Combinatorics Seminar 2018

Speaker: Nobuaki Obata, Tohoku University

Date: Sun, Nov 18, 2018

Time: 10:30 - 12:00

Venue: Middle Meeting Room

Title: Asymptotic spectral analysis of growing graphs (II)


Graph spectrum is a topic extensively studied in algebraic graph theory but for its asymptotics for growing graphs we need analytic techniques. In this talk, we overview how the idea of quantum (non-commutative) probability is applied to the asymptotic spectral analysis of growing graphs.

I) The method of quantum decomposition: This is closely related to orthogonal polynomials in one-variable and applied to distance-regular graphs and some generalizations. A bivariate extension is an interesting topic.

II) There are several central limit theorems corresponfing to several concepts of independence. Some graph products enjoy this structure and their asymptotic spectral distributions are obtained as a corollary of quantum central limit theorems.


[1] N. Obata: Spectral Analysis of Growing Graphs, Springer, Singapore, 2017.

[2] Akihito Hora and Nobuaki Obata: Quantum Probability and Spectral Analysis of Graphs. Springer-Verlag Berlin Heidelberg, 2007.

Slides: View slides