Industrial firm in an open microeconomic system

An open stationary microeconomics system is considered operating between two markets. The system consists of a number of economic agents. The crucial elements of the system is an industrial firm processing input resources. The firm aims at maximum of profit extracted from the system. A model of the system is made taking into account the structure of the firm and type of the input resources (whether they are comlementary ones or substitutes). An extremal priciple is formulated which determines the equilibrium distribution of the resources among economic agents.