منابع مشابه
Independent domination in directed graphs
In this paper we initialize the study of independent domination in directed graphs. We show that an independent dominating set of an orientation of a graph is also an independent dominating set of the underlying graph, but that the converse is not true in general. We then prove existence and uniqueness theorems for several classes of digraphs including orientations of complete graphs, paths, tr...
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Let G = (V,E) be a simple un-weighted graph, and let → d= (d1, d2, · · ·, dm) be a sequence of positive reals. For a positive real r, let Sr denote the circle on R 2 centered at the origin with circumference r. A circular r−coloring for G with distance constraint → d is a mapping f : V (G) → Sr such that |f(u) − f(v)|r ≥ di, whenever the distance between u and v in G is i (where |x− y|r is the ...
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Let $D=(V,A)$ be a finite simple directed graph. A function$f:Vlongrightarrow {-1,0,1}$ is called a twin minus dominatingfunction (TMDF) if $f(N^-[v])ge 1$ and $f(N^+[v])ge 1$ for eachvertex $vin V$. The twin minus domination number of $D$ is$gamma_{-}^*(D)=min{w(f)mid f mbox{ is a TMDF of } D}$. Inthis paper, we initiate the study of twin minus domination numbersin digraphs and present some lo...
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The study of distance-regular directed graphs can be reduced to that of short distance-regular directed graphs. We consider the eigenspaces of the intersection matrix of a short distance-regular directed graph and show that nearly all the eigenvalues are nonreal. Next we show that a nontrivial short distance-regular directed graph is primitive.
متن کاملThe Directed Distance Dimension of Oriented Graphs
For a vertex v of a connected oriented graph D and an ordered set W = {w1, w2, . . . , wk} of vertices of D, the (directed distance) representation of v with respect to W is the ordered k-tuple r(v ∣ ∣ W ) = (d(v,w1), d(v, w2), . . . , d(v, wk)), where d(v, wi) is the directed distance from v to wi. The set W is a resolving set for D if every two distinct vertices of D have distinct representat...
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ژورنال
عنوان ژورنال: Mathematica Bohemica
سال: 1997
ISSN: 0862-7959,2464-7136
DOI: 10.21136/mb.1997.125917