Partitioning planar graph of girth 5 into two forests with maximum degree 4
Min Chen, André Raspaud, Weifan Wang, Weiqiang Yu · Czechoslovak Mathematical Journal · 2024
summary:Given a graph $G=(V, E)$, if we can partition the vertex set $V$ into two nonempty subsets $V_1$ and $V_2$ which satisfy $\Delta (G[V_1])\le d_1$ and $\Delta (G[V_2])\le d_2$, then we say $G$ has a $(\Delta _{d_{1}},\Delta _{d_{2}})$-partition. And we say $G$ admits an $(F_{d_{1}}, F_{d_{2}})$-partition if $G[V_1]$ and $G[V_2]$ are both forests whose maximum degree is at most $d_{1}$ and $d_{2}$, respectively. We show that every planar graph with girth at least 5 has an $(F_4, F_4)$-partition.