It is proposed a method for factory operation. The method includes providing manufacturing tasks each represented by a law describing a manufacturing of a product by one or more manageable machines. The method includes obtaining one or more manufacturing constraints and one or more manufacturing events. The method includes determining an operating mode of the factory based on the one or more manufacturing constraints and on one or more product constraints. The determining includes one or more iterations. Each iteration computes a respective propensity of each manufacturing task representing a frequency with which the task is chosen for manufacturing the product given the constraints and/or a previous event(s) occurrence. The iteration ranks the tasks according to a propensity descending order. The iteration visits the tasks according to the ranking and affecting to each task one or more manageable machines and resources. The iteration executes the tasks until an event(s).