We present a characterization of level planar graphs in terms of minimal forbidden subgraphs called minimal level non-planar (MLNP) subgraph patterns. We show that an MLNP subgraph pattern is completely characterized by either a tree, a level non-planar cycle or a level planar cycle with certain path augmentations. © 2003 Elsevier B.V. All rights reserved.
Healy, P., Kuusik, A., & Leipert, S. (2004). A characterization of level planar graphs. Discrete Mathematics, 280(1–3), 51–63. https://doi.org/10.1016/j.disc.2003.02.001