The ISO 26262 standard defines straightforward metrics for evaluating the "safeness" of a design by defining safety goals, safety mechanisms, and fault metrics. However, determining those metrics is difficult because evaluating every possible fault is impractical on the size of today's designs. Formal verification tools have an advantage over other approaches because formal tools have the unique ability to trace cones of influence and eliminate large numbers of irrelevant faults in a process known as fault pruning. With a significantly reduced fault list, fault analysis can be performed exhaustively with formal techniques like sequential logic equivalency checking (SLEC), or coupled together with fault simulation and emulation for checking software based safety mechanisms. Formal tools provide unique capabilities that are essential for any automotive functional safety flow.
