Distance Constrained Labelings of Trees
نویسندگان
چکیده
An H(p, q)-labeling of a graph G is a vertex mapping f : VG → VH such that the distance (in the graph H) of f(u) and f(v) is at least p (at least q) if the vertices u and v are adjacent in G (are at distance two in G, respectively). This notion generalizes the notions of L(p, q)and C(p, q)-labelings of graphs studied as a graph model of the Frequency Assignment Problem. We study the computational complexity of the problem of deciding the existence of such a labeling when the graphs G and H come from restricted graph classes. In this way we are extending known results for linear and cyclic labelings of trees, with a hope that our results would help to open a new angle of view on the still open open problem of L(p, q)-labeling of trees for fixed p > q > 1 (i.e., when G is a tree and H a path). Our main results are a polynomial time algorithm for H(p, 1)-labeling of trees for arbitrary H, and NP-completeness results for H(p, q)-labeling of trees when H is a q-caterpillar, and L(p, q)-labeling of trees for fixed q > 1 and p part of input.
منابع مشابه
Distance constrained labelings of K4-minor free graphs
Motivated by previous results on distance constrained labelings and coloring of squares of K4-minor free graphs, we show that for every p ≥ q ≥ 1, there exists ∆0 such that every K4-minor free graph G with maximum degree ∆ ≥ ∆0 has an L(p, q)-labeling of span at most qb3∆(G)/2c. The obtained bound is the best possible.
متن کاملSnakes and Caterpillars in Graceful Graphs
Graceful labelings use a prominent place among difference vertex labelings. In this work we present new families of graceful graphs all of them obtained applying a general substitution result. This substitution is applied here to replace some paths with some trees with a more complex structures. Two caterpillars with the same size are said to be textit{analogous} if thelarger stable sets, in bo...
متن کاملLabeling trees with a condition at distance two
An L(h, k)-labeling of a graph G is an integer labeling of vertices of G, such that adjacent vertices have labels which differ by at least h, and vertices at distance two have labels which differ by at least k. The span of an L(h, k)-labeling is the difference between the largest and the smallest label. We investigate L(h, k)-labelings of trees of maximum degree ∆, seeking those with small span...
متن کاملExact Distance Labelings Yield Additive-Stretch Compact Routing Schemes
Distance labelings and compact routing schemes have both been active areas of recent research. It was already known that graphs with constant-sized recursive separators, such as trees, outerplanar graphs, series-parallel graphs and graphs of bounded treewidth, support both exact distance labelings and optimal (additive stretch 0, multiplicative stretch 1) compact routing schemes, but there are ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2008