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Wyszukujesz frazę "Jendroľ, Stanislav" wg kryterium: Autor


Tytuł:
Conflict-Free Vertex-Connections of Graphs
Autorzy:
Li, Xueliang
Zhang, Yingying
Zhu, Xiaoyu
Mao, Yaping
Zhao, Haixing
Jendrol’, Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/31868621.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
vertex-coloring
conflict-free vertex-connection
2-connected graph
tree
Opis:
A path in a vertex-colored graph is called conflict-free if there is a color used on exactly one of its vertices. A vertex-colored graph is said to be conflict-free vertex-connected if any two vertices of the graph are connected by a conflict-free path. This paper investigates the question: for a connected graph G, what is the smallest number of colors needed in a vertex-coloring of G in order to make G conflict-free vertex-connected. As a result, we get that the answer is easy for 2-connected graphs, and very difficult for connected graphs with more cut-vertices, including trees.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 51-65
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Facial Incidence Colorings of Embedded Multigraphs
Autorzy:
Jendrol’, Stanislav
Horňák, Mirko
Soták, Roman
Powiązania:
https://bibliotekanauki.pl/articles/31343708.pdf
Data publikacji:
2019-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
embedded multigraph
incidence
facial incidence coloring
Opis:
Let G be a cellular embedding of a multigraph in a 2-manifold. Two distinct edges e1, e2 ∈ E(G) are facially adjacent if they are consecutive on a facial walk of a face f ∈ F(G). An incidence of the multigraph G is a pair (v, e), where v ∈ V (G), e ∈ E(G) and v is incident with e in G. Two distinct incidences (v1, e1) and (v2, e2) of G are facially adjacent if either e1 = e2 or e1, e2 are facially adjacent and either v1 = v2 or v1 ≠ v2 and there is i ∈ {1, 2} such that ei is incident with both v1, v2. A facial incidence coloring of G assigns a color to each incidence of G in such a way that facially adjacent incidences get distinct colors. In this note we show that any embedded multigraph has a facial incidence coloring with seven colors. This bound is improved to six for several wide families of plane graphs and to four for plane triangulations.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 1; 81-93
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light classes of generalized stars in polyhedral maps on surfaces
Autorzy:
Jendrol', Stanislav
Voss, Heinz-Jürgen
Powiązania:
https://bibliotekanauki.pl/articles/744433.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
polyhedral maps
embeddings
light subgraphs
path
star
2-dimensional manifolds
surface
Opis:
A generalized s-star, s ≥ 1, is a tree with a root Z of degree s; all other vertices have degree ≤ 2. $S_i$ denotes a generalized 3-star, all three maximal paths starting in Z have exactly i+1 vertices (including Z). Let be a surface of Euler characteristic χ() ≤ 0, and m():= ⎣(5 + √{49-24χ( )})/2⎦. We prove:
(1) Let k ≥ 1, d ≥ m() be integers. Each polyhedral map G on with a k-path (on k vertices) contains a k-path of maximum degree ≤ d in G or a generalized s-star T, s ≤ m(), on d + 2- m() vertices with root Z, where Z has degree ≤ k·m() and the maximum degree of T∖{Z} is ≤ d in G. Similar results are obtained for the plane and for large polyhedral maps on ..
