29 Reusing Schema and mapping information Schema S1 Purchase order2 Product BillTo Name Address ShipTo Name Address ContactPhone Schema S2 Purchase order Product BillTo Name Address ShipTo Name Address Contact Name Address Schema S POrder Article Payee BillAddress Recipient ShipAddress Goal: Mapping S1 to S matching result between S2 and S are previously determent and can be reused to map S1 to S EX: