The document discusses various lot sizing techniques used to determine optimal batch sizes for production and purchasing. It describes techniques like economic order quantity (EOQ), fixed order quantity (FOQ), lot-for-lot (LFL), periods of supply (POS), period order quantity (POQ), least unit cost (LUC), least total cost (LTC), and part period balancing (PPB). Examples are provided to illustrate how each technique works and the optimal lot size is calculated. The goal of lot sizing is to minimize total inventory costs by balancing setup/ordering costs and carrying costs.