System and method to analyze VLSI designs

Briefly, a system and a method of formal verification and failure analysis and rectification of models or designs, e.g., VLSI designs, of processors, circuits and logical systems. Embodiments of the system may include a multi-value annotation scheme for annotating different types of values of signals, and a post-annotation scheme for further analysis based on the annotated values. Some embodiments of the invention may optionally include a generator of counter-examples of a given length.