17000769
On crossing minimization problem
In this paper, we consider a problem related to global routing postoptimization: the crossing minimization problem (CMP). Given a global routing representation, the CMP is to minimize redundant crossings between every pair of nets. In particular, there are two kinds of CMP: constrained CMP (CCMP) and unconstrained CMP (UCMP). These problems have been studied previously where an O(m/sup 2/n) algorithm was proposed for CCMP, and where an (mn/sup 2/+/spl xi//sup 2/) algorithm was proposed for UCMP where m is the total number of modules, n is the number of nets, and /spl xi/ is the number of crossings defined by an initial global routing topology. We present a simpler and faster O(mn) algorithm for CCMP and an O[n(m+/spl xi/)] time algorithm for UCMP. Both algorithms improve over the time bounds of the previously proposed algorithms. The novel part of our algorithm is that it uses the plane embedding information of globally routed nets in the routing area to construct a graph-based framework and obtain a good junction terminal assignment that minimizes the number of crossings.
10484740
Labeling Points on a Single Line
In this paper, we consider a map labeling problem where the points to be labeled are restricted on a line. It is known that the 1d-4P and the 1d-4S unit-square label placement problem and the Slope-4P unit-square label placement problem can both be solved in linear time and the Slope-4S unit-square label placement problem can be solved in quadratic time in Ref. [8]. We extend the result to the following label placement problem: Slope-4P fixed-height (width) label or elastic label placement problem and present a linear time algorithm for it provided that the input points are given sorted. We further show that if the points are not sorted, the label placement problems have a lower bound of Ω(n log n), where n is the input size, under the algebraic computation tree model. Optimization versions of these point labeling problems are also considered.
34901507
A faster algorithm for rubber-band equivalent transformation for planar VLSI layouts
In this paper we consider the problem of transforming a single-layer topological routing of n two-terminal nets into a rubber-band equivalent using rectilinear wires in the presence of rectilinear circuit modules. Given a topological planar VLSI layout sketch with |F| features and |W| noncrossing wire segments connecting n two-terminal nets, we present an O(|F|/spl middot/|W|) time algorithm to do the vertex-disjoint rubber-band equivalent transformation of these n nets if it exists. The algorithm consists of two phases, computing a loose homotopy with four spokes matrices, and computing a vertex-disjoint rubber-band equivalent of the given homotopy, each phase taking O(|F|/spl middot/|W|) time and space. Both complexities are asymptotically optimal in the worst case. From the vertex-disjoint rubber-band equivalent of the given homotopy, one can obtain the detailed routing within the same time complexity. Experimental results are also presented.
18326125
Finding Rectilinear Paths Among Obstacles in a Two-Layer Interconnection Model
Finding the best rectilinear path with respect to the bends and teh lengths of paths connecting two given points in the presence of rectilinear obstacles in a two-layer model is studied in this paper. In this model, rectilinear obstacles on each layer are specified separately, and the orientation of routing in each layer is fixed. An algorithm is presented to transform any problem instance in the two-layer model to one in a one-layer model, so that almost all algorithms for finding rectilinear paths among obstacles in the plane can be applied. The transformation algorithm runs in O(e log e) time where e is the number of edges on obstacles lying on both layers. A direct graph-theoretic approach to finding a shortest path in the two-layer model, which is easier to implement is also presented. The algorithm runs in O(e log2 e) time.
16325574
Finding an Approximate Minimum-Link Visibility Path Inside a Simple Polygon
37965905
Rectilinear Paths among Rectilinear Obstacles
Given a set of obstacles and two distinguished points in the plane the problem of finding a collision-free path subject to a certain optimization function is a fundamental problem that arises in many fields, such as motion planning in robotics, wire routing in VLSI and logistics in operations research. In this survey we emphasize its applications to VLSI design and limit ourselves to the rectilinear domain in which the goal path to be computed and the underlying obstacles are all rectilinearly oriented, i.e., the segments are either horizontal or vertical. We consider different routing environments, and various optimization criteria pertaining to VLSI design, and provide a survey of results that have been developed in the past, present current results and give open problems for future research.
42364168
An Algorithm for Incremental Nearest Neighbor Search in High-Dimensional Data Spaces
The SPY-TEC (Spherical Pyramid-Technique) [8] was proposed as a new indexing method for high-dimensional data spaces using a special partitioning strategy that divides a d-dimensional data space into 2d spherical pyramids. Although the authors of [8] proposed an efficient algorithm for processing hyperspherical range queries, they did not propose an algorithm for processing k-nearest neighbor queries that are frequently used in similarity search. In this paper, we propose an efficient algorithm for processing exact nearest neighbor queries on the SPY-TEC by extending the incremental nearest neighbor algorithm proposed in [10]. We also introduce a metric that can be used to guide an ordered best-first traversal when finding nearest neighbors on the SPYTEC. Finally, we show that our technique significantly outperforms the related techniques in processing k-nearest neighbor queries by comparing it to the R*-tree, the X-tree, and the sequential scan through extensive experiments.
31110512
Discontinuity Detection and Thresholding-A Stochastic Approach
We study discontinuity detection and thresholding using a stochastic approach. We discuss a general form of detectors, which includes a number of well known detectors as special cases. Thresholding is indispensable to eliminate spurious responses from the detection process. We propose a Weighted Thresholding, which is designed to cope with a variety of anomalies. Our analysis and experimental results on real images show that intelligent thresholding methods can make a significant difference for discontinuity detection.
7421438
A reliable position estimation method of the service robot by map matching
In this paper, a reliable position estimation method of the indoor service robot is proposed. The service robot PSR1 is a wheeled mobile manipulator which navigates in office buildings. Our localization method is a map-matching scheme using scanned range data, without using any artificial landmark. The proposed algorithm can provide solutions for both a global localization problem and a local position tracking. A probabilistic position estimation scheme is designed based on MCL (Monte Carlo localization). Two measure functions are developed for computing positional probabilities. The robot automatically decides whether it uses geometric pattern matching (i.e. walls, pillars) by Hough transform. The proposed scheme shows reliable performance in both polygonal environments and non-polygonal environments even there exist many obstacles. Experimental results demonstrate the validity and feasibility of the proposed localization algorithm for the service robot to navigate in an office building, using the natural environmental characteristics.
16966197
Integrated system interoperability testing with applications to VoIP
This work has been motivated by the need to test interoperability of systems carrying voice calls over the IP network. The voice over IP (VoIP) systems must be integrated and interoperate with the existing public switched telephone network (PSTN) before they are widely adopted. Standards have been developed to address this problem, but unfortunately different standards bodies and commercial consortiums have defined different standards. Furthermore, the prevailing VoIP standard such as H.323 is incomplete, complex, and presents the implementers with "vendors latitudes". As a result, there is no guarantee that the integrated VoIP systems would interoperate properly even if the implementations are all H.323-compliant. Thus interoperability testing has become indispensable. We want to test all the system interoperations by exercising all the required patterns of "interoperating behaviors". On the other hand, test execution in real environment is expensive, and we want to minimize the number of tests while maintaining the coverage. We present a general method for automatic generation of test cases, which cover all the required system interoperations and contain a minimal number of tests. We study data structures and efficient test generation algorithms, which take time proportional to the total test case size. Finally, we report experimental results on VoIP systems.
7389460
Fault Detection of Hierarchical Networks with Probabilistic Testing Algorithms
As communications networks are expanding to larger areas the control and maintenance of routing information are becoming a formidable task. To cope with its size and complexity and to make the network reliable and scalable hierarchical network has been proposed with new features to support the information infrastructure. However, the network hierarchy adds more complications to the network design and implementations and that hampers the network reliability and quality of services. Conformance testing is known to be a powerful tool for network fault detection yet most of the works in the published literature are on networks without hierarchy. We present probabilistic algorithms for testing hierarchical networks along with the added features. Based on a formal model of the networks, we provide a formal analysis that shows that our probabilistic algorithms guarantee a high fault coverage with a feasible number of tests. To further reduce the number of tests we identify test equivalence classes and that enables us to significantly reduce the number of tests yet without losing the fault coverage. Experimental results on Internet OSPF protocol are reported.