22. The method of claim 2 , further comprising: defining, by at least one data processor, a product phrase as a logical product bundle across time, which comprises a consistent time-stamped sequence of products, wherein each product consistently co-occurs with all others in said product phrase with their relative time-lags, wherein a product phrase comprises: a product set containing a set of products in said phrase; and pair-wise time lags which contain time-lags between all product pairs; wherein time lags are measured in a time resolution unit which comprises any of days, weeks, months, quarters, or years depending on the application and retailer; a set of time-lag constraints where the time-lag between every pair of products in a phrase is the sum of the time lag between all successive products between them; and a slack parameter which determines how strictly product phrase time-lag constraints are imposed depending on how far said products are in said phrase.
22. The method of claim 2 , further comprising: defining, by at least one data processor, a product phrase as a logical product bundle across time, which comprises a consistent time-stamped sequence of products, wherein each product consistently co-occurs with all others in said product phrase with their relative time-lags, wherein a product phrase comprises: a product set containing a set of products in said phrase; and pair-wise time lags which contain time-lags between all product pairs; wherein time lags are measured in a time resolution unit which comprises any of days, weeks, months, quarters, or years depending on the application and retailer; a set of time-lag constraints where the time-lag between every pair of products in a phrase is the sum of the time lag between all successive products between them; and a slack parameter which determines how strictly product phrase time-lag constraints are imposed depending on how far said products are in said phrase. 24. The method of claim 22 , further comprising: quantifying, by at least one data processor, cohesiveness of a phrase by a measure of phraseness; wherein phraseness is computed by: extracting a phrase-sub-matrix from a fluid context matrix; computing seedness measures of each product; and aggregating the seedness measures into a phraseness measure.