Trace signals: The meanings of stigmergy

When agents act is a common environment they leave traces. In this paper we explore the importance of using such traces as signals (stigma). Trace signals enable a flexible way to support indirect interaction between agents without adopting dedicated communication channels and signals. Although the kind of messages that can be exchanged with traces is limited, their importance for decentralized and dynamic multi-agent systems is vast. A taxonomy of trace-signals is provided and their role in different social interactions is explored. Some of the benefits and limitations of this trace-based communication are discussed.