Description: The value of the identity function is a subset of the argument. (An artifact of our function value definition.) (Contributed by Mario Carneiro, 27-Feb-2016)
Ref | Expression | ||
---|---|---|---|
Assertion | fviss | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id | |
|
2 | elfvex | |
|
3 | fvi | |
|
4 | 2 3 | syl | |
5 | 1 4 | eleqtrd | |
6 | 5 | ssriv | |