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Description: Define conjunction ('and') of three wff's. Definition *4.34 of WhiteheadRussell p. 118. This abbreviation reduces the number of parentheses and emphasizes that the order of bracketing is not important by virtue of the associative law anass . (Contributed by NM, 8-Apr-1994)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-3an | ⊢ ( ( 𝜑 ∧ 𝜓 ∧ 𝜒 ) ↔ ( ( 𝜑 ∧ 𝜓 ) ∧ 𝜒 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | wph | ⊢ 𝜑 | |
| 1 | wps | ⊢ 𝜓 | |
| 2 | wch | ⊢ 𝜒 | |
| 3 | 0 1 2 | w3a | ⊢ ( 𝜑 ∧ 𝜓 ∧ 𝜒 ) |
| 4 | 0 1 | wa | ⊢ ( 𝜑 ∧ 𝜓 ) |
| 5 | 4 2 | wa | ⊢ ( ( 𝜑 ∧ 𝜓 ) ∧ 𝜒 ) |
| 6 | 3 5 | wb | ⊢ ( ( 𝜑 ∧ 𝜓 ∧ 𝜒 ) ↔ ( ( 𝜑 ∧ 𝜓 ) ∧ 𝜒 ) ) |