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Wyszukujesz frazę "traceable" wg kryterium: Temat


Wyświetlanie 1-13 z 13
Tytuł:
Extremal traceable graphs with non-traceable edges
Autorzy:
Wojda, A. P.
Powiązania:
https://bibliotekanauki.pl/articles/255301.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
traceable graph
non-traceable edge
Opis:
By NT(n) we denote the set of graphs of order n which are traceable but have non-traceable edges, i.e. edges which are not contained in any hamiltonian path. The class NT(re) has been considered by Balińska and co-authors in a paper published in 2003, where it was proved that the maximum size t(max)(n) of a graph in NT(n) is at least (n2-5n+14)/2 (for n≥ 12). The authors also found t(max)(n) for 5 ≤ n ≤ 11. We prove that, for n n≥ 5, t(max) (n) = max {(n-2/2) + 4, [formula] and, moreover, we characterize the extremal graphs (in fact we prove that these graphs are exactly those already described in the paper by Balińska et al). We also prove that a traceable graph of order n n≥ 5 may have at most [n-3/2] [n-3/2] non traceable edges (this result was conjectured in the mentioned paper by Balińska and co-authors).
Źródło:
Opuscula Mathematica; 2009, 29, 1; 89-92
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Every 8-Traceable Oriented Graph Is Traceable
Autorzy:
Aardt, Susan A. van
Powiązania:
https://bibliotekanauki.pl/articles/31341593.pdf
Data publikacji:
2017-11-27
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
oriented graph
traceable
hypotraceable
k-traceable
generalized tournament
Opis:
A digraph of order n is k-traceable if n ≥ k and each of its induced subdigraphs of order k is traceable. It is known that if 2 ≤ k ≤ 6, every k-traceable oriented graph is traceable but for k = 7 and for each k ≥ 9, there exist k-traceable oriented graphs that are nontraceable. We show that every 8-traceable oriented graph is traceable.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 4; 963-973
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On a conjecture of quintas and arc-traceability in upset tournaments
Autorzy:
Busch, Arthur
Jacobson, Michael
Reid, K.
Powiązania:
https://bibliotekanauki.pl/articles/744384.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
tournament
upset tournament
traceable
Opis:
A digraph D = (V,A) is arc-traceable if for each arc xy in A, xy lies on a directed path containing all the vertices of V, i.e., hamiltonian path. We prove a conjecture of Quintas [7]: if D is arc-traceable, then the condensation of D is a directed path. We show that the converse of this conjecture is false by providing an example of an upset tournament which is not arc-traceable. We then give a characterization for upset tournaments in terms of their score sequences, characterize which arcs of an upset tournament lie on a hamiltonian path, and deduce a characterization of arc-traceable upset tournaments.
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 3; 225-239
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved Sufficient Conditions for Hamiltonian Properties
Autorzy:
Bode, Jens-P.
Fricke, Anika
Kemnitz, Arnfried
Powiązania:
https://bibliotekanauki.pl/articles/31339476.pdf
Data publikacji:
2015-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Hamiltonian
traceable
Hamiltonian-connected
Opis:
In 1980 Bondy [2] proved that a (k+s)-connected graph of order n ≥ 3 is traceable (s = −1) or Hamiltonian (s = 0) or Hamiltonian-connected (s = 1) if the degree sum of every set of k+1 pairwise nonadjacent vertices is at least ((k+1)(n+s−1)+1)/2. It is shown in [1] that one can allow exceptional (k+1)-sets violating this condition and still implying the considered Hamiltonian property. In this note we generalize this result for s = −1 and s = 0 and graphs that fulfill a certain connectivity condition.
