Abstract:
In this paper we obtain the lower bound of number of edges in a unit distance graph $\Gamma$ in an infinitesimal plane layer $\mathbb R^2\times[0,\varepsilon]^d$ which compares number of edges $e(\Gamma)$, number of vertices $\nu(\Gamma)$ and independence number $\alpha(\Gamma)$. Our bound $e(\Gamma)\ge\frac{19\nu\Gamma)-50\alpha(\Gamma)}3$ is generalizing of previous bound for distance graphs in plane and a strong upgrade of Turán's bound when $\frac15\le\frac{\alpha(\Gamma)}{\nu(\Gamma)}\le\frac27$.
Key words and phrases:
distance graph, independence number, Turán type bounds.
Citation:
L. E. Shabanov, “Turán type results for distance graphs in infinitesimal plane layer”, Combinatorics and graph theory. Part IX, Zap. Nauchn. Sem. POMI, 464, POMI, St. Petersburg, 2017, 132–168; J. Math. Sci. (N. Y.), 236:5 (2019), 554–578