Walk-powers and homomorphism bound of planar graphs

Reza Naserasr, Sagnik Sen, Qiang Sun

As an extension of the Four-Color Theorem it is conjectured that every planar graph of odd-girth at least $2k+1$ admits a homomorphism to $PC_{2k}=(\mathbb{Z}_2^{2k}, \{e_1, e_2, .…