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Wyszukujesz frazę "additive" wg kryterium: Temat


Tytuł:
Unique factorisation of additive induced-hereditary properties
Autorzy:
Farrugia, Alastair
Richter, R.
Powiązania:
https://bibliotekanauki.pl/articles/744519.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
additive and hereditary graph classes
unique factorization
Opis:
An additive hereditary graph property is a set of graphs, closed under isomorphism and under taking subgraphs and disjoint unions. Let ₁,...,ₙ be additive hereditary graph properties. A graph G has property (₁∘...∘ₙ) if there is a partition (V₁,...,Vₙ) of V(G) into n sets such that, for all i, the induced subgraph $G[V_i]$ is in $_i$. A property is reducible if there are properties , such that = ∘ ; otherwise it is irreducible. Mihók, Semanišin and Vasky [8] gave a factorisation for any additive hereditary property into a given number dc() of irreducible additive hereditary factors. Mihók [7] gave a similar factorisation for properties that are additive and induced-hereditary (closed under taking induced-subgraphs and disjoint unions). Their results left open the possiblity of different factorisations, maybe even with a different number of factors; we prove here that the given factorisations are, in fact, unique.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 2; 319-343
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On a characterization of graphs by average labellings
Autorzy:
Harminc, Matúš
Powiązania:
https://bibliotekanauki.pl/articles/971968.pdf
Data publikacji:
1997
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
property of graphs
additive
hereditary
linear forest
Opis:
The additive hereditary property of linear forests is characterized by the existence of average labellings.
Źródło:
Discussiones Mathematicae Graph Theory; 1997, 17, 1; 133-136
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acyclic reducible bounds for outerplanar graphs
Autorzy:
Borowiecki, Mieczysław
Fiedorowicz, Anna
Hałuszczak, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/743164.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
acyclic colouring
additive hereditary class
outerplanar graph
Opis:
For a given graph G and a sequence ₁, ₂,..., ₙ of additive hereditary classes of graphs we define an acyclic (₁, ₂,...,Pₙ)-colouring of G as a partition (V₁, V₂,...,Vₙ) of the set V(G) of vertices which satisfies the following two conditions:
1. $G[V_i] ∈ _i$ for i = 1,...,n,
2. for every pair i,j of distinct colours the subgraph induced in G by the set of edges uv such that $u ∈ V_i$ and $v ∈ V_j$ is acyclic.
A class R = ₁ ⊙ ₂ ⊙ ... ⊙ ₙ is defined as the set of the graphs having an acyclic (₁, ₂,...,Pₙ)-colouring. If ⊆ R, then we say that R is an acyclic reducible bound for . In this paper we present acyclic reducible bounds for the class of outerplanar graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2009, 29, 2; 219-239
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized chromatic numbers and additive hereditary properties of graphs
Autorzy:
Broere, Izak
Dorfling, Samantha
Jonck, Elizabeth
Powiązania:
https://bibliotekanauki.pl/articles/743358.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
property of graphs
additive
hereditary
generalized chromatic number
Opis:
An additive hereditary property of graphs is a class of simple graphs which is closed under unions, subgraphs and isomorphisms. Let and be additive hereditary properties of graphs. The generalized chromatic number $χ_{}()$ is defined as follows: $χ_{}() = n$ iff ⊆ ⁿ but $ ⊊ ^{n-1}$. We investigate the generalized chromatic numbers of the well-known properties of graphs ₖ, ₖ, ₖ, ₖ and ₖ.
Źródło:
Discussiones Mathematicae Graph Theory; 2002, 22, 2; 259-270
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Further results on sequentially additive graphs
Autorzy:
Hegde, Suresh
Miller, Mirka
Powiązania:
https://bibliotekanauki.pl/articles/743768.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
simply (k-)sequentially additive labelings (graphs)
segregated labelings
Opis:
Given a graph G with p vertices, q edges and a positive integer k, a k-sequentially additive labeling of G is an assignment of distinct numbers k,k+1,k+2,...,k+p+q-1 to the p+q elements of G so that every edge uv of G receives the sum of the numbers assigned to the vertices u and v. A graph which admits such an assignment to its elements is called a k-sequentially additive graph. In this paper, we give an upper bound for k with respect to which the given graph may possibly be k-sequentially additive using the independence number of the graph. Also, we prove a variety of results on k-sequentially additive graphs, including the number of isolated vertices to be added to a complete graph with four or more vertices to be simply sequentially additive and a construction of an infinite family of k-sequentially additive graphs from a given k-sequentially additive graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2007, 27, 2; 251-268
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized edge-chromatic numbers and additive hereditary properties of graphs
Autorzy:
Dorfling, Michael
Dorfling, Samantha
Powiązania:
https://bibliotekanauki.pl/articles/743370.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
property of graphs
additive
hereditary
generalized edge-chromatic number
Opis:
An additive hereditary property of graphs is a class of simple graphs which is closed under unions, subgraphs and isomorphisms. Let and be hereditary properties of graphs. The generalized edge-chromatic number $ρ'_{}()$ is defined as the least integer n such that ⊆ n. We investigate the generalized edge-chromatic numbers of the properties → H, ₖ, ₖ, *ₖ, ₖ and ₖ.
