Description: A function on a singleton. (Contributed by Alexander van der Vekens, 3-Dec-2017) (Proof shortened by AV, 18-Apr-2021)
Ref | Expression | ||
---|---|---|---|
Assertion | 1fv | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0z | |
|
2 | 1 | a1i | |
3 | id | |
|
4 | 2 3 | fsnd | |
5 | fvsng | |
|
6 | 1 5 | mpan | |
7 | 4 6 | jca | |
8 | 7 | adantr | |
9 | id | |
|
10 | fz0sn | |
|
11 | 10 | a1i | |
12 | 9 11 | feq12d | |
13 | fveq1 | |
|
14 | 13 | eqeq1d | |
15 | 12 14 | anbi12d | |
16 | 15 | adantl | |
17 | 8 16 | mpbird | |