7761968
A PTAS for Semiconductor Burn-in Scheduling
In this paper a polynomial time approximation scheme, PTAS for short, is presented for the problem of scheduling jobs in a batch processing system. Each job has a pre-defined release date, which indicates when the job is available, and a pre-defined burn-in time, which is the least time needed for processing the job. At one time, at most B jobs can be processed together, where B is a pre-given number. No preemption is permitted.
40174055
A PTAS for Distinguishing (Sub)string Selection
Consider two sets of strings, B (bad genes) and G (good genes), as well as two integers db and dg (db ? dg). A frequently occurring problem in computational biology (andother fields) is to finda (distinguishing) substring s of length L that distinguishes the bad strings from goodstrings, i.e., for each string si ? B there exists a length-L substring ti of si with d(s, ti) ? db (close to badstrings) andfor every substring ui of length L of every string gi ? G, d(s, ui) ? dg (far from goodstrings). We present a polynomial time approximation scheme to settle the problem, i.e., for any constant ? > 0, the algorithm finds a string s of length L such that for every si ? B, there is a length-L substring ti of si with d(ti, s) ? (1+?)db and for every substring ui of length L of every gi ? G, d(ui, s) ? (1 - ?)dg, if a solution to the original pair (db ? dg) exists.
29830975
A PTAS for Minimizing Total Completion Time of Bounded Batch Scheduling
We consider a batch processing system {pi : i = 1, 2,…,n} where pi is the processing time of job i, and up to B jobs can be processed together such that the handling time of a batch is the longest processing time among jobs in the batch. The number of job types m is not fixed and all the jobs are released at the same time. Jobs are executed non-preemptively. Our objective is to assign jobs to batches and sequence the batches so as to minimize the total completion time. The best previously known result is a 2–approximation algorithm. In this paper, we establish the first polynomial time approximation scheme (PTAS) for the problem.
11626813
Sorting Signed Permutations by Fixed-length Reversals
A signed n-permutation is a permutation on {1,2,…,n} in which each element is labelled by a positive or negative sign. Here we consider the problem of sorting signed permutations by fixed-length reversals. Indeed, limiting the transformations to reversals of length exactly k can be very restrictive, for example, (+1,+3,+2,+4,…,+n) can never be sorted to (+1,+2,+3,+4,…,+n) by 2-reversals. That is, for given two signed permutations it is not obvious whether they can be sorted to each other by k-reversals. Thus in 1996, Chen and Skiena gave the following open problem: what is the connectedness of signed permutations under fixed-length reversals? In this paper, we resolve this open problem when "fixed-length" is even, and give a characterization of the connectedness of signed n-permutations under 2l-reversal, for both linear and circular permutations.
26295637
A Linear-Time Algorithm for Computing Translocation Distance between Signed Genomes
The study of evolution based on rearrangements leads to a rearrangement distance problem, i.e., computing the minimum number of rearrangement events required to transform one geonome to another. In this paper we study the translocation distance problem, modeling the evolution of genomes by translocations. We present a linear-time algorithm for computing the translocation distance between signed genomes in this paper, improving a previous O(n 3) bound by Hannenhalli in 1996.
664043
Evolutionary structure learning algorithm for Bayesian network and Penalized Mutual Information metric
The paper formulates the problem of learning Bayesian network structures from data as determining the structure that best approximates the probability distribution indicated by the data. A new metric, Penalized Mutual Information metric, is proposed, and an evolutionary algorithm is designed to search for the best structure among alternatives. The experimental results show that this approach is reliable and promising.
920610
Interactive visualization of three-dimensional vector fields with flexible appearance control
We present an interactive texture-based algorithm for visualizing three-dimensional steady and unsteady vector fields. The goal of the algorithm is to provide a general volume rendering framework allowing the user to compute three-dimensional flow textures interactively and to modify the appearance of the visualization on the fly. To achieve our goal, we decouple the visualization pipeline into two disjoint stages. First, flow lines are generated from the 3D vector data. Various geometric properties of the flow paths are extracted and converted into a volumetric form using a hardware-assisted slice sweeping algorithm. In the second phase of the algorithm, the attributes stored in the volume are used as texture coordinates to look up an appearance texture to generate both informative and aesthetic representations of the vector field. Our algorithm allows the user to interactively navigate through different regions of interest in the underlying field and experiment with various appearance textures. With our algorithm, visualizations with enhanced structural perception using various visual cues can be rendered in real time. A myriad of existing geometry-based and texture-based visualization techniques can also be emulated.
31540088
Analyzing iKP Security in Applied Pi Calculus
The security for electronic payments is very important in electronic commerce. Many electronic payment protocols have been proposed recently to meet the security requirements. Since the design of a protocol is a difficult and error-prone task, the use of formal methods that allow for the verification of such protocols has received increasing attention. In this paper we take a look at the iKP from the point of view of the applied pi calculus. The iKP is described in the calculus and some security properties, mainly the authentication and anonymity properties, are verified.
9002368
Effective keyword-based selection of relational databases
The wide popularity of free-and-easy keyword based searches over World Wide Web has fueled the demand for incorporating keyword-based search over structured databases. However, most of the current research work focuses on keyword-based searching over a single structured data source. With the growing interest in distributed databases and service oriented architecture over the Internet, it is important to extend such a capability over multiple structured data sources. One of the most important problems for enabling such a query facility is to be able to select the most useful data sources relevant to the keyword query. Traditional database summary techniques used for selecting unstructured datasources developed in IR literature are inadequate for our problem, as they do not capture the structure of the data sources. In this paper, we study the database selection problem for relational data sources, and propose a method that effectively summarizes the relationships between keywords in a relational database based on its structure. We develop effective ranking methods based on the keyword relationship summaries in order to select the most useful databases for a given keyword query. We have implemented our system on PlanetLab. In that environment we use extensive experiments with real datasets to demonstrate the effectiveness of our proposed summarization method.
5926837
Composite Subscriptions in Content-Based Publish/Subscribe Systems
Distributed publish/subscribe systems are naturally suited for processing events in distributed systems. However, support for expressing patterns about distributed events and algorithms for detecting correlations among these events are still largely unexplored. Inspired from the requirements of decentralized, event-driven workflow processing, we design a subscription language for expressing correlations among distributed events. We illustrate the potential of our approach with a workflow management case study. The language is validated and implemented in PADRES. In this paper we present an overview of PADRES, highlighting some of its novel features, including the composite subscription language, the coordination patterns, the composite event detection algorithms, the rule-based router design, and a detailed case study illustrating the decentralized processing of workflows. Our experimental evaluation shows that rule-based brokers are a viable and powerful alternative to existing, special-purpose, content-based routing algorithms. The experiments also show that the use of composite subscriptions in PADRES significantly reduces the load on the network. Complex workflows can be processed in a decentralized fashion with a gain of 40% in message dissemination cost. All processing is realized entirely in the publish/subscribe paradigm.