Achieving Mediated Agreements Using Agreement Spaces

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Slides used in the Workshop of Agreement Technologies (WAT'09). Sevilla (Spain)

Slides used in the Workshop of Agreement Technologies (WAT'09). Sevilla (Spain)

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  • 1. Introduction Context Spaces Agreement Concepts Agreement-Related Interaction Protocols Using Agreement Spaces for Mediators Example Conclusions Achieving Mediated Agreements Using Agreement Space Modeling C. Carrascosa and M. Rebollo Univ. Politécnica de Valencia (Spain) Workshop on Agreement Technologies November 2009, Sevilla Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 2. Introduction Context Spaces Agreement Concepts Agreement-Related Interaction Protocols Using Agreement Spaces for Mediators Example Conclusions Outline 1 Introduction 2 Context Spaces 3 Agreement Concepts 4 Agreement-Related Interaction Protocols 5 Using Agreement Spaces for Mediators 6 Example Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 3. Introduction Context Spaces Agreement Concepts Agreement-Related Interaction Protocols Using Agreement Spaces for Mediators Example Conclusions Introduction Importance of the context Approach focused on the agreement concept itself Agreement defined as a multi-dimensional Euclidean space Geometrical properties of agreements → solved as a CSP A counselor mediates the process to evaluate its feasibility Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 4. Introduction Context Spaces Agreement Concepts Agreement-Related Interaction Protocols Using Agreement Spaces for Mediators Example Conclusions Context Spaces Context-aware computing: context defined as a set of attributes and their domains Context algebra to represent states and reason about them Operations: scalar difference (similarity) and intersection (new spaces) States are multi-dimensional objects Regions of acceptable values defined Each attribute is considered one dimension in a multi-dimensional Euclidean space. Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 5. Introduction Context Spaces Agreement Concepts Agreement Definition Agreement-Related Interaction Protocols Agreement Process Using Agreement Spaces for Mediators Agreement Space Example Conclusions Agreement Definitions Definition (Agreement) An agreement Ag is defined as Ag = (E , Cx ), where: E = {E1 , E2 , . . . En } is a set of participant entities I Cx = {(cxo , cxo )|cxo ∈ I Oi , cxo ⊆ Do } i Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 6. Introduction Context Spaces Agreement Concepts Agreement Definition Agreement-Related Interaction Protocols Agreement Process Using Agreement Spaces for Mediators Agreement Space Example Conclusions Agreement Definitions Definition (Agreement Discourse Universe (ADU)) It is the set of concepts known by at least two entities participating in the agreement and it is defined as ADU(Ag) = i Oi − D Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 7. Introduction Context Spaces Agreement Concepts Agreement Definition Agreement-Related Interaction Protocols Agreement Process Using Agreement Spaces for Mediators Agreement Space Example Conclusions Agreement Process 1 Reach an agreement: 1 ADU definition (common vocabulary) 2 agreement terms defined (valid instances) 2 Agreement execution Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 8. Introduction Context Spaces Agreement Concepts Agreement Definition Agreement-Related Interaction Protocols Agreement Process Using Agreement Spaces for Mediators Agreement Space Example Conclusions Agreement Space Definition (Agreement Discourse Space (ADS)) The Agreement Discourse Space of an agreement Ag ADS(Ag) is defined by considering as a dimension (in an Euclidean space) each concept included in an Agreement Discourse Universe of an agreement Ag. That is, the ADS(Ag) is an n-dimensional space, where n is the cardinality of the ADU(Ag) Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 9. Introduction Context Spaces Agreement Concepts Agreement Definition Agreement-Related Interaction Protocols Agreement Process Using Agreement Spaces for Mediators Agreement Space Example Conclusions Agreement Space Definition (Agreement Space)) It is a projection of the Agreement Discourse Space onto the dimensions defining the agreement. That is, this space will be defined by the features the different entities Ei making the agreement are going to negotiate (Cx ), each one of such features defining a dimension in this space (∀i : di ∈ dim(Ei , Ag)). Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 10. Introduction Context Spaces Agreement Concepts Agreement Definition Agreement-Related Interaction Protocols Agreement Process Using Agreement Spaces for Mediators Agreement Space Example Conclusions Agreement Space Definition (Agreement Local Space) for entity Ei in the agreement Ag is defined as the projection over the dimensions of interest of entity Ei in such Agreement Space. Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 11. Introduction Context Spaces Agreement Concepts ADU Interaction Protocol Agreement-Related Interaction Protocols Mediated Agreement Interaction Protocol Using Agreement Spaces for Mediators Example Conclusions Agreement-Related Interaction Protocols WS-Agreement: standard to model conversations for one-to-one negotiation processes service agreement: service provider selection using FIPA iterated contract net Protocols to conversate with Counselor ADU Iteraction Protocol: vocabulary definition Mediated-Agreement Interaction Protocol: space definition Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 12. Introduction Context Spaces Agreement Concepts ADU Interaction Protocol Agreement-Related Interaction Protocols Mediated Agreement Interaction Protocol Using Agreement Spaces for Mediators Example Conclusions ADU Interaction Protocol Initiator Counsellor Participant i call for counsellor m j <= n not-understood n k <= n - j refuse l=n-j-k agree failure-no-match deadline request not-understood refuse agree call for agreement p r <= p not-understood p s <= p - r refuse t=p-r-s agree failure-proxy t t inform t Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 13. Introduction Context Spaces Agreement Concepts ADU Interaction Protocol Agreement-Related Interaction Protocols Mediated Agreement Interaction Protocol Using Agreement Spaces for Mediators Example Conclusions Mediated Agreement Interaction Protocol Initiator Counsellor Participant i (a) Counsellor Participant i (b) inform-context p call for agreement not-understood call-for-terms p p refuse inform-term agree [¬consistent] reject call for context p [redundant] r <= p not-understood reject p s <= p - r refuse [consistent] accept t=p-r-s agree call-for-terms proxied-communicative-act inform-done agreement terms failure subprotocol reply-message Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 14. Introduction Context Spaces Agreement Concepts ADU Interaction Protocol Agreement-Related Interaction Protocols Mediated Agreement Interaction Protocol Using Agreement Spaces for Mediators Example Conclusions The final result is the definition of the Agreement Space, modeled as a hyperpolyhedron formed by all accepted constraints (agreement terms). During the execution of the agreement, all interactions have to be inside this space as the participants have agreed. Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 15. Introduction Context Spaces Agreement Concepts Agreement Spaces as a CSP Agreement-Related Interaction Protocols Counselor Algorithm Using Agreement Spaces for Mediators Example Conclusions Agreement Spaces as a CSP Participant entities must arrange a valid interval for each dimension Participant restrictions can be considered as CSP constraints in the n-dimensional space Mediator checks incrementally the consistence among all the constraints The Agreement Space is the result of the constraints intersection HSA = algorithm is used to check the coherence and to build the space Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 16. Introduction Context Spaces Agreement Concepts Agreement Spaces as a CSP Agreement-Related Interaction Protocols Counselor Algorithm Using Agreement Spaces for Mediators Example Conclusions Agreement Spaces as a CSP Counselor Algorithm Receive a new constraint Ci if ¬ consistent( Ci , Polyh ) reject Ci else if redundant( Ci , Polyh ) reject Ci else accept Ci add_constraint( Ci , Polyh ) endif Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 17. Introduction Context Spaces Agreement Concepts Agreement-Related Interaction Protocols Using Agreement Spaces for Mediators Example Conclusions Example. Definition Let it be a set of agents interested in taking piano classes. The group is formed by one teacher and two students. They agree to negotiate over three dimensions: the number of classes (n), its duration (d) and its price (p). Teacher at least 10 classes: n ≥ 10 duration between 60 and 120 min: d ≥ 60 and d ≤ 120 at least 20 euros/hour: p ≥ 20 Student 1 no more than 20 classes: n ≤ 20 less than 30 euros/hour: p ≤ 30 Student 2 minimum 15 classes: n ≥ 15 duration between 45 and 90 min: d ≥ 45 and d ≤ 90 Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 18. Introduction Context Spaces Agreement Concepts Agreement-Related Interaction Protocols Using Agreement Spaces for Mediators Example Conclusions Example. Execution Agent Mess Param Agent Mess Param 1 C inform n, d ,p 16 C accept n ≤ 20 2 C call-for-terms 17 C call-for-terms 3 T inform n ≥ 10 18 S2 inform d ≥ 45 4 C accept n ≥ 10 19 C reject d ≥ 45 5 C call-for-terms 20 C call-for-terms 6 S1 inform p ≤ 30 21 T inform d ≤ 120 7 C accept p ≤ 30 22 C accept d ≤ 120 8 C call-for-terms 23 C call-for-terms 9 S2 inform n ≥ 15 24 T inform p ≥ 20 10 C accept n ≥ 15 25 C accept p ≥ 20 11 C call-for-terms 26 C call-for-terms 12 T inform d ≥ 60 27 S2 inform d ≤ 90 13 C accept d ≥ 60 28 C accept d ≤ 90 14 C call-for-terms 29 C inform-done 15 S1 inform n ≤ 20 Carrascosa & Rebollo Achieving Mediated Agreements. . .
  • 19. Introduction Context Spaces Agreement Concepts Agreement-Related Interaction Protocols Using Agreement Spaces for Mediators Example Conclusions Conclusions Context spaces seems a valid approach to model agreements The agreement space is a hyperpolyedron in a n-dimensional space The problem of defining the space associated with an agreement can be seen as a CSP Mediators are used to check the consistence of the space incrementally The communication protocols and algorithms used by the mediator have been presented As future work, the dynamics of the agreement are going to be studied. Carrascosa & Rebollo Achieving Mediated Agreements. . .