WDM and Directed Star Arboricity
نویسندگان
چکیده
منابع مشابه
WDM and Directed Star Arboricity
A digraph is m-labelled if every arcs is labelled by an integer in {1, . . . , m}. Motivated by wavelength assignment for multicasts in optical star networks, we study n-fiber colourings of labelled digraph which are colourings of the arcs of D such that at each vertex v, for each colour in λ, in(v, λ) + out(v, λ) ≤ n with in(v, λ) the number of arcs coloured λ entering v and out(v, λ) the numb...
متن کاملStar arboricity
A star forest is a forest all of whose components are stars. The star arboricity, st(G) of a graph G is the minimum number of star forests whose union covers all the edges of G. The arboricity, A(G), of a graph G is the minimum number of forests whose union covers all the edges of G. Clearly st(G) > A(G). In fact, Algor and Alon have given examples which show that in some cases st(G) can be as ...
متن کاملAcircuitic directed star arboricity of planar graphs with large girth
A directed star forest is a forest all of whose components are stars with arcs emanating from the center to the leaves. The acircuitic directed star arboricity of an oriented graph G is the minimum number of edge-disjoint directed star forests whose union covers all edges of G and such that the union of two such forests is acircuitic. We show that graphs with maximum average degree less than 7 ...
متن کاملOn star and caterpillar arboricity
We give new bounds on the star arboricity and the caterpillar arboricity of planar graphs with given girth. One of them answers an open problem of Gyárfás and West: there exist planar graphs with track number 4. We also provide new NP-complete problems.
متن کاملOn the star arboricity of hypercubes
A hypercube Qn is a graph in which the vertices are all binary vectors of length n, and two vertices are adjacent if and only if their components differ in exactly one place. A galaxy or a star forest is a union of vertex disjoint stars. The star arboricity of a graph G, sa(G), is the minimum number of galaxies which partition the edge set of G. In this paper among other results, we determine t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Combinatorics, Probability and Computing
سال: 2010
ISSN: 0963-5483,1469-2163
DOI: 10.1017/s0963548309990551