Association rule discovery has emerged as an important problem in knowledge
discovery and data mining. The association mining task consists of identif
ying the frequent itemsets and then, forming conditional implication rules
among them. In this paper. we present efficient algorithms for the discover
y of frequent itemsets which forms the compute intensive phase of the task.
The algorithms utilize the structural properties of frequent itemsets to f
acilitate fast discovery. The items are organized into a subset lattice sea
rch space, which is decomposed into small independent chunks or sublattices
, which can be solved in memory. Efficient lattice traversal techniques are
presented which quickly identify all the long frequent itemsets and their
subsets if required. We also present the effect of using different database
layout schemes combined with the proposed decomposition and traversal tech
niques. We experimentally compare the new algorithms against the previous a
pproaches, obtaining improvements of more than an order of magnitude for ou
r test databases.