2. The method of claim 1 wherein said quantizing also uses a second quantizer to quantize values for a second attribute in the auxiliary page ranking vectors associated with said collection.
2. The method of claim 1 wherein said quantizing also uses a second quantizer to quantize values for a second attribute in the auxiliary page ranking vectors associated with said collection. 3. The method of claim 2 wherein the values y for said second attribute in the auxiliary page ranking vectors associated with said collection are distributed in a power-law distribution n; and wherein, prior to quantization by said second quantizer, the method comprises transforming by the data-processing system the values y with a second function F2(y) such that the transformed values become uniformly distributed; and wherein said second quantizer partitions the plurality of transformed second values into a plurality of uniformly spaced cells.