Description: A contradiction implies anything. Inference associated with pm2.21 . Its associated inference is pm2.24ii . (Contributed by NM, 16-Sep-1993)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | pm2.21i.1 | |- -. ph |
|
| Assertion | pm2.21i | |- ( ph -> ps ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | pm2.21i.1 | |- -. ph |
|
| 2 | 1 | a1i | |- ( -. ps -> -. ph ) |
| 3 | 2 | con4i | |- ( ph -> ps ) |