Search tree

Abstract. The restricted rotation distance dR(S, T) between two binary trees S, T of n vertices is the minimum number of rotations by which S can be transformed into T, where rotations can only take place at the root of the tree, or at the right child of the root. A sharp upper bound ...

Recently, a main memory index structure called the cache conscious-generalized search tree (CC-GiST) was proposed. The CC-GiST is such a novel index structure that it can be used for implementing all the existing cache conscious trees with the minimal efforts. It incorporates the pointer compression and the key compression techniques, which were adopted by the existing cache conscious trees to reduce the cache misses, in a single framework. In this paper, we formally analyze the performance of the CC-GiST. We compare the performance of the CC-GiST with the existing cache conscious trees. The result shows that the CC-GiST has the negligible overhead for supporting all the existing cache conscious trees in a single framework, and the performance of the tree is almost unaffected.

Tabling is an implementation technique that improves the declarativeness and expressiveness of Prolog by reusing solutions to goals. Quite a few interesting applications of tabling have been developed in the last few years, andsev eral are by nature non-deterministic. This raises the question of whether parallel search techniques can be usedto improve the performance of tabled applications. In this work we demonstrate that the mechanisms proposed to parallelize search in the context of SLD resolution naturally generalize to parallel tabledcomputations, and that resulting systems can achieve goodp erformance on multi-processors. To do so, we present the OPTYap parallel engine. In our system individual SLG engines communicate data through stack copying. Completion is detected through a novel parallel completion algorithm that builds upon the data structures proposed for or-parallelism. Scheduling is simplified by building on previous research on or-parallelism. We show initial performance results for our implementation. Our best result is for an actual application, model checking, where we obtain linear speedups.

A fractal structure is a tool that is used to study the fractal behavior of a space. In this paper, we show how to apply a new concept of fractal dimension for fractal structures, extending the use of the box-counting dimension to new contexts. In particular, we define a fractal structure on the domain of words and show how to use the new fractal dimension to study the fractal pattern of a language generated by a regular expression, how to calculate
the efficiency of an encoding language and how to estimate the number of nodes of a given depth in a search tree.

Abstract. The restricted rotation distance dR(S, T) between two binary trees S, T of n vertices is the minimum number of rotations by which S can be transformed into T, where rotations can only take place at the root of the tree, or at the right child of the root. A sharp upper bound ...

– The Job Shop Scheduling Problem (JSSP) is a notorious difficult problem in combinatorial optimization for which extensive investigation has been devoted to the development of efficient algorithms to find optimal or near-optimal solutions. This paper proposes a new heuristic algorithm for the JSSP that effectively combines the classical shifting bottleneck procedure (SBP) with a dynamic and adaptive neighborhood search procedure based on a filter and fan method (F&F). In the algorithm, SBP is used to generate a starting solution as well as to re-optimize the best schedules produced by the F&F method. The F&F is a local search procedure that generates compound moves in a tree search fashion. Computational results carried out on a standard set of 43 benchmark problems shows that the F&F algorithm performs more robustly and effectively than a number of leading metaheuristic algorithms and rivals the best.

An impediment to the practical use of fixed-delay tree search with decision feedback (FDTS/DF) for retrieving data from hard disk drives is that four additions and one multiplications must be evaluated in one clock cycle. It is shown here that on recording channels using 2/3(1,7) run-length-limited (RLL) coding, a detector achieving the performance of FDTS/DG can be implemented with a

We explore problems related to computing graph distances in the data-stream model. The goal is to design algorithms that can process the edges of a graph in an arbitrary order given only a limited amount of working memory. We are motivated by both the practical challenge of processing massive graphs such as the web graph and the desire for a better theoretical understanding of the data-stream model. In particular, we are interested in the trade-offs between model parameters such as per-data-item processing time, total space, and the number of passes that may be taken over the stream. These trade-offs are more apparent when considering graph problems than they were in previous streaming work that solved problems of a statistical nature. Our results include the following: (1) Spanner construction: There exists a single-pass, (O) over tilde (tn(1+1/ t))-space, (O) over tilde (t(2)n(1/t))-time-per-edge algorithm that constructs a (2t + 1)-spanner. For t = Omega(log n/log log n), the alg...