Abstract

This paper presents two efficient concurrent-read concurrent-write parallel algorithms that find all palindromes in a given string: 1. An O(log n) time, n-processor algorithm over general alphabets. In case of constant size alphabets the algorithm requires only n= log n processors, and thus achieves an optimal-speedup. 2. An O(log log n) time, n log n= log log n-processor algorithm over general alphabets. This is the fastest possible time with the number of processors used. These new results improve on the known parallel palindrome detection algorithms by using smaller auxiliary space and either by making fewer operations or by achieving a faster running time. 1 Introduction Palindromes are symmetric strings that read the same forward and backward. Palindromes have been studied for centuries as word puzzles and more recently have found several important uses in formal languages and computability theory. Formally, a non-empty string w is a palindrome if w = w R , where w R denotes...

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