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Wyszukujesz frazę "interval graph" wg kryterium: Temat


Wyświetlanie 1-11 z 11
Tytuł:
A characterization of 2-tree probe interval graphs
Autorzy:
Brown, David E.
Flesch, Breeann M.
Lundgren, J. Richard
Powiązania:
https://bibliotekanauki.pl/articles/30148257.pdf
Data publikacji:
2014-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
interval graph
probe interval graph
2-tree
Opis:
A graph is a probe interval graph if its vertices correspond to some set of intervals of the real line and can be partitioned into sets P and N so that vertices are adjacent if and only if their corresponding intervals intersect and at least one belongs to P. We characterize the 2-trees which are probe interval graphs and extend a list of forbidden induced subgraphs for such graphs created by Pržulj and Corneil in [2-tree probe interval graphs have a large obstruction set, Discrete Appl. Math. 150 (2005) 216-231]
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 3; 509-527
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Phylogeny Graphs of Doubly Partial Orders
Autorzy:
Park, Boram
Sano, Yoshio
Powiązania:
https://bibliotekanauki.pl/articles/29551728.pdf
Data publikacji:
2013-09-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
competition graph
phylogeny graph
doubly partial order
interval graph
Opis:
The competition graph of a doubly partial order is known to be an interval graph. The CCE graph and the niche graph of a doubly partial order are also known to be interval graphs if the graphs do not contain a cycle of length four and three as an induced subgraph, respectively. Phylogeny graphs are variant of competition graphs. The phylogeny graph P(D) of a digraph D is the (simple undirected) graph defined by V (P(D)) := V (D) and E(P(D)) := {xy | N+D (x) ∩ N+D(y) ¹ ⊘ } ⋃ {xy | (x,y) ∈ A(D)}, where N+D(x):= {v ∈ V(D) | (x,v) ∈ A (D)}. In this note, we show that the phylogeny graph of a doubly partial order is an interval graph. We also show that, for any interval graph G̃, there exists an interval graph G such that G̃ contains the graph G as an induced subgraph and that G̃ is the phylogeny graph of a doubly partial order.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 4; 657-664
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The list Distinguishing Number Equals the Distinguishing Number for Interval Graphs
Autorzy:
Immel, Poppy
Wenger, Paul S.
Powiązania:
https://bibliotekanauki.pl/articles/31342143.pdf
Data publikacji:
2017-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distinguishing
distinguishing number
list distinguishing
interval graph
Opis:
A distinguishing coloring of a graph G is a coloring of the vertices so that every nontrivial automorphism of G maps some vertex to a vertex with a different color. The distinguishing number of G is the minimum k such that G has a distinguishing coloring where each vertex is assigned a color from {1, . . ., k}. A list assignment to G is an assignment L = {L(v)}v∈V (G) of lists of colors to the vertices of G. A distinguishing L-coloring of G is a distinguishing coloring of G where the color of each vertex v comes from L(v). The list distinguishing number of G is the minimum k such that every list assignment to G in which |L(v)| = k for all v ∈ V (G) yields a distinguishing L-coloring of G. We prove that if G is an interval graph, then its distinguishing number and list distinguishing number are equal.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 1; 165-174
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A reduction of the Graph Reconstruction Conjecture
Autorzy:
Monikandan, S.
Balakumar, J.
Powiązania:
https://bibliotekanauki.pl/articles/30148259.pdf
Data publikacji:
2014-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
reconstruction
diameter
geodetic graph
interval-regular graph
Opis:
A graph is said to be reconstructible if it is determined up to isomorphism from the collection of all its one-vertex deleted unlabeled subgraphs. Reconstruction Conjecture (RC) asserts that all graphs on at least three vertices are reconstructible. In this paper, we prove that interval-regular graphs and some new classes of graphs are reconstructible and show that RC is true if and only if all non-geodetic and non-interval-regular blocks G with diam(G) = 2 or diam(G) = diam(Ḡ) = 3 are reconstructible.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 3; 529-537
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The niche graphs of interval orders
Autorzy:
Park, Jeongmi
Sano, Yoshio
Powiązania:
https://bibliotekanauki.pl/articles/30148237.pdf
Data publikacji:
2014-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
competition graph
niche graph
semiorder
interval order
Opis:
The niche graph of a digraph $D$ is the (simple undirected) graph which has the same vertex set as $D$ and has an edge between two distinct vertices $x$ and $y$ if and only if $N_D^+(x) ∩ N_D^+(y) ≠ ∅ or N_D^−(x) ∩ N_D^−(y) ≠ ∅$, where $N_D^+(x)$ (resp. $N_D^−(x)$) is the set of out-neighbors (resp. in-neighbors) of $x$ in $D$. A digraph $D = (V,A)$ is called a semiorder (or a unit interval order) if there exist a real-valued function $f : V → \mathbb{R}$ on the set $V$ and a positive real number $δ ∈ \mathbb{R}$ such that $(x, y) ∈ A$ if and only if $f(x) > f(y)+δ$. A digraph $D = (V,A)$ is called an interval order if there exists an assignment $J$ of a closed real interval $J(x) ⊂ \mathbb{R}$ to each vertex $x ∈ V$ such that $(x, y) ∈ A$ if and only if $min J(x) > max J(y)$. Kim and Roberts characterized the competition graphs of semiorders and interval orders in 2002, and Sano characterized the competition-common enemy graphs of semiorders and interval orders in 2010. In this note, we give characterizations of the niche graphs of semiorders and interval orders
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 2; 353-359
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Forbidden Structures for Planar Perfect Consecutively Colourable Graphs
Autorzy:
Borowiecka-Olszewska, Marta
Drgas-Burchardt, Ewa
Powiązania:
https://bibliotekanauki.pl/articles/31341980.pdf
Data publikacji:
2017-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge colouring
consecutive (interval) colouring
deficiency
Sevastjanov graph
forbidden graph
Opis:
