Metamath Proof Explorer


Theorem fndmi

Description: The domain of a function. (Contributed by Wolf Lammen, 1-Jun-2024)

Ref Expression
Hypothesis fndmi.1 F Fn A
Assertion fndmi dom F = A

Proof

Step Hyp Ref Expression
1 fndmi.1 F Fn A
2 fndm F Fn A dom F = A
3 1 2 ax-mp dom F = A