1. Operational reliability, a necessity

Over the last fifty years or so, we have witnessed an extraordinary evolution in the performance of the many systems that surround us, such as automated production systems, transport systems (airplanes, high-speed trains, automobiles), telecommunication systems (telephony, internet)....

The high level of performance required would dictate failure-free operation. But as their performance has evolved, the complexity of these systems has also increased considerably, resulting in a growing number of potential sources of failure. What's more, today's economic imperatives dictate ever-shorter time-to-market or time-to-operations, without any significant feedback on failures, especially when it comes to entirely new devices.

These failures or malfunctions can have serious consequences: harm to human health or the environment, loss of human life,...