The paper presents a formal model for negotiation between autonomous agents, focusing on service-oriented negotiations where one agent (the client) requires a service from another (the server). The model defines strategies and tactics agents can use to generate initial offers, evaluate proposals, and make counteroffers. It is based on computationally tractable assumptions and has been empirically evaluated. The key contributions include: 1. **Rich and Flexible Negotiation Schemes**: The model allows for a wide range of negotiation behaviors. 2. **Realistic Assumptions**: It is based on realistic assumptions for autonomous computational agents. 3. **Empirical Evaluation**: The model has been evaluated empirically. 4. **Convergence of Negotiation**: Some initial results on the convergence of negotiation are presented. The model is structured around negotiation threads, which are sequences of offers and counteroffers between two agents. Agents use tactics to generate values for negotiation issues, and strategies to combine these tactics over time. The paper also introduces different types of tactics, such as time-dependent, resource-dependent, and imitative tactics, and discusses their applicability conditions. The experimental evaluation focuses on the behavior and interdependencies of the model's basic elements, using a simplified bilateral negotiation scenario to assess agent performance.The paper presents a formal model for negotiation between autonomous agents, focusing on service-oriented negotiations where one agent (the client) requires a service from another (the server). The model defines strategies and tactics agents can use to generate initial offers, evaluate proposals, and make counteroffers. It is based on computationally tractable assumptions and has been empirically evaluated. The key contributions include: 1. **Rich and Flexible Negotiation Schemes**: The model allows for a wide range of negotiation behaviors. 2. **Realistic Assumptions**: It is based on realistic assumptions for autonomous computational agents. 3. **Empirical Evaluation**: The model has been evaluated empirically. 4. **Convergence of Negotiation**: Some initial results on the convergence of negotiation are presented. The model is structured around negotiation threads, which are sequences of offers and counteroffers between two agents. Agents use tactics to generate values for negotiation issues, and strategies to combine these tactics over time. The paper also introduces different types of tactics, such as time-dependent, resource-dependent, and imitative tactics, and discusses their applicability conditions. The experimental evaluation focuses on the behavior and interdependencies of the model's basic elements, using a simplified bilateral negotiation scenario to assess agent performance.