Description: The alternate function value at a class A is defined, i.e., in the range of the function, iff A is in the domain of the function. (Contributed by AV, 3-Sep-2022)
Ref | Expression | ||
---|---|---|---|
Assertion | dmafv2rnb | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | iba | |
|
2 | df-dfat | |
|
3 | dfatafv2rnb | |
|
4 | 2 3 | bitr3i | |
5 | 1 4 | bitrdi | |