Źródło:
Discussiones Mathematicae Graph Theory; 2015, 35, 2; 329-334
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral Radius and Hamiltonicity of Graphs
Autorzy:
Yu, Guidong
Fang, Yi
Fan, Yizheng
Cai, Gaixiang
Powiązania:
https://bibliotekanauki.pl/articles/31343181.pdf
Data publikacji:
2019-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spectral radius
singless Laplacian spectral radius
traceable
Hamiltonian-connected
traceable from every vertex
minimum degree
Opis:
In this paper, we study the Hamiltonicity of graphs with large minimum degree. Firstly, we present some conditions for a simple graph to be Hamilton-connected and traceable from every vertex in terms of the spectral radius of the graph or its complement, respectively. Secondly, we give the conditions for a nearly balanced bipartite graph to be traceable in terms of spectral radius, signless Laplacian spectral radius of the graph or its quasi-complement, respectively.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 4; 951-974
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decompositions into two paths
Autorzy:
Skupień, Zdzisław
Powiązania:
https://bibliotekanauki.pl/articles/744378.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
multigraph
path decomposition
hamiltonian decomposition
traceable
Opis:
It is proved that a connected multigraph G which is the union of two edge-disjoint paths has another decomposition into two paths with the same set, U, of endvertices provided that the multigraph is neither a path nor cycle. Moreover, then the number of such decompositions is proved to be even unless the number is three, which occurs exactly if G is a tree homeomorphic with graph of either symbol + or ⊥. A multigraph on n vertices with exactly two traceable pairs is constructed for each n ≥ 3. The Thomason result on hamiltonian pairs is used and is proved to be sharp.
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 3; 325-329
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mácajová and Škoviera conjecture on cubic graphs
Autorzy:
Fouquet, Jean-Luc
Vanherpe, Jean-Marie
Powiązania:
https://bibliotekanauki.pl/articles/744280.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Cubic graph
edge-partition
traceable graphs
Opis:
A conjecture of Mácajová and Skoviera asserts that every bridgeless cubic graph has two perfect matchings whose intersection does not contain any odd edge cut. We prove this conjecture for graphs with few vertices and we give a stronger result for traceable graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2010, 30, 2; 315-333
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decompositions of Cubic Traceable Graphs
Autorzy:
Liu, Wenzhong
Li, Panpan
Powiązania:
https://bibliotekanauki.pl/articles/31867897.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
decomposition
cubic traceable graph
spanning tree
matching
2-regular graph
Opis:
A traceable graph is a graph with a Hamilton path. The 3-Decomposition Conjecture states that every connected cubic graph can be decomposed into a spanning tree, a 2-regular graph and a matching. We prove the conjecture for cubic traceable graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 35-49
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note of arbitrarily vertex decomposable graphs
Autorzy:
Marczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/254919.pdf
Data publikacji:
2006
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
arbitrarily vertex decomposable graphs
traceable graphs
independence number
perfect matching
Opis:
A graph G of order n is said to be arbitrarily vertex decomposable if for each sequence (n1,..., nk) of positive integers such that n1 + ... + nk = n there exists a partition (V1,..., Vk) of the vertex set of G such that for each i ∈ {1,..., k}, Vi induces a connected subgraph of G on ni vertices. In this paper we show that if G is a two-connected graph on n vertices with the independence number at most ⌈n/2⌉ and such that the degree sum of any pair of non-adjacent vertices is at least n - 3, then G is arbitrarily vertex decomposable. We present another result for connected graphs satisfying a similar condition, where the bound n - 3 is replaced by n - 2.
