منابع مشابه
Positive binary labelling of graphs
(V,E) be a finite undirected graph with vertex set V and edge set E. A mapping f ~ {O.l}m is called an M-coding of G, if the induced mapping g : V ~ {O,l • defined as g(v) f(uv). assigns ueV,uveE different vectors to the vertices of G, where all summations are mod 2.An M-coding f is calle~ positive if the zero vector is not assigned to any edge and the induced labelling g does not assign the ze...
متن کاملGood edge-labelling of graphs
A good edge-labelling of a graph G is a labelling of its edges such that for any two distinct vertices u, v, there is at most one (u, v)-path with non-decreasing labels. This notion was introduced in [3] to solve wavelength assignment problems for specific categories of graphs. In this paper, we aim at characterizing the class of graphs that admit a good edge-labelling. First, we exhibit infini...
متن کاملCanonical Labelling of Site Graphs
We investigate algorithms for canonical labelling of site graphs, i.e. graphs in which edges bind vertices on sites with locally unique names. We first show that the problem of canonical labelling of site graphs reduces to the problem of canonical labelling of graphs with edge colourings. We then present two canonical labelling algorithms based on edge enumeration, and a third based on an exten...
متن کاملLabelling Graphs with the Circular Difference∗
For positive integers k and d ≥ 2, a k-S(d, 1)-labelling of a graph G is a function on the vertex set of G, f : V (G) → {0, 1, 2, · · · , k− 1}, such that |f(u)− f(v)|k ≥ { d if dG(u, v) = 1; 1 if dG(u, v) = 2, where |x|k = min{|x|, k − |x|} is the circular difference modulo k. In general, this kind of labelling is called the S(d, 1)-labelling. The σdnumber of G, σd(G), is the minimum k of a k-...
متن کاملL(0, 1)-Labelling of Cactus Graphs
An -labelling of a graph is an assignment of nonnegative integers to the vertices of such that the difference between the labels assigned to any two adjacent vertices is at least zero and the difference between the labels assigned to any two vertices which are at distance two is at least one. The span of an 0,1 L G G 0,1 L -labelling is the maximum label number assigned to any vertex of...
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ژورنال
عنوان ژورنال: Nature
سال: 1985
ISSN: 0028-0836,1476-4687
DOI: 10.1038/318586b0