Patent ID: 6882970

Claim:
A comparison apparatus comprising: a receiver operable to receive first and second sequences of labels; an identifier operable to identify a plurality of different first sub-sequences of labels within said first sequence of labels; a first determiner operable to determine and to output the number of times each of said different first sub-sequences occurs within said first sequence of labels; a definer operable to define a plurality of second sub-sequences of labels from said second sequence of labels; a second determiner operable to determine and to output the number of times each of said different first sub-sequences occurs within said second sequence of labels by comparing each first sub-sequence of labels with each second sub-sequence of labels; and a similarity measure calculator operable to calculate a measure of the similarity between the first and second sequences of labels by comparing the numbers output from said first determiner with the numbers output from said second determiner; wherein said second determiner comprises: a comparator operable to compare a current first sub-sequence of labels with each second sub-sequence of labels using predetermined data including confusion information which defines confusability between different labels, to provide a set of sub-sequence similarity measures; and a counter operable to count the number of times the current first sub-sequence of labels occurs within the second sequence of labels in dependence upon the set of sub-sequence similarity measures provided by said comparator for the current first sub-sequence of labels.