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Tytuł:
Pm-saturated graphs with minimum size
Autorzy:
Dudek, A.
Wojda, A.P.
Powiązania:
https://bibliotekanauki.pl/articles/2050147.pdf
Data publikacji:
2004
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
graph
saturated graph
extremal graph
Opis:
By Pm we denote a path of order m. A graph G is saidto be P$\text{}_{m}$ - saturated if G has no subgraph isomorphic to P$\text{}_{m}$ and adding any new edge to G creates a Pm in G. In 1986 L. Kaszonyi and Zs. Tuza considered the following problem: for given m and n find the minimum size $sat(n; P\text{}_{m}$) of P$\text{}_{m}$-saturated graph and characterize the graphs of $Sat(n; P\text{}_{m}$) - the set of P$\text{}_{m}$-saturated graphs of minimum size. They have solved this problem for $n \geq a_{m}$ where $$ a_{m} = \begin{cases} 3 \cdot 2^{k-1} - 2~~\text{if}~m = 2k,k~~~~~~~\\ 2^{k+1} - 2~~~~~~\text{if}~m = 2k + 1, k \geq 2 \end{cases} $$ We define $$ b_{m} = \begin{cases} 3 \cdot 2^{k-2}~~~~~~~\text{if}~m = 2k,k \geq 3 \\ 3 \cdot 2 ^{k-1} - 1~~\text{if}~m = 2k + 1,k \geq 3 \end{cases} $$ and give $sat(n; P\text{}_{m}$) and $Sat(n; P\text{}_{m})$ for $m \geq 6$ and $b_{m} \leq n < a_{m}$
Źródło:
Opuscula Mathematica; 2004, 24, 1; 43-55
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
α2-labeling of graphs
Autorzy:
Froncek, D.
Powiązania:
https://bibliotekanauki.pl/articles/255852.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
graph decomposition
graph labeling
Opis:
We show that if a graph G on n edges allows certain special type of rosy labeling (a.k.a. rho;-labeling), called α2-labeling, then for any positive integer k the complete graph K2nk+1 can be decomposed into copies of G. This notion generalizes the α-labeling introduced in 1967 by A. Rosa.
Źródło:
Opuscula Mathematica; 2009, 29, 4; 393-397
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decomposition of complete graphs into small graphs
Autorzy:
Froncek, D.
Powiązania:
https://bibliotekanauki.pl/articles/255502.pdf
Data publikacji:
2010
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
graph decomposition
graph labeling
Opis:
In 1967, A. Rosa proved that if a bipartite graph G with n edges has an α-labeling, then for any positive integer p the complete graph K(2np+1) can be cyclically decomposed into copies of G. This has become a part of graph theory folklore since then. In this note we prove a generalization of this result. We show that every bipartite graph H which decomposes K(k) and K(m) also decomposes K(km).
Źródło:
Opuscula Mathematica; 2010, 30, 3; 277-280
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Open trails in digraphs
Autorzy:
Cichacz, S.
Gorlich, A.
Powiązania:
https://bibliotekanauki.pl/articles/254857.pdf
Data publikacji:
2011
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
trail
graph decomposition
bipartite graph
Opis:
It has been shown in [S. Cichacz, A. Görlich, Decomposition of complete bipartite graphs into open trails, Preprint MD 022, (2006)] that any bipartite graph Ka,b, is decomposable into open trails of prescribed even lengths. In this article we consider the corresponding question for directed graphs. We show that the complete directed graphs ↔K n and ↔K a,b are arbitrarily decomposable into directed open trails.
Źródło:
Opuscula Mathematica; 2011, 31, 4; 599-604
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bipartite embedding of (p, q)-trees
Autorzy:
Orchel, B.
Powiązania:
https://bibliotekanauki.pl/articles/254921.pdf
Data publikacji:
2006
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
bipartite graph
tree
embedding graph
Opis:
A bipartite graph G = (L, R; E) where V(G) = L ∪ R, |L| = p, |R| = q is called a (p, q)-tree if |E(G)| = p + q - 1 and G has no cycles. A bipartite graph G = (L, R; E) is a subgraph of a bipartite graph H = (L'. R'; E') if L ⊆ L', R ⊆ R' and E ⊆ E'. In this paper we present sufficient degree conditions for a bipartite graph to contain a (p, q)-tree.
