Tiling Databases

In this paper, we consider 0/1 databases and provide an alternative way of extracting knowledge from such databases using tiles. A tile is a region in the database consisting solely of ones. The interestingness of a tile is measured by the number of ones it consists of, i.e., its area. We present an efficient method for extracting all tiles with area at least a given threshold. A collection of tiles constitutes a tiling. We regard tilings that have a large area and consist of a small number of tiles as appealing summaries of the large database. We analyze the computational complexity of several algorithmic tasks related to finding such tilings. We develop an approximation algorithm for finding tilings which approximates the optimal solution within reasonable factors. We present a preliminary experimental evaluation on real data sets.