Metamath Proof Explorer


Theorem elmapi

Description: A mapping is a function, forward direction only with superfluous antecedent removed. (Contributed by Stefan O'Rear, 10-Oct-2014)

Ref Expression
Assertion elmapi
|- ( A e. ( B ^m C ) -> A : C --> B )

Proof

Step Hyp Ref Expression
1 elmapex
 |-  ( A e. ( B ^m C ) -> ( B e. _V /\ C e. _V ) )
2 elmapg
 |-  ( ( B e. _V /\ C e. _V ) -> ( A e. ( B ^m C ) <-> A : C --> B ) )
3 1 2 syl
 |-  ( A e. ( B ^m C ) -> ( A e. ( B ^m C ) <-> A : C --> B ) )
4 3 ibi
 |-  ( A e. ( B ^m C ) -> A : C --> B )