Źródło:
Opuscula Mathematica; 2006, 26, 1; 119-125
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research problems from the 18th Workshop '3in1' 2009
Autorzy:
Meszka, M. [ed.]
Powiązania:
https://bibliotekanauki.pl/articles/255619.pdf
Data publikacji:
2010
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Hamilton-connected graph
hamiltonian graph
dominating cycle
bihomogeneously traceble graph
Opis:
A collection of open problems that were posed at the 18th Workshop '3in1', held on November 26-28, 2009 in Krakow, Poland. The problems are presented by Zdenek Ryjacek in "Does the Thomassen's conjecture imply N=NP?" and "Dominating cycles and hamiltonian prisms", and by Carol T. Zamfirescu in "Two problems on bihomogeneously traceable digraphs".
Źródło:
Opuscula Mathematica; 2010, 30, 4; 527-532
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minimal unavoidable sets of cycles in plane graphs
Autorzy:
Madaras, T.
Tamasova, M.
Powiązania:
https://bibliotekanauki.pl/articles/255251.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
plane graph
polyhedral graph
set of cycles
Opis:
A set S of cycles is minimal unavoidable in a graph family [formula] if each graph [formula] contains a cycle from S and, for each proper subset S' ⊂ S, there exists an infinite subfamily [formula] such that no graph from [formula] contains a cycle from S'. In this paper, we study minimal unavoidable sets of cycles in plane graphs of minimum degree at least 3 and present several graph constructions which forbid many cycle sets to be unavoidable. We also show the minimality of several small sets consisting of short cycles
Źródło:
Opuscula Mathematica; 2018, 38, 6; 859-870
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on possible density and diameter of countere xamples to the Seymour’s second neighborhood conjecture
Autorzy:
Zelenskiy, Oleksiy
Darmosiuk, Valentyna
Nalivayko, Illia
Powiązania:
https://bibliotekanauki.pl/articles/2052069.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
graph theory
Seymour’s second neighborhood conjecture
density of graph
diameter of graph
Opis:
Seymour’s second neighborhood conjecture states that every simple digraph without loops or 2-cycles contains a vertex whose second neighborhood is at least as large as its first. In this paper we show, that from falsity of Seymour’s second neighborhood conjecture it follows that there exist strongly-connected counterexamples with both low and high density (dense and sparse graph). Moreover, we show that if there is a counterexample to conjecture, then it is possible to construct counterexample with any diameter k ≥ 3
Źródło:
Opuscula Mathematica; 2021, 41, 4; 601-605
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tree domatic number in graphs
Autorzy:
Chen, X. G.
Powiązania:
https://bibliotekanauki.pl/articles/255594.pdf
Data publikacji:
2007
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
tree domatic number
regular graph
planar graph
Cartesian product
Opis:
A dominating set S in a graph G is a tree dominating set of G if the subgraph induced by S is a tree. The tree domatic number of G is the maximum number of pairwise disjoint tree dominating sets in V(G). First, some exact values of and sharp bounds for the tree domatic number are given. Then, we establish a sharp lower bound for the number of edges in a connected graph of given order and given tree domatic number, and we characterize the extremal graphs. Finally, we show that a tree domatic number of a planar graph is at most 4 and give a characterization of planar graphs with the tree domatic number 3.
Źródło:
Opuscula Mathematica; 2007, 27, 1; 5-11
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the dimension of Archimedean solids
Autorzy:
Madaras, T.
Siroczki, P.
Powiązania:
https://bibliotekanauki.pl/articles/255658.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Archimedean solid
unit-distance graph
dimension of a graph
Opis:
We study the dimension of graphs of the Archimedean solids. For most of these graphs we find the exact value of their dimension by finding unit-distance embeddings in the euclidean plane or by proving that such an embedding is not possible.
Źródło:
Opuscula Mathematica; 2014, 34, 1; 123-138
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on M2-edge colorings of graphs
Autorzy:
Czap, J.
Powiązania:
https://bibliotekanauki.pl/articles/255532.pdf
Data publikacji:
2015
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
edge colouring
graph
Opis:
An edge coloring φ of a graph G is called an M2-edge coloring if [formula] every vertex v of G, where φ(v) is the set of colors of edges incident with v. Let K2(G) denote the maximum number of colors used in an M2-edge coloring of G. Let G1, G2 and G3 be graphs such that G1 ⊆ G2 ⊆ G3. In this paper we deal with the following question: Assuming that K2(G1) = K2(G3), does it hold K2(G1) = K2(G2) = K2(G3)?
