Metamath Proof Explorer


Theorem elmapfun

Description: A mapping is always a function. (Contributed by Stefan O'Rear, 9-Oct-2014) (Revised by Stefan O'Rear, 5-May-2015)

Ref Expression
Assertion elmapfun A B C Fun A

Proof

Step Hyp Ref Expression
1 elmapi A B C A : C B
2 1 ffund A B C Fun A