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Description: Introduction of conjunct inside of a contradiction. (Contributed by NM, 10-Jul-2005)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | intnand.1 | ||
| Assertion | intnanrd |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | intnand.1 | ||
| 2 | simpl | ||
| 3 | 1 2 | nsyl |