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S. Negami conjectured in that a connected graph has a finite planar cover if and only if it embeds in the projective plane. It follows from the works of D. Archdeacon, M. Fellows, P. Hliněný, and S. Negami that this conjecture is true if the graph has no finite planar cover. We prove a number of structural results about putative finite planar covers of that may be of independent interest. We then apply these results to prove that has no planar cover of fold number less than .

生成讲解博客的中文版本

生成AI智能校验的中文版本