A consecutive colouring of a graph is a proper edge colouring with posi- tive integers in which the colours of edges incident with each vertex form an interval of integers. The idea of this colouring was introduced in 1987 by Asratian and Kamalian under the name of interval colouring. Sevast- janov showed that the corresponding decision problem is NP-complete even restricted to the class of bipartite graphs. We focus our attention on the class of consecutively colourable graphs whose all induced subgraphs are consecutively colourable, too. We call elements of this class perfect consecutively colourable to emphasise the conceptual similarity to perfect graphs. Obviously, the class of perfect consecutively colourable graphs is induced hereditary, so it can be characterized by the family of induced forbidden graphs. In this work we give a necessary and sufficient conditions that must be satisfied by the generalized Sevastjanov rosette to be an induced forbid- den graph for the class of perfect consecutively colourable graphs. Along the way, we show the exact values of the deficiency of all generalized Sevastjanov rosettes, which improves the earlier known estimating result. It should be mentioned that the deficiency of a graph measures its closeness to the class of consecutively colourable graphs. We motivate the investigation of graphs considered here by showing their connection to the class of planar perfect consecutively colourable graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 2; 315-336
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interval Incidence Coloring of Subcubic Graphs
Autorzy:
Małafiejska, Anna
Małafiejski, Michał
Powiązania:
https://bibliotekanauki.pl/articles/31341833.pdf
Data publikacji:
2017-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
interval incidence coloring
incidence coloring
subcubic graph
Opis:
In this paper we study the problem of interval incidence coloring of subcubic graphs. In [14] the authors proved that the interval incidence 4-coloring problem is polynomially solvable and the interval incidence 5-coloring problem is NP-complete, and they asked if Xii(G) ≤ 2Δ(G) holds for an arbitrary graph G. In this paper, we prove that an interval incidence 6-coloring always exists for any subcubic graph G with Δ(G) = 3.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 2; 427-441
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Some Properties of Antipodal Partial Cubes
Autorzy:
Polat, Norbert
Powiązania:
https://bibliotekanauki.pl/articles/31512721.pdf
Data publikacji:
2020-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
antipodal graph
partial cube
interval monotony
girth
diameter
Opis:
We prove that an antipodal bipartite graph is a partial cube if and only it is interval monotone. Several characterizations of the principal cycles of an antipodal partial cube are given. We also prove that an antipodal partial cube G is a prism over an even cycle if and only if its order is equal to 4(diam(G) − 1), and that the girth of an antipodal partial cube is less than its diameter whenever it is not a cycle and its diameter is at least equal to 6.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 3; 755-770
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Note on the Interval Function of a Disconnected Graph
Autorzy:
Changat, Manoj
Hossein Nezhad, Ferdoos
Mulder, Henry Martyn
Narayanan, N.
Powiązania:
https://bibliotekanauki.pl/articles/31342443.pdf
Data publikacji:
2018-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
interval function
transit function
axiomatic characterization
disconnected graph
Opis:
In this note we extend the Mulder-Nebeský characterization of the interval function of a connected graph to the disconnected case. One axiom needs to be adapted, but also a new axiom is needed in addition.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 1; 39-48
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interval edge colorings of some products of graphs
Autorzy:
Petrosyan, Petros
Powiązania:
https://bibliotekanauki.pl/articles/743918.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge coloring
interval coloring
regular graph
products of graphs
Opis:
An edge coloring of a graph G with colors 1,2,...,t is called an interval t-coloring if for each i ∈ {1,2,...,t} there is at least one edge of G colored by i, and the colors of edges incident to any vertex of G are distinct and form an interval of integers. A graph G is interval colorable, if there is an integer t ≥ 1 for which G has an interval t-coloring. Let ℜ be the set of all interval colorable graphs. In 2004 Kubale and Giaro showed that if G,H ∈ , then the Cartesian product of these graphs belongs to . Also, they formulated a similar problem for the lexicographic product as an open problem. In this paper we first show that if G ∈ , then G[nK₁] ∈ for any n ∈ ℕ. Furthermore, we show that if G,H ∈ and H is a regular graph, then strong and lexicographic products of graphs G,H belong to . We also prove that tensor and strong tensor products of graphs G,H belong to if G ∈ and H is a regular graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2011, 31, 2; 357-373
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
p-Wiener intervals and p-Wiener free intervals
Autorzy:
Kathiresan, Kumarappan
Arockiaraj, S.
Powiązania:
https://bibliotekanauki.pl/articles/743709.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Wiener index of a graph
Wiener graphical
p-Wiener interval
p-Wiener free interval
hyper-Wiener index of a graph
radius
diameter
Opis:
A positive integer n is said to be Wiener graphical, if there exists a graph G with Wiener index n. In this paper, we prove that any positive integer n(≠ 2,5) is Wiener graphical. For any positive integer p, an interval [a,b] is said to be a p-Wiener interval if for each positive integer n ∈ [a,b] there exists a graph G on p vertices such that W(G) = n. For any positive integer p, an interval [a,b] is said to be p-Wiener free interval (p-hyper-Wiener free interval) if there exist no graph G on p vertices with a ≤ W(G) ≤ b (a ≤ WW(G) ≤ b). In this paper, we determine some p-Wiener intervals and p-Wiener free intervals for some fixed positive integer p.
Źródło:
Discussiones Mathematicae Graph Theory; 2012, 32, 1; 121-127
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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