Resilience more than the Sum of Security and Dependability: Cognition is what makes the Difference

The term resilience is appearing more and more often in computer science, but there is no common definition of what features differentiate a resilient from non-resilient system. Often resilience is merely used as a synonym for redundancy. In this paper we discuss resilience definitions from different disciplines and argue that the core feature of a resilient system is its capability to adapt itself under stress (faults/attacks etc.) while still providing a certain level of its functionality.