | 16 | eleq2d |  |-  ( D e. V -> ( P e. dom N <-> P e. ran ( w e. Word T |-> ( G gsum w ) ) ) ) | 
						
							| 18 |  | eqid |  |-  ( w e. Word T |-> ( G gsum w ) ) = ( w e. Word T |-> ( G gsum w ) ) | 
						
							| 19 |  | ovex |  |-  ( G gsum w ) e. _V | 
						
							| 20 | 18 19 | elrnmpti |  |-  ( P e. ran ( w e. Word T |-> ( G gsum w ) ) <-> E. w e. Word T P = ( G gsum w ) ) | 
						
							| 21 | 17 20 | bitrdi |  |-  ( D e. V -> ( P e. dom N <-> E. w e. Word T P = ( G gsum w ) ) ) |