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Wyszukujesz frazę "isometric" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
On the Isometric Path Partition Problem
Autorzy:
Manuel, Paul
Powiązania:
https://bibliotekanauki.pl/articles/32323579.pdf
Data publikacji:
2021-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
path cover problem
isometric path partition problem
isometric path cover problem
multi-dimensional grids
cylinder
torus
Opis:
The isometric path cover (partition) problem of a graph consists of finding a minimum set of isometric paths which cover (partition) the vertex set of the graph. The isometric path cover (partition) number of a graph is the cardinality of a minimum isometric path cover (partition). We prove that the isometric path partition problem and the isometric k-path partition problem for k 3 are NP-complete on general graphs. Fisher and Fitzpatrick in [The isometric number of a graph, J. Combin. Math. Combin. Comput. 38 (2001) 97–110] have shown that the isometric path cover number of the (r × r)-dimensional grid is ⌈2r/3 ⌉. We show that the isometric path cover (partition) number of the (r × s)-dimensional grid is s when r s(s − 1). We establish that the isometric path cover (partition) number of the (r × r)-dimensional torus is r when r is even and is either r or r + 1 when r is odd. Then, we demonstrate that the isometric path cover (partition) number of an r-dimensional Benes network is 2r. In addition, we provide partial solutions for the isometric path cover (partition) problems for cylinder and multi-dimensional grids. We apply two di erent techniques to achieve these results.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 4; 1077-1089
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The strong isometric dimension of finite reflexive graphs
Autorzy:
Fitzpatrick, Shannon
Nowakowski, Richard
Powiązania:
https://bibliotekanauki.pl/articles/743675.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
isometric
embedding
strong product
injective hull
paths
distance
metric
Opis:
The strong isometric dimension of a reflexive graph is related to its injective hull: both deal with embedding reflexive graphs in the strong product of paths. We give several upper and lower bounds for the strong isometric dimension of general graphs; the exact strong isometric dimension for cycles and hypercubes; and the isometric dimension for trees is found to within a factor of two.
Źródło:
Discussiones Mathematicae Graph Theory; 2000, 20, 1; 23-38
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Median and quasi-median direct products of graphs
Autorzy:
Brešar, Boštjan
Jha, Pranava
Klavžar, Sandi
Zmazek, Blaž
Powiązania:
https://bibliotekanauki.pl/articles/744332.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
median graph
direct product
quasi-median graph
isometric embeddings
convexity
Opis:
Median graphs are characterized among direct products of graphs on at least three vertices. Beside some trivial cases, it is shown that one component of G×P₃ is median if and only if G is a tree in that the distance between any two vertices of degree at least 3 is even. In addition, some partial results considering median graphs of the form G×K₂ are proved, and it is shown that the only nonbipartite quasi-median direct product is K₃×K₃.
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 1-2; 183-196
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Antipodal and Diametrical Partial Cubes
Autorzy:
Polat, Norbert
Powiązania:
https://bibliotekanauki.pl/articles/32222718.pdf
Data publikacji:
2021-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
diametrical graph
harmonic graph
antipodal graph
partial cube
diameter
isometric dimension
Opis:
We prove that any diametrical partial cube of diameter at most 6 is antipodal. Because any antipodal graph is harmonic, this gives a partial answer to a question of Fukuda and Handa [Antipodal graphs and oriented matroids, Discrete Math. 111 (1993) 245–256] whether any diametrical partial cube is harmonic, and improves a previous result of Klavžar and Kovše [On even and harmonic-even partial cubes, Ars Combin. 93 (2009) 77–86].
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 4; 1127-1145
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the rainbow connection of Cartesian products and their subgraphs
Autorzy:
Klavžar, Sandi
Mekiš, Gašper
Powiązania:
https://bibliotekanauki.pl/articles/743307.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
rainbow connection
strong rainbow connection
Cartesian product of graphs
isometric subgraph
hypercube
Opis:
Rainbow connection number of Cartesian products and their subgraphs are considered. Previously known bounds are compared and non-existence of such bounds for subgraphs of products are discussed. It is shown that the rainbow connection number of an isometric subgraph of a hypercube is bounded above by the rainbow connection number of the hypercube. Isometric subgraphs of hypercubes with the rainbow connection number as small as possible compared to the rainbow connection of the hypercube are constructed. The concept of c-strong rainbow connected coloring is introduced. In particular, it is proved that the so-called Θ-coloring of an isometric subgraph of a hypercube is its unique optimal c-strong rainbow connected coloring.
Źródło:
Discussiones Mathematicae Graph Theory; 2012, 32, 4; 783-793
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tree-like isometric subgraphs of hypercubes
Autorzy:
Brešar, Bostjan
Imrich, Wilfried
Klavžar, Sandi
Powiązania:
https://bibliotekanauki.pl/articles/743405.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
isometric embeddings
partial cubes
expansion procedures
trees
median graphs
graph automorphisms
automorphism groups
dismantlable graphs
Opis:
Tree-like isometric subgraphs of hypercubes, or tree-like partial cubes as we shall call them, are a generalization of median graphs. Just as median graphs they capture numerous properties of trees, but may contain larger classes of graphs that may be easier to recognize than the class of median graphs. We investigate the structure of tree-like partial cubes, characterize them, and provide examples of similarities with trees and median graphs. For instance, we show that the cube graph of a tree-like partial cube is dismantlable. This in particular implies that every tree-like partial cube G contains a cube that is invariant under every automorphism of G. We also show that weak retractions preserve tree-like partial cubes, which in turn implies that every contraction of a tree-like partial cube fixes a cube. The paper ends with several Frucht-type results and a list of open problems.
Źródło:
Discussiones Mathematicae Graph Theory; 2003, 23, 2; 227-240
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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