A simple optimal randomized algorithm for sorting on the PDM

The Parallel Disks Model (PDM) has been proposed to alleviate the I/O bottleneck that arises in the processing of massive data sets. Sorting has been extensively studied on the PDM model due to the fundamental nature of the problem. Several randomized algorithms are known for sorting. Most of the prior algorithms suffer from undue complications in memory layouts, implementation, or lack of tight analysis. In this paper we present a simple randomized algorithm that sorts in optimal time with high probablity and has all the desirable features for practical implementation

Resource-bounded Information Extraction: Acquiring Missing Feature Values On Demand

We present a general framework for the task of extracting specific information ``on demand\u27\u27 from a large corpus such as the Web under resource-constraints. Given a database with missing or uncertain information, the proposed system automatically formulates queries, issues them to a search interface, selects a subset of the documents, extracts the required information from them, and fills the missing values in the original database. We also exploit inherent dependency within the data to obtain useful information with fewer computational resources. We build such a system in the citation database domain that extracts the missing publication years using limited resources from the Web. We discuss a probabilistic approach for this task and present first results. The main contribution of this paper is to propose a general, comprehensive architecture for designing a system adaptable to different domains

Succinct and I/O Efficient Data Structures for Traversal in Trees ⋆

Abstract. We present two results for path traversal in trees, where the traversal is performed in an asymptotically optimal number of I/Os and the tree structure is represented succinctly. Our first result is for bottom-up traversal that starts with a node in a tree on N nodes and traverses a path to the root. For a bottom-up path of length K, we design data structures that permit traversal of this path in O(K/B) I/Os (B denotes the size of a disk block) using only 2N + ǫN log B N +o(N) bits, for an arbitrarily selected constant, ǫ, where 0 < ǫ < 1. Our second result is for top-down traversal in binary trees. We store the tree in (3 + q)N + o(N) bits, where q is the number of bits required to store a key, while top-down traversal can still be performed in an asymptotically optimal number of I/Os. Keywords succinct data structures, I/O efficient data structures, data structures, trees, path traversal

Standardizing Agent Communication

An Agent Communication Language (ACL) is a collection of speech-act-like message types, with agreed-upon semantics, which facilitate the knowledge and information exchange between software agents

Crafting data structures: A study of reference locality in refinement-based path finding

Abstract. The widening gap between processor speed and memory latency increases the importance of crafting data structures and algorithms to exploit temporal and spatial locality. Refinement-based pathfinding algorithms, such as Classic Refinement, find near-optimal paths in very large sparse graphs where traditional search techniques fail to generate paths in acceptable time. In this paper we present a performance evaulation study of three simple data structure transformation oriented techniques aimed at improving the data reference locality of Classic Refinement. In our experiments these techniques improved data reference locality resulting in consistently positive performance improvements upwards of 51.2%. In addition, these techniques appear to be orthogonal to compiler optimizations and robust with respect to hardware architecture.

External-memory breadth-first search with sublinear I/O

Breadth-first search (BFS) is a basic graph exploration technique. We give the first external memory algorithm for sparse undirected graphs with sublinear I/O. The best previous algorithm requires \Theta (n + n+mD\Delta B \Delta logM=B n+mB) I/Os on a graph with n nodes and m edges and a machine with main-memory of size M, D parallel disks, and block size B. We present two versions of a new algorithm which requires only O i (p 1D\Delta B + p nm) \Delta n+mpD\Delta B \Delta logM=B n+m

Open Multi-Agent Systems: Agent Communication and Integration

In this paper, we study the open-ended nature of multi-agent systems, which refers to the property to allow for the dynamic integration of new agents into an existing system. In particular, the focus of this study is on the issues of agent communication and integration. We define an abstract programming language for open multi-agent systems that is based on concepts and mechanisms as introduced and studied in concurrency theory. Moreover, an important ingredient is the generalisation of the traditional concept of value-passing to a communication mechanism that allows for the exchange of information. Additionally, an operational model for the language is given in terms of a transition system, which allows the formal derivation of computations