We consider the problem of discovering association rules between items in a large database
of sales transactions. We present two new algorithms for solving this problem that are fundamentally
dierent from the known algorithms. Experiments with synthetic as well as real-life
data show that these algorithms outperform the known algorithms by factors ranging from three
for small problems to more than an order of magnitude for large problems. We also show how
the best features of the two proposed algorithms can be combined into a hybrid algorithm,
called AprioriHybrid. Scale-up experiments show that AprioriHybrid scales linearly with the
number of transactions. AprioriHybrid also has excellent scale-up properties with respect to the
transaction size and the number of items in the database.