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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