منابع مشابه
Hypo-efficient domination and hypo-unique domination
For a graph $G$ let $gamma (G)$ be its domination number. We define a graph G to be (i) a hypo-efficient domination graph (or a hypo-$mathcal{ED}$ graph) if $G$ has no efficient dominating set (EDS) but every graph formed by removing a single vertex from $G$ has at least one EDS, and (ii) a hypo-unique domination graph (a hypo-$mathcal{UD}$ graph) if $G$ has at least two minimum dominating sets...
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Let / be an integer-valued function defined on the vertex set V(G) of a graph G. A subset D of V(G) is an /-dominating set if each vertex x outside D is adjacent to at least f(x) vertices in D. The minimum number of vertices in an /-dominating set is denned to be the /-domination number, denoted by 7/(G). In a similar way one can define the connected and total /-domination numbers 7 C| /(G) and...
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A dominating set of a graph G is a vertex subset that any vertex of G either belongs to or is adjacent to. A total dominating set is a dominating set whose induced subgraph does not contain isolated vertices. The minimal size of a total dominating set, the total domination number, is denoted by γt. The maximal size of an inclusionwise minimal total dominating set, the upper total domination num...
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The domination number γ(G), the independent domination number ι(G), the connected domination number γc(G), and the paired domination number γp(G) of a graph G (without isolated vertices, if necessary) are related by the simple inequalities γ(G) ≤ ι(G), γ(G) ≤ γc(G), and γ(G) ≤ γp(G). Very little is known about the graphs that satisfy one of these inequalities with equality. I.E. Zverovich and V...
متن کاملSymplectic subspaces of symplectic Grassmannians
Let V be a non-degenerate symplectic space of dimension 2n over the field F and for a natural number l < n denote by Cl(V ) the incidence geometry whose points are the totally isotropic l-dimensional subspaces of V . Two points U, W of Cl (V ) will be collinear when W ⊂ U⊥ and dim(U ∩ W ) = l − 1 and then the line on U and W will consist of all the l-dimensional subspaces of U + W which contain...
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ژورنال
عنوان ژورنال: Bulletin of the London Mathematical Society
سال: 2020
ISSN: 0024-6093,1469-2120
DOI: 10.1112/blms.12402