collaborators

12 papers

math.CO2026

Extremal graphs for the -th eigenvalue

Hitesh Kumar, Bojan Mohar, Seyed Ahmad Mojallal +1

For a simple graph of order , let denote its adjacency eigenvalues. Hong's problem asks for the optimal upper bound for . A recent theo…

math.CO2026

Energy and independence number

Hitesh Kumar, Shivaramakrishna Pragada

For a graph of order , with adjacency eigenvalues , the \emph{energy} of is defined to be \[\mathcal{E}(G)=\sum_{i=1}^{n} |λ_i(G)|.\]…

math.CO2026

An improved bound for the strong clique index of graphs

Hitesh Kumar, Bojan Mohar, Shivaramakrishna Pragada

For a graph with line graph , and are called the \emph{strong chromatic index} and \emph{strong clique index} of , respectively. A well-known…

math.CO2026

Spectral Radius, Vertex Deletion, and Chromatic Number of Signed Graphs

Abhay Jayarajan, M. Rajesh Kannan, Priti Prasanna Mondal +1

A signed graph is a graph with edges given signs or defined by the function . The adjacency matrix of is defined as per these signs. The relation betw…

math.CO2026

Localized Turán-type inequalities for -index

M. Rajesh Kannan, Hitesh Kumar, Shivaramakrishna Pragada

For a connected graph \(G\), let denote the -index of , i.e., the largest eigenvalue of its signless Laplacian matrix. Abreu and Nikiforov (2013) showed that \[ q(G) \…

math.CO2026

Maximum spectral sum of graphs

Hitesh Kumar, Lele Liu, Hermie Monterde +2

For a graph of order , the spectral sum of is defined to be the sum , where (resp. ) is the largest (resp. second largest) adjacenc…