10320854
Conformance testing of protocols specified as communicating FSMs
An approach for conformance testing of protocols specified as a collection of communicating finite state machines (FSMs) with two parts, pruning and a guided random walk procedure, is presented. First the protocol is pruned to various sets of machines; each set provides only one service. This significantly reduces the test sequence length. Then a guided random walk procedure that attempts to cover all transitions in the component FSMs is used. The results of applying the procedure to the full-duplex alternating bit protocol and the asynchronous transfer mode (ATM) adaptation layer convergence protocol are presented. For the ATM adaptation layer, 99% of component FSMs' edges can be covered in a test with 11692 input steps. Previous approaches cannot generate conformance tests for standard protocols (such as ATM adaptation layer) specified as a collection of communicating FSMs.<<ETX>>
45853491
Testing Finite-State Machines: State Identification and Verification
We study the complexity of two fundamental problems in the testing of finite-state machines. 1) Distinguishing sequences (state identification). We show that it is PSPACE-complete to determine whether a finite-state machine has a preset distinguishing sequence. There are machines that have distinguishing sequences, but only of exponential length. We give a polynomial time algorithm that determines whether a finite-state machine has an adaptive distinguishing sequence. (The previous classical algorithms take exponential time.) Furthermore, if there is an adaptive distinguishing sequence, then we give an efficient algorithm that constructs such a sequence of length at most n(n/spl minus/1)/2 (which is the best possible), where n is the number of states. 2) Unique input output sequences (state verification). It is PSPACE-complete to determine whether a state of a machine has a unique input output sequence. There are machines whose states have unique input output sequences but only of exponential length. >
11856887
Approximation of linear functionals on a banach space with a Gaussian measure
Abstract We study approximation of linear functionals on separable Banach spaces equipped with a Gaussian measure. We study optimal information and optimal algorithms in average case, probabilistic, and asymptotic settings, for a general error criterion. We prove that adaptive information is not more powerful than nonadaptive information and that μ-spline algorithms, which are linear, are optimal in all three settings. Some of these results hold for approximation of linear operators. We specialize our results to the space of functions with continuous r th derivatives, equipped with a Wiener measure. In particular, we show that the natural splines of degree 2 r + I yield the optimal algorithms. We apply the general results to the problem of integration.
206418940
Residual Analysis for Feature Detection
It is shown that in a very simple form residual analysis achieves results that are at least as good as if not better than those obtained by other techniques. There are many ways for extensions of the method. For example, moving average filters of regularization can be used to obtain the residual images. Also, the strength of the correlation, measured by D/sub rr/(O), can be used to eliminate noise, weak edges, etc. A more ambitious extension is by considering smoothing filters that leave invariant the function representing the reflectance from smooth surfaces. >
206832588
Optimization problems from feature testing of communication protocols
In feature testing of communication protocols, we want to construct a minimal number of tests with a desirable fault coverage. We model the protocols by extended finite state machines and reduce the test generation process to optimization problems on graphs. We study efficient algorithms and their complexity. We report experimental results on real systems, including Personal HandyPhone System, a 5ESS based ISDN wireless system, and 5ESS Intelligent Network Application Protocol.
38528864
Coping With Discontinuities In Computer Vision: Their Detection, Classification, And Measurement
7800252
Imprecise data computation for high performance asynchronous processors
Instruction level parallelism(ILP) is strictly limited by various dependencies. In particular , data dependency is the major performance bottleneck of data intensive applications. To accelerate the execution of sequential code serialized due to data dependencies, this paper proposes an imprecise computation as a fast data computing technique for a high-performance asynchronous processor. To show the performance benefits of the suggested computing model, simulation results are presented. The imprecise computation can be used effectively in data intensive processing with a microprocessor, a Digital Signal Processor or a multimedia processor.
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.
995590
k best cuts for circular-arc graphs
Given a set ofn nonnegativeweighted circular arcs on a unit circle, and an integerk, thek Best Cust for Circular-Arcs problem, abbreviated as thek-BCCA problem, is to find a placement ofk points, calledcuts, on the circle such that the total weight of the arcs that contain at least one cut is maximized.We first solve a simpler version, thek Best Cuts for Intervals (k-BCI) problem, inO(kn+n logn) time andO(kn) space using dynamic programming. The algorithm is then extended to solve a variation, called thek-restricted BCI problem, and the space complexity of thek-BCI problem can be improved toO(n). Based on these results, we then show that thek-BCCA problem can be solved inO(I(k,n)+nlogn) time, whereI(k, n) is the time complexity of thek-BCI problem. As a by-product, thek Maximum Cliques Cover problem (k>1) for the circular-arc graphs can be solved inO(I(k,n)+nlogn) time.
38005392
Towards Web-Based Computing
In a problem solving environment for geometric computing, a graphical user interface, or GUI, for visualization has become an essential component for geometric software development. In this paper we describe a visualization system, called GeoJAVA, which consists of a GUI and a geometric visualization library that enables the user or algorithm designer to (1) execute and visualize an existing algorithm in the library or (2) develop new code over the Internet. The library consists of geometric code written in C/C++. The GUI is written using the Java programming language. Taking advantage of the socket classes and system-independent application programming interfaces (API's) provided with the Java language, GeoJAVA offers a platform independent environment for distributed geometric computing that combines Java and C/C++. Users may remotely join a "channel" or discussion group in a location transparent manner to do collaborative research. The visualization of an algorithm, a C/C++ program located locally or remotely and controlled by a "floor manager", can be viewed by all the members in the channel through a visualization sheet called GeoJAVASheet. A chat box is also provided to enable dialogue among the members. Furthermore, this system not only allows visualization of pre-compiled geometric code, but also serves as a web-based programming environment where the user may submit a geometric code, compile it with the libraries provided by the system, and visualize it directly over the web sharing it with other users immediately.
17000976
A Faster One-Dimensional Topological Compaction Algorithm
We consider the problem of one-dimensional topological compaction with jog insertions. Combining both geometric and graph theoretic approaches we present a faster and simpler algorithm, improving over previous results. The compaction algorithm takes as input a sketch consisting of a set F of features and a set W of wires, and minimizes the horizontal width of the sketch while maintaining its routability. The algorithm consists of the following steps: constructing a horizontal constraint graph, computing all possible jog positions, computing the critical path, relocating the features and reconstructing a new sketch homotopic to the input sketch suitable for detailed routing. The algorithm runs in O(|F| · |W|) worst-case time and space, which is asymptotically optimal in the worst case. Experimental results are also presented.