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Wyszukujesz frazę "list colouring" wg kryterium: Temat


Wyświetlanie 1-7 z 7
Tytuł:
A note on a list colouring of hypergraphs
Autorzy:
Drgas-Burchardt, E.
Powiązania:
https://bibliotekanauki.pl/articles/2050379.pdf
Data publikacji:
2004
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
hypergraph
list colouring
Opis:
In the note we present two results. The first of them gives a sufficient condition for a colouring of a hypergraph from an assigned list. It generalises the analogous fact for graphs. The second result states that for every $k \geq 3$ and every $l \geq 2$, a distance between the list chromatic number and the chromatic number can be arbitrarily large in the class of k-uniform hypergraphs with the chromatic number bounded below by l. A similar result for k-uniform, 2-colorable hypergraphs is known but the proof techniques are different.
Źródło:
Opuscula Mathematica; 2004, 24, 2; 171-175
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Corrigendum to "acyclic sum-list-colouring of grids and other classes of graphs" [Opuscula Math. 37, no. 4 (2017), 535 556]
Autorzy:
Drgas-Burchardt, E.
Drzystek, A.
Powiązania:
https://bibliotekanauki.pl/articles/254952.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
sum-list colouring
acyclic colouring
grids
generalized Petersen graphs
Opis:
This note provides some minor corrections to the article [Acyclic sum-list-colouring of grids and other classes of graphs, Opuscula Math. 37, no. 4 (2017), 535-556].
Źródło:
Opuscula Mathematica; 2018, 38, 6; 899-901
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acyclic sum-list-colouring of grids and other classes of graphs
Autorzy:
Drgas-Burchardt, E.
Drzystek, A.
Powiązania:
https://bibliotekanauki.pl/articles/254959.pdf
Data publikacji:
2017
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
sum-list colouring
acyclic colouring
grids
generalized Petersen graphs
Opis:
In this paper we consider list colouring of a graph G in which the sizes of lists assigned to different vertices can be different. We colour G from the lists in such a way that each colour class induces an acyclic graph. The aim is to find the smallest possible sum of all the list sizes, such that, according to the rules, G is colourable for any particular assignment of the lists of these sizes. This invariant is called the D1-sum-choice-number of G. In the paper we investigate the D1-sum-choice-number of graphs with small degrees. Especially, we give the exact value of the D1-sum-choice-number for each grid [formula], when at least one of the numbers n, rn is less than five, and for each generalized Petersen graph. Moreover, we present some results that estimate the D1-sum-choice-number of an arbitrary graph in terms of the decycling number, other graph invariants and special subgraphs.
Źródło:
Opuscula Mathematica; 2017, 37, 4; 535-556
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
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:
Sum-List Colouring of Unions of a Hypercycle and a Path with at Most Two Vertices in Common
Autorzy:
Drgas-Burchardt, Ewa
Sidorowicz, Elżbieta
Powiązania:
https://bibliotekanauki.pl/articles/31527293.pdf
Data publikacji:
2020-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hypergraphs
sum-list colouring
induced hereditary classes
forbidden hypergraphs
Opis:
Given a hypergraph \(\mathcal{H}\) and a function \(f : V (\mathcal{H}) → ℕ\), we say that \(\mathcal{H}\) is $f$-choosable if there is a proper vertex colouring $ϕ$ of \(\mathcal{H}\) such that $ϕ (v) ∈ L(v)$ for all \(v ∈ V (\mathcal{H})\), where \(L : V (\mathcal{H}) → 2^ℕ\) is any assignment of $f(v)$ colours to a vertex $v$. The sum choice number \(\mathcal{H}i_{sc}(\mathcal{H})\) of \(\mathcal{H}\) is defined to be the minimum of \(Σ_{v∈V(\mathcal{H})}f(v)\) over all functions $f$ such that \(\mathcal{H}\) is $f$-choosable. For an arbitrary hypergraph \(\mathcal{H}\) the inequality \(χ_{sc}(\mathcal{H}) ≤ |V (\mathcal{H})| + |ɛ (\mathcal{H})|\) holds, and hypergraphs that attain this upper bound are called $sc$-greedy. In this paper we characterize $sc$-greedy hypergraphs that are unions of a hypercycle and a hyperpath having at most two vertices in common. Consequently, we characterize the hypergraphs of this type that are forbidden for the class of $sc$-greedy hypergraphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 3; 893-917
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some totally 4-choosable multigraphs
Autorzy:
Woodall, Douglas
Powiązania:
https://bibliotekanauki.pl/articles/743409.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
maximum average degree
planar graph
total choosability
list total colouring
Opis:
It is proved that if G is multigraph with maximum degree 3, and every submultigraph of G has average degree at most 2(1/2) and is different from one forbidden configuration C⁺₄ with average degree exactly 2(1/2), then G is totally 4-choosable; that is, if every element (vertex or edge) of G is assigned a list of 4 colours, then every element can be coloured with a colour from its own list in such a way that no two adjacent or incident elements are coloured with the same colour. This shows that the List-Total-Colouring Conjecture, that ch''(G) = χ''(G) for every multigraph G, is true for all multigraphs of this type. As a consequence, if G is a graph with maximum degree 3 and girth at least 10 that can be embedded in the plane, projective plane, torus or Klein bottle, then ch''(G) = χ''(G) = 4. Some further total choosability results are discussed for planar graphs with sufficiently large maximum degree and girth.
Źródło:
Discussiones Mathematicae Graph Theory; 2007, 27, 3; 425-455
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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