Abstract: A translation memory for computer assisted translation based upon an aligned file having a number of source language text strings paired with target language text strings. A posting vector file includes a posting vector associated with each source language text string in the aligned file. Each posting vector includes a document identification number corresponding to a selected one of the source language text strings in the aligned file and a number of entropy weight values, each of the number of weight values corresponding to a unique letter n-gram that appears in the selected source language text string. Preferably, the translation memory further includes an inverted index comprising a listing of source language letter n-grams and a pointer to each of the posting vectors including an entry for the listed letter n-gram.