1 Constraint-based Negotiation in a Multi-Agent Information System with Multiple Platform Support Dickson K.W. Chiu Ho-fung Leung Dept. of Computer Science & Engineering The Chinese University of Hong Kong S.C. Cheung Dept. of Computer Science Hong Kong University of Science & Technology Patrick C.K. Hung CSIRO, Australia

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 2 Motivation and Background Agents - programs that act on behalf of their human users and exhibit some aspects of intelligent behavior Multi-agent information system (MAIS) used to conduct e- commerce activities Support ubiquitous access through mobile devices over wired and wireless networks Extension of an existing negotiation support system (NSS) into an MAIS infrastructure with multi-platform support Users need different degree of delegation to agents External users without agent support can also participate in the NSS

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 3 Approach Summary Meeting schedule negotiation as example - a very common collaboration task that is time-consuming and tedious Our approach Constraint based negotiation Belief-Desire-Intension negotiating agent Multi-platform user-interface support

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 4 BDI Agent Model Commonly used in AI community

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 5 BDI Example (Meeting Scheduling) belief revision function brf( ) Appointment Constraint: Date = 6/1/2002 Time > 9:00 Time < 12:00 Location = CUHK Appointment Requirement: Date: June 1, 2002 Time: 9: :00 Location: CUHK Duration: 30 minutes Duration = 30 minutes Schedules: 6/1/2002: 10:30-11:30: Meeting 12:00-13:00: Lunch options generation function Options (Available Time Slots): 1) 6/1/ 2002: 9:00-10:30 2) 6/1/2002: 11:30-12:00 options( ) 1) 6/1/ 2002: 9:00-10:30 2) 6/1/2002: 11:30-12:00 Appointment Constraint: Date = 6/1/2002 Time > 9:00 Time < 12:00 Location = CUHK filter func t ion Options (Available Time Slots): Solutions: 1) Date: 6/1/2002 Time: 9:30 Location: CUHK filter( ) Duration = 30 minutes

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS tier Architecture with Agents SMS Gateway WAP Gateway Internet Messenger Web Service Enterprise Processes Negotiation Process Users Alerts Negotiating Agents Other Agents DBMS PDA memory Negotiation Process Negotiation Support System Negotiating Agents User Front EndApplication LogicBackend

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 7 Adaptations for Various Platforms Platforms Tiers EnterprisePDAWAPSMS User Front End Web Service interface for programmed interactions Simplified screen layout Low resolution graphics Panning and zooming WML translation Highly reduced screen SMS message presentation Application Logic Cross- organizational process interoperation Simplified process steps and proceduresSMS dialogue presentation Backend Database Mutually agreed schema and semantics for interoperation Omit some fields Summarized information May need to access PDA memory Mandatory fields only Highly summarized information Highly summarized and mandatory information as message content

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 8 Application Logic Adaptation: Agent Based Negotiation Protocol User input meeting request Agent send options to participants User / agent decide options [with good option] [without good option] Reply YES/NO for each option Reply Counter Options Reply Constraints Agent evaluate constraints and options Inform all participants chosen details [good option found] [max round not exceeded] [max round exceeded] Inform all participants failure [passive mode] [constraint mode] [counter-offer mode] Meeting Caller (Master)Other Meeting Participants

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 9 Application Logic: Negotiator Features on Different Platforms Negotiators Features EnterprisePDA / Desktop User WAP UserSMS User Service Request Web ServiceBrowser interface or programmed action WAP interfaceSMS Automation Business Process on Server Agent run on PDAAgent run on server (and on some new handsets) Alerts SOAP MessageICQ, (or SMS if user also accessible) SMS User response mode Passive, Counter-offer, Constraint Passive, Counter-offer Passive

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 10 Data Schema and View Design View for display

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 11 Multi-platform User Interface Design for PDA users for WAP users

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 12 User Interface Implementation Activity XML Processor XML Document Object NSS Presentation Object XSL Style Sheet XML Schemas User Inputs Generated User Interfaces Screen / Form

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 13 Applicability and Validation of Negotiation Protocol Trade-off among privacy protection, message exchange costs, computational efficiency, and complexity of user interface Centralized open-calendar protocol not suitable - no privacy protection, too much unnecessary data is sent Passive mode - inefficient protocol but simple, least data sent, suitable for SMS users In between: reply counter-option mode or reply constraints – but more complicated user interface required All these can be translated into constraints and therefore into a standard CSP problem Formal validation / consistency check => our paper in IEEE TSMC Part A Nov 2003

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 14 Overcoming Platform Limitations Feasibility of implementing agents on PDA platforms - Microsoft embedded Visual C++ mobile agents can run the constraints in a few seconds Does not need a centralized server and therefore can be highly scalable Summarization and customizing of information to be displayed on different platforms needs knowledge on the information beforehand => contract template (our HICSS36 paper) To overcome the limitation of the small screen size of mobile devices, decomposing a complex negotiation problem into smaller sets of related issues with our developed methodology further helps (our ER2002 paper) E.g., Party organization => ({meeting place, time}, {activities, cost}, {cost-sharing})

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 15 Further and Ongoing work Detailed methodology of adapting the display of negotiation information Process customization for mobile platform e-Marketplaces negotiation support Ranking of preferences Alert management for mobile platforms Location depend application, such as mobile workforce management and mobile customer relationship management (CRM) applications Adaptation techniques for mobile computing at program code level.

Dickson Chiu – HICSS37, Big Island, HawaiiConstraint based NSS - 16 Conclusion Using constraints and BDI agents for NSS adaptation for mobile users Support for both human users and user delegated autonomous agents (with customizable degree of delegation) in a NSS Use of constraints to limit data exchange and to reduce bandwidth consumption for mobile users Detailed implementation framework