[x3,x1] x4 [x3,x2] x5 [x4,x1] x6 [x4,x3] x7 [x5,x1] x8 [x8,x1] x9 [x8,x3] x10 [x9,x1] x11 x2x1 x1x2 x5x2 x2x5 x5x3 x3x5 x6x1 x1x6 x6x3 x3x6 x6x4 x4x6 x7x1 x1x7 x7x3 x3x7 x7x4 x4x7 x7x6 x6x7 x8x2 x2x8 x9x2 x2x9 x10x2 x2x10 x8x5 x5x8 x10x5 x5x10 x9x5 x5x9 x9x8 x8x9 [X4,X2] x8x10 [x4,x2,x2] @ [x4,X2,x2] @ [X4,x2,x2] @ [X4,X2,x2] @ [x5x8,X4] x10 [x4,x2] [x4,x5]x8 [x4,x5,x2] @