Metamath Proof Explorer

Theorem fofn

Description: An onto mapping is a function on its domain. (Contributed by NM, 16-Dec-2008)

Ref Expression
Assertion fofn 
|- ( F : A -onto-> B -> F Fn A )

Proof

Step Hyp Ref Expression
1 fof 
 |-  ( F : A -onto-> B -> F : A --> B )
2 1 ffnd 
 |-  ( F : A -onto-> B -> F Fn A )