1 Introduction
Recently, there have been growing interests in multidimensional analysis of relational databases, transactional databases, and data warehouses. Most of such analysis involve data cube-based summary or transaction-based association analysis. However, in many interesting applications, one may want to analyze the changes of measures in multidimensional space. For example, one may want to ask what are associated with significant changes of the average house price in the Vancouver area in 2000 compared against 1999, and the answer could include statements of the form “the average price for those sold to professionals in the West End went down by 20 percent, while those sold to business people in Metrotown went up by 10 percent etc.” Expressions such as “professionals in the West End” correspond to cells in data cubes and describe sectors of the business modeled by the data cube.