| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eqid |  |-  ( Base ` Z ) = ( Base ` Z ) | 
						
							| 2 |  | eqid |  |-  ( 0g ` Z ) = ( 0g ` Z ) | 
						
							| 3 |  | eqid |  |-  ( 1r ` Z ) = ( 1r ` Z ) | 
						
							| 4 | 1 2 3 | 0ring1eq0 |  |-  ( Z e. ( Ring \ NzRing ) -> ( 1r ` Z ) = ( 0g ` Z ) ) | 
						
							| 5 | 4 | adantr |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( 1r ` Z ) = ( 0g ` Z ) ) | 
						
							| 6 | 5 | adantr |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> ( 1r ` Z ) = ( 0g ` Z ) ) | 
						
							| 7 | 6 | eqcomd |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> ( 0g ` Z ) = ( 1r ` Z ) ) | 
						
							| 8 | 7 | fveq2d |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> ( f ` ( 0g ` Z ) ) = ( f ` ( 1r ` Z ) ) ) | 
						
							| 9 |  | eqid |  |-  ( 1r ` R ) = ( 1r ` R ) | 
						
							| 10 | 3 9 | rhm1 |  |-  ( f e. ( Z RingHom R ) -> ( f ` ( 1r ` Z ) ) = ( 1r ` R ) ) | 
						
							| 11 | 10 | adantl |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> ( f ` ( 1r ` Z ) ) = ( 1r ` R ) ) | 
						
							| 12 | 8 11 | eqtrd |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> ( f ` ( 0g ` Z ) ) = ( 1r ` R ) ) | 
						
							| 13 |  | rhmghm |  |-  ( f e. ( Z RingHom R ) -> f e. ( Z GrpHom R ) ) | 
						
							| 14 | 13 | adantl |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> f e. ( Z GrpHom R ) ) | 
						
							| 15 |  | eqid |  |-  ( 0g ` R ) = ( 0g ` R ) | 
						
							| 16 | 2 15 | ghmid |  |-  ( f e. ( Z GrpHom R ) -> ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) | 
						
							| 17 | 14 16 | syl |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) | 
						
							| 18 | 12 17 | jca |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ f e. ( Z RingHom R ) ) -> ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) | 
						
							| 19 | 18 | ralrimiva |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> A. f e. ( Z RingHom R ) ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) | 
						
							| 20 | 9 15 | nzrnz |  |-  ( R e. NzRing -> ( 1r ` R ) =/= ( 0g ` R ) ) | 
						
							| 21 | 20 | necomd |  |-  ( R e. NzRing -> ( 0g ` R ) =/= ( 1r ` R ) ) | 
						
							| 22 | 21 | adantl |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( 0g ` R ) =/= ( 1r ` R ) ) | 
						
							| 23 | 22 | adantr |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) -> ( 0g ` R ) =/= ( 1r ` R ) ) | 
						
							| 24 |  | neeq1 |  |-  ( ( f ` ( 0g ` Z ) ) = ( 0g ` R ) -> ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) <-> ( 0g ` R ) =/= ( 1r ` R ) ) ) | 
						
							| 25 | 24 | adantl |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) -> ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) <-> ( 0g ` R ) =/= ( 1r ` R ) ) ) | 
						
							| 26 | 23 25 | mpbird |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) -> ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) ) | 
						
							| 27 | 26 | orcd |  |-  ( ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) -> ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) \/ ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) ) ) | 
						
							| 28 | 27 | expcom |  |-  ( ( f ` ( 0g ` Z ) ) = ( 0g ` R ) -> ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) \/ ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) ) ) ) | 
						
							| 29 |  | olc |  |-  ( ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) -> ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) \/ ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) ) ) | 
						
							| 30 | 29 | a1d |  |-  ( ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) -> ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) \/ ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) ) ) ) | 
						
							| 31 | 28 30 | pm2.61ine |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) \/ ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) ) ) | 
						
							| 32 |  | neorian |  |-  ( ( ( f ` ( 0g ` Z ) ) =/= ( 1r ` R ) \/ ( f ` ( 0g ` Z ) ) =/= ( 0g ` R ) ) <-> -. ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) | 
						
							| 33 | 31 32 | sylib |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> -. ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) | 
						
							| 34 |  | con3 |  |-  ( ( f e. ( Z RingHom R ) -> ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) -> ( -. ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) -> -. f e. ( Z RingHom R ) ) ) | 
						
							| 35 | 33 34 | syl5com |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( ( f e. ( Z RingHom R ) -> ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) -> -. f e. ( Z RingHom R ) ) ) | 
						
							| 36 | 35 | alimdv |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( A. f ( f e. ( Z RingHom R ) -> ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) -> A. f -. f e. ( Z RingHom R ) ) ) | 
						
							| 37 |  | df-ral |  |-  ( A. f e. ( Z RingHom R ) ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) <-> A. f ( f e. ( Z RingHom R ) -> ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) ) ) | 
						
							| 38 |  | eq0 |  |-  ( ( Z RingHom R ) = (/) <-> A. f -. f e. ( Z RingHom R ) ) | 
						
							| 39 | 36 37 38 | 3imtr4g |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( A. f e. ( Z RingHom R ) ( ( f ` ( 0g ` Z ) ) = ( 1r ` R ) /\ ( f ` ( 0g ` Z ) ) = ( 0g ` R ) ) -> ( Z RingHom R ) = (/) ) ) | 
						
							| 40 | 19 39 | mpd |  |-  ( ( Z e. ( Ring \ NzRing ) /\ R e. NzRing ) -> ( Z RingHom R ) = (/) ) |