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Wyszukujesz frazę "Jendroľ, Stanislav" wg kryterium: Autor


Wyświetlanie 1-9 z 9
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:
An inequality concerning edges of minor weight in convex 3-polytopes
Autorzy:
Fabrici, Igor
Jendrol', Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/972043.pdf
Data publikacji:
1996
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar graph
convex 3-polytope
normal map
Opis:
Let $e_{ij}$ be the number of edges in a convex 3-polytope joining the vertices of degree i with the vertices of degree j. We prove that for every convex 3-polytope there is $20e_{3,3} + 25e_{3,4} + 16e_{3,5} + 10e_{3,6} + 6[2/3]e_{3,7} + 5e_{3,8} + 2[1/2]e_{3,9} + 2e_{3,10} + 16[2/3]e_{4,4} + 11e_{4,5} + 5e_{4,6} + 1[2/3]e_{4,7} + 5[1/3]e_{5,5} + 2e_{5,6} ≥ 120$; moreover, each coefficient is the best possible. This result brings a final answer to the conjecture raised by B. Grünbaum in 1973.
Źródło:
Discussiones Mathematicae Graph Theory; 1996, 16, 1; 81-87
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:
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:
Colouring vertices of plane graphs under restrictions given by faces
Autorzy:
Czap, Július
Jendrol', Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/744449.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
vertex colouring
plane graph
weak parity vertex colouring
strong parity vertex colouring
proper colouring
Lebesgue theorem
Opis:
We consider a vertex colouring of a connected plane graph G. A colour c is used k times by a face α of G if it appears k times along the facial walk of α. We prove that every connected plane graph with minimum face degree at least 3 has a vertex colouring with four colours such that every face uses some colour an odd number of times. We conjecture that such a colouring can be done using three colours. We prove that this conjecture is true for 2-connected cubic plane graphs. Next we consider other three kinds of colourings that require stronger restrictions.
Źródło:
Discussiones Mathematicae Graph Theory; 2009, 29, 3; 521-543
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:
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:
Paths of low weight in planar graphs
Autorzy:
Fabrici, Igor
Harant, Jochen
Jendrol', Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/743525.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar graphs
polytopal graphs
paths
weight of an edge
weight of a path
Opis:
The existence of paths of low degree sum of their vertices in planar graphs is investigated. The main results of the paper are:
1. Every 3-connected simple planar graph G that contains a k-path, a path on k vertices, also contains a k-path P such that for its weight (the sum of degrees of its vertices) in G it holds
$w_G(P): = ∑_{u∈ V(P)} deg_G(u) ≤ (3/2)k² + (k)$
2. Every plane triangulation T that contains a k-path also contains a k-path P such that for its weight in T it holds
$w_T(P): = ∑_{u∈ V(P)} deg_T(u) ≤ k² +13 k$
3. Let G be a 3-connected simple planar graph of circumference c(G). If c(G) ≥ σ| V(G)| for some constant σ > 0 then for any k, 1 ≤ k ≤ c(G), G contains a k-path P such that
$w_G(P) = ∑_{u∈ V(P)} deg_G(u) ≤ (3/σ + 3)k$.
Źródło:
Discussiones Mathematicae Graph Theory; 2008, 28, 1; 121-135
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parity vertex colouring of graphs
Autorzy:
Borowiecki, Piotr
Budajová, Kristína
Jendrol', Stanislav
Krajci, Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/743850.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
parity colouring
graph colouring
vertex ranking
ordered colouring
tree
hypercube
Fibonacci number
Opis:
A parity path in a vertex colouring of a graph is a path along which each colour is used an even number of times. Let χₚ(G) be the least number of colours in a proper vertex colouring of G having no parity path. It is proved that for any graph G we have the following tight bounds χ(G) ≤ χₚ(G) ≤ |V(G)|-α(G)+1, where χ(G) and α(G) are the chromatic number and the independence number of G, respectively. The bounds are improved for trees. Namely, if T is a tree with diameter diam(T) and radius rad(T), then ⌈log₂(2+diam(T))⌉ ≤ χₚ(T) ≤ 1+rad(T). Both bounds are tight. The second thread of this paper is devoted to relationships between parity vertex colourings and vertex rankings, i.e. a proper vertex colourings with the property that each path between two vertices of the same colour q contains a vertex of colour greater than q. New results on graphs critical for vertex rankings are also presented.
Źródło:
Discussiones Mathematicae Graph Theory; 2011, 31, 1; 183-195
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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