Nonexistence of the specified planar semi-cover of K1,2,2,2K_{1,2,2,2}

Let K1,2,2,2K_{1,2,2,2} be the complete multipartite graph with parts of sizes 1,2,2,21,2,2,2. A planar semi-cover GG' is the planar graph notion defined in the source, and let HH be the subgraph required to satisfy the conditions listed in Lemma

. **Nonexistence conjecture.** There is no planar semi-cover $G'$ of $K_{1,2, 2, 2}$ having the properties listed in Lemma

.

The source presents this as a strengthening of Negami's conjecture and aims to prove it as part of the analysis of possible planar covers of K1,2,2,2K_{1,2,2,2}. The supplied text does not establish the claim, so its resolution is left open.

Sources & referencesView supporting material

Primary source

Dickson Y. B. Annor, Yuri Nikolayevsky and Michael S. Payne, “K_1,2,2,2 has no n-fold planar cover graph for n<14”, arXiv:2311.01672 (2024).

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