Constraint Programming for Supply Chain Management

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Constraint Programming for Supply Chain Management
SCM Information Day, Nov. 21/02

• J. Christopher BeckCork Constraint Computation
  Centre (4C)
• c.beck_at_4c.ucc.ie

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Outline

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

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A Puzzle
You have 5 minutes!

• Place the numbers 1 through 8 in the nodes such
  that
• Each number appears exactly once

• No connected nodes have consecutive numbers

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Modeling

• Each node ? a variable
• 1, , 8 ? values in the domain of each variable
• No consecutive numbers ? a constraint
• (vi, vj) ? vi vj gt 1
• All values used ? all-different constraint

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Heuristic Search
1, 2, 3, 4, 5, 6, 7, 8
1
8
6
Inference/Propagation
1, 2, 3, 4, 5, 6, 7, 8
1
8
1, 2, 3, 4, 5, 6, 7, 8
7
Inference/Propagation
3, 4, 5, 6
3, 4, 5, 6
6
4
3, 4, 5, 6, 7
2, 3, 4, 5, 6
1
8
7
2
3
5
3, 4, 5, 6
3, 4, 5, 6
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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
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Outline

• What is Constraint Computation?
• What does constraint computation have to do with
  SCM?

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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
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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

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Example Vehicle Routing
10 20
15 15
10
10 20
25 20
15
10
Depot
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Example Vehicle Routing
10 20
20 20
10
10 20
10 10
15
10
Depot
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SCM is Distributed
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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!)

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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

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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

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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

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4C - Contact Information

• Director Professor Gene Freuder
• E-mail e.freuder_at_4c.ucc.ie
• External Liaison Officer Dr. James Little
• Phone [phone]
• E-mail j.little_at_4c.ucc.ie
• Post 4C, UCC, Cork, Ireland
• www.4c.ucc.ie