Research Summary
We are working on a project known as CALO (Cognitive Agent that Learns and
Organizes), a personal assistant agent that will observe and learn from its
user and the environment, assist its user with tasks, and communicate with
other CALOs. This work is supported by the Defense
Advanced Research Projects Agency (DARPA), through the Department of the
Interior, NBC, Acquisition Services Division, under Contract No. NBCHD030010.
Our work as part of the CALO project is to explore these topics in the
domain of distributed task allocation, in which personal agents must work
together, either to schedule multiple events which their users must attend, or
to assign tasks to users as part of a project plan. While cooperating, the
agents are also attempting to honor their users' preferences and privacy
concerns. and operate effectively given a dynamic,
uncertain environment (new conflicts may arise, events may need to be
rescheduled, new tasks may be added to a project plan, communication between
agents may be unreliable, etc.)
Currently, our work falls into four threads: Distributed Constraint
Optimization, Adjustable Autonomy, Privacy, and Teamwork.
Distributed Constraint Optimization
Our research in this area is concerned with constraint-based techniques for
coordination between autonomous agents in dynamic, uncertain environments. In
many domains, such as scheduling, multiple spacecraft coordination, disaster
rescue and reconnaissance, agents must try to agree on how to meet group-level
goals in a timely fashion.
Our approach is to model these types of problems as DCOPs
(Distributed Constraint Optimization Problems). We are exploring modifications
to existing DCOP algorithms, as well as new DCOP algorithms, and examining
their performance in different types of DCOPs in
different domains.
Visit our DCOP web
page for code, datasets, and more information regarding DCOP.
Key papers:
- Jonathan Pearce, Milind Tambe,
“Quality Guarantees on k-Optimal Solutions for Distributed Constraint Optimization Problems”, accepted in International Joint Conference on Artificial Intelligence (IJCAI),
2007
- Emma
Bowring, Milind Tambe,
Makoto Yokoo,
“Multiply constrained
distributed constraint optimization”, accepted in International Joint Conference on
Autonomous Agents and Multiagent Systems (AAMAS),
2006
- Jonathan
Pearce, Rajiv Maheswaran,
Milind Tambe,
“Solution sets for DCOPs and Graphical
Games”, accepted in International
Joint Conference on Autonomous Agents and Multiagent
Systems (AAMAS), 2006.
- Emma
Bowring, Milind Tambe,
Makoto Yokoo,
“Multiply-constrained DCOPs for Distributed Planning and Scheduling”,
accepted in AAAI Spring Symposium on
Distributed Planning and Scheduling, 2006
- J. P.
Pearce, R. T. Maheswaran and M. Tambe, "How
Local Is That Optimum? k-optimality for DCOP," poster paper in Proceedings of the 4th International
Joint Conference on Autonomous Agents and Multi-Agent Systems (AAMAS), Utrecht, The
Netherlands, July 25-29, 2005.
- R. T. Maheswaran, J. P.
Pearce and M. Tambe, "A
Family of Graphical-Game-Based Algorithms for Distributed Constraint
Optimization Problems," in Coordination of Large-Scale Multiagent Systems, Springer-Verlag,
Heidelberg, Germany, 2005.
- J. P. Pearce, R. T. Maheswaran and M. Tambe, "DCOP
Games for Multi-Agent Coordination," in CP Workshop on
Distributed Constraint Reasoning (DCR), 2004.
- E.
Bowring and M. Tambe, "Optimize
My Schedule But Keep It Flexible: Distributed Multi-Criteria Negotiation
for Personal Assistants," in Proceedings of the AAAI Spring
Symposium, 2004.
- R. T. Maheswaran, J. P. Pearce and M. Tambe,
"Distributed
Algorithms for DCOP: A Graphical-Game-Based Approach," in Proceedings
of the 17th International Conference on Parallel and Distributed Computing
Systems (PDCS), 2004.
- R. T. Maheswaran, M. Tambe, E. Bowring, J. P. Pearce and P. Varakantham,
"Taking
DCOP to the Real World: Efficient Complete Solutions for Distributed Event
Scheduling," In Proceedings of the Third International Joint
Conference on Agents and Multi Agent Systems (AAMAS), 2004.
Background work:
Adjustable Autonomy
Adjustable autonomy (AA) encompasses the strategies by which
an agent selects the appropriate entity (itself, a human user, or another
agent) to make a decision at key moments when an action is required. Our
initial work on AA for CALO has focused on the use of Partially Observed Markov
Decision Processes (POMDPs) to account for the
uncertainties in the domain. The key point of this work is it exploits the
notion of progress present in Personal Assistant Domains for enhancing the
performance of these POMDPs.
