1. |
2. Total positivity of Toeplitz matrices of recursive hypersequencesTomislav Došlić, Ivica Martinjak, Riste Škrekovski, 2019, izvirni znanstveni članek Ključne besede: total positivity, totally positive matrix, Toeplitz matrix, Hankel matrix, hyperfibonacci sequence, log-concavity Objavljeno v RUP: 03.01.2022; Ogledov: 731; Prenosov: 24 Celotno besedilo (254,44 KB) |
3. On [plus/minus] 1 eigenvectors of graphsDragan Stevanović, 2016, izvirni znanstveni članek Opis: While discussing his spectral bound on the independence number of a graph, Herbert Wilf asked back in 1986 what kind of a graph admits an eigenvector consisting solely of ▫$\pm 1$▫ entries? We prove that Wilf's problem is NP-complete, but also that the set of graphs having a ▫$\pm 1$▫ eigenvector is quite rich, being closed under a number of different graph compositions. Ključne besede: eigenvector, adjacency matrix, Wilf's problem Objavljeno v RUP: 03.01.2022; Ogledov: 663; Prenosov: 25 Celotno besedilo (325,02 KB) |
4. On minimal forbidden subgraphs for the class of EDM-graphsGašper Jaklič, Jolanda Modic, 2015, izvirni znanstveni članek Opis: In this paper, a relation between graph distance matrices and Euclidean distance matrices (EDM) is considered. Graphs, for which the distance matrix is not an EDM (NEDM-graphs), are studied. All simple connected non-isomorphic graphs on ▫$n \le 8$▫ nodes are analysed and a characterization of the smallest NEDM-graphs, i.e., the minimal forbidden subgraphs, is given. It is proven that bipartite graphs and some subdivisions of the smallest NEDM-graphs are NEDM-graphs, too. Ključne besede: graph theory, graph, Euclidean distance matrix, distance, eigenvalue Objavljeno v RUP: 31.12.2021; Ogledov: 860; Prenosov: 18 Celotno besedilo (711,65 KB) |
5. Commuting graphs and extremal centralizersGregor Dolinar, Aleksandr Èmilevič Guterman, Bojan Kuzma, Polona Oblak, 2014, izvirni znanstveni članek Opis: We determine the conditions for matrix centralizers which can guarantee the connectedness of the commuting graph for the full matrix algebra ▫$M_n(\mathbb{F})$▫ over an arbitrary field ▫$\mathbb{F}$▫. It is known that if ▫$\mathbb{F}$▫ is an algebraically closed field and ▫$n \ge 3$▫, then the diameter of the commuting graph of ▫$M_n(\mathbb{F})$▫ is always equal to four. We construct a concrete example showing that if ▫$\mathbb{F}$▫ is not algebraically closed, then the commuting graph of ▫$M_n(\mathbb{F})$▫ can be connected with the diameter at least five. Ključne besede: commuting graph, matrix ring, centralizer Objavljeno v RUP: 31.12.2021; Ogledov: 725; Prenosov: 22 Celotno besedilo (228,78 KB) |
6. |
7. |
8. |
9. O ekstremnih grafih z dano stopnjo in premerom/ožino : doktorska disertacijaSlobodan Filipovski, 2018, doktorska disertacija Ključne besede: adjacency matrix, antipodal graphs, cages, excess, defect, Ramanujan graphs, selfrepeats, degree/diameter problem, spectrum, Moore graphs, asymptotic density, distance matrices, Bermond and Bollobas problem Objavljeno v RUP: 21.01.2019; Ogledov: 2540; Prenosov: 0 |
10. Mamart, Siwaporn: A group commutator involving the last distance matrix and dual distance matrix of a Q-polynomial distance-regular graph: the Hamming graph case. - Graphs Combin. 34 (2018), no. 4, 803--817Safet Penjić, 2018, recenzija, prikaz knjige, kritika Ključne besede: distance-regular graph, Q-polynomial, distance matrix, dual distance matrix Objavljeno v RUP: 21.01.2019; Ogledov: 1431; Prenosov: 15 Povezava na celotno besedilo |