def calc_domset_graph(domset, dominators, d):
h = Graph.on(domset)
for v in dominators:
if v in domset:
continue
# Collect closest pairs
sorted_doms = filter(lambda s: len(s) > 0, [dominators[v][r] for r in xrange(d+1)])
if len(sorted_doms[0]) >= 2:
for x,y in itertools.combinations(sorted_doms[0],2):
h.add_edge(x,y)
else:
assert len(sorted_doms[0]) == 1
x = iter(sorted_doms[0]).next()
if len(sorted_doms) >= 2:
for y in sorted_doms[1]:
h.add_edge(x,y)
return h
