An approximate string-matching algorithm

An approximate string-matching algorithm is described based on earlier attribute-matching algorithms. The algorithm involves building a trie from the text string which takes time O(N log2 N), for a text string of length N. Once this data structure has been built any number of approximate searches can be made for pattern strings of length m. The expected complexity analysis is given for the look-up phase of the algorithm based on certain regularity assumptions about the background language. The expected look-up time for each pattern is O(m log2 N). The ideas employed in the algorithm have been shown effective in practice before, but have not previously received any theoretical analysis.