English
Related papers

Related papers: On the degrees of regular nut graphs and Cayley nu…

200 papers

A nut graph is a simple graph whose adjacency matrix is singular with $1$-dimensional kernel such that the corresponding eigenvector has no zero entries. In 2020, Fowler et al. characterised for each $d \in \{3,4,\ldots,11\}$ all values $n$…

Combinatorics · Mathematics 2021-02-09 Nino Bašić , Martin Knor , Riste Škrekovski

A nut graph is a nontrivial simple graph whose adjacency matrix has a simple eigenvalue zero such that the corresponding eigenvector has no zero entries. It is known that the order $n$ and degree $d$ of a vertex-transitive nut graph satisfy…

Combinatorics · Mathematics 2026-01-14 Ivan Damnjanović

A nut graph is a non-trivial simple graph such that its adjacency matrix has a one-dimensional null space spanned by a full vector. It was recently shown by the authors that there exists a $d$-regular circulant nut graph of order $n$ if and…

Combinatorics · Mathematics 2023-05-31 Ivan Damnjanović

A nut graph is a singular graph with one-dimensional kernel and corresponding eigenverctor with no zero elements. The problem of determining the orders $n$ for which $d$-regular nut graphs exist was recently posed by Gauci, Pisanski and…

Combinatorics · Mathematics 2019-11-07 Patrick W. Fowler , John Baptist Gauci , Jan Goedgebeur , Tomaž Pisanski , Irene Sciriha

A nut graph is a simple graph of order 2 or more for which the adjacency matrix has a single zero eigenvalue such that all non-zero kernel eigenvectors have no zero entry (i.e. are full). It is shown by construction that every finite group…

Combinatorics · Mathematics 2024-05-08 Nino Bašić , Patrick W. Fowler

A nut graph is a nontrivial graph whose adjacency matrix has a one-dimensional null space spanned by a vector without zero entries. Recently, it was shown that a nut graph has more edge orbits than vertex orbits. It was also shown that for…

Combinatorics · Mathematics 2026-01-26 Nino Bašić , Ivan Damnjanović

A nut graph is a simple graph whose adjacency matrix has the eigenvalue~0 with multiplicity~1 such that its corresponding eigenvector has no zero entries. Motivated by a question of Fowler et al.~[\emph{Disc. Math. Graph Theory} 40 (2020),…

Combinatorics · Mathematics 2021-06-03 Ivan Damnjanović , Dragan Stevanović

A nut graph is a graph on at least 2 vertices whose adjacency matrix has nullity 1 and for which non-trivial kernel vectors do not contain a zero. Chemical graphs are connected, with maximum degree at most three. We present a new algorithm…

Combinatorics · Mathematics 2017-09-14 Kris Coolsaet , Patrick W. Fowler , Jan Goedgebeur

A nut graph is a simple graph for which the adjacency matrix has a single zero eigenvalue such that all non-zero kernel eigenvectors have no zero entry. If the isolated vertex is excluded as trivial, nut graphs have seven or more vertices;…

Combinatorics · Mathematics 2023-12-07 Nino Bašić , Patrick W. Fowler , Tomaž Pisanski

A circulant nut graph is a non-trivial simple graph such that its adjacency matrix is a circulant matrix whose null space is spanned by a single vector without zero elements. Regarding these graphs, the order-degree existence problem can be…

Combinatorics · Mathematics 2025-06-09 Ivan Damnjanović

Nut graphs are graphs whose adjacency matrix is singular with one-dimensional null space spanned by a vector with no zero entries. In a recent paper, Ba\v{s}i\'c, Fowler and Pisanski proved that the automorphism group of a nut graph has…

Combinatorics · Mathematics 2025-08-26 Ksenija Rozman , Primož Šparl

A nut graph is a simple graph whose kernel is spanned by a single full vector (i.e. the adjacency matrix has a single zero eigenvalue and all non-zero kernel eigenvectors have no zero entry). We classify generalisations of nut graphs to nut…

Combinatorics · Mathematics 2025-03-14 Nino Bašić , Patrick W. Fowler , Maxine M. McCarthy , Primož Potočnik

A nut graph is a nontrivial simple graph whose adjacency matrix contains a one-dimensional null space spanned by a vector without zero entries. Moreover, an $\ell$-circulant graph is a graph that admits a cyclic group of automorphisms…

Combinatorics · Mathematics 2025-06-09 Nino Bašić , Ivan Damnjanović

A circulant graph is a simple graph whose adjacency matrix can be represented in the form of a circulant matrix, while a nut graph is considered to be a graph whose null space is spanned by a single full vector. In a previous study by…

Combinatorics · Mathematics 2026-01-26 Ivan Damnjanović

A nut graph is a simple graph whose adjacency matrix has the eigenvalue zero with multiplicity one such that its corresponding eigenvector has no zero entries. It is known that there exist no cubic circulant nut graphs. A bicirculant (resp.…

Combinatorics · Mathematics 2024-05-27 Ivan Damnjanović , Nino Bašić , Tomaž Pisanski , Arjana Žitnik

Molecular graphs of unsaturated carbon frameworks or hydrocarbons pruned of hydrogen atoms, are chemical graphs. A chemical graph is a connected simple graph of maximum degree $3$ or less. A nut graph is a connected simple graph with a…

Combinatorics · Mathematics 2020-09-04 Patrick W. Fowler , Tomaž Pisanski , Nino Bašić

A graph is called a nut graph if zero is its eigenvalue of multiplicity one and its corresponding eigenvector has no zero entries. A graph is a bicirculant if it admits an automorphism with two equally sized vertex orbits. There are four…

Combinatorics · Mathematics 2025-02-11 Ivan Damnjanović , Nino Bašić , Tomaž Pisanski , Arjana Žitnik

For an $n \times n$ matrix $A$, let $q(A)$ be the number of distinct eigenvalues of $A$. If $G$ is a connected graph on $n$ vertices, let $\mathcal{S}(G)$ be the set of all real symmetric $n \times n$ matrices $A=[a_{ij}]$ such that for…

Combinatorics · Mathematics 2023-05-19 Wayne Barrett , Shaun Fallat , Veronika Furst , Shahla Nasserasr , Brendan Rooney , Michael Tait

A graph is called integral if all its eigenvalues are integers. A Cayley graph is called normal if its connection set is a union of conjugacy classes. We show that a non-empty integral normal Cayley graph for a group of odd order has an odd…

Combinatorics · Mathematics 2023-12-21 Arnbjörg Soffía Árnadóttir , Chris Godsil

A nuciferous graph is a simple graph with a non-singular $0$-$1$ adjacency matrix $A$ such that all the diagonal entries of $A^{-1}$ are zero and all the off-diagonal entries of $A^{-1}$ are non-zero. Sciriha et al. conjectured that except…

Combinatorics · Mathematics 2016-03-18 Ebrahim Ghorbani
‹ Prev 1 2 3 10 Next ›