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Wyszukujesz frazę "vertex partition" wg kryterium: Temat


Wyświetlanie 1-15 z 15
Tytuł:
On Graphs with Disjoint Dominating and 2-Dominating Sets
Autorzy:
Henning, Michael A.
Rall, Douglas F.
Powiązania:
https://bibliotekanauki.pl/articles/30146715.pdf
Data publikacji:
2013-03-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination
2-domination
vertex partition
Opis:
A DD2-pair of a graph G is a pair (D,D2) of disjoint sets of vertices of G such that D is a dominating set and D2 is a 2-dominating set of G. Although there are infinitely many graphs that do not contain a DD2-pair, we show that every graph with minimum degree at least two has a DD2-pair. We provide a constructive characterization of trees that have a DD2-pair and show that K3,3 is the only connected graph with minimum degree at least three for which D ∪ D2 necessarily contains all vertices of the graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 1; 139-146
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A path(ological) partition problem
Autorzy:
Broere, Izak
Dorfling, Michael
Dunbar, Jean
Frick, Marietjie
Powiązania:
https://bibliotekanauki.pl/articles/744209.pdf
Data publikacji:
1998
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
vertex partition
τ-partitionable
decomposable graph
Opis:
Let τ(G) denote the number of vertices in a longest path of the graph G and let k₁ and k₂ be positive integers such that τ(G) = k₁ + k₂. The question at hand is whether the vertex set V(G) can be partitioned into two subsets V₁ and V₂ such that τ(G[V₁] ) ≤ k₁ and τ(G[V₂] ) ≤ k₂. We show that several classes of graphs have this partition property.
Źródło:
Discussiones Mathematicae Graph Theory; 1998, 18, 1; 113-125
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Domination in partitioned graphs
Autorzy:
Tuza, Zsolt
Vestergaard, Preben
Powiązania:
https://bibliotekanauki.pl/articles/743565.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
dominating set
domination number
vertex partition
Opis:
Let V₁, V₂ be a partition of the vertex set in a graph G, and let $γ_i$ denote the least number of vertices needed in G to dominate $V_i$. We prove that γ₁+γ₂ ≤ [4/5]|V(G)| for any graph without isolated vertices or edges, and that equality occurs precisely if G consists of disjoint 5-paths and edges between their centers. We also give upper and lower bounds on γ₁+γ₂ for graphs with minimum valency δ, and conjecture that γ₁+γ₂ ≤ [4/(δ+3)]|V(G)| for δ ≤ 5. As δ gets large, however, the largest possible value of (γ₁+γ₂)/|V(G)| is shown to grow with the order of (logδ)/(δ).
Źródło:
Discussiones Mathematicae Graph Theory; 2002, 22, 1; 199-210
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maximal graphs with respect to hereditary properties
Autorzy:
Broere, Izak
Frick, Marietjie
Semanišin, Gabriel
Powiązania:
https://bibliotekanauki.pl/articles/972029.pdf
Data publikacji:
1997
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hereditary property of graphs
maximal graphs
vertex partition
Opis:
A property of graphs is a non-empty set of graphs. A property P is called hereditary if every subgraph of any graph with property P also has property P. Let P₁, ...,Pₙ be properties of graphs. We say that a graph G has property P₁∘...∘Pₙ if the vertex set of G can be partitioned into n sets V₁, ...,Vₙ such that the subgraph of G induced by V_i has property $P_i$; i = 1,..., n. A hereditary property R is said to be reducible if there exist two hereditary properties P₁ and P₂ such that R = P₁∘P₂. If P is a hereditary property, then a graph G is called P- maximal if G has property P but G+e does not have property P for every e ∈ E([G̅]). We present some general results on maximal graphs and also investigate P-maximal graphs for various specific choices of P, including reducible hereditary properties.
Źródło:
Discussiones Mathematicae Graph Theory; 1997, 17, 1; 51-66
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the factorization of reducible properties of graphs into irreducible factors
Autorzy:
Mihók, P.
Vasky, R.
Powiązania:
https://bibliotekanauki.pl/articles/972030.pdf
Data publikacji:
1995
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hereditary property of graphs
additivity
reducibility
vertex partition
Opis:
A hereditary property R of graphs is said to be reducible if there exist hereditary properties P₁,P₂ such that G ∈ R if and only if the set of vertices of G can be partitioned into V(G) = V₁∪V₂ so that ⟨V₁⟩ ∈ P₁ and ⟨V₂⟩ ∈ P₂. The problem of the factorization of reducible properties into irreducible factors is investigated.
