Description: A singleton of an ordered pair is a function. (Contributed by AV, 17-Apr-2021)
Ref | Expression | ||
---|---|---|---|
Hypotheses | fsnd.a | |
|
fsnd.b | |
||
Assertion | fsnd | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fsnd.a | |
|
2 | fsnd.b | |
|
3 | 1 2 | jca | |
4 | f1sng | |
|
5 | f1f | |
|
6 | 3 4 5 | 3syl | |