CMSC 477/677 - Spring 2007

Discussion Questions for Class #17, April 3

Reading: Tambe, "Agent Architectures for Flexible, Practical Teamwork"; Scerri, Pynadath, and Tambe, "Towards Adjustable Autonomy for the Real World."

Tambe (STEAM)

• Summarize the three key ideas of STEAM beyond the theoretical framework of joint intentions:
  1. Team synchronization
  2. Monitoring of joint intentions and repair
  3. Decision-theoretic methods for determining what and when to communicate
• The key to team synchronization is establishing joint commitment, which in turn entails that the agents behave in certain ways in response to external events. Give some examples of external events that would trigger action in the context of an established joint commitment.
• STEAM formulates a top-level "team plan," which individual agents expand further to construct their individual plans. The individual plans are then executed in the context of the team plan. In the team planning phase, "all team members must simultaneously select OP to establish a joint intention." This phase requires that there is a team leader who develops the team plan. This is a very different model from the PGP distributed planning system. Discuss the tradeoffs (benefits and disadvantages) of these two models.
• The operator hierarchy in STEAM ("hierarchical reactive plans") represents a somewhat limited notion of planning. A more general planning system might use hierarchical task network planning to construct new strategies on the fly, do more sophisticated situation analysis and variable binding, include contingency plans in case of action failures, and/or use probabilistic models to project likely outcomes and select the best alternatives.
  • How would these planning extensions improve the performance and/or increase the complexity of the overall STEAM system?
  • What kinds of problems might arise in the joint planning activity if individual planners incorporated these extensions?
• What triggers a plan repair in STEAM? What are the repair actions that can be taken?
• What does "decision-theoretic communication selectivity" mean in the context of STEAM? How is the value of a communication action decided?
• What are the influences from SharedPlans and joint intentions theory in STEAM?

Scerri, Pynadath, and Tambe (Adjustable Autonomy, Electric Elves)

• What are the two types of transfer-of-control actions that are presented in this work?
• What is a Markov Decision Process? What might be some of their limitations for the adjustable autonomy problem?
• What is the relationship of this work (if any) to STEAM and joint intentions theory?