The article presents a proposal for a combined application of fuzzy logic and genetic algorithms to control the procurement process in the enterprise. The approach presented in this paper draws particular attention to the impact of external random factors in the form of demand and lead time uncertainty. The model uses time-variable membership function parameters in a dynamic fashion to describe the modelled output fuzzy (sets) values. An additional element is the use of genetic algorithms for optimisation of fuzzy rule base in the proposed method. The approach presented in this paper was veryfied according to four criteria based on a computer simulation performed on the basis of the actual data from an enterprise.
OVERVIEW OF INVENTORY MANAGEMENT ISSUESAs a result of the on-going globalisation and mass consumption, the demand on the goods market is characterised by intense dynamics and a certain level of uncertainty, especially in large agglomerations and urban areas. The logistical processes that occur there as part of supply networks focus primarily on the flow of the streams of material goods, but also take into account the flows of necessary information and financial resources. The volatility of these processes and certain level of uncertainty cause all sorts of inventory to amass at various levels of the logistic network in order to ensure the continuity of production and the uninterrupted availability of the finished products to customers. The goods amassed in the nodal points of the logistic network act as buffers that mitigate the differences in customer demand for the products. In practice, despite the use of modern systems, such as JIT (Just In Time), ERP (Enterprise Resource Planning), MRP (Material resource Planning), it is not possible to entirely eliminate the inventory. In fact, economic processes are stochastic in nature (which results from both the operating environment of these processes and the impact of their surroundings), so it is possible to identify them only to a certain extent, with a greater or smaller error (Wolski, 2010). Due to the impact of random factors on the nodal elements of the supply network (manufacturing plants, distribution centres, warehouses, etc.) through the volatility of demand for semi-finished products or finished products, lead time changeability, vendors' limited capabilities, etc., the optimal policy for the supply and inventory control logistics is of utmost importance to the effectiveness of the entire logistic network. As a result of the above-mentioned factors and the ever-increasing competition among entities, logistics companies are often forced to keep a high inventory level in order to maintain the desired service level. This behaviour makes it possible to dynamically respond