Description: An alternate function value belongs to the range of the function, analogous to fvelrn . (Contributed by AV, 3-Sep-2022)
Ref | Expression | ||
---|---|---|---|
Assertion | afv2elrn | |- ( ( Fun F /\ A e. dom F ) -> ( F '''' A ) e. ran F ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fundmdfat | |- ( ( Fun F /\ A e. dom F ) -> F defAt A ) |
|
2 | dfatafv2rnb | |- ( F defAt A <-> ( F '''' A ) e. ran F ) |
|
3 | 1 2 | sylib | |- ( ( Fun F /\ A e. dom F ) -> ( F '''' A ) e. ran F ) |