Use of Median String for Classification

A string that minimizes the sum of distances to the strings of a given set is known as (generalized) median string of the set. This concept is important in Pattern Recognition for modelling a (large) set of garbled strings or patterns. The search of such a string is an NP-Hard problem and, therefore, no efficient algorithms to compute the median strings can be designed. Recently a greedy approach was proposed to compute an approximate median string of a set of strings. In this work an algorithm is proposed that iteratively improves the approximate solution given above. Experiments have been carried out on synthetic and real data to compare the performances of the approximate median string with the conventional set median. These experiments showed that the proposed median string is a better representation of a given set than the corresponding set median.