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Wyszukujesz frazę "distance graph" wg kryterium: Temat


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:
Coloring of the dth Power of the Face-Centered Cubic Grid
Autorzy:
Gastineau, Nicolas
Togni, Olivier
Powiązania:
https://bibliotekanauki.pl/articles/32228468.pdf
Data publikacji:
2021-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
face-centered cubic grid
distance coloring
dth power of graph
Opis:
The face-centered cubic grid is a three dimensional 12-regular infinite grid. This graph represents an optimal way to pack spheres in the three-dimensional space. We give lower and upper bounds on the chromatic number of the dth power of the face-centered cubic grid. In particular, in the case d = 2 we prove that the chromatic number of this grid is 13. We also determine sharper bounds for d = 3 and for subgraphs of the face-centered cubic grid.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 4; 1001-1020
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dualizing Distance-Hereditary Graphs
Autorzy:
McKee, Terry A.
Powiązania:
https://bibliotekanauki.pl/articles/32083836.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance-hereditary graph
dual graph
graph duality
Opis:
Distance-hereditary graphs can be characterized by every cycle of length at least 5 having crossing chords. This makes distance-hereditary graphs susceptible to dualizing, using the common extension of geometric face/vertex planar graph duality to cycle/cutset duality as in abstract matroidal duality. The resulting “DH* graphs” are characterized and then analyzed in terms of connectivity. These results are used in a special case of plane-embedded graphs to justify viewing DH* graphs as the duals of distance-hereditary graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 285-296
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minimal Graphs with Respect to Geometric Distance Realizability
Autorzy:
Madaras, Tomáš
Široczki, Pavol
Powiązania:
https://bibliotekanauki.pl/articles/32083776.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
unit-distance graph
odd-distance graph
Euclidean plane
Opis:
A graph G is minimal non-unit-distance graph if there is no drawing of G in Euclidean plane having all edges of unit length, but, for each edge e of G, G − e has such a drawing. We prove that, for infinitely many n, the number of non-isomorphic n-vertex minimal non-unit-distance graphs is at least exponential in n.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 65-73
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Few Examples and Counterexamples in Spectral Graph Theory
Autorzy:
Stevanović, Dragan
Milosavljević, Nikola
Vukičević, Damir
Powiązania:
https://bibliotekanauki.pl/articles/31563587.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
communicability distance
spectral radius
integral graph
second Zagreb index
Wiener index
estrada index
almost cospectral graphs
NEPS of graphs
Opis:
We present a small collection of examples and counterexamples for selected problems, mostly in spectral graph theory, that have occupied our minds over a number of years without being completely resolved.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 637-662
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Metric Dimension of Directed and Undirected Circulant Graphs
Autorzy:
Vetrík, Tomáš
Powiązania:
https://bibliotekanauki.pl/articles/31870010.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
metric dimension
resolving set
circulant graph
distance
Opis:
