On robust toric ideals of weighted oriented graphs

In this work, we study the equivalence of various robustness properties of toric ideals of weighted oriented graphs. For any weighted oriented graph $D$, if its toric ideal $I_D$ is generalized robust (or weakly robust), then we show that $D$ does not have forbidden subgraphs $D_1,D_2$ of certain structures. We give a significant class of weighted oriented graphs $D$ whose toric ideals $I_D$ have the following equivalence. (i) $I_{D}$ is strongly robust (equivalently, $I_{D}$ is robust); (ii) $I_{D}$ is generalized robust (equivalently, $I_{D}$ is weakly robust); (iii) $D$ does not have subgraphs equal to $D_{1}$ and $D_{2}$.