**3.3.2 Space complexity**

To calculate the space complexity, every node in our tree requires 2 × r × a × b places for the path bitmap (any attribute needs two places in the path bitmap) and r × a × b places for the counter bitmap and (m + 1) links. Like (Chang & Hu, 2010), if supposing that every place and each link needs 32 bits, the total number of bits required is n × (32 × (2 × r × a × b + r × a × b + (m + 1))) = O(nrab + nm).
