Fig. 5: Chosen projection of the wheel geometry (top) onto a chain (bottom).
From: Symmetry-protected Bose-Einstein condensation of interacting hardcore bosons

This reduces the long-range interaction from the first to the last site that is replaced by multiple NNN interactions compared to a straight forward periodic boundary implementation. The center site (star) of the wheel is placed in the middle of this chain—again in order to reduce the long-range interaction to a minimum.