(2) Let k and i be integers with k ≥ 3, 1 ≤ i ≤ [k/2]. If a polyhedral map G on with a large enough number of vertices contains a k-path then G contains a k-path or a 3-star $S_i$ of maximum degree ≤ 4(k+i) in G. This bound is tight. Similar results hold for plane graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 1; 85-107
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maximum Edge-Colorings Of Graphs
Autorzy:
Jendrol’, Stanislav
Vrbjarová, Michaela
Powiązania:
https://bibliotekanauki.pl/articles/31341153.pdf
Data publikacji:
2016-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge-coloring
r -maximum k -edge-coloring
unique-maximum edge-coloring
weak-odd edge-coloring
weak-even edge-coloring
Opis:
An $r$-maximum $k$-edge-coloring of $G$ is a $k$-edge-coloring of $G$ having a property that for every vertex $v$ of degree $d_G(v) = d, d \ge r$, the maximum color, that is present at vertex $v$, occurs at $v$ exactly $r$ times. The $r$-maximum index $ \chi_r^′ (G) $ is defined to be the minimum number $k$ of colors needed for an $r$-maximum $k$-edge-coloring of graph $G$. In this paper we show that $ \chi_r^′ (G) \le 3 $ for any nontrivial connected graph $G$ and $ r = 1$ or 2. The bound 3 is tight. All graphs $G$ with $ \chi_1^' (G) =i $, $i = 1, 2, 3$ are characterized. The precise value of the $r$-maximum index, $ r \ge 1 $, is determined for trees and complete graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 1; 117-125
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On light subgraphs in plane graphs of minimum degree five
Autorzy:
Jendrol', Stanislav
Madaras, Tomáš
Powiązania:
https://bibliotekanauki.pl/articles/972033.pdf
Data publikacji:
1996
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar graph
light subgraph
star
triangulation
Opis:
A subgraph of a plane graph is light if the sum of the degrees of the vertices of the subgraph in the graph is small. It is well known that a plane graph of minimum degree five contains light edges and light triangles. In this paper we show that every plane graph of minimum degree five contains also light stars $K_{1,3}$ and $K_{1,4}$ and a light 4-path P₄. The results obtained for $K_{1,3}$ and P₄ are best possible.
Źródło:
Discussiones Mathematicae Graph Theory; 1996, 16, 2; 207-217
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
3-Paths in Graphs with Bounded Average Degree
Autorzy:
Jendrol, Stanislav
Maceková, Mária
Montassier, Mickaël
Soták, Roman
Powiązania:
https://bibliotekanauki.pl/articles/31340952.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
average degree
structural property
3-path
degree sequence
Opis:
In this paper we study the existence of unavoidable paths on three vertices in sparse graphs. A path uvw on three vertices u, v, and w is of type (i, j, k) if the degree of u (respectively v, w) is at most i (respectively j, k). We prove that every graph with minimum degree at least 2 and average degree strictly less than m contains a path of one of the types Moreover, no parameter of this description can be improved.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 339-353
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on face coloring entire weightings of plane graphs
Autorzy:
Jendrol, Stanislav
Šugerek, Peter
Powiązania:
https://bibliotekanauki.pl/articles/31232002.pdf
Data publikacji:
2014-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
entire weighting
plane graph
face colouring
Opis:
Given a weighting of all elements of a 2-connected plane graph $G = (V,E, F)$, let $f(α)$ denote the sum of the weights of the edges and vertices incident with the face α and also the weight of α. Such an entire weighting is a proper face colouring provided that $f(α) ≠ f(β)$ for every two faces α and β sharing an edge. We show that for every 2-connected plane graph there is a proper face-colouring entire weighting with weights 1 through 4. For some families we improved 4 to 3.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 2; 421-426
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Facial Rainbow Coloring of Plane Graphs
Autorzy:
Jendroľ, Stanislav
Kekeňáková, Lucia
Powiązania:
https://bibliotekanauki.pl/articles/31343192.pdf
Data publikacji:
2019-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
cyclic coloring
rainbow coloring
plane graphs
Opis:
A vertex coloring of a plane graph $G$ is a facial rainbow coloring if any two vertices of $G$ connected by a facial path have distinct colors. The facial rainbow number of a plane graph $G$, denoted by $ rb(G) $, is the minimum number of colors that are necessary in any facial rainbow coloring of $G$. Let $L(G)$ denote the order of a longest facial path in $G$. In the present note we prove that $ rb(T) \le \floor{ 3/2 L(T) } $ for any tree $T$ and $rb(G) \le \ceil{ 5/3 L(G) } $ for arbitrary simple graph $G$. The upper bound for trees is tight. For any simple 3-connected plane graph $G$ we have $ rb(G) \le L(G) + 5 $.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 4; 889-897
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distance coloring of the hexagonal lattice
Autorzy:
Jacko, Peter
Jendrol', Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/744329.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance coloring
distant chromatic number
hexagonal lattice of the plane
hexagonal tiling
hexagonal grid
radio channel frequency assignment
Opis:
Motivated by the frequency assignment problem we study the d-distant coloring of the vertices of an infinite plane hexagonal lattice H. Let d be a positive integer. A d-distant coloring of the lattice H is a coloring of the vertices of H such that each pair of vertices distance at most d apart have different colors. The d-distant chromatic number of H, denoted $χ_d(H)$, is the minimum number of colors needed for a d-distant coloring of H. We give the exact value of $χ_d(H)$ for any d odd and estimations for any d even.
