Optimally fast parallel algorithms for preprocessing and pattern matching in one and two dimensions

  • Authors:
  • R. Cole;M. Crochemore;Z. Galil;L. Gasieniec;R. Eariharan;S. Muthukrishnan;K. Park;W. Rytter

  • Affiliations:
  • Courant Inst. of Math. Sci., New York, NY, USA;-;-;-;-;-;-;-

  • Venue:
  • SFCS '93 Proceedings of the 1993 IEEE 34th Annual Foundations of Computer Science
  • Year:
  • 1993

Quantified Score

Hi-index 0.00

Visualization

Abstract

All algorithms below are optimal alphabet-independent parallel CRCW PRAM algorithms. In one dimension: Given a pattern string of length m for the string-matching problem, we design an algorithm that computes a deterministic sample of a sufficiently long substring in constant time. This problem used to be a bottleneck in the pattern preprocessing for one- and two-dimensional pattern matching. The best previous time bound was O(log/sup 2/ m/log log m). We use this algorithm to obtain the following results. 1. Improving the preprocessing of the constant-time text search algorithm from O(log/sup 2/ m/log log m) to n(log log m), which is now best possible. 2. A constant-time deterministic string-matching algorithm in the case that the text length n satisfies n=/spl Omega/(m/sup 1+/spl epsiv//) for a constant /spl epsiv/0. 3. A simple probabilistic string-matching algorithm that has constant time with high probability for random input. 4. A constant expected time Las-Vegas algorithm for computing the period of the pattern and all witnesses and thus string matching itself, solving the main open problem remaining in string matching.