Metamath Proof Explorer


Theorem aovvfunressn

Description: If the operation value of a class for an argument is a set, the class restricted to the singleton of the argument is a function. (Contributed by Alexander van der Vekens, 26-May-2017)

Ref Expression
Assertion aovvfunressn
|- ( (( A F B )) e. C -> Fun ( F |` { <. A , B >. } ) )

Proof

Step Hyp Ref Expression
1 df-aov
 |-  (( A F B )) = ( F ''' <. A , B >. )
2 1 eleq1i
 |-  ( (( A F B )) e. C <-> ( F ''' <. A , B >. ) e. C )
3 afvvfunressn
 |-  ( ( F ''' <. A , B >. ) e. C -> Fun ( F |` { <. A , B >. } ) )
4 2 3 sylbi
 |-  ( (( A F B )) e. C -> Fun ( F |` { <. A , B >. } ) )