  In this article, an agent-based negotiation model for negotiation teams that
negotiate a deal with an opponent is presented. Agent-based negotiation teams
are groups of agents that join together as a single negotiation party because
they share an interest that is related to the negotiation process. The model
relies on a trusted mediator that coordinates and helps team members in the
decisions that they have to take during the negotiation process: which offer is
sent to the opponent, and whether the offers received from the opponent are
accepted. The main strength of the proposed negotiation model is the fact that
it guarantees unanimity within team decisions since decisions report a utility
to team members that is greater than or equal to their aspiration levels at
each negotiation round. This work analyzes how unanimous decisions are taken
within the team and the robustness of the model against different types of
manipulations. An empirical evaluation is also performed to study the impact of
the different parameters of the model.
