Now showing items 1-5 of 5

    • Fast approximation schemes for K_{3,3}-minor-free or K_{5}-minor-free graphs 

      Hajiaghayi, Mohammad Taghi; Nishimura, Naomi; Ragde, Prabhakar; Thilikos Touloupas, Dimitrios (2002-05)
      External research report
      Open Access
      As the class of graphs of bounded treewidth is of limited size, we need to solve NP-hard problems for wider classes of graphs than this class. Eppstein introduced a new concept which can be considered as a generalization ...
    • Fast fixed-parameter tractable algorithms for (nontrivial) generalizations of vertex cover 

      Nishimura, Naomi; Ragde, Prabhakar; Thilikos Touloupas, Dimitrios (2001-09)
      External research report
      Open Access
      Our goal in this paper is the development of fast algorithms for recognizing general classes of graphs. We seek algorithms whose complexity can be expressed as a linear function of the graph size plus an exponential function ...
    • Finding smallest supertrees under minor containment 

      Nishimura, Naomi; Prabhakar, Ragde; Thilikos Touloupas, Dimitrios (1999-10)
      External research report
      Open Access
      The diversity of application areas relying on tree-structured data results in a wide interest in algorithms which determine differences or similarities among trees. One way of measuring the similarity between trees ...
    • On graph powers for leaf-labeled trees 

      Nishimura, Naomi; Prabhakar, Ragde; Thilikos Touloupas, Dimitrios (2000-07)
      External research report
      Open Access
      We extend the well-studied concept of a graph power to that of a k-leaf power G of a tree T: G is formed by creating a node for each leaf in the tree and an edge between a pair of nodes if and only if the associated ...
    • Smaller kernels for hitting set problems of constant arity 

      Nishimura, Naomi; Ragde, Prabhakar; Thilikos Touloupas, Dimitrios (2004-05)
      External research report
      Open Access
      We demonstrate a kernel of size O(k^2) for 3-HITTING SET when all subsets in the collection to be hit are of size at most three), giving a partial answer to an open question of Niedermeier by improving on the O(k^3) ...