Metamath Proof Explorer


Theorem funcnvcnv

Description: The double converse of a function is a function. (Contributed by NM, 21-Sep-2004)

Ref Expression
Assertion funcnvcnv ( Fun 𝐴 → Fun ◡ ◡ 𝐴 )

Proof

Step Hyp Ref Expression
1 cnvcnvss ⊢ ◡ ◡ 𝐴 ⊆ 𝐴
2 funss ⊢ ( ◡ ◡ 𝐴 ⊆ 𝐴 → ( Fun 𝐴 → Fun ◡ ◡ 𝐴 ) )
3 1 2 ax-mp ⊢ ( Fun 𝐴 → Fun ◡ ◡ 𝐴 )