Źródło:
Opuscula Mathematica; 2006, 26, 1; 109-118
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Ryjáček Closure and a Forbidden Subgraph
Autorzy:
Saito, Akira
Xiong, Liming
Powiązania:
https://bibliotekanauki.pl/articles/31340869.pdf
Data publikacji:
2016-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
closure
claw-free graph
Hamiltonian graph
perfect matching
traceable graph
Opis:
The Ryjáček closure is a powerful tool in the study of Hamiltonian properties of claw-free graphs. Because of its usefulness, we may hope to use it in the classes of graphs defined by another forbidden subgraph. In this note, we give a negative answer to this hope, and show that the claw is the only forbidden subgraph that produces non-trivial results on Hamiltonicity by the use of the Ryjáček closure.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 3; 621-628
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dense Arbitrarily Partitionable Graphs
Autorzy:
Kalinowski, Rafał
Pilśniak, Monika
Schiermeyer, Ingo
Woźniak, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/31341197.pdf
Data publikacji:
2016-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
arbitrarily partitionable graph
Erdös-Gallai condition
traceable graph
perfect matching
Opis:
A graph $G$ of order $n$ is called arbitrarily partitionable (AP for short) if, for every sequence $(n_1, . . ., n_k)$ of positive integers with $n_1 + ⋯ + n_k = n$, there exists a partition $(V_1, . . ., V_k)$ of the vertex set $V(G)$ such that $V_i$ induces a connected subgraph of order $n_i$ for $i = 1, . . ., k$. In this paper we show that every connected graph $G$ of order $n \ge 22$ and with \( ‖G‖ > \binom{n-4}{2} + 12 \) edges is AP or belongs to few classes of exceptional graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 1; 5-22
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heavy subgraph pairs for traceability of block-chains
Autorzy:
Li, Binlong
Broersma, Hajo
Zhang, Shenggui
Powiązania:
https://bibliotekanauki.pl/articles/30148234.pdf
Data publikacji:
2014-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
block-chain traceable graph
Ore-type condition
forbidden subgrap
$o_{−1}$-heavy subgraph
Opis:
A graph is called traceable if it contains a Hamilton path, i.e., a path containing all its vertices. Let G be a graph on n vertices. We say that an induced subgraph of G is $o_{−1}$-heavy if it contains two nonadjacent vertices which satisfy an Ore-type degree condition for traceability, i.e., with degree sum at least $n−1$ in $G$. A block-chain is a graph whose block graph is a path, i.e., it is either a $P_1$, $P_2$, or a 2-connected graph, or a graph with at least one cut vertex and exactly two end-blocks. Obviously, every traceable graph is a block-chain, but the reverse does not hold. In this paper we characterize all the pairs of connected $o_{−1}$-heavy graphs that guarantee traceability of block-chains. Our main result is a common extension of earlier work on degree sum conditions, forbidden subgraph conditions and heavy subgraph conditions for traceability
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 2; 287-307
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nested Locally Hamiltonian Graphs and the Oberly-Sumner Conjecture
Autorzy:
de Wet, Johan P.
Frick, Marietjie
Powiązania:
https://bibliotekanauki.pl/articles/32222536.pdf
Data publikacji:
2022-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
locally traceable
locally hamiltonian
Hamilton Cycle Problem
locally k -nested-hamiltonian
Oberly-Sumner Conjecture
Opis:
A graph G is locally P, abbreviated L, if for every vertex v in G the open neighbourhood N(v) of v is non-empty and induces a graph with property P. Specifically, a graph G without isolated vertices is locally connected (LC) if N(v) induces a connected graph for each v ∈ V (G), and locally hamiltonian (LH) if N(v) induces a hamiltonian graph for each v ∈ V (G). A graph G is locally locally P (abbreviated L2P) if N(v) is non-empty and induces a locally P graph for every v ∈ V (G). This concept is generalized to an arbitrary degree of nesting. For any k ≥ 0 we call a graph locally k-nested-hamiltonian if it is LmC for m = 0, 1, . . ., k and LkH (with L0C and L0H meaning connected and hamiltonian, respectively). The class of locally k-nested-hamiltonian graphs contains important subclasses. For example, Skupień had already observed in 1963 that the class of connected LH graphs (which is the class of locally 1-nested-hamiltonian graphs) contains all triangulations of closed surfaces. We show that for any k ≥ 1 the class of locally k-nested-hamiltonian graphs contains all simple-clique (k + 2)-trees. In 1979 Oberly and Sumner proved that every connected K1,3-free graph that is locally connected is hamiltonian. They conjectured that for k ≥ 1, every connected K1,k+3-free graph that is locally (k + 1)-connected is hamiltonian. We show that locally k-nested-hamiltonian graphs are locally (k + 1)-connected and consider the weaker conjecture that every K1,k+3-free graph that is locally k-nested-hamiltonian is hamiltonian. We show that if our conjecture is true, it would be “best possible” in the sense that for every k ≥ 1 there exist K1,k+4-free locally k-nested-hamiltonian graphs that are non-hamiltonian. We also attempt to determine the minimum order of non-hamiltonian locally k-nested-hamiltonian graphs and investigate the complexity of the Hamilton Cycle Problem for locally k-nested-hamiltonian graphs with restricted maximum degree.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 4; 1281-1312
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-13 z 13

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