The undirected circulant graph $C_n(±1, ±2, . . ., ±t)$ consists of vertices $v_0, v_1, . . ., v_{n−1}$ and undirected edges $v_iv_{i+j}$, where $0 ≤ i ≤ n − 1, 1 ≤ j ≤ t (2 ≤ t ≤ \frac{n}{2})$, and the directed circulant graph $C_n(1, t)$ consists of vertices $v_0, v_1, . . ., v_{n−1}$ and directed edges $v_iv_{i+1}, v_iv_{i+t}$, where $0 ≤ i ≤ n − 1 (2 ≤ t ≤ n−1)$, the indices are taken modulo $n$. Results on the metric dimension of undirected circulant graphs $C_n(±1, ±t)$ are available only for special values of $t$. We give a complete solution of this problem for directed graphs $C_n(1, t)$ for every $t ≥ 2$ if $n ≥ 2t^2$. Grigorious et al. [On the metric dimension of circulant and Harary graphs, Appl. Math. Comput. 248 (2014) 47–54] presented a conjecture saying that dim $(C_n(±1, ±2, . . ., ±t)) = t + p − 1$ for $n = 2tk + t + p$, where $3 ≤ p ≤ t + 1$. We disprove it by showing that dim $(C_n(±1, ±2, . . ., ±t)) ≤ t + \frac{p+1}{2}$ for $n = 2tk + t + p$, where $t ≥ 4$ is even, $p$ is odd, $1 ≤ p ≤ t + 1$ and $k ≥ 1$.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 67-76
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2-Distance Colorings of Integer Distance Graphs
Autorzy:
Benmedjdoub, Brahim
Bouchemakh, Isma
Sopena, Éric
Powiązania:
https://bibliotekanauki.pl/articles/31343379.pdf
Data publikacji:
2019-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
2-distance coloring
integer distance graph
Opis:
A 2-distance k-coloring of a graph G is a mapping from V (G) to the set of colors {1,. . ., k} such that every two vertices at distance at most 2 receive distinct colors. The 2-distance chromatic number χ2(G) of G is then the smallest k for which G admits a 2-distance k-coloring. For any finite set of positive integers D = {d1, . . ., d}, the integer distance graph G = G(D) is the infinite graph defined by V (G) = ℤ and uv ∈ E(G) if and only if |v − u| ∈ D. We study the 2-distance chromatic number of integer distance graphs for several types of sets D. In each case, we provide exact values or upper bounds on this parameter and characterize those graphs G(D) with χ2(G(D)) = ∆(G(D)) + 1.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 2; 589-603
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Some Characterizations of Antipodal Partial Cubes
Autorzy:
Polat, Norbert
Powiązania:
https://bibliotekanauki.pl/articles/31343441.pdf
Data publikacji:
2019-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
diametrical graph
harmonic graph
antipodal graph
distance-balanced graph
partial cube
pre-hull number
Opis:
We prove that any harmonic partial cube is antipodal, which was conjectured by Fukuda and K. Handa, Antipodal graphs and oriented matroids, Discrete Math. 111 (1993) 245–256. Then we prove that a partial cube G is antipodal if and only if the subgraphs induced by Wab and Wba are isomorphic for every edge ab of G. This gives a positive answer to a question of Klavžar and Kovše, On even and harmonic-even partial cubes, Ars Combin. 93 (2009) 77–86. Finally we prove that the distance-balanced partial cube that are antipodal are those whose pre-hull number is at most 1.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 2; 439-453
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Orientable $ \mathbb{Z}_N $-Distance Magic Graphs
Autorzy:
Cichacz, Sylwia
Freyberg, Bryan
Froncek, Dalibor
Powiązania:
https://bibliotekanauki.pl/articles/31343411.pdf
Data publikacji:
2019-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance magic graph
digraph
flow graph
Opis:
Let $ G = (V, E) $ be a graph of order $n$. A distance magic labeling of $G$ is a bijection $ \mathcal{l}: V \rightarrow {1, 2, . . ., n} $ for which there exists a positive integer $k$ such that $ \Sigma_{ x \in N(v) } \mathcal{l} (x) = k $ for all $ v \in V $, where $ N(v) $ is the open neighborhood of $v$. Tuttes flow conjectures are a major source of inspiration in graph theory. In this paper we ask when we can assign $n$ distinct labels from the set $ {1, 2, . . ., n} $ to the vertices of a graph $G$ of order $n$ such that the sum of the labels on heads minus the sum of the labels on tails is constant modulo $n$ for each vertex of $G$. Therefore we generalize the notion of distance magic labeling for oriented graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 2; 533-546
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Distance Magic Index of a Graph
Autorzy:
Godinho, Aloysius
Singh, Tarkeshwar
Arumugam, S.
