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Description: Theorem *5.71 of WhiteheadRussell p. 125. (Contributed by Roy F. Longton, 23-Jun-2005)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | pm5.71 | ⊢ ( ( 𝜓 → ¬ 𝜒 ) → ( ( ( 𝜑 ∨ 𝜓 ) ∧ 𝜒 ) ↔ ( 𝜑 ∧ 𝜒 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | orel2 | ⊢ ( ¬ 𝜓 → ( ( 𝜑 ∨ 𝜓 ) → 𝜑 ) ) | |
| 2 | orc | ⊢ ( 𝜑 → ( 𝜑 ∨ 𝜓 ) ) | |
| 3 | 1 2 | impbid1 | ⊢ ( ¬ 𝜓 → ( ( 𝜑 ∨ 𝜓 ) ↔ 𝜑 ) ) |
| 4 | 3 | anbi1d | ⊢ ( ¬ 𝜓 → ( ( ( 𝜑 ∨ 𝜓 ) ∧ 𝜒 ) ↔ ( 𝜑 ∧ 𝜒 ) ) ) |
| 5 | pm2.21 | ⊢ ( ¬ 𝜒 → ( 𝜒 → ( ( 𝜑 ∨ 𝜓 ) ↔ 𝜑 ) ) ) | |
| 6 | 5 | pm5.32rd | ⊢ ( ¬ 𝜒 → ( ( ( 𝜑 ∨ 𝜓 ) ∧ 𝜒 ) ↔ ( 𝜑 ∧ 𝜒 ) ) ) |
| 7 | 4 6 | ja | ⊢ ( ( 𝜓 → ¬ 𝜒 ) → ( ( ( 𝜑 ∨ 𝜓 ) ∧ 𝜒 ) ↔ ( 𝜑 ∧ 𝜒 ) ) ) |