1. Argumentation-based negotiation Rahwan, Ramchurn, Jennings, McBurney, Parsons and Sonenberg, 2004 Presented by Jean-Paul Calbimonte

2. Negotiation? interactions Mutually acceptable agreement Scarce resources: time money services, anything Automate! Approaches  Game-theoretic analysis  Heuristic-based  Argumentation-based

3. Classical negotiation  Agents exchange proposals  Limitations  Computational constraints (analytical game-theoretic)  Sub-optimal approximate outcomes (heuristic-based)  Require extensive empirical evaluation (heuristic)  No additional info exchanged  Agents preferences need to be fully characterized  Lack information to evaluate/compare proposals  Fixed agents preferences proposals

4. Argumentation-based negotiation  Exchange additional information  Argument: piece of information  Reasons for refusal  Justification of a proposal  Change object of negotiation  Promise rewards  Emit threats  Components  External elements  Own elements

5. Non-ABN Elements Proposal Database Locution Interpretation Opponent/ Environment Model & Mental Attitudes Proposal Evaluation Generation Locution Generation Outgoing Locutions Incoming Locutions query / update query Proposal content propose / accept / reject

6. ABN elements Proposal Database Locution Interpretation Opponent/ Environment Model & Mental Attitudes Proposal Evaluation Generation Locution Generation Outgoing Locutions Incoming Locutions query / update query Proposal content propose / accept / reject Argument Interpretation Argument Generation Argument Selection Argument content

7. External elements  Communication language  Interaction between agents  Locutions, utterances  Domain language  Concepts & meta information about the world  Negotiation protocol  Conventions, rules of dialogue: who is allowed to say what?  Information stores  Keep track of utterances, behavior  Internal, external repositories accept reject propose reject(b,a,Price=$200 and Item=palmI30)

8. Communication & domain language  Rich languages, clear semantics request(j,i, Do(i,α),Do(i,α)  Do(j,β))  Express preferences  Express plans, intentions  Standardized domain languages  Heterogeneous environments  Semantic & Syntactic interoperability i j Do(i, α ) Do(i, α )  Do(j, β )

9. Negotiation protocol  Interaction, dialogue rules  Finite state machines  Dialogue games  Enforce fairness, rule consistency  Termination, avoid infinite interactions  Enusre guaranteed success  Endless interactions?  Conformance checking  Utterance acceptable?  Admission to negotiation

10. Information stores  Keep track of past utterances  Internal  Centralized  Commitment stores  Promise to initiate, execute, maintain  Defend claims  Commitment rules  Retract from commitments  Allowed  Forced

11. Elements of ABN agents  Argument and proposal evaluation  Incoming arguments, update mental state  Argument and proposal generation  Generate set of candidates  Argument selection  Choosing a candidate

12. Argument and proposal evaluation  Objective considerations  Argument acceptability, evaluation  Subjective considerations  Consider own preferences and motivations  Combine objective + subjective  Combine belief arguments and value arguments  Provide unified framework for evaluation of goal, belief, plan, etc.  Probabilistic evaluation

13. Argument and proposal generation  Generate candidate arguments  Increase, maximize utilities  Rule-based generation  Characterization of possible arguments  Take into account other factors:  Protocol  Authority  Expectations  Utility  Honesty

14. Argument selection  Choose candidate argument  ABN strategy  Use strength order:  common practice, appeal, self interest, promise,threat  Use factors: trust-utility  I need this but I don’t trust you  Opponents information,  Probabilistic models, uncertainty  Learning techniques  Consider behavior & mental model behind

15. Conlcusions  ABN: increasing importance  Enables rational dialogue  Richer models of negotiation  How agents use objective reasoning to reach subjective goals?  Challenges  Communicative rationality  Social influence  Trust  Mediated negotiation  Complexity