1. In a digital information processing system wherein a model of a finite state machine (FSM) receives a plurality of FSM inputs and produces a plurality of FSM outputs, a method for updating soft decision information on said FSM input symbols into higher confidence information, the method comprising: (a) inputting said soft decision information in a first index set; (b) combining said input soft decision information with knowledge regarding said finite state machine; (c) outputting said higher confidence information; (d) modifying said input soft decision information using said output higher confidence information via a feedback path; and (e) repeating steps (a) to (d) until a termination condition is met.