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Towards automated procurement via agent-aware negotiation support Andrea Giovannucci, Juan A. Rodríguez-Aguilar Antonio Reyes, Jesus Cerquides, Xavier Noria. Artificial Intelligence Research Institute. Ljubljana March 1st 2005. Agenda. Motivation Requirements Model Implementation Demo.
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Towards automated procurement via agent-aware negotiation support Andrea Giovannucci, Juan A. Rodríguez-Aguilar Antonio Reyes, Jesus Cerquides, Xavier Noria Artificial Intelligence Research Institute Ljubljana March 1st 2005
Agenda Motivation Requirements Model Implementation Demo
PART NUMBER DESCRIPTION UNITS 1 FRONT HUB 2 7 LOWER CONTROL ARM BUSHINGS 3 8 STRUT 4 9 COIL SPRING 2 14 STABILIZER BAR 1 Motivation. Parts purchasing FRONT SUSPENSION, FRONT WHEEL BEARINGACQUISITION GOAL: BUY PARTS TO PRODUCE 200 CARS
PART DESCRIPTION UNITS 1 FRONT HUB 2 7 LOWER CONTROL ARM BUSHINGS 3 8 STRUT 4 9 COIL SPRING 2 14 STABILIZER BAR 1 Motivation Typical negotiation (sourcing) event in industrial procurement
Motivation • Multi-item, multi-unit, multi-attribute negotiations in industrial procurement pose serious challenges to buying agents when trying to determine the best set of providing agents’ offers. • A buying agent’s decision involves a large variety of preferences expressing his business rules. • Providers require to express their business rules over their offering.
Goal • To provide a negotiation service for buying agents to help them determine the optimal bundle of offers based on a large variety of constraints and preferences. • assistance to buyers in one-to-many negotiations; and • automated winner-determination in combinatorial auctions. • To relieve buying agents with the burden of solving too hard a problem (NP problem) and concentrate on strategic issues.
Agenda Motivation Requirements Model Implementation Demo
Requirements Buyer side • Negotiation over multiple items. • “Fuzzy” expressiveness to compose demands(e.g. quantity requested per item lies within some range). • Safety constraints. Establish minimum/maximum percentage of units per item that can be allocated to a single provider. • Capacity constraints. Allocated units cannot excede providers’ capacities. • Item constraints. Capability of imposing constraints on the values a given item’s attributes take on. • Inter-item constraints. Capability of imposing relationship on different items’ attributes.
Requirements Provider side • Multiple bids/offers per provider • Offers expressed over quantity ranges in batch sizes (e.g. Provider P offers Buyer B from 100 to 200 3-inches screws in 25-unit buckets) • Offers over bundles of items • Types of offers over bundles • XOR. Exclusive offers that cannot be simultaneously accepted. • AND. Useful for providers whose pricing expressed as a combination of basis price and volumen-based price (e.g. Provider P’s unit price is $2.5 and different discounts are applied depending on volume of required items: 1-10 units (2%), 10-99 (3%), 100-1000 (5%)). • Homogeneous offers that enforce buyers to select equal number of units per offer item.
Agenda Motivation & Goal Requirements Model Agent Service Description Demo
Model • Modelled as a combinatorial problem defined as the optimisation(maximisation or minimisation) of: