6074974
Vertex Ranking of Asteroidal Triple-Free Graphs
We present an efficient algorithm for computing the vertex ranking number of an asteroidal triple-free graph. Its running time is bounded by a polynomial in the number of vertices and the number of minimal separators of the input graph.
34486647
Minimum Fill-In on Circle and Circular-Arc Graphs
We present two algorithms solving the minimum fill-in problem on circle graphs and on circular-arc graphs in time O(n3).
8508688
New algorithms for the rectilinear Steiner tree problem
An approach to constructing the rectilinear Steiner tree (RST) of a given set of points in the plane, starting from a minimum spanning tree (MST), is discussed. The main idea in this approach is to find layouts for the edges of the MST that maximize the overlaps between the layouts, thus minimizing the cost (i.e. wire length) of the resulting rectilinear Steiner tree. Two algorithms for constructing rectilinear Steiner trees from MSTs, which are optimal under the conditions that the layout of each edge of the MST is an L shape or any staircase, respectively, are described. The first algorithm has linear time complexity and the second algorithm has a higher polynomial time complexity. Steiner trees produced by the second algorithm have a property called stability, which allows the rerouting of any segment of the tree, while maintaining the cost of the tree, and without causing overlaps with the rest of the tree. Stability is a desirable property in VLSI global routing applications. >
12009161
Dynamic Placement of Records in Linear Storage
This paper considers allocation of space in a hnear storage medium when space must be allocated dynamically as customers arrive A heuristic is proposed for this problem and for a simple model of the resultmg reference sequence, we show that the average distance between consecutive references is asymptotically 7n/30, where n is the size of the storage For optimal static placement where one waits for all arrivals before any space allocation, the average distance is shown to be asymptotically 7n/30 For random placement, the average distance is asymptotically n/3 Thus, the heuristic is asymptotically optimal in a strong sense For reasonable values of n, we demonstrate that the heuristic is nearly as good as optimal static placement and much better than random placement
7180182
Minimizing mean flow time with error constraint
In a new model of task systems studied by J.W.S. Liu et al. (1987) each task is logically decomposed into two subtasks, mandatory and optional. The authors discuss preemptively scheduling this kind of task system on p>or=1 identical processors so as to minimize the mean flow time. Given a task system and an error threshold K, the goal is to find a preemptive schedule such that each task is executed in the interval of its release time and deadline, the average error is no more than K, and the mean flow time of the schedule is minimized. Such a schedule is called an optimal schedule. It is shown that the problem of finding an optimal schedule is NP-hard for each p>or=1, even if all tasks have the same ready time and deadline. For a single processor, a pseudo-polynomial time algorithm and polynomial time algorithms for various special cases of the problem are given.<<ETX>>
10692185
Optimal and Near-Optimal Scheduling Algorithms for Batched Processing in Linear Storage
In this paper, we consider the accessing of batched requests in a linear storage medium. The batch size is assumed fixed and the access probabilities of individual records known. For a given arrangement of records in the storage, we consider the problem of read/write head scheduling to minimize the expected access time for a batch measured in terms of the distance traveled by the head. In the first part of the paper, several simple algorithms are proposed, analyzed and compared. The effect of different record arrangements is also discussed. In the second part of the paper, a family of algorithms called B-optimal rules are described. When B is $\infty $, an $\infty $-optimal rule is indeed optimal in the sense of minimizing expected distance traveled by the head per batch when accessing an arbitrarily large number of batches. A procedure to calculate an $\infty $-optimal rule for any given record arrangement is described, which is based on the idea of “discrete dynamic programming”.
35666520
Automatic Lyrics Alignment on Popular Music