init(3)
insert(0,1)
transitive closure?
insert(0,2)
transitive closure?
insert(1,2)
transitive closure?
delete(1,2)
transitive closure?
insert(2,1)
transitive closure?
delete(0,1)
transitive closure?
insert(1,0)
transitive closure?
delete(0,2)
transitive closure?
insert(2,0)
transitive closure?
