1. Constraint Programming for Supply Chain Management J. Christopher Beck Cork Constraint Computation Centre (4C) c.beck@4c.ucc.ie SCM Information Day, Nov. 21/02

2. 2 Outline What is Constraint Computation? –aka Constraint Programming (CP) What does constraint computation have to do with supply chain management?

3. 3 A Puzzle Place the numbers 1 through 8 in the nodes such that: –Each number appears exactly once ? ? ? ? ? ? ?? –No connected nodes have consecutive numbers You have 5 minutes!

4. 4 Modeling Each node  a variable {1, …, 8}  values in the domain of each variable No consecutive numbers  a constraint –(v i, v j )  |v i – v j | > 1 All values used  all-different constraint

5. 5 Heuristic Search ? ? ? ? ? ? ?? 18 {1, 2, 3, 4, 5, 6, 7, 8}

6. 6 Inference/Propagation ? ? ? ? ? ? ?? 18

7. 7 Inference/Propagation ? ? ? ? ? ? ?? 18 {3, 4, 5, 6} 72 64 35 {3, 4, 5, 6, 7}{2, 3, 4, 5, 6}

8. 8 The Core of Constraint Computation Modeling –What should the variables/domains/constraints be? Heuristic Search –Quality vs. complexity trade-off Inference/Propagation –How much effort should be spent on inference? Focus of 4C: Automating the process of constraint modeling and solution strategy configuration

9. 9 Outline What is Constraint Computation? What does constraint computation have to do with SCM?

10. 10 A Commercial Reality First-tier software vendors embed CP technology in their SCM software This is not to imply that SCM is a “solved” problem Nor that CP is (just) a matter of engineering

11. 11 CP & SCM The puzzle is actually a hard problem –NP-complete Can apply the same technology to core SCM problems –Vehicle routing –Scheduling –Warehouse location

12. 12 Example: Vehicle Routing Depot 10 15 [10 20][15 15] [10 20][25 20]

13. 13 Example: Vehicle Routing Depot 10 15 [10 20] [20 20] [10 10]

14. 14 SCM is Distributed

15. 15 Distributed Problem Solving SCM cannot be solved centrally –Problem size, authority, corporate structure Distributed problem solving is key –Sub-problems are still important (and hard!)

16. 16 SCM-related Research at 4C Scheduling & vehicle routing Distributed scheduling Negotiation & privacy Soft constraints & preferences Focus on reducing the cognitive load for using existing technology

17. 17 Research at 4C: Extending SCM Concurrent engineering –Extend the supply chain to design phase On-line configuration –Bring the individual into the supply chain Dealing with uncertainty –The course of true SCM never did run smooth

18. 18 Take Home Message CP is a commercial reality in SCM Insight into the core of CP technology 4C is pushing the bounds of CP –Automation of hard parts of using CP –Application of CP to new problems 4C is interested is SCM –Application for on-going research –New opportunities

19. 19 Director: Professor Gene Freuder E-mail: e.freuder@4c.ucc.iee.freuder@4c.ucc.ie External Liaison Officer: Dr. James Little Phone: +353-(0)21-4255410 E-mail: j.little@4c.ucc.iej.little@4c.ucc.ie Post: 4C, UCC, Cork, Ireland www.4c.ucc.ie 4C - Contact Information