The excluded minor structure theorem with planarly embedded wall

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A graph is nearly embedded in a surface if it consists of graph G₀ that is embedded in the surface, together with a bounded number of vortices having no large transactions. It is shown that every large wall (or grid minor) in a nearly embedded graph, many rows of which intersect the embedded subgraph G₀ of the near-embedding, contains a large subwall that is planarly embedded within G₀. This result provides some hidden details needed for a strong version of the Robertson and Seymour's excluded minor theorem as presented in [K. Kawarabayashi, B. Mohar, Some recent progress and applications in graph minor theory, Graphs Combin. 23 (2007) 1-46].