Źródło:
Discussiones Mathematicae Graph Theory; 1995, 15, 2; 195-203
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uniquely partitionable graphs
Autorzy:
Bucko, Jozef
Frick, Marietjie
Mihók, Peter
Vasky, Roman
Powiązania:
https://bibliotekanauki.pl/articles/972032.pdf
Data publikacji:
1997
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hereditary property of graphs
additivity
reducibility
vertex partition
Opis:
Let ₁,...,ₙ be properties of graphs. A (₁,...,ₙ)-partition of a graph G is a partition of the vertex set V(G) into subsets V₁, ...,Vₙ such that the subgraph $G[V_i]$ induced by $V_i$ has property $_i$; i = 1,...,n. A graph G is said to be uniquely (₁, ...,ₙ)-partitionable if G has exactly one (₁,...,ₙ)-partition. A property is called hereditary if every subgraph of every graph with property also has property . If every graph that is a disjoint union of two graphs that have property also has property , then we say that is additive. A property is called degenerate if there exists a bipartite graph that does not have property . In this paper, we prove that if ₁,..., ₙ are degenerate, additive, hereditary properties of graphs, then there exists a uniquely (₁,...,ₙ)-partitionable graph.
Źródło:
Discussiones Mathematicae Graph Theory; 1997, 17, 1; 103-113
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The directed path partition conjecture
Autorzy:
Frick, Marietjie
van Aardt, Susan
Dlamini, Gcina
Dunbar, Jean
Oellermann, Ortrud
Powiązania:
https://bibliotekanauki.pl/articles/744375.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
longest path
Path Partition Conjecture
vertex partition
digraph
prismatic colouring
Opis:
The Directed Path Partition Conjecture is the following: If D is a digraph that contains no path with more than λ vertices then, for every pair (a,b) of positive integers with λ = a+b, there exists a vertex partition (A,B) of D such that no path in D⟨A⟩ has more than a vertices and no path in D⟨B⟩ has more than b vertices. We develop methods for finding the desired partitions for various classes of digraphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 3; 331-343
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On generalized list colourings of graphs
Autorzy:
Borowiecki, Mieczysław
Broere, Izak
Mihók, Peter
Powiązania:
https://bibliotekanauki.pl/articles/972024.pdf
Data publikacji:
1997
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hereditary property of graphs
list colouring
vertex partition number
Opis:
Vizing [15] and Erdős et al. [8] independently introduce the idea of considering list-colouring and k-choosability. In the both papers the choosability version of Brooks' theorem [4] was proved but the choosability version of Gallai's theorem [9] was proved independently by Thomassen [14] and by Kostochka et al. [11]. In [3] some extensions of these two basic theorems to (,k)-choosability have been proved.
In this paper we prove some extensions of the well-known bounds for the -chromatic number to the (,k)-choice number and then an extension of Brooks' theorem.
Źródło:
Discussiones Mathematicae Graph Theory; 1997, 17, 1; 127-132
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized list colourings of graphs
Autorzy:
Borowiecki, Mieczysław
Drgas-Burchardt, Ewa
Mihók, Peter
Powiązania:
https://bibliotekanauki.pl/articles/972045.pdf
Data publikacji:
1995
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hereditary property of graphs
list colouring
vertex partition number
Opis:
We prove: (1) that $ch_P(G) - χ_P(G)$ can be arbitrarily large, where $ch_P(G)$ and $χ_P(G)$ are P-choice and P-chromatic numbers, respectively, (2) the (P,L)-colouring version of Brooks' and Gallai's theorems.
Źródło:
Discussiones Mathematicae Graph Theory; 1995, 15, 2; 185-193
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Partitioning a graph into a dominating set, a total dominating set, and something else
Autorzy:
Henning, Michael
Löwenstein, Christian
Rautenbach, Dieter
Powiązania:
https://bibliotekanauki.pl/articles/744065.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination
total domination
domatic number
vertex partition
Petersen graph
Opis:
A recent result of Henning and Southey (A note on graphs with disjoint dominating and total dominating set, Ars Comb. 89 (2008), 159-162) implies that every connected graph of minimum degree at least three has a dominating set D and a total dominating set T which are disjoint. We show that the Petersen graph is the only such graph for which D∪T necessarily contains all vertices of the graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2010, 30, 4; 563-574
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remarks on the existence of uniquely partitionable planar graphs
Autorzy:
Borowiecki, Mieczysław
Mihók, Peter
Tuza, Zsolt
Voigt, M.