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 1-2; 151-166
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Total edge irregularity strength of trees
Autorzy:
Ivančo, Jaroslav
Jendrol', Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/743612.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph labelling
tree
irregularity strength
total labellings
total edge irregularity strength
Opis:
A total edge-irregular k-labelling ξ:V(G)∪ E(G) → {1,2,...,k} of a graph G is a labelling of vertices and edges of G in such a way that for any different edges e and f their weights wt(e) and wt(f) are distinct. The weight wt(e) of an edge e = xy is the sum of the labels of vertices x and y and the label of the edge e. The minimum k for which a graph G has a total edge-irregular k-labelling is called the total edge irregularity strength of G, tes(G). In this paper we prove that for every tree T of maximum degree Δ on p vertices
tes(T) = max{⎡(p+1)/3⎤,⎡(Δ+1)/2⎤}.
Źródło:
Discussiones Mathematicae Graph Theory; 2006, 26, 3; 449-456
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Maximum Weight of a Bipartite Graph of Given Order and Size
Autorzy:
Horňák, Mirko
Jendrol’, Stanislav
Schiermeyer, Ingo
Powiązania:
https://bibliotekanauki.pl/articles/30146711.pdf
Data publikacji:
2013-03-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
weight of an edge
weight of a graph
bipartite graph
Opis:
The weight of an edge xy of a graph is defined to be the sum of degrees of the vertices x and y. The weight of a graph G is the minimum of weights of edges of G. More than twenty years ago Erd˝os was interested in finding the maximum weight of a graph with n vertices and m edges. This paper presents a complete solution of a modification of the above problem in which a graph is required to be bipartite. It is shown that there is a function w*(n,m) such that the optimum weight is either w*(n,m) or w*(n,m) + 1.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 1; 147-165
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unavoidable set of face types for planar maps
Autorzy:
Horňák, Mirko
Jendrol, Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/972016.pdf
Data publikacji:
1996
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
normal planar map
plane graph
type of a face
unavoidable set
cyclic chromatic number
Opis:
The type of a face f of a planar map is a sequence of degrees of vertices of f as they are encountered when traversing the boundary of f. A set of face types is found such that in any normal planar map there is a face with type from . The set has four infinite series of types as, in a certain sense, the minimum possible number. An analogous result is applied to obtain new upper bounds for the cyclic chromatic number of 3-connected planar maps.
Źródło:
Discussiones Mathematicae Graph Theory; 1996, 16, 2; 123-141
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lightweight paths in graphs
Autorzy:
Harant, Jochen
Jendrol, Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/255411.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
weighted graph
lightweight path
Opis:
Let k be a positive integer, G be a graph on V(G) containing a path on k vertices, and w be a weight function assigning each vertex v ∈ V(G) a real weight w(y). Upper bounds on the weight [formula] of P are presented, where P is chosen among all paths of G on k vertices with smallest weight.
Źródło:
Opuscula Mathematica; 2019, 39, 6; 829-837
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On long cycles through four prescribed vertices of a polyhedral graph
Autorzy:
Harant, Jochen
Jendrol', Stanislav
Walther, Hansjoachim
Powiązania:
https://bibliotekanauki.pl/articles/743057.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
long cycle
prescribed vertices
Opis:
For a 3-connected planar graph G with circumference c ≥ 44 it is proved that G has a cycle of length at least (1/36)c+(20/3) through any four vertices of G.
Źródło:
Discussiones Mathematicae Graph Theory; 2008, 28, 3; 441-451
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on vertex colorings of plane graphs
Autorzy:
Fabrici, Igor
Jendrol’, Stanislav
Soták, Roman
Powiązania:
https://bibliotekanauki.pl/articles/30148722.pdf
Data publikacji:
2014-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
plane graph
vertex coloring
Opis:
Given an integer valued weighting of all elements of a 2-connected plane graph G with vertex set V, let c(v) denote the sum of the weight of v ∈ V and of the weights of all edges and all faces incident with v. This vertex coloring of G is proper provided that c(u) ≠ c(v) for any two adjacent vertices u and v of G. We show that for every 2-connected plane graph there is such a proper vertex coloring with weights in {1, 2, 3}. In a special case, the value 3 is improved to 2.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 4; 849-855
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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