| Step | Hyp | Ref | Expression | 
						
							| 1 |  | cntzun.b |  |-  B = ( Base ` M ) | 
						
							| 2 |  | cntzun.z |  |-  Z = ( Cntz ` M ) | 
						
							| 3 |  | cntzsnid.1 |  |-  .0. = ( 0g ` M ) | 
						
							| 4 | 1 3 | mndidcl |  |-  ( M e. Mnd -> .0. e. B ) | 
						
							| 5 |  | eqid |  |-  ( +g ` M ) = ( +g ` M ) | 
						
							| 6 | 1 5 2 | elcntzsn |  |-  ( .0. e. B -> ( x e. ( Z ` { .0. } ) <-> ( x e. B /\ ( x ( +g ` M ) .0. ) = ( .0. ( +g ` M ) x ) ) ) ) | 
						
							| 7 | 4 6 | syl |  |-  ( M e. Mnd -> ( x e. ( Z ` { .0. } ) <-> ( x e. B /\ ( x ( +g ` M ) .0. ) = ( .0. ( +g ` M ) x ) ) ) ) | 
						
							| 8 | 1 5 3 | mndrid |  |-  ( ( M e. Mnd /\ x e. B ) -> ( x ( +g ` M ) .0. ) = x ) | 
						
							| 9 | 1 5 3 | mndlid |  |-  ( ( M e. Mnd /\ x e. B ) -> ( .0. ( +g ` M ) x ) = x ) | 
						
							| 10 | 8 9 | eqtr4d |  |-  ( ( M e. Mnd /\ x e. B ) -> ( x ( +g ` M ) .0. ) = ( .0. ( +g ` M ) x ) ) | 
						
							| 11 | 10 | ex |  |-  ( M e. Mnd -> ( x e. B -> ( x ( +g ` M ) .0. ) = ( .0. ( +g ` M ) x ) ) ) | 
						
							| 12 | 11 | pm4.71d |  |-  ( M e. Mnd -> ( x e. B <-> ( x e. B /\ ( x ( +g ` M ) .0. ) = ( .0. ( +g ` M ) x ) ) ) ) | 
						
							| 13 | 7 12 | bitr4d |  |-  ( M e. Mnd -> ( x e. ( Z ` { .0. } ) <-> x e. B ) ) | 
						
							| 14 | 13 | eqrdv |  |-  ( M e. Mnd -> ( Z ` { .0. } ) = B ) |