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Wyszukujesz frazę "tree graph" wg kryterium: Temat


Tytuł:
On the tree graph of a connected graph
Autorzy:
Figueroa, Ana
Rivera-Campo, Eduardo
Powiązania:
https://bibliotekanauki.pl/articles/743083.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
tree graph
property Δ*
property Δ⁺
Opis:
Let G be a graph and C be a set of cycles of G. The tree graph of G defined by C, is the graph T(G,C) that has one vertex for each spanning tree of G, in which two trees T and T' are adjacent if their symmetric difference consists of two edges and the unique cycle contained in T ∪ T' is an element of C. We give a necessary and sufficient condition for this graph to be connected for the case where every edge of G belongs to at most two cycles in C.
Źródło:
Discussiones Mathematicae Graph Theory; 2008, 28, 3; 501-510
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
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:
2-placement of (p,q)-trees
Autorzy:
Orchel, Beata
Powiązania:
https://bibliotekanauki.pl/articles/743376.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
tree
bipartite graph
packing graph
Opis:
Let G = (L,R;E) be a bipartite graph such that V(G) = L∪R, |L| = p and |R| = q. G is called (p,q)-tree if G is connected and |E(G)| = p+q-1.
Let G = (L,R;E) and H = (L',R';E') be two (p,q)-tree. A bijection f:L ∪ R → L' ∪ R' is said to be a biplacement of G and H if f(L) = L' and f(x)f(y) ∉ E' for every edge xy of G. A biplacement of G and its copy is called 2-placement of G. A bipartite graph G is 2-placeable if G has a 2-placement. In this paper we give all (p,q)-trees which are not 2-placeable.
Źródło:
Discussiones Mathematicae Graph Theory; 2003, 23, 1; 23-36
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Clique graph representations of ptolemaic graphs
Autorzy:
McKee, Terry
Powiązania:
https://bibliotekanauki.pl/articles/744102.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Ptolemaic graph
clique graph
chordal graph
clique tree
graph representation
Opis:
A graph is ptolemaic if and only if it is both chordal and distance-hereditary. Thus, a ptolemaic graph G has two kinds of intersection graph representations: one from being chordal, and the other from being distance-hereditary. The first of these, called a clique tree representation, is easily generated from the clique graph of G (the intersection graph of the maximal complete subgraphs of G). The second intersection graph representation can also be generated from the clique graph, as a very special case of the main result: The maximal Pₙ-free connected induced subgraphs of the p-clique graph of a ptolemaic graph G correspond in a natural way to the maximal $P_{n+1}$-free induced subgraphs of G in which every two nonadjacent vertices are connected by at least p internally disjoint paths.
Źródło:
Discussiones Mathematicae Graph Theory; 2010, 30, 4; 651-661
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Arboreal structure and regular graphs of median-like classes
Autorzy:
Brešar, Bostjan
Powiązania:
https://bibliotekanauki.pl/articles/743403.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
median graph
tree
gatedness
amalgam
periphery
regular graph
Opis:
We consider classes of graphs that enjoy the following properties: they are closed for gated subgraphs, gated amalgamation and Cartesian products, and for any gated subgraph the inverse of the gate function maps vertices to gated subsets. We prove that any graph of such a class contains a peripheral subgraph which is a Cartesian product of two graphs: a gated subgraph of the graph and a prime graph minus a vertex. Therefore, these graphs admit a peripheral elimination procedure which is a generalization of analogous procedure in median graphs. We characterize regular graphs of these classes whenever they enjoy an additional property. As a corollary we derive that regular weakly median graphs are precisely Cartesian products in which each factor is a complete graph or a hyperoctahedron.
