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Description: A group isomorphism maps the zero of one group (and only the zero) to the zero of the other group. (Contributed by AV, 24-Oct-2019) (Revised by Thierry Arnoux, 23-May-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | gim0to0.a | |- A = ( Base ` R ) |
|
| gim0to0.b | |- B = ( Base ` S ) |
||
| gim0to0.n | |- N = ( 0g ` S ) |
||
| gim0to0.0 | |- .0. = ( 0g ` R ) |
||
| Assertion | gim0to0 | |- ( ( F e. ( R GrpIso S ) /\ X e. A ) -> ( ( F ` X ) = N <-> X = .0. ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | gim0to0.a | |- A = ( Base ` R ) |
|
| 2 | gim0to0.b | |- B = ( Base ` S ) |
|
| 3 | gim0to0.n | |- N = ( 0g ` S ) |
|
| 4 | gim0to0.0 | |- .0. = ( 0g ` R ) |
|
| 5 | gimghm | |- ( F e. ( R GrpIso S ) -> F e. ( R GrpHom S ) ) |
|
| 6 | 1 2 | gimf1o | |- ( F e. ( R GrpIso S ) -> F : A -1-1-onto-> B ) |
| 7 | f1of1 | |- ( F : A -1-1-onto-> B -> F : A -1-1-> B ) |
|
| 8 | 6 7 | syl | |- ( F e. ( R GrpIso S ) -> F : A -1-1-> B ) |
| 9 | 5 8 | jca | |- ( F e. ( R GrpIso S ) -> ( F e. ( R GrpHom S ) /\ F : A -1-1-> B ) ) |
| 10 | 9 | anim1i | |- ( ( F e. ( R GrpIso S ) /\ X e. A ) -> ( ( F e. ( R GrpHom S ) /\ F : A -1-1-> B ) /\ X e. A ) ) |
| 11 | df-3an | |- ( ( F e. ( R GrpHom S ) /\ F : A -1-1-> B /\ X e. A ) <-> ( ( F e. ( R GrpHom S ) /\ F : A -1-1-> B ) /\ X e. A ) ) |
|
| 12 | 10 11 | sylibr | |- ( ( F e. ( R GrpIso S ) /\ X e. A ) -> ( F e. ( R GrpHom S ) /\ F : A -1-1-> B /\ X e. A ) ) |
| 13 | 1 2 4 3 | f1ghm0to0 | |- ( ( F e. ( R GrpHom S ) /\ F : A -1-1-> B /\ X e. A ) -> ( ( F ` X ) = N <-> X = .0. ) ) |
| 14 | 12 13 | syl | |- ( ( F e. ( R GrpIso S ) /\ X e. A ) -> ( ( F ` X ) = N <-> X = .0. ) ) |