Źródło:
Discussiones Mathematicae Graph Theory; 2002, 22, 2; 349-359
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The decomposability of additive hereditary properties of graphs
Autorzy:
Broere, Izak
Dorfling, Michael
Powiązania:
https://bibliotekanauki.pl/articles/743814.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
property of graphs
additive
hereditary
decomposable property of graphs
Opis:
An additive hereditary property of graphs is a class of simple graphs which is closed under unions, subgraphs and isomorphisms. If ₁,...,ₙ are properties of graphs, then a (₁,...,ₙ)-decomposition of a graph G is a partition E₁,...,Eₙ of E(G) such that $G[E_i]$, the subgraph of G induced by $E_i$, is in $_i$, for i = 1,...,n. We define ₁ ⊕...⊕ ₙ as the property {G ∈ : G has a (₁,...,ₙ)-decomposition}. A property is said to be decomposable if there exist non-trivial hereditary properties ₁ and ₂ such that = ₁⊕ ₂. We study the decomposability of the well-known properties of graphs ₖ, ₖ, ₖ, ₖ, ₖ, ₖ and $ ^{p}$.
Źródło:
Discussiones Mathematicae Graph Theory; 2000, 20, 2; 281-291
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minimal reducible bounds for hom-properties of graphs
Autorzy:
Berger, Amelie
Broere, Izak
Powiązania:
https://bibliotekanauki.pl/articles/744144.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph homomorphisms
minimal reducible bounds
additive hereditary graph property
Opis:
Let H be a fixed finite graph and let → H be a hom-property, i.e. the set of all graphs admitting a homomorphism into H. We extend the definition of → H to include certain infinite graphs H and then describe the minimal reducible bounds for → H in the lattice of additive hereditary properties and in the lattice of hereditary properties.
Źródło:
Discussiones Mathematicae Graph Theory; 1999, 19, 2; 143-158
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:
Additive List Coloring of Planar Graphs with Given Girth
Autorzy:
Brandt, Axel
Jahanbekam, Sogol
White, Jennifer
Powiązania:
https://bibliotekanauki.pl/articles/31525335.pdf
Data publikacji:
2020-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
lucky labeling
additive coloring
reducible configuration
discharging method
Combinatorial Nullstellensatz
Opis:
An additive coloring of a graph G is a labeling of the vertices of G from {1, 2, . . ., k} such that two adjacent vertices have distinct sums of labels on their neighbors. The least integer k for which a graph G has an additive coloring is called the additive coloring number of G, denoted χΣ (G). Additive coloring is also studied under the names lucky labeling and open distinguishing. In this paper, we improve the current bounds on the additive coloring number for particular classes of graphs by proving results for a list version of additive coloring. We apply the discharging method and the Combinatorial Nullstellensatz to show that every planar graph G with girth at least 5 has χΣ (G) ≤ 19, and for girth at least 6, 7, and 26, χΣ (G) is at most 9, 8, and 3, respectively. In 2009, Czerwiński, Grytczuk, and Żelazny conjectured that χΣ (G) ≤ χ(G), where χ(G) is the chromatic number of G. Our result for the class of non-bipartite planar graphs of girth at least 26 is best possible and affirms the conjecture for this class of graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 3; 855-873
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Survey of the Path Partition Conjecture
Autorzy:
Frick, Marietjie
Powiązania:
https://bibliotekanauki.pl/articles/30146727.pdf
Data publikacji:
2013-03-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Path Partition Conjecture
Path Kernel Conjecture
generalized colourings
additive hereditary properties
Opis:
The Path Partition Conjecture (PPC) states that if G is any graph and (λ1, λ2) any pair of positive integers such that G has no path with more than λ1 + λ2 vertices, then there exists a partition (V1, V2) of the vertex set of G such that Vi has no path with more than λi vertices, i = 1, 2. We present a brief history of the PPC, discuss its relation to other conjectures and survey results on the PPC that have appeared in the literature since its first formulation in 1981.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 1; 117-131
