Repeats and Palindromes: an Overview

With a long text string like DNA, repeats and palindromes are not easily spotted. Yet nding such substrings is important; for instance, repeats in DNA are indicators of certain hereditary disorders and are used as genetic markers. We discuss repeats and then palindromes and then we relate the two. In our discussion of repeats, we rst de ne an exact repeat and then ve de nitions of approximate repeats. We mention algorithms that search a text string for substrings that satisfy these six de nitions. In addition, we categorize the ve approximate repeats in ve di erent ways. When we look at palindromes, we look at Manacher's algorithm to nd the longest exact palindrome in a string and also an algorithm that nds the longest approximate palindrome in compressed data.