Description: Proof of Gödel's theorem from Löb's theorem (see comments at bj-babygodel and bj-babylob for details). (Contributed by BJ, 20-Apr-2019) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | bj-godellob.s | |- ( ph <-> -. Prv ph ) | |
| bj-godellob.1 | |- -. Prv F. | ||
| Assertion | bj-godellob | |- F. | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | bj-godellob.s | |- ( ph <-> -. Prv ph ) | |
| 2 | bj-godellob.1 | |- -. Prv F. | |
| 3 | dfnot | |- ( -. Prv ph <-> ( Prv ph -> F. ) ) | |
| 4 | 1 3 | bitri | |- ( ph <-> ( Prv ph -> F. ) ) | 
| 5 | 2 | pm2.21i | |- ( Prv F. -> F. ) | 
| 6 | 4 5 | bj-babylob | |- F. |