3 papers
math.CO2025
On minors of non-hamiltonian graphs
On-Hei Solomon Lo
A theorem of Tutte states that every 4-connected non-hamiltonian graph contains as a minor. We strengthen this result by proving that such a graph must contain …
math.CO2025
Colouring normal quadrangulations of projective spaces
Tomáš Kaiser, On-Hei Solomon Lo, Atsuhiro Nakamoto +2
Youngs proved that every non-bipartite quadrangulation of the projective plane is 4-chromatic. Kaiser and Stehl\'ık [J. Combin. Theory Ser. B 113 (2015), 1…
math.CO2023
Defective acyclic colorings of planar graphs
On-Hei Solomon Lo, Ben Seamone, Xuding Zhu
This paper studies two variants of defective acyclic coloring of planar graphs. For a graph and a coloring of , a 2CC transversal is a subset of that interse…