Źródło:
Opuscula Mathematica; 2015, 35, 3; 287-291
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metric dimension of Andrasfai graphs
Autorzy:
Pejman, S. Batool
Payrovi, Shiroyeh
Behtoei, Ali
Powiązania:
https://bibliotekanauki.pl/articles/254963.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
resolving set
metric dimension
Andrasfai graph
Cayley graph
Cartesian product
Opis:
A set W ⊆ V(G) is called a resolving set, if for each pair of distinct vertices u,v ∈ V(G) there exists t ∈ W such that d(u,t) ≠ d(v,t), where d(x,y) is the distance between vertices x and y. The cardinality of a minimum resolving set for G is called the metric dimension of G and is denoted by dimM(G). This parameter has many applications in different areas. The problem of finding metric dimension is NP-complete for general graphs but it is determined for trees and some other important families of graphs. In this paper, we determine the exact value of the metric dimension of Andrasfai graphs, their complements and [formula]. Also, we provide upper and lower bounds for [formula].
Źródło:
Opuscula Mathematica; 2019, 39, 3; 415-423
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Upper bounds on distance vertex irregularity strength of some families of graphs
Autorzy:
Cichacz, Sylwia
Görlich, Agnieszka
Semaničová-Feňovčíková, Andrea
Powiązania:
https://bibliotekanauki.pl/articles/2216229.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
distance vertex irregularity strength of a graph
hypercube
tree
graph
Opis:
For a graph G its distance vertex irregularity strength is the smallest integer k for which one can find a labeling f : V (G) → {1, 2, . . . , k} such that $ \sum_{x \in N(v)} f(x) \neq \sum_{x \in N(u)} f(x) $ for all vertices u, v of G, where N(v) is the open neighborhood of v. In this paper we present some upper bounds on distance vertex irregularity strength of general graphs. Moreover, we give upper bounds on distance vertex irregularity strength of hypercubes and trees.
Źródło:
Opuscula Mathematica; 2022, 42, 4; 561--571
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
More on linear and metric tree maps
Autorzy:
Kozerenko, Sergiy
Powiązania:
https://bibliotekanauki.pl/articles/1397335.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Markov graph
metric map
non-expanding map
linear map
graph homomorphism
Opis:
We consider linear and metric self-maps on vertex sets of finite combinatorial trees. Linear maps are maps which preserve intervals between pairs of vertices whereas metric maps are maps which do not increase distances between pairs of vertices. We obtain criteria for a given linear or a metric map to be a positive (negative) under some orientation of the edges in a tree, we characterize trees which admit maps with Markov graphs being paths and prove that the converse of any partial functional digraph is isomorphic to a Markov graph for some suitable map on a tree.
Źródło:
Opuscula Mathematica; 2021, 41, 1; 55-70
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On incidence coloring of graph fractional powers
Autorzy:
Mozafari-Nia, Mahsa
Iradmusa, Moharram N.
Powiązania:
https://bibliotekanauki.pl/articles/29519190.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
incidence coloring
incidence chromatic number
subdivision of graph
power of graph
Opis:
For any $ n ∈ \mathbb{N} $, the n-subdivision of a graph $ G $ is a simple graph $ G^\frac{1}{n} $ which is constructed by replacing each edge of $ G $ with a path of length n. The m-th power of $ G $ is a graph, denoted by $ G^m $, with the same vertices of $ G $, where two vertices of $ G^m $ are adjacent if and only if their distance in $ G $ is at most m. In [M.N. Iradmusa, On colorings of graph fractional powers, Discrete Math. 310 (2010), no. 10-11, 1551-1556] the m-th power of the n-subdivision of $ G $, denoted by $ G^\frac{m}{n} $ is introduced as a fractional power of $ G $. The incidence chromatic number of $ G $, denoted by $ χ_i(G) $, is the minimum integer k such that $ G $ has an incidence k-coloring. In this paper, we investigate the incidence chromatic number of some fractional powers of graphs and prove the correctness of the incidence coloring conjecture for some powers of graphs.
Źródło:
Opuscula Mathematica; 2023, 43, 1; 109-123
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł

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