<p>An apparatus which efficiently coordinates the association of resource and lot data in a manufacturing environment is disclosed. The apparatus includes a memory structure which associates resource and lot data only with other resource and lot data from a common dependency. A dependency is a characteristic of lots which share common resources and of resources which are shared by common lots. The memory includes nodes which describe the dependencies. The dependency nodes link to resource lists and to lot lists. The resource and lot nodes are part of resource and lot lists, respectively. Usage nodes are included to describe every use each lot makes of each resource. The usage nodes are linked to both resource nodes and lot nodes. The usage nodes are also linked together to define the order in which each lot uses its resources and the order in which each resource is used by its lots. A processor couples to the memory and receives externally-originated messages commanding various operations on the memory structure. In one operation a single dependency may be broken into several dependencies. In another operation multiple dependencies may be combined into a single dependency. The accurate maintenance of the maximum number of dependencies in resource-lot association data allows manufacturing environment simulation and other automation to respond to a manufacturing event by processing only information related to a portion of the environment. Thus, processing time decreases, and simulations may take place in real time.</p>
