Iskanje po repozitoriju

Ključne besede: (near-) linear space, projective plane, affine plane, partial geometry, generalized quadrangle, strongly regular graph, partial difference set, automorphism group
Objavljeno v RUP: 25.12.2024; Ogledov: 946; Prenosov: 4
Celotno besedilo (1,22 MB)

Opis: The complementary prism $\Gamma \overline{\Gamma}$ is obtained from the union of a graph $\Gamma$ and its complement $\overline{\Gamma}$ where each pair of identical vertices in $\Gamma$ and $\overline{\Gamma}$ is joined by an edge. It generalizes the Petersen graph, which is the complementary prism of the pentagon. The core of a vertex-transitive complementary prism is studied. In particular, it is shown that a vertex-transitive complementary prism $\Gamma \overline{\Gamma}$ is a core, i.e. all its endomorphisms are automorphisms, whenever $\Gamma$ is a core or its core is a complete graph.
Ključne besede: graph homomorphism, complementary prism, self-complementary graph, vertex-transitive graph, core
Objavljeno v RUP: 06.11.2023; Ogledov: 1428; Prenosov: 6
Celotno besedilo (305,54 KB)

Opis: In this paper we introduce a product-like operation that generalizes the construction of the generalized Sierpiński graphs. Let $G, \, H$ be graphs and let $f: V(G) \to V(H)$ be a function. Then the Sierpiński product of graphs $G$ and $H$ with respect to $f$, denoted by $G\otimes_f H$, is defined as the graph on the vertex set $V(G) \times V(H)$, consisting of $|V(G)|$ copies of $H$; for every edge $\{g, g'\}$ of $G▫$ there is an edge between copies ▫$gH$ and $g'H$ of form $\{(g, f(g'), (g', f(g))\}$. Some basic properties of the Sierpiński product are presented. In particular, we show that the graph $G\otimes_f H$ is connected if and only if both graphs $G$ and $H$ are connected and we present some conditions that $G, \, H$ must fulfill for $G\otimes_f H$ to be planar. As for symmetry properties, we show which automorphisms of $G$ and $H$ extend to automorphisms of $G\otimes_f H$. In several cases we can also describe the whole automorphism group of the graph $G\otimes_f H$. Finally, we show how to extend the Sierpiński product to multiple factors in a natural way. By applying this operation $n$ times to the same graph we obtain an alternative approach to the well-known $n$-th generalized Sierpiński graph.
Ključne besede: Sierpiński graphs, graph products, connectivity, planarity, symmetry
Objavljeno v RUP: 06.11.2023; Ogledov: 999; Prenosov: 4
Celotno besedilo (526,44 KB)

Ključne besede: (un)directed Cayley graph, cyclic group, (un)directed circulant graph, Cayley isomorphism, (un)directed CI-graph, (D)CI-group, m-(D)CI-group, key, generalised multiplier
Objavljeno v RUP: 11.09.2023; Ogledov: 1173; Prenosov: 19
Celotno besedilo (520,27 KB)

Ključne besede: distance-regularized vertex, pseudo-distance-regularized vertex, Terwilliger algebra, irreducible module, distance-balanced graph, nicely distance-balanced graph, strongly distance-balanced graph
Objavljeno v RUP: 15.02.2023; Ogledov: 2295; Prenosov: 109
Povezava na celotno besedilo