-- -*- M2-comint -*- {* hash: -2016180709 *}

i1 : R = QQ[a..f];

i2 : G = cycle(R,6);

i3 : allEvenHoles G

o3 = {{a, b, c, d, e, f}}

o3 : List

i4 : H = graph(monomialIdeal(a*b,b*c,c*d,d*e,e*f,a*f,a*d)) --6-cycle with a chord

o4 = Graph{edges => {{a, b}, {b, c}, {a, d}, {c, d}, {d, e}, {a, f}, {e, f}}}
           ring => R
           vertices => {a, b, c, d, e, f}

o4 : Graph

i5 : allEvenHoles H --two 4-cycles

o5 = {{a, b, c, d}, {a, d, e, f}}

o5 : List

i6 :