-- -*- M2-comint -*- {* hash: 2098030930 *} i1 : R = QQ[x_1..x_6]; i2 : G = graph({x_1*x_2,x_2*x_3,x_3*x_4,x_4*x_5,x_1*x_5,x_1*x_6,x_5*x_6}) --5-cycle and a triangle o2 = Graph{edges => {{x , x }, {x , x }, {x , x }, {x , x }, {x , x }, {x , x }, {x , x }}} 1 2 2 3 3 4 1 5 4 5 1 6 5 6 ring => R vertices => {x , x , x , x , x , x } 1 2 3 4 5 6 o2 : Graph i3 : allOddHoles G --only the 5-cycle should appear o3 = {{x , x , x , x , x }} 1 2 3 4 5 o3 : List i4 : H = graph({x_1*x_2,x_2*x_3,x_3*x_4,x_4*x_5,x_1*x_5,x_1*x_6,x_5*x_6,x_1*x_4}) --no odd holes o4 = Graph{edges => {{x , x }, {x , x }, {x , x }, {x , x }, {x , x }, {x , x }, {x , x }, {x , x }}} 1 2 2 3 1 4 3 4 1 5 4 5 1 6 5 6 ring => R vertices => {x , x , x , x , x , x } 1 2 3 4 5 6 o4 : Graph i5 : allOddHoles H o5 = {} o5 : List i6 :