Powiązania:
https://bibliotekanauki.pl/articles/31342438.pdf
Data publikacji:
2018-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance magic labeling
distance magic index
S -magic graph
S -magic labeling
Opis:
Let $G$ be a graph of order $n$ and let $S$ be a set of positive integers with $ |S| = n $. Then $G$ is said to be $S$-magic if there exists a bijection $ \phi : V (G) \rightarrow S $ satisfying $ \Sigma_{ x \in N } (u) \ \phi (x) = k $ (a constant) for every $ u \in V (G) $. Let $ \alpha (S) = \text{max} \{ s : s \in S \} $. Let $ i(G) = \text{min} \ \alpha (S) $, where the minimum is taken over all sets $S$ for which the graph $G$ admits an $S$-magic labeling. Then $ i(G) − n $ is called the distance magic index of the graph $G$. In this paper we determine the distance magic index of trees and complete bipartite graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 1; 135-142
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Union of Distance Magic Graphs
Autorzy:
Cichacz, Sylwia
Nikodem, Mateusz
Powiązania:
https://bibliotekanauki.pl/articles/31342130.pdf
Data publikacji:
2017-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance magic labeling
magic constant
sigma labeling
graph labeling
union of graphs
lexicographic product
direct product
Kronecker product
Kotzig array
Opis:
A distance magic labeling of a graph $G = (V,E)$ with $|V | = n$ is a bijection $ \mathcal{l} $ from $V$ to the set ${1, . . ., n}$ such that the weight $ w(x) = \Sigma_{ y \in N_G } (x) \mathcal{l}(y) $ of every vertex $ x \in V $ is equal to the same element $ \mu $, called the magic constant. In this paper, we study unions of distance magic graphs as well as some properties of such graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 1; 239-249
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distance Magic Cartesian Products of Graphs
Autorzy:
Cichacz, Sylwia
Froncek, Dalibor
Krop, Elliot
Raridan, Christopher
Powiązania:
https://bibliotekanauki.pl/articles/31340995.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance magic labeling
magic constant
sigma labeling
Cartesian product
hypercube
complete multipartite graph
cycle
Opis:
A distance magic labeling of a graph G = (V,E) with |V | = n is a bijection ℓ : V → {1, . . ., n} such that the weight of every vertex v, computed as the sum of the labels on the vertices in the open neighborhood of v, is a constant. In this paper, we show that hypercubes with dimension divisible by four are not distance magic. We also provide some positive results by proving necessary and sufficient conditions for the Cartesian product of certain complete multipartite graphs and the cycle on four vertices to be distance magic.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 299-308
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frames and factorization of graph Laplacians
Autorzy:
Jorgensen, P.
Tian, F.
Powiązania:
https://bibliotekanauki.pl/articles/255936.pdf
Data publikacji:
2015
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
unbounded operators
deficiency-indices
Hilbert space
boundary values
weighted graph
reproducing kernel
Dirichlet form
graph Laplacian
resistance network
harmonic analysis
frame
Parseval frame
Friedrichs extension
reversible random walk
resistance distance
energy Hilbert space
Opis:
Using functions from electrical networks (graphs with resistors assigned to edges), we prove existence (with explicit formulas) of a canonical Parseval frame in the energy Hilbert space [formula] of a prescribed infinite (or finite) network. Outside degenerate cases, our Parseval frame is not an orthonormal basis. We apply our frame to prove a number of explicit results: With our Parseval frame and related closable operators in [formula] we characterize the Priedrichs extension of the [formula]-graph Laplacian. We consider infinite connected network-graphs G = (V, E), V for vertices, and E for edges. To every conductance function c on the edges E of G, there is an associated pair [formula] where [formula] in an energy Hilbert space, and Δ (=Δc) is the c-graph Laplacian; both depending on the choice of conductance function c. When a conductance function is given, there is a current-induced orientation on the set of edges and an associated natural Parseval frame in [formula] consisting of dipoles. Now Δ is a well-defined semibounded Hermitian operator in both of the Hilbert [formula] and [formula]. It is known to automatically be essentially selfadjoint as an [formula]-operator, but generally not as an [formula] operator. Hence as an [formula] operator it has a Friedrichs extension. In this paper we offer two results for the Priedrichs extension: a characterization and a factorization. The latter is via [formula].
Źródło:
Opuscula Mathematica; 2015, 35, 3; 293-332
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Extremal unicyclic graphs with minimal distance spectral radius
Autorzy:
Lu, Hongyan
Luo, Jing
Zhu, Zhongxun
Powiązania:
https://bibliotekanauki.pl/articles/30148716.pdf
Data publikacji:
2014-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance matrix
distance spectral radius
unicyclic graph
matching
Opis:
The distance spectral radius $ρ(G)$ of a graph $G$ is the largest eigenvalue of the distance matrix $D(G)$. Let $\mathcal{U} (n,m)$ be the class of unicyclic graphs of order $n$ with given matching number $m (m ≠ 3)$. In this paper, we determine the extremal unicyclic graph which has minimal distance spectral radius in $\mathcal{U} (n,m)$ \ $C_n$.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 4; 735-749
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maximal buttonings of trees
Autorzy:
Short, Ian
Powiązania:
https://bibliotekanauki.pl/articles/31232001.pdf
Data publikacji:
2014-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
centroid
graph metric
tree
walk
Wiener distance
Opis:
A buttoning of a tree that has vertices $v_1, v_2, . . ., v_n$ is a closed walk that starts at $v_1$ and travels along the shortest path in the tree to $v_2$, and then along the shortest path to $v_3$, and so forth, finishing with the shortest path from $v_n$ to $v_1$. Inspired by a problem about buttoning a shirt inefficiently, we determine the maximum length of buttonings of trees.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 2; 415-420
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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