Bojan Mohar

collaborators

3 papers

math.CO2025

A Counterexample to a Conjecture of Lovász

Alexander Clow, Penny Haxell, Bojan Mohar

In 1975 Lovász conjectured that every $r$ -partite, $r$ -uniform hypergraph contains $r - 1$ vertices whose deletion reduces the matching number. If true, this statement would imply a…

math.CO2025

Refinement of a conjecture on positive square energy of graphs

Saieed Akbari, Hitesh Kumar, Bojan Mohar +2

Let $G$ be a simple graph of order $n$ with eigenvalues $λ_{1} (G) \geq \dots \geq λ_{n} (G)$ . Define \[s^+(G)=\sum_{λ_i >0} λ_i^2(G), \quad s^-(G)=\sum_{λ_i<0} λ_i^2(G).\] It was conjec…

math.CO2024

On the second largest adjacency eigenvalue of trees with given diameter

Hitesh Kumar, Bojan Mohar, Shivaramakrishna Pragada +1

For a graph $G$ , let $λ_{2} (G)$ denote the second largest eigenvalue of the adjacency matrix of $G$ . We determine the extremal trees with maximum/minimum adjacency eigenvalue $λ_{2}$ i…