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Wyszukujesz frazę "kernel perfect digraph" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
On graphs all of whose {C₃,T₃}-free arc colorations are kernel-perfect
Autorzy:
Galeana-Sánchez, Hortensia
García-Ruvalcaba, José
Powiązania:
https://bibliotekanauki.pl/articles/743429.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
kernel
kernel-perfect digraph
m-coloured digraph
Opis:
A digraph D is called a kernel-perfect digraph or KP-digraph when every induced subdigraph of D has a kernel.
We call the digraph D an m-coloured digraph if the arcs of D are coloured with m distinct colours. A path P is monochromatic in D if all of its arcs are coloured alike in D. The closure of D, denoted by ζ(D), is the m-coloured digraph defined as follows:
V( ζ(D)) = V(D), and
A( ζ(D)) = ∪_{i} {(u,v) with colour i: there exists a monochromatic path of colour i from the vertex u to the vertex v contained in D}.
We will denoted by T₃ and C₃, the transitive tournament of order 3 and the 3-directed-cycle respectively; both of whose arcs are coloured with three different colours.
Let G be a simple graph. By an m-orientation-coloration of G we mean an m-coloured digraph which is an asymmetric orientation of G.
By the class E we mean the set of all the simple graphs G that for any m-orientation-coloration D without C₃ or T₃, we have that ζ(D) is a KP-digraph.
In this paper we prove that if G is a hamiltonian graph of class E, then its complement has at most one nontrivial component, and this component is K₃ or a star.
Źródło:
Discussiones Mathematicae Graph Theory; 2001, 21, 1; 77-93
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On (k,l)-kernel perfectness of special classes of digraphs
Autorzy:
Kucharska, Magdalena
Powiązania:
https://bibliotekanauki.pl/articles/744319.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
kernel
(k,l)-kernel
kernel-perfect digraph
Opis:
In the first part of this paper we give necessary and sufficient conditions for some special classes of digraphs to have a (k,l)-kernel. One of them is the duplication of a set of vertices in a digraph. This duplication come into being as the generalization of the duplication of a vertex in a graph (see [4]). Another one is the D-join of a digraph D and a sequence α of nonempty pairwise disjoint digraphs. In the second part we prove theorems, which give necessary and sufficient conditions for special digraphs presented in the first part to be (k,l)-kernel-perfect digraphs. The concept of a (k,l)-kernel-perfect digraph is the generalization of the well-know idea of a kernel perfect digraph, which was considered in [1] and [6].
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 1-2; 103-119
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kernels by Monochromatic Paths and Color-Perfect Digraphs
Autorzy:
Galeana-Śanchez, Hortensia
Sánchez-López, Rocío
Powiązania:
https://bibliotekanauki.pl/articles/31340961.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
kernel
kernel perfect digraph
kernel by monochromatic paths
color-class digraph
quasi color-perfect digraph
color-perfect digraph
Opis:
For a digraph D, V (D) and A(D) will denote the sets of vertices and arcs of D respectively. In an arc-colored digraph, a subset K of V(D) is said to be kernel by monochromatic paths (mp-kernel) if (1) for any two different vertices x, y in N there is no monochromatic directed path between them (N is mp-independent) and (2) for each vertex u in V (D) \ N there exists v ∈ N such that there is a monochromatic directed path from u to v in D (N is mp-absorbent). If every arc in D has a different color, then a kernel by monochromatic paths is said to be a kernel. Two associated digraphs to an arc-colored digraph are the closure and the color-class digraph C(D). In this paper we will approach an mp-kernel via the closure of induced subdigraphs of D which have the property of having few colors in their arcs with respect to D. We will introduce the concept of color-perfect digraph and we are going to prove that if D is an arc-colored digraph such that D is a quasi color-perfect digraph and C(D) is not strong, then D has an mp-kernel. Previous interesting results are generalized, as for example Richardson′s Theorem.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 309-321
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
KP-digraphs and CKI-digraphs satisfying the k-Meyniels condition
Autorzy:
Galeana-Sánchez, H.
Neumann-Lara, V.
Powiązania:
https://bibliotekanauki.pl/articles/972038.pdf
Data publikacji:
1996
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
digraph
kernel
independent set of vertices
absorbing set of vertices
kernel-perfect digraph
critical-kernel-imperfect digraph
τ-system
τ₁-system
indepedent kernel modulo Q
co-rooted tree
τ-construction
τ₁-construction
Opis:
A digraph D is said to satisfy the k-Meyniel’s condition if each odd directed cycle of D has at least k diagonals. The study of the k-Meyniel’s condition has been a source of many interesting problems, questions and results in the development of Kernel Theory. In this paper we present a method to construct a large variety of kernel-perfect (resp. critical kernel-imperfect) digraphs which satisfy the k-Meyniel’s condition.
Źródło:
Discussiones Mathematicae Graph Theory; 1996, 16, 1; 5-16
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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