Formalizing Excusableness of Failures in Multi-Agent Systems

To estimate how much an agent can be trusted, its trustworthiness needs to be assessed. Usually, poor performance of an agent leads to a decrease of trust in that agent. This is not always reasonable. If the environment interferes with the performance, the agent is possibly not to blame for the failure. We examine which failures can be called excusable and hence must not be seen as bad performances. Knowledge about these failures makes assessments of trustworthiness more accurate. In order to approach a formal definition of excusableness, we introduce a generic formalism for describing environments of Multi-Agent Systems. This formalism provides a basis for the definition of environmental interference. We identify the remaining criteria for excusableness and give a formal definition for it. Our analysis reveals that environmental interference and a strong commitment of the performing agent do not suffice to make a failure excusable.