Distance Constrained Labelings of Trees

نویسندگان

  • Jirí Fiala
  • Petr A. Golovach
  • Jan Kratochvíl
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.

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تاریخ انتشار 2008