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Description: Deduction eliminating an antecedent. (Contributed by NM, 27-Apr-1994) (Proof shortened by Wolf Lammen, 12-Sep-2013)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | pm2.61d.1 | ⊢ ( 𝜑 → ( 𝜓 → 𝜒 ) ) | |
| pm2.61d.2 | ⊢ ( 𝜑 → ( ¬ 𝜓 → 𝜒 ) ) | ||
| Assertion | pm2.61d | ⊢ ( 𝜑 → 𝜒 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | pm2.61d.1 | ⊢ ( 𝜑 → ( 𝜓 → 𝜒 ) ) | |
| 2 | pm2.61d.2 | ⊢ ( 𝜑 → ( ¬ 𝜓 → 𝜒 ) ) | |
| 3 | 2 | con1d | ⊢ ( 𝜑 → ( ¬ 𝜒 → 𝜓 ) ) |
| 4 | 3 1 | syld | ⊢ ( 𝜑 → ( ¬ 𝜒 → 𝜒 ) ) |
| 5 | 4 | pm2.18d | ⊢ ( 𝜑 → 𝜒 ) |