Tight distance-regular graphs and the Q-polynomial property

• Main Author: Pascasio, Arlene A.
• Format: text
• Published: Animo Repository 2001
• Subjects: Graph theory; Polynomials; Mathematics
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/3622; https://animorepository.dlsu.edu.ph/context/faculty_research/article/4624/type/native/viewcontent/s003730170063.html
• Institution: De La Salle University

Let Γ denote a distance-regular graph with diameter d ≥ 3, and assume Γ is tight (in the sense of Jurišić, Koolen and Terwilliger). Let θ denote the second largest or smallest eigenvalue of Γ, and let σ0, σ1, . . . , σd denote the associated cosine sequence. We obtain an inequality involving σ0, σ1,...