Description: A word is a zero-based sequence with a recoverable upper limit, deduction version. (Contributed by Thierry Arnoux, 22-Dec-2021)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | wrdfd.n | ||
| wrdfd.w | |||
| Assertion | wrdfd |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wrdfd.n | ||
| 2 | wrdfd.w | ||
| 3 | wrdf | ||
| 4 | 2 3 | syl | |
| 5 | 1 | oveq2d | |
| 6 | 5 | feq2d | |
| 7 | 4 6 | mpbird |