Powiązania:
https://bibliotekanauki.pl/articles/744146.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
property of graphs
additive
hereditary
vertex partition
uniquely partitionable graphs
Opis:
We consider the problem of the existence of uniquely partitionable planar graphs. We survey some recent results and we prove the nonexistence of uniquely (₁,₁)-partitionable planar graphs with respect to the property ₁ "to be a forest".
Źródło:
Discussiones Mathematicae Graph Theory; 1999, 19, 2; 159-166
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized Hypergraph Coloring
Autorzy:
Schweser, Thomas
Powiązania:
https://bibliotekanauki.pl/articles/32083810.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hypergraph decomposition
vertex partition
degeneracy
coloring of hypergraphs
hypergraph properties
Opis:
A smooth hypergraph property \(\mathcal{P}\) is a class of hypergraphs that is hereditary and non-trivial, i.e., closed under induced subhypergraphs and it contains a non-empty hypergraph but not all hypergraphs. In this paper we examine \(\mathcal{P}\)-colorings of hypergraphs with smooth hypergraph properties \(\mathcal{P}\). A \(\mathcal{P}\)-coloring of a hypergraph $H$ with color set $C$ is a function $\varphi : V(H) → C$ such that \(H\big[\varphi^{−1}(c)\big]\) belongs to \(\mathcal{P}\) for all $c ∈ C$. Let $L : V (H) → 2^C$ be a so called list-assignment of the hypergraph $H$. Then, a (\(\mathcal{P}, L\))-coloring of $H$ is a \(\mathcal{P}\)-coloring $\varphi$ of $H$ such that $\varphi(v) ∈ L(v)$ for all $v ∈ V (H)$. The aim of this paper is a characterization of (\(\mathcal{P}, L\))-critical hypergraphs. Those are hypergraphs $H$ such that $H − v$ is (\(\mathcal{P}, L\))-colorable for all $v ∈ V (H)$ but $H$ itself is not. Our main theorem is a Gallai-type result for critical hypergraphs, which implies a Brooks-type result for (\(\mathcal{P}, L\))-colorable hypergraphs. In the last section, we prove a Gallai-type bound for the degree sum of (\(\mathcal{P}, L\))-critical locally simple hypergraphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 103-121
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A survey of hereditary properties of graphs
Autorzy:
Borowiecki, Mieczysław
Broere, Izak
Frick, Marietjie
Mihók, Peter
Semanišin, Gabriel
Powiązania:
https://bibliotekanauki.pl/articles/971986.pdf
Data publikacji:
1997
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hereditary property of graphs
vertex partition
reducible property
graph invariants
complexity
Opis:
In this paper we survey results and open problems on the structure of additive and hereditary properties of graphs. The important role of vertex partition problems, in particular the existence of uniquely partitionable graphs and reducible properties of graphs in this structure is emphasized. Many related topics, including questions on the complexity of related problems, are investigated.
Źródło:
Discussiones Mathematicae Graph Theory; 1997, 17, 1; 5-50
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detour chromatic numbers
Autorzy:
Frick, Marietjie
Bullock, Frank
Powiązania:
https://bibliotekanauki.pl/articles/743511.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
detour
generalised chromatic number
longest path
vertex partition
girth
circumference
nearly bipartite
Opis:
The nth detour chromatic number, χₙ(G) of a graph G is the minimum number of colours required to colour the vertices of G such that no path with more than n vertices is monocoloured. The number of vertices in a longest path of G is denoted by τ( G). We conjecture that χₙ(G) ≤ ⎡(τ(G))/n⎤ for every graph G and every n ≥ 1 and we prove results that support the conjecture. We also present some sufficient conditions for a graph to have nth chromatic number at most 2.
Źródło:
Discussiones Mathematicae Graph Theory; 2001, 21, 2; 283-291
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Partitions of a graph into cycles containing a specified linear forest
Autorzy:
Matsubara, Ryota
Matsumura, Hajime
Powiązania:
https://bibliotekanauki.pl/articles/743517.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
partition of a graph
vertex-disjoint cycle
2-factor
linear forest
Opis:
In this note, we consider the partition of a graph into cycles containing a specified linear forest. Minimum degree and degree sum conditions are given, which are best possible.
Źródło:
Discussiones Mathematicae Graph Theory; 2008, 28, 1; 97-107
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-15 z 15

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