Abstract: A pattern analysis system and method that is robust against errors, misalignments and failures of process that may be caused by unexpected events. By performing multiple, redundant overlapping analyses with different operating characteristics and by actively testing for disagreements and errors, the invention detects errors and either corrects them or at least eliminates their harmful effects. The invention is especially effective in highly constrained situations, such as training a model to a script that is presumed correct or recognition with a highly constrained grammar or language model. In particular, it is effective when unexpected events may be rare but disastrous when they occur. The system and method handle errors that would otherwise be undetected as well as errors that would cause catastrophic failures.