Wojciech Szpankowskit Department of Computer Science Purdue University W. Lafayette, IN 47907 U.S.A. spa~cs.purdue.edu We study the height of a digital search tree (DST in short) built from n random strings generated by an unbiased memoryless source (i.e., all symbols are equally likely). We shall argue that the height of such a tree is equivalent to the length of the longest phrase in the Lemp...

This paper presents stochastic tree search, an alternative method to local search. Stochastic tree search consists of the exploration of a search tree, making use of heuristics for guiding the choice of the next branch, and a combination of diving and randomized selection of the path for exploring the tree. Stochastic tree search efficiency relies on avoiding the repetition of the search on the...

Extended Abstract In recent years, multimedia content-based retrieval has become an important research problem. In order to provide effective and also efficient access to relevant data stored in large (often distributed) digital repositories, advanced software tools are necessary. Content-based retrieval works on the idea of abstracting the contents of an object, for example color or shape in t...

Advisor: Stuart M. Shieber Adaptive Tree Search Wheeler Ruml Combinatorial optimization and constraint satisfaction problems are ubiquitous in computer science, arising in areas as diverse as resource allocation, automated design, planning, and logical inference. Finding optimal solutions to such problems often entails searching an intractably large tree of possibilities. Problems beyond the re...

representation of the game. It was programmed in LISP. Further use of abstraction was also studied by Friedenbach (1980). The combination of search, heuristics, and expert systems led to the best programs in the eighties. At the end of the eighties a new type of Go programs emerged. These programs made an intensive use of pattern recognition. This approach was discussed in detail by Boon (1990)...

We propose two new online methods for estimating the size of a backtracking search tree. The first method is based on a weighted sample of the branches visited by chronological backtracking. The second is a recursive method based on assuming that the unexplored part of the search tree will be similar to the part we have so far explored. We compare these methods against an old method due to Knut...

This paper introduces the APHID (Asynchronous Parallel Hierarchical Iterative Deepening) game-tree search algorithm. An APHID search is controlled by a master and a series of slave processors. The master searches the rst d 0 ply of the game-tree repeatedly. The slaves are responsible for the bottom plies of the game-tree. The slaves asynchronously read work lists from the master and return scor...

Poor branching decisions in a search tree can increase solve time by orders of magnitude. We introduce a new approach where, instead of committing to the tree so far, we restructure the tree throughout the search. This has the advantages of removing unnecessary decisions from the tree and relocating important decisions closer to the root. We define two tree-modifying operators: delete and promo...

s possibly many failures, where individual values have been tested and the constraint system failed. The advantage is the more compact form of the search, the disadvantage is the difficulty to explain the propagation which led