1. A computing device for state transitions of recursive state machines, the computing device comprising: a processor for processing digital data; a memory device for storing digital data including computer program code coupled to the processor; a data interface for sending and receiving data coupled to the processor, wherein the processor is controlled by the computer program code to: receive via the data interface, event data representing an event in relation to a first object; receive via the data interface, first object data representing the first object; receive via the data interface, second object data representing a second object; receive via the data interface, data representing a predicate relationship between the second object and the first object; calculate a first state in relation to the first object; calculate a second state in relation to the second object; and calculate a valid state transition in accordance with the predicate relationship between the second state and the first state.