Key papers:
- Pradeep Varakantham, Rajiv T.
Maheswaran, Tapana Gupta, Milind Tambe,
“Towards efficient computation of error bounded solutions in POMDPs: Expected Value Approximation and Dynamic Disjunctive Beliefs”, accepted in International Joint Conference on Artificial Intelligence (IJCAI),
2007
- Pradeep Varakantham, Milind Tambe, Ranjit Nair, Makoto Yokoo,
“Winning back the cup for distributed POMDPs:
Planning over continuous belief spaces”, accepted in International Joint Conference on
Autonomous Agents and Multiagent Systems (AAMAS),
2006
- M. Tambe, E. Bowring, J. P. Pearce, P. Varakantham, P. Scerri, D.
V. Pynadath, "Electric
Elves: What Went Wrong and Why," in AAAI Spring Symposium on What Went Wrong and Why: Lessons from AI
Research and Applications, Stanford, CA, March 27-29, 2006.
- Pradeep Varakantham, Rajiv T.
Maheswaran, Milind Tambe. “Implementation
Techniques for solving POMDPs in Personal
Assistant Domains”. To appear, Programming Multiagent Systems (PROMAS),
Springer Press Book Chapter, 2006.
- P. Varakantham, R. Maheswaran, M.
Tambe. "Exploiting
Belief Bounds: Practical POMDPs for Personal
Assistant Agents", in Proceedings
of the International Conference on Autonomous Agents and Multiagent Systems, AAMAS-2005.
- P. Varakantham, R. T. Maheswaran
and M. Tambe, "Practical
POMDPs for Personal Assistant Domains,"
in Proceedings of the AAAI Spring Symposium, 2004.
- P. Varakantham, R. T. Maheswaran
and M. Tambe, "Agent Modeling in Partially
Observable Domains," in AAMAS Workshop on Game Theoretic and
Decision Theoretic Agents, 2004.
- R. T. Maheswaran, M. Tambe, P. Varakantham and K. Myers, "Adjustable
Autonomy Challenges in Personal Assistant Agents: A Position Paper,"
in Proceedings of Autonomy'03
Background work:
Privacy
Although members of a multi-agent team are working together
toward a common goal, it is often desirable to preserve the privacy of team
members. We are exploring DCOP as a testbed for
evaluating privacy in collaborative multi-agent systems.
Key papers:
- Rachel
Greenstadt, Emma Bowring, Jonathan Pearce, Milind Tambe,
“Experimental analysis of privacy loss in DCOP
algorithms”, accepted in International
Joint Conference on Autonomous Agents and Multiagent
Systems (AAMAS), 2006 (short paper)
- R. Maheswaran, J.P. Pearce, E.
Bowring, P. Varakantham and M. Tambe, “Privacy
Loss in Distributed Constraint Reasoning: A Quantitative Framework
for Analysis and its Applications” to appear in Journal of Autonomous Agents and Multiagent Systems, 2006.
- R. T. Maheswaran, J. P. Pearce, P. Varakantham,
E. Bowring and M. Tambe, "Valuation
of Possible States: A Unifying Quantitative Framework for Evaluating
Privacy in Collaboration," in Proceedings of the 4th
International Joint Conference on Autonomous Agents and Multi-Agent
Systems (AAMAS), Utrecht, The Netherlands, July 25-29, 2005.
- R. T. Maheswaran, J. P. Pearce, P. Varakantham,
E. Bowring and M. Tambe, "Valuations
of Possible States (VPS): A Quantitative Framework for Analysis of Privacy
Loss Among Collaborative
Personal Assistant Agents," in AAAI Spring Symposium on
Persistent Assistants: Living and Working with AI, Menlo Park, CA,
March 21-23, 2005.
Teamwork
The Machinetta proxy will be used
to allow multiple CALO agents to coordinate as a team. Please go here for more information
about Machinetta.
Key papers:
- N. Schurr, S. Okamoto,
R. T. Maheswaran, P. Scerri
and M. Tambe, "From STEAM to Machinetta: The evolution of a BDI teamwork
model," In Cognition and Multi-Agent Interaction: From Cognitive
Modeling to Social Simulation. Ron Sun (editor), Cambridge University
Press, 2004.
Links
CALO Project:
SRI's CALO page
CALO home page.
(account needed)
TEAMCORE group home page
agents@usc