In this brief review we analyse some ideas about simulation of imitation by means of artificial agents. Dr. Trajkovski is Director of Cognitive Agency and Robotics Lab in Towson University (USA). He is specialized in Cognitive Engineering and has published books like "An imitation-based approach to modeling homogenous agents and societies" or the recents "Handbook of Research on Agent-Based Societies: Social and Cultural Interactions" or "Handbook of Research on Computational Arts and Creative Informatics". Trajkovski introduces agents capable of performing four elementary actions (forward, backward, left, and right) and of noticing 10 different percepts. Each agent is equipped with one food sensor and has one hunger drive. When the hunger drive is activated for the first time, the agent performs random walk during which expectancies are stored in the associative memory. When food is sensed, expectancy emotional context is set to a positive value. Every time in the future the hunger drive is activated, the agent uses the context values of the expectancies to direct its actions. It chooses the action that will lead to expectancy with maximum context value.
Agents inhabit a two-dimensional world surrounded by walls and populated with obstacles. Sensing another agents takes the agent into its imitating mode. The agents have begun to inhabit the environment at different times. They are also being born in different places in the environment. While inhabiting the environment, they explore different portions of the environment that may be very different, or perceptually similar. In environments inhabited by heterogeneous agents, the fundamental problem is the problem of interagent communication. According to Trajkovski, an example of interagent communication is the phenomenon of multilingual agents that can serve as translators. The author proposes an enactivist (Varela, Thompson and Rosch, 1991) representation model, based on the treatment of agents as dynamical systems. The agent during the interaction with the environment generates its inputs and makes a mapping from the continuous domain of the inputs to the discrete domain of the percepts. The sequence of these percepts would reflect the structure of the environment. The basic idea is to divide up the set of possible states into a finite number of pieces and keep track of which piece the state of the system lays in at every iteration. Each piece is associated with a symbol, and in this way the evolution of the system is described by an infinite sequence of symbols. The agent generates symbols or percepts.
Trajkovski shows that imitation is far from a trivial phenomenon and that humans are wired for imitation by means of the research in multi-agent systems. He gives a solid and fertile attempt to establish a mechanism of interagent communication in the multi-agent environment using classical algebraic theories and fuzzy algebraic structures. His contributions are very relevant for the social cognition, mixing studies about animal intelligence (Thorndike) with studies about imitation in humans.
