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Mirrors > Home > MPE Home > Th. List > df-3an | Structured version Visualization version GIF version |
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 469. (Contributed by NM, 8-Apr-1994.) |
Ref | Expression |
---|---|
df-3an | ⊢ ((𝜑 ∧ 𝜓 ∧ 𝜒) ↔ ((𝜑 ∧ 𝜓) ∧ 𝜒)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | wph | . . 3 wff 𝜑 | |
2 | wps | . . 3 wff 𝜓 | |
3 | wch | . . 3 wff 𝜒 | |
4 | 1, 2, 3 | w3a 1086 | . 2 wff (𝜑 ∧ 𝜓 ∧ 𝜒) |
5 | 1, 2 | wa 396 | . . 3 wff (𝜑 ∧ 𝜓) |
6 | 5, 3 | wa 396 | . 2 wff ((𝜑 ∧ 𝜓) ∧ 𝜒) |
7 | 4, 6 | wb 205 | 1 wff ((𝜑 ∧ 𝜓 ∧ 𝜒) ↔ ((𝜑 ∧ 𝜓) ∧ 𝜒)) |
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