So, to sum it up: I would like to implement following approximate distance functions as an extension of Boost String Algorithm library: Hamming distance Levenstein distance Generalized Levenstein (weighted Levenstein) distance Damerau–Levenshtein distance Weighted Damerau–Levenshtein distance Jaro distance Jaro-Winkler distance For an ordered alphabet, I would also implement Delta distance Gamma distance The interface for most distances would look like: template< typename Range1T, typename Range2T > std::size_t hamming_distance( Range1T first, Range2T second ); Jaro and Jaro-Winkler distances have following interface (return float instead of size_t): template< typename Range1T, typename Range2T > float hamming_distance( Range1T first, Range2T second ); Finally, I would implement functions template <typename TRange> find_iterator<TRange> approximate_find (TRange text, TRange pattern, approximate_distance<TRange>& distance); template <typename TRange> find_iteratorstd::size_t approximate_find_index (TRange text, TRange pattern, approximate_distance<TRange>& distance); These would return all approximate matches of pattern int text. The first one return the approximate string itself, the later one returns its index. Do you have any further suggestions? Is there anybody willing to mentor this project? Jan Strnad