6519527
A dynamic firing speculation to speedup distributed symbolic state-space generation
The saturation strategy for symbolic state-space generation is very effective for globally-asynchronous locally-synchronous discrete-state systems. Its inherently sequential nature, however, makes it difficult to parallelize on a NOW. An initial attempt that utilizes idle workstations to recognize event firing patterns and then speculatively compute firings conforming to these patterns is at times effective but can introduce large memory overheads. We suggest an implicit method to encode the firing history of decision diagram nodes, where patterns can be shared by nodes. By preserving the actual firing history efficiently and effectively, the speculation is more informed. Experiments show that our implicit encoding method not only reduces the memory requirements but also enables dynamic speculation schemes that further improve runtime
229363
A Pattern Recognition Approach for Speculative Firing Prediction in Distributed Saturation State-Space Generation
The saturation strategy for symbolic state-space generation is particularly effective for globally-asynchronous locally-synchronous systems. A distributed version of saturation, SaturationNOW, uses the overall memory available on a network of workstations to effectively spread the memory load, but its execution is essentially sequential. To achieve true parallelism, we explore a speculative firing prediction, where idle workstations work on predicted future event firing requests. A naive approach where all possible firings may be explored a priori, given enough idle time, can result in excessive memory requirements. Thus, we introduce a history-based approach for firing prediction that recognizes firing patterns and explores only firings conforming to these patterns. Experiments show that our heuristic improves the runtime and has a small memory overhead.
850145
Multiple sequence alignment using simulated annealing
Multiple sequence alignment is a useful technique for studying molecular evolution and analyzing structure-sequence relationships. Dynamic programming of multiple sequence alignment has been widely used to find an optimal alignment. However, dynamic programming does not allow for certain types of gap costs, and it limits the number of sequences that can be aligned due to its high computational complexity. The focus of this paper is to use simulated annealing as the basis for developing an efficient multiple sequence alignment algorithm. An algorithm called Multiple Sequence Alignment using Simulated Annealing (MSASA) has been developed. The computational complexity of MSASA is significantly reduced by replacing the high-temperature phase of the annealing process by a fast heuristic algorithm. This heuristic algorithm facilitates in minimizing the solution set of the low-temperature phase of the annealing process. Compared to the dynamic programming approach, MSASA can (i) use natural gap costs which can generate better solution, (ii) align more sequences and (iii) take less computation time.
92691
A Formal Approach to Managing Design Processes
To capture market opportunities, competition within the microelectronics industry demands ever-faster product development, which means ever-shorter design cycles. Shorter design cycles can be achieved by carefully managing the design process during rapid prototyping. Careful management is important because the design process must be (1) adjusted to accommodate constraints such as product performance and design time, and (2) frequently updated to take advantage of new design tools and methodologies. Traditionally, designers have used whatever tools seemed convenient to them at the time, which has made it virtually impossible to determine what methodology was used to produce a given design. These problems can be avoided through design methodology management, which ensures that appropriate tools are selected and executed in the appropriate sequence. Effective design management requires an environment equipped with a formal representation of supported design processes and tools, and an execution environment that helps designers select and execute an appropriate design process. We propose a methodology management system that provides this functionality. >