Description: A subset of an injective function is injective. (Contributed by AV, 20-Nov-2020)
Ref | Expression | ||
---|---|---|---|
Assertion | f1ssf1 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | funssres | |
|
2 | funres11 | |
|
3 | cnveq | |
|
4 | 3 | funeqd | |
5 | 2 4 | syl5ibr | |
6 | 5 | eqcoms | |
7 | 1 6 | syl | |
8 | 7 | ex | |
9 | 8 | com23 | |
10 | 9 | 3imp | |