Źródło:
Discussiones Mathematicae Graph Theory; 2003, 23, 2; 215-225
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Graphs that are Critical for the Packing Chromatic Number
Autorzy:
Brešar, Boštjan
Ferme, Jasmina
Powiązania:
https://bibliotekanauki.pl/articles/32318620.pdf
Data publikacji:
2022-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
packing coloring
critical graph
diameter
block graph
tree
Opis:
Given a graph G, a coloring c : V (G) → {1, …, k} such that c(u) = c(v) = i implies that vertices u and v are at distance greater than i, is called a packing coloring of G. The minimum number of colors in a packing coloring of G is called the packing chromatic number of G, and is denoted by χρ(G). In this paper, we propose the study of χρ-critical graphs, which are the graphs G such that for any proper subgraph H of G, χρ(H) < χρ(G). We characterize χρ-critical graphs with diameter 2, and χρ-critical block graphs with diameter 3. Furthermore, we characterize χρ-critical graphs with small packing chromatic number, and we also consider χρ-critical trees. In addition, we prove that for any graph G and every edge e ∈ E(G), we have (χρ(G)+1)/2 ≤ χρ(G−e) ≤ χρ(G), and provide a corresponding realization result, which shows that χρ(G − e) can achieve any of the integers between these bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 2; 569-589
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On non-z(mod k) dominating sets
Autorzy:
Caro, Yair
Jacobson, Michael
Powiązania:
https://bibliotekanauki.pl/articles/743399.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
dominating set
tree
unicyclic graph
Opis:
For a graph G, a positive integer k, k ≥ 2, and a non-negative integer with z < k and z ≠ 1, a subset D of the vertex set V(G) is said to be a non-z (mod k) dominating set if D is a dominating set and for all x ∈ V(G), |N[x]∩D| ≢ z (mod k).For the case k = 2 and z = 0, it has been shown that these sets exist for all graphs. The problem for k ≥ 3 is unknown (the existence for even values of k and z = 0 follows from the k = 2 case.) It is the purpose of this paper to show that for k ≥ 3 and with z < k and z ≠ 1, that a non-z(mod k) dominating set exist for all trees. Also, it will be shown that for k ≥ 4, z ≥ 1, 2 or 3 that any unicyclic graph contains a non-z(mod k) dominating set. We also give a few special cases of other families of graphs for which these dominating sets must exist.
Źródło:
Discussiones Mathematicae Graph Theory; 2003, 23, 1; 189-199
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spanning tree congestion of rooks graphs
Autorzy:
Kozawa, Kyohei
Otachi, Yota
Powiązania:
https://bibliotekanauki.pl/articles/743607.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spanning tree congestion
Rook's graph
Opis:
Let G be a connected graph and T be a spanning tree of G. For e ∈ E(T), the congestion of e is the number of edges in G joining the two components of T - e. The congestion of T is the maximum congestion over all edges in T. The spanning tree congestion of G is the minimum congestion over all its spanning trees. In this paper, we determine the spanning tree congestion of the rook's graph Kₘ ☐ Kₙ for any m and n.
Źródło:
Discussiones Mathematicae Graph Theory; 2011, 31, 4; 753-761
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
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 Trees as Star Complements in Regular Graphs
Autorzy:
Rowlinson, Peter
Powiązania:
https://bibliotekanauki.pl/articles/31562766.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
eigenvalue
regular graph
star complement
tree
Opis:
Let G be a connected r-regular graph (r > 3) of order n with a tree of order t as a star complement for an eigenvalue µ ∉ {−1, 0}. It is shown that n ≤ 1/2 (r + 1)t − 2. Equality holds when G is the complement of the Clebsch graph (with µ = 1, r = 5, t = 6, n = 16).
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 621-636
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
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:
Statuses and double branch weights of quadrangular outerplanar graphs
Autorzy:
Bielak, Halina
Powroźnik, Kamil
Powiązania:
https://bibliotekanauki.pl/articles/747004.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
Centroid
median
outerplanar graph
status
tree
Opis:
In this paper we study some distance properties of outerplanar graphs with the Hamiltonian cycle whose all bounded faces are cycles isomorphic to the cycle C4. We call this family of graphs quadrangular outerplanar graphs. We give the lower and upper bound on the double branch weight and the status for this graphs. At the end of this paper we show some relations between median and double centroid in quadrangular outerplanar graphs.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica; 2015, 69, 1
0365-1029
2083-7402
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Difference labelling of digraphs
Autorzy:
Sonntag, Martin
Powiązania:
https://bibliotekanauki.pl/articles/744591.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph labelling
difference digraph
oriented tree
Opis:
A digraph G is a difference digraph iff there exists an S ⊂ N⁺ such that G is isomorphic to the digraph DD(S) = (V,A), where V = S and A = {(i,j):i,j ∈ V ∧ i-j ∈ V}.For some classes of digraphs, e.g. alternating trees, oriented cycles, tournaments etc., it is known, under which conditions these digraphs are difference digraphs (cf. [5]). We generalize the so-called source-join (a construction principle to obtain a new difference digraph from two given ones (cf. [5])) and construct a difference labelling for the source-join of an even number of difference digraphs. As an application we obtain a sufficient condition guaranteeing that certain (non-alternating) trees are difference digraphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 3; 509-527
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decompositions of Cubic Traceable Graphs
Autorzy:
Liu, Wenzhong
Li, Panpan
Powiązania:
https://bibliotekanauki.pl/articles/31867897.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
decomposition
cubic traceable graph
spanning tree
matching
2-regular graph
Opis:
A traceable graph is a graph with a Hamilton path. The 3-Decomposition Conjecture states that every connected cubic graph can be decomposed into a spanning tree, a 2-regular graph and a matching. We prove the conjecture for cubic traceable graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 35-49
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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