Showing papers by "John Iacono published in 2002"

A locality-preserving cache-oblivious dynamic dictionary

Abstract: This paper presents a simple dictionary structure designed for a hierarchical memory The proposed data structure is cache oblivious and locality preserving A cache-oblivious data structure has memory performance optimized for all levels of the memory hierarchy even though it has no memory-hierarchy-specific parameterization A locality-preserving dictionary maintains elements of similar key values stored close together for fast access to ranges of data with consecutive keysThe data structure presented here is a simplification of the cache-oblivious B-tree of Bender, Demaine, and Farach-Colton Like the cache-oblivious B-tree, this structure supports search operations using only O(logBN) block operations at a level of the memory hierarchy with block size B Insertion and deletion operations use O(logBN + log2N/B) amortized block transfers Finally, the data structure returns all k data items in a given search range using O(logBN + k/B) block operationsThis data structure was implemented and its performance was evaluated on a simulated memory hierarchy This paper presents the results of this simulation for various combinations of block and memory sizes

In-Place Planar Convex Hull Algorithms

Abstract: An in-place algorithm is one in which the output is given in the same location as the input and only a small amount of additional memory is used by the algorithm. In this paper we describe three in-place algorithms for computing the convex hull of a planar point set. All three algorithms are optimal, some more so than others.

Key Independent Optimality

Abstract: A new form of optimality for comparison based static dictionaries is introduced. This type of optimality, key-independent optimality, is motivated by applications that assign key values randomly. It is shown that any data structure that is key-independently optimal is expected to execute any access sequence where the key values are assigned arbitrarily to unordered data as fast as any offline binary search tree algorithm, within a multiplicative constant. Asymptotically tight upper and lower bounds are presented for key-independent optimality. Splay trees are shown to be key-independently optimal.