Description: The range of a function expressed as a collection of the function's values. (Contributed by NM, 20-Oct-2005) (Proof shortened by Mario Carneiro, 31-Aug-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | fnrnfv | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dffn5 | |
|
2 | rneq | |
|
3 | 1 2 | sylbi | |
4 | eqid | |
|
5 | 4 | rnmpt | |
6 | 3 5 | eqtrdi | |