Description: Define the redundancy operator for propositions, cf. df-redund . (Contributed by Peter Mazsa, 23-Oct-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-redundp | ⊢ ( redund ( 𝜑 , 𝜓 , 𝜒 ) ↔ ( ( 𝜑 → 𝜓 ) ∧ ( ( 𝜑 ∧ 𝜒 ) ↔ ( 𝜓 ∧ 𝜒 ) ) ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 0 | wph | ⊢ 𝜑 | |
| 1 | wps | ⊢ 𝜓 | |
| 2 | wch | ⊢ 𝜒 | |
| 3 | 0 1 2 | wredundp | ⊢ redund ( 𝜑 , 𝜓 , 𝜒 ) | 
| 4 | 0 1 | wi | ⊢ ( 𝜑 → 𝜓 ) | 
| 5 | 0 2 | wa | ⊢ ( 𝜑 ∧ 𝜒 ) | 
| 6 | 1 2 | wa | ⊢ ( 𝜓 ∧ 𝜒 ) | 
| 7 | 5 6 | wb | ⊢ ( ( 𝜑 ∧ 𝜒 ) ↔ ( 𝜓 ∧ 𝜒 ) ) | 
| 8 | 4 7 | wa | ⊢ ( ( 𝜑 → 𝜓 ) ∧ ( ( 𝜑 ∧ 𝜒 ) ↔ ( 𝜓 ∧ 𝜒 ) ) ) | 
| 9 | 3 8 | wb | ⊢ ( redund ( 𝜑 , 𝜓 , 𝜒 ) ↔ ( ( 𝜑 → 𝜓 ) ∧ ( ( 𝜑 ∧ 𝜒 ) ↔ ( 𝜓 ∧ 𝜒 ) ) ) ) |