isCM -- determines if a (hyper)graph is Cohen-Macaulay

• Usage:

  b = isCM H

• Inputs:
  • H, a hypergraph,
• Outputs:
  • b, a Boolean value, true if the edgeIdeal of H is Cohen-Macaulay

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

i2 : C = cycle R;

i3 : UnmixedTree = graph {a*b, b*c, c*d};

i4 : MixedTree = graph {a*b, a*c, a*d};

i5 : isCM C

o5 = true

i6 : isCM UnmixedTree

o6 = true

i7 : isCM MixedTree

o7 = false