# MS-21 Spectral Graph Theory

### Organizers: Nair Abreu (Universidade Federal do Rio de Janeiro, Brazil) and Leonardo de Lima (Federal Center of Technological Education Celso Suckow da Fonseca, Brazil)

Spectral Graph Theory studies interactions of graphs and matrices. Topics of interest include, but are not limited to, the following: (i) characteristic polynomials, eigenvalues and eigenvectors of matrices related to graphs such as the adjacency matrix, the Laplacian and normalized Laplacian matrices, the signless Laplacian matrix, Seidel matrix and distance matrices; (ii) relations between the spectrum and the structure of a graph; (iii) cospectral graphs and graphs characterized by their spectra; (iv) the usage of spectral techniques to prove graph-theoretical results; (v) applications of spectral graph theory in combinatorics, chemistry, physics, computer science, engineering and other areas are welcome. Recent developments in spectral graph theory and an opportunity to exchange new ideas are expected as outcomes of this mini-symposium.

### Speakers

**Gabriel Coutinho**, LAA Early Career Speaker, *Quantum walks on trees*

**Aida Abiad**, *An application of Hoffman graphs for spectral characterizations of graphs*

**Enide Andrade**, *A lower bound for the energy of symmetric matrices and graphs*

**Domingos Cardoso**, *Lexicographic polynomials of graphs and their spectra*

**Sebastian Cioaba**, *Maximizing the order of a regular graph with given valency and second eigenvalue*

**Geir Dahl**, *Laplacian Energy, threshold graphs and majorization*

**Leonardo De Lima**, *Graphs with all but two eigenvalues in [-2,0]*

**Krystal Guo**, *Quantum walks and graph isomorphism*

**Carlos Hoppen**, *Eigenvalue location for graphs of small clique-width*

**Jephian C.-H. Lin**, *Note on von Neumann and Rényi entropies of a graph*

**Margarida Mitjana**, *Spectra of the generalized subdivision and other extensions of a network*

**Suil O**, *The second largest eigenvalue and vertex-connectivity in regular graphs*

**Carolyn Reinhart**, *Results on the minimum number of distinct eigenvalues of graphs*

**María Robbiano**, *α-Adjacency Spectra of a Compound Graph of Weighted Bethe Trees*

**Mike Tait**, *The spectral radius of a graph with no induced K _{s,t}*

**Vilmar Trevisan**, *Ordering starlike trees by their indices*