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Journals and Conferences
The group Steiner tree problem is a generalization of the Steiner tree problem where we are given several subsets (groups) of vertices in a weighted graph, and the goal is to find a minimum-weight connected subgraph containing at least one vertex from each group. The problem was introduced by Reich and Widmayer and linds applications in VLSI design. The… (More)
Network-on-chip (NoC) has been proposed as a solution for the communication challenges of system-on-chip (SoC) design in the nanoscale regime. SoC design offers the opportunity for incorporating custom NoC architectures that are more suitable for a particular application, and do not necessarily conform to regular topologies. This paper presents novel linear… (More)
Given a finite set of '~red" elements R, a finite set of "blue" elements B and a family ,.q C 2 RuB, the red-blue set cover problem is to find a subfamily C _C S which covers all blue elements, but which covers the minimum possible number of red elements. We note that RED-BLuE SET COVER is closely related to several combinatorial optimization problems… (More)
We present simple semi-definite programming relaxations for the NP-hard minimum bandwidth and minimum length linear ordering problems. We then show how these relaxations can be rounded in a natural way (via random projection) to obtain new approximation guarantees for both of these vertex-ordering problems.
Network-on-chip (NoC) has been proposed as a solution to the communication challenges of system-on-chip (SoC) design in nanoscale technologies. Application specific SoC design offers the opportunity for incorporating custom NoC architectures that are more suitable for a particular application, and do not necessarily conform to regular topologies. Custom NoC… (More)
We combine the results of Bartal [Proc. 37th FOCS, 1996, pp. 184–193] on probabilistic approximation of metric spaces by tree metrics, with those of Klein, Plotkin and Rao [Proc. 25th STOC, 1993, pp. 682–690] on decompositions of graphs without small Ks,s minors (such as planar graphs) to show that metrics induced by such graphs (with unit lengths on the… (More)
A tree (tour) cover of an edge-weighted graph is a set of edges which forms a tree (closed walk) and covers every other edge in the graph. Arkin et al. give approximation algorithms with ratios 3.55 (tree cover) and 5.5 (tour cover). We present algorithms with a worst-case ratio of 3 for both problems.
We study ways to restrict or prevent the damage that can be caused in a peer-to-peer network by corrupt entities creating multiple pseudonyms. We show that it is possible to <i>remotely</i> issue certificates that can be used to test the distinctness of identities. To our knowledge, this is the first work that shows that remote anonymous certification of… (More)