 A triple bond is handled the same way except that A and B are each connected to two ghost atoms of the other.If two substituents on an atom are geometric isomers of each other, the "Z"-isomer has higher priority than the "E"-isomer.To handle a molecule containing one or more cycles, one must first expand it into a tree (called a hierarchical digraph) by traversing bonds in all possible paths starting at the stereocenter.