Equation Icon  0 0 0 0 ψ˙2 = − ∂ψ3 + σ ψ 4, (245 ) ψ˙0 = − ∂ψ0 + 2σ0ψ0 , (246 ) 10 20 0 30 ψ˙0 = − ∂ψ1 + 3σ ψ 2, (247 )