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gallais innequality for critical graphs of reducible hereditary properties
Autorzy:
Mihók, Peter
Skrekovski, Riste
Powiązania:
https://bibliotekanauki.pl/articles/743466.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
additive induced-hereditary property of graphs
reducible property of graphs
critical graph
Gallai's Theorem
Opis:
In this paper Gallai's inequality on the number of edges in critical graphs is generalized for reducible additive induced-hereditary properties of graphs in the following way. Let $₁,₂,...,ₖ$ (k ≥ 2) be additive induced-hereditary properties, $ = ₁ ∘ ₂ ∘ ... ∘ₖ$ and $δ = ∑_{i=1}^k δ(_i)$. Suppose that G is an -critical graph with n vertices and m edges. Then 2m ≥ δn + (δ-2)/(δ²+2δ-2)*n + (2δ)/(δ²+2δ-2) unless = ² or $G = K_{δ+1}$. The generalization of Gallai's inequality for -choice critical graphs is also presented.
Źródło:
Discussiones Mathematicae Graph Theory; 2001, 21, 2; 167-177
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized Sum List Colorings of Graphs
Autorzy:
Kemnitz, Arnfried
Marangio, Massimiliano
Voigt, Margit
Powiązania:
https://bibliotekanauki.pl/articles/31343297.pdf
Data publikacji:
2019-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
sum list coloring
sum choice number
generalized sum list coloring
additive hereditary graph property
Opis:
A (graph) property \( \mathcal{P} \) is a class of simple finite graphs closed under isomorphisms. In this paper we consider generalizations of sum list colorings of graphs with respect to properties \( \mathcal{P} \). If to each vertex $v$ of a graph $G$ a list $L(v)$ of colors is assigned, then in an \( (L, \mathcal{P} ) \)-coloring of $G$ every vertex obtains a color from its list and the subgraphs of $G$ induced by vertices of the same color are always in \( \mathcal{P} \). The \( \mathcal{P} \)-sum choice number \( X_{sc}^\mathcal{P} (G) \) of $G$ is the minimum of the sum of all list sizes such that, for any assignment $L$ of lists of colors with the given sizes, there is always an \( (L, \mathcal{P} ) \)-coloring of $G$. We state some basic results on monotonicity, give upper bounds on the \( \mathcal{P} \)-sum choice number of arbitrary graphs for several properties, and determine the \( \mathcal{P} \)-sum choice number of specific classes of graphs, namely, of all complete graphs, stars, paths, cycles, and all graphs of order at most 4.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 3; 689-703
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nordhaus-Gaddum-Type Results for Resistance Distance-Based Graph Invariants
Autorzy:
Das, Kinkar Ch.
Yang, Yujun
Xu, Kexiang
Powiązania:
https://bibliotekanauki.pl/articles/31340811.pdf
Data publikacji:
2016-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
resistance distance
Kirchhoff index
additive degree-Kirchhoff index
multiplicative degree-Kirchhoff index
Nordhaus-Gaddum-type result
Opis:
Two decades ago, resistance distance was introduced to characterize “chemical distance” in (molecular) graphs. In this paper, we consider three resistance distance-based graph invariants, namely, the Kirchhoff index, the additive degree-Kirchhoff index, and the multiplicative degree-Kirchhoff index. Some Nordhaus-Gaddum-type results for these three molecular structure descriptors are obtained. In addition, a relation between these Kirchhoffian indices is established.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 3; 695-707
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on joins of additive hereditary graph properties
Autorzy:
Drgas-Burchardt, Ewa
Powiązania:
https://bibliotekanauki.pl/articles/743593.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hereditary property
lattice of additive hereditary graph properties
minimal forbidden subgraph family
join in the lattice
Opis:
Let $L^a$ denote a set of additive hereditary graph properties. It is a known fact that a partially ordered set $(L^a, ⊆ )$ is a complete distributive lattice. We present results when a join of two additive hereditary graph properties in $(L^a, ⊆ )$ has a finite or infinite family of minimal forbidden subgraphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2006, 26, 3; 413-418
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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