Description: Lemma 1 for satffun : induction basis. (Contributed by AV, 28-Oct-2023)
Ref | Expression | ||
---|---|---|---|
Assertion | satffunlem1 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | satfv0fun | |
|
2 | satffunlem1lem1 | |
|
3 | 1 2 | syl | |
4 | satffunlem1lem2 | |
|
5 | funun | |
|
6 | 1 3 4 5 | syl21anc | |
7 | peano1 | |
|
8 | eqid | |
|
9 | 8 | satfvsuc | |
10 | 7 9 | mp3an3 | |
11 | 10 | funeqd | |
12 | 6 11 | mpbird | |