c1,4(2)⁢s1,4(2)⁢d3,4(2)+c3,4(2)⁢s3,4(2)⁢d1,4(2)=c2,4(2)⁢s2,4(2)⁢d4,4(2)+c4,4(2)⁢s4,4(2)⁢d2,4(2)=0.