No abstract

The original publication misspelled the name of Duda Kvitsiani in the author list, which has been corrected here and in the article online.

Abstract. We have developed a methodology for predicting the performance of parallel algorithms on real parallel machines. The methodology consists of two steps. First, we characterize a machine by enumerating the primitive operations that it is capable of performing along with the cost of each operation. Next, we analyze an algorithm by making a precise count of the number of times the algorithm performs each type of operation. We have used this methodology to evaluate many of the parallel sorting algorithms proposed in the literature. Of these, we selected the three most promising, Batcher's bitonic sort, a parallel radix sort, and a sample sort similar to Reif and Valiant's flashsort, and implemented them on the connection Machine model CM-2. This paper analyzes the three algorithms in detail and discusses the issues that led us to our particular implementations. On the CM-2 the predicted performance of the algorithms closely matches the observed performance, and hence our methodology can be used to tune the algorithms for optimal performance. Although our programs were designed for the CM-2, our conclusions about the merits of the three algorithms apply to other parallel machines as well. *

Although game-tree search works well in perfect-information games, it is less suitable for imperfect-information games such as contract bridge. The lack of knowledge about the opponents' possible moves gives the game tree a very large branching factor, making it impossible to search a significant portion of this tree in a reasonable amount of time.This paper describes our approach for overcoming this problem. We represent information about bridge in a task network extended to represent multi-agency and uncertainty. Our game-playing procedure uses this task network to generate game trees in which the set of alternative choices is determined not by the set of possible actions, but by the set of available tactical and strategic schemes.We have tested this approach on declarer play in the game of bridge, in an implementation called Tignum 2. On SO00 randomly generated notrump deals, Tignum 2 beat the strongest commercially available program by 1394 to 1302. with 2304 ties. These results are statistically significant at the a = 0.05 level. Tignum 2 searched an average of only 8745.6 moves per deal in an average time of only 27.5 seconds per deal on a Sun SPARCstation 10. Further enhancements to 'Iignum 2 are currently underway.

This paper reports on the development of the process-planning module for EDAPS, an integrated system for designing and planning the manufacture of microwave modules. Microwave modules are complex devices having both electrical and mechanical properties, and EDAPS integrates electrical design, mechanical design, and process planning for both the mechanical and electrical domains. EDAPS's process planning module provides an integrated approach to process planning in both the electronic and mechanical domains, specifically in the manufacture of microwave transmit-receive (T jR) modules. It enables EDAPS to generate process plans concurrently with design~and we are develop'ing ways for EDAPS to use the process planning information provide feedback to designers about manufacturability, cost, and lead time for manufacturing their designs. The planning module is based on a modified version of an AI planning methodology called Hierarchical Task Network (HTN) planning. We provide an overview of its operation, and compare and contrast it to how HTN planning is normally done.