Issues of fairness in hierarchies have been mostly investigated - both theoretically and experimentally - within dyadic principle-agent relationships. In this paper we consider triangular principal-multiagents structures, integrating vertical hierarchical relationships with horizontal agent-to-agent ones. We explore in the laboratory a game that allows to investigate how principal's fairness affects cooperation between two interdependent agents performing a simple production task. Our experimental findings show that perceived fairness of principal's actions may trigger reciprocation in agent's behavior, affecting how agents play the production game
