Suppose that a large store has a transactional database that is distributed among four locations. Transactions in each component database have the same format, namely \(T_{j}:\left\{i_{1}, \ldots, i_{m}ight\}\), where \(T_{j}\) is a transaction identifier, and \(i_{k}(1 \leq k \leq m)\) is the identifier of an item purchased in the transaction. Propose an efficient algorithm to mine global association rules. Your algorithm should not require shipping all the data to one site and should not cause excessive network communication overhead.