On vertices , join cyclic indices differing by one or two modulo eight. The resulting planar graph has a square face bounded in order by . Deleting at most three vertices cannot disconnect it: each break in the surviving cyclic chain requires two consecutive deleted vertices, and two separate breaks require four deletions. It is therefore four-connected. Disjoint paths joining to and to would cross in the complementary disk of the square face, contrary to the Jordan curve theorem. Thus four-connectivity does not guarantee two-linkage.
Articles by others on the same topic
There are currently no matching articles.