Equation Icon  ( 0 0 0 0 ) λ 1 λ2 λ 3 λ4 || λ1 λ1 λ1 λ1 || ν := det | 1 2 3 4 | = 1𝜖ijklλAi λBj πkA′πlB ′𝜀AB 𝜀A′B′ = 1𝜀αβγδZα1 Zβ2Z γ3Z δ4, (7.7 ) |( π10′ π20′ π30′ π40′|) 4 4 1 2 3 4 π1′ π1′ π1′ π 1′