1. PM All rights reserved (Tsang et al) BT’s Collaborator Problem Regions Engineers Jobs P Controllers Time Job Duration / Engineer Availability Manager Research Agenda: To define for management a mechanism to achieve all-win solutions

2. PM All rights reserved (Tsang et al) Flexible Workforce Scheduling for Staff-empowerment Edward Tsang, Qingfu Zhang, Wudong Liu and Tim Gosling Botond Virginas, Chris Voudouris and G Owusu All rights reserved; no part of this presentation should be copied or distributed without prior consent by the authors

3. PM All rights reserved (Tsang et al) The RECONNET Model Manager SellersBuyers Solve Request, Control Coefficients Solution Reports Invitation to bids Bids Contract Retraction Offers / Acceptance / Reject / Wait (Example) M Implementation Results Offers / rejects (binding) Accept / Reject Offers (binding) Multi-objective optimisation

4. PM All rights reserved (Tsang et al) RECONNET Buyers Region Buyer = Controller Element For Completing Jobs Job = {Start Time, Duration, Skill Required, Position, Value} Reports Control Information Revenue, Distance, Preference & Incompletion Coefficients Job Complete / Incomplete, Distance, Preference

5. PM All rights reserved (Tsang et al) RECONNET Sellers Region Seller = Controller Element For Assigning Engineers Engineer = {Position, Availability, Skill Preference} Reports Control Information Assignment, Distance, Redundancy, Load Balancing Contracts: Job, Distance, Preference, Engineer Engineers: Usage Availability = Times Engineer Available Skill Preference = Skills in preference order

6. PM All rights reserved (Tsang et al) Manager: Multi-objective Optimisation Manager SellersBuyers Interact to form contracts Repeat Control Coefficients Buyer: Distance, Preference, Revenue & Incompletion Seller: Assignments, Distance, Redundancy, Load Balancing Solution Reports Jobs: Completion, Distance & Preference Contracts: Distance, Preference, Engineer Engineers: Total and available time Look after company interests

7. PM All rights reserved (Tsang et al) Building Pareto Set of solutions Weights f-values Run 1 W 1,1 w 1,2 w 1,3 f 1,1 f 1,2 f1f1 f2f2 Run 2 W 2,1 w 2,2 w 2,3 f 2,1 f 2,2 Run 3 W 3,1 w 3,2 w 3,3 f 3,1 f 3,2 Run 4 W 4,1 w 4,2 w 4,3 f 4,1 f 4,2 Run 5 W 5,1 w 5,2 w 5,3 f 5,1 f 5,2 Given quality metric for Pareto sets Attempt to learn mapping from variable space to fitness space

8. PM All rights reserved (Tsang et al) Communication System Details Problem solved over multiple rounds One round consists of four phases –Phase 1: Buyer to Buyer (Retraction Requests) –Phase 2: Buyer to Seller (Option requests, offers and rejections) –Phase 3: Seller to Buyer (Options, Offer Accept, Option Retract/Reject) –Phase 4: Buyer to Buyer (Retraction Accept, Reject & Wait) System synchronises on the end of each round to keep everyone in step & prevent unfair advantage Comms System 2

9. PM All rights reserved (Tsang et al) Communication System Determines Control Parameters Manager Buyer Seller Control Parameters Start Solving Retract RequestsOption Requests,Option Offers, Option Rejects Options (including Retraction based options), Option Accepts, Option Retracts (rejects) Retract Accepts, Retract Rejects,Retract Waits End Detected Report Request Reports Phase 1Phase 2Phase 3 Phase 4 Round 1Round n Solution Start Solution End Four Communication Phase in Each Round As Round 1 Retraction Example

10. PM All rights reserved (Tsang et al) Implementation Use of Weblogic for communication –JMS Use of Java for solution implementation Distributed implementation File based configuration and HTML/spreadsheet friendly output Flexible architecture allows easy expansion and modification

11. PM All rights reserved (Tsang et al) Contract Retraction Mechanism Allows Hill-Climbing to find better solutions –Without it solutions are ‘one shot’ Buyer 1Buyer 2 Seller Possible Chain of contract release …. Seller (2) Bids that requires Contract- release ($20) (3) Binding request for contract release, with a compensation offer ($60) (4) Accept contract-release (4) Release contract (1) Request for bids Unserved job ($100)

12. PM All rights reserved (Tsang et al) General Results The system is able to generate solutions to ‘real’ sized problems in about 5 minutes The system’s hill climbing mechanism allows initial solutions to be improved upon Managers are able to effect the solutions discovered by Buyer and Sellers

13. PM All rights reserved (Tsang et al) Management Power Force reduction in distance at Buyers Force reduction in preference at Buyers Force reduction in distance at Sellers Different Buyer configurations

14. PM All rights reserved (Tsang et al) Hill Climbing Demonstrated Use of retraction based options for improvement Demonstration 3 Unfulfilled Free

15. PM All rights reserved (Tsang et al) Related Work

16. PM All rights reserved (Tsang et al) Related Work Contract Net Protocol – no backtracking –Smith 1980, IEEE Trans Computers Decommitting among cooperative Agents –Sen & Durfee 1994, 96, 98 Contingency Contract –Based on future events, Raiffa, 1982 Leveled Commitment Protocol   –Sandholm & Lesser 2001, 02 Two-phased negotiation –Price change between phases only, Akinee 2004

17. PM All rights reserved (Tsang et al) Leveled Commitment Protocol Self-interested agents Decommission by penalties –Computed before contracts become binding Difficult to determine in a dynamic situation Could find global optimal –Through systematically search Intractable for BT’s problem with up to 10 5 jobs Nash equilibrium can be derived –Assuming perfect information Not true in many real life problems

18. PM All rights reserved (Tsang et al) Conclusions Scheduling+Management problem –Motivated by BT’s application –Multi-objectives optimisation Invented protocol for distributed hill climbing –Incorporating release & pricing mechanism –General protocol, could be used to implement different HC strategies, such as GLS, Tabu Search This is a practical solution: –Management control –Local ownership –Found solutions to real sized problem in 5 mins C

19. PM All rights reserved (Tsang et al) Questions

20. PM All rights reserved (Tsang et al) Future Expansion Buyer: Contract Ordering and Selection –When is a retraction option the better risk? –Conflict detection and offer delay Seller: Contract Generation and Pruning –When to issue retraction options or not –Is there a place for multiple retraction based options? –Should all contracts be priced? Seller: Contraction Offer acceptance –Should we consider delays to acceptance? –How do we bundle acceptances? Managers –How best to control solution formation in the Pareto set –How to present options to users

21. PM All rights reserved (Tsang et al) Distributed v Centralised Centralised Advantages –Strong central control –Standardisation –No comms cost in solution finding Disadvantages –Little local ownership –High comms cost in dynamic environments Distributed Advantages –Local ownership –Reduced scheduling time –Divide and conquer –Natural to problem Disadvantages –Difficult to manage –Difficult to enforce standards –Comms overhead

22. PM All rights reserved (Tsang et al) Mechanism Design Nobel Prize in Economics 2007 For having laid the foundations of mechanism design theory Leonid Hurwicz Minnesota b.1917 Eric S Maskin Princeton b.1950 Roger B Myerson Chicago b.1951