منابع مشابه
An inequality for regular near polygons
Let Γ denote a near polygon distance-regular graph with diameter d ≥ 3, valency k and intersection numbers a1 > 0, c2 > 1. Let θ1 denote the second largest eigenvalue of Γ. We show θ1 ≤ k − a1 − c2 c2 − 1 . We show the following (i)–(iii) are equivalent. (i) Equality is attained above; (ii) Γ is Q-polynomial with respect to θ1; (iii) Γ is a dual polar graph or a Hamming graph.
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The inequality of Higman for generalized quadrangles of order (s, t) with s > 1 states that t ≤ s. We will generalize this by proving that the intersection number ci of a regular near 2d-gon of order (s, t) with s > 1 satisfies the tight bound ci ≤ (s − 1)/(s − 1), and we give properties in case of equality. It is known that hemisystems in generalized quadrangles meeting the Higman bound induce...
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In this note we will generalize the Higman-Haemers inequalities for generalized polygons to thick regular near polygons.
متن کاملA Note on Regular Near Polygons
In this note we prove several inequalities for regular near polygons. ∗This work was partly supported by the Grant-in-Aid for Scientific Research (No 14740072), the Ministry of Education, Science and Culture, JAPAN. †This work was partly done when the author was at the ComMaC center at the Pohang University of Science and Technology. He would like to thank the ComMaC-KOSEF for its support.
متن کاملAn Edge-Minimization Problem for Regular Polygons
In this paper we will examine the following problem: What is the minimum number of unit edges required to construct k identical size regular polygons in the plane if sharing of edges is allowed?
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ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 2005
ISSN: 0195-6698
DOI: 10.1016/j.ejc.2004.03.001