In this way, each nonterminal has two endpoints, and adjacent nonterminals share one endpoint.
the left-hand side nonterminal shares one endpoint with the left-most Dependency graph for the CFG rule S → A B C D (left) and the SCFG rule Gadget grid G i in the construction of cyclic permutation multigraph M, assuming nonterminal in the right-hand side and one endpoint with the right-most nonterminal in the right-hand side.