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Wyświetlanie 1-4 z 4
Tytuł:
The forcing steiner number of a graph
Autorzy:
Santhakumaran, A.
John, J.
Powiązania:
https://bibliotekanauki.pl/articles/743843.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
geodetic number
Steiner number
forcing geodetic number
forcing Steiner number
Opis:
For a connected graph G = (V,E), a set W ⊆ V is called a Steiner set of G if every vertex of G is contained in a Steiner W-tree of G. The Steiner number s(G) of G is the minimum cardinality of its Steiner sets and any Steiner set of cardinality s(G) is a minimum Steiner set of G. For a minimum Steiner set W of G, a subset T ⊆ W is called a forcing subset for W if W is the unique minimum Steiner set containing T. A forcing subset for W of minimum cardinality is a minimum forcing subset of W. The forcing Steiner number of W, denoted by fₛ(W), is the cardinality of a minimum forcing subset of W. The forcing Steiner number of G, denoted by fₛ(G), is fₛ(G) = min{fₛ(W)}, where the minimum is taken over all minimum Steiner sets W in G. Some general properties satisfied by this concept are studied. The forcing Steiner numbers of certain classes of graphs are determined. It is shown for every pair a, b of integers with 0 ≤ a < b, b ≥ 2, there exists a connected graph G such that fₛ(G) = a and s(G) = b.
Źródło:
Discussiones Mathematicae Graph Theory; 2011, 31, 1; 171-181
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the forcing geodetic and forcing steiner numbers of a graph
Autorzy:
Santhakumaran, A.
John, J.
Powiązania:
https://bibliotekanauki.pl/articles/743992.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
geodetic number
Steiner number
forcing geodetic number
forcing Steiner number
Opis:
For a connected graph G = (V,E), a set W ⊆ V is called a Steiner set of G if every vertex of G is contained in a Steiner W-tree of G. The Steiner number s(G) of G is the minimum cardinality of its Steiner sets and any Steiner set of cardinality s(G) is a minimum Steiner set of G. For a minimum Steiner set W of G, a subset T ⊆ W is called a forcing subset for W if W is the unique minimum Steiner set containing T. A forcing subset for W of minimum cardinality is a minimum forcing subset of W. The forcing Steiner number of W, denoted by fₛ(W), is the cardinality of a minimum forcing subset of W. The forcing Steiner number of G, denoted by fₛ(G), is fₛ(G) = min{fₛ(W)}, where the minimum is taken over all minimum Steiner sets W in G. The geodetic number g(G) and the forcing geodetic number f(G) of a graph G are defined in [2]. It is proved in [6] that there is no relationship between the geodetic number and the Steiner number of a graph so that there is no relationship between the forcing geodetic number and the forcing Steiner number of a graph. We give realization results for various possibilities of these four parameters.
Źródło:
Discussiones Mathematicae Graph Theory; 2011, 31, 4; 611-624
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The forcing geodetic number of a graph
Autorzy:
Chartrand, Gary
Zhang, Ping
Powiązania:
https://bibliotekanauki.pl/articles/744241.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
geodetic set
geodetic number
forcing geodetic number
Opis:
For two vertices u and v of a graph G, the set I(u, v) consists of all vertices lying on some u-v geodesic in G. If S is a set of vertices of G, then I(S) is the union of all sets I(u,v) for u, v ∈ S. A set S is a geodetic set if I(S) = V(G). A minimum geodetic set is a geodetic set of minimum cardinality and this cardinality is the geodetic number g(G). A subset T of a minimum geodetic set S is called a forcing subset for S if S is the unique minimum geodetic set containing T. The forcing geodetic number $f_G(S)$ of S is the minimum cardinality among the forcing subsets of S, and the forcing geodetic number f(G) of G is the minimum forcing geodetic number among all minimum geodetic sets of G. The forcing geodetic numbers of several classes of graphs are determined. For every graph G, f(G) ≤ g(G). It is shown that for all integers a, b with 0 ≤ a ≤ b, a connected graph G such that f(G) = a and g(G) = b exists if and only if (a,b) ∉ {(1,1),(2,2)}.
Źródło:
Discussiones Mathematicae Graph Theory; 1999, 19, 1; 45-58
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The upper edge geodetic number and the forcing edge geodetic number of a graph
Autorzy:
Santhakumaran, A. P.
John, J.
Powiązania:
https://bibliotekanauki.pl/articles/255845.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
geodetic number
edge geodetic basis
edge geodetic number
upper edge geodetic number
forcing edge geodetic number
Opis:
An edge geodetic set of a connected graph G of order p ≥ 2 is a set S ⊆ V(G) such that every edge of G is contained in a geodesic joining some pair of vertices in S. The edge geodetic number g1(G) of G is the minimum cardinality of its edge geodetic sets and any edge geodetic set of cardinality g1(G) is a minimum edge geodetic set of G or an edge geodetic basis of G. An edge geodetic set S in a connected graph G is a minimal edge geodetic set if no proper subset of S is an edge geodetic set of G. The upper edge geodetic number g1+(G) of G is the maximum cardinality of a minimal edge geodetic set of G. The upper edge geodetic number of certain classes of graphs are determined. It is shown that for every two integers a and b such that 2 ≤ a ≤ b, there exists a connected graph G with g1(G) = a and g1+(G) = b. For an edge geodetic basis S of G, a subset T ⊆ S is called a forcing subset for S if S is the unique edge geodetic basis containing T. A forcing subset for S of minimum cardinality is a minimum forcing subset of S. The forcing edge geodetic number of S denoted by ƒ1(S), is the cardinality of a minimum forcing subset of S. The forcing edge geodetic number of G, denoted by ƒ1(G), is ƒ1(G) = min{ ƒ1(S)}, where the minimum is taken over all edge geodetic bases S in G. Some general properties satisfied by this concept are studied. The forcing edge geodetic number of certain classes of graphs are determined. It is shown that for every pair a, b of integers with 0 ≤ a < b and b ≥ 2, there exists a connected graph G such thatƒ1(G) = a and g1(G) = b.
Źródło:
Opuscula Mathematica; 2009, 29, 4; 427-441
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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