Patent ID: 8359315

Claim:
A method for generating a representative sub-signature of a particular cluster of signatures, the method comprising: reading a sub-signature of a signature of the particular cluster, wherein the signature includes an identifier of an item; calculating a first factor for the sub-signature, wherein the first factor is based on how many signatures in the particular cluster contain the sub-signature; calculating a second factor for the sub-signature, wherein the second factor is based on how many signatures in other clusters contain the sub-signature; calculating an effectiveness score for the sub-signature, wherein the effectiveness score is based on at least the first factor and the second factor; determining one or more representative sub-signatures for the particular cluster, wherein the one or more sub-signatures are based on one or more effectiveness scores; and at least one of: reading one or more additional sub-signatures of a signature of the particular cluster; calculating a first factor for each additional sub-signature; calculating a second factor for each additional sub-signature; and calculating an effectiveness score for each additional sub-signature, wherein calculating the first factor comprises increasing the first factor as the number of signatures containing the sub-signature in the particular cluster increases, wherein calculating the second factor comprises increasing the second factor as the number of signatures in other clusters containing the sub-signature increases, and wherein calculating the effectiveness score comprises dividing the first factor by the second factor.