A more redundant description of the same process is shown in Fig. 3, this description is called trellis. In a trellis, each node corresponds to a distinct state at a given time, and each arrow represents a transition to some new state at the next instant of time. The trellis begins and ends at the known states c0 and cn. Its most important property is that to every possible state sequence C there corresponds a unique path through the trellis, and vice versa.