Bojan Mohar

activity

20242026

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3 papers · 1 filter

math.CO2025

Spectrally symmetric orientations of graphs

Saieed Akbari, Jonathan Aloni, Maxwell Levit +2

The Hermitian adjacency matrices of digraphs based on the sixth root of unity were introduced in [B. Mohar, A new kind of Hermitian matrices for digraphs, Linear Alg. Appl. (2020)]…

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…