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Description: Conjunction in antecedent versus disjunction in consequent. Theorem *5.6 of WhiteheadRussell p. 125. (Contributed by NM, 8-Jun-1994)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | pm5.6 | ⊢ ( ( ( 𝜑 ∧ ¬ 𝜓 ) → 𝜒 ) ↔ ( 𝜑 → ( 𝜓 ∨ 𝜒 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | impexp | ⊢ ( ( ( 𝜑 ∧ ¬ 𝜓 ) → 𝜒 ) ↔ ( 𝜑 → ( ¬ 𝜓 → 𝜒 ) ) ) | |
| 2 | df-or | ⊢ ( ( 𝜓 ∨ 𝜒 ) ↔ ( ¬ 𝜓 → 𝜒 ) ) | |
| 3 | 2 | imbi2i | ⊢ ( ( 𝜑 → ( 𝜓 ∨ 𝜒 ) ) ↔ ( 𝜑 → ( ¬ 𝜓 → 𝜒 ) ) ) |
| 4 | 1 3 | bitr4i | ⊢ ( ( ( 𝜑 ∧ ¬ 𝜓 ) → 𝜒 ) ↔ ( 𝜑 → ( 𝜓 ∨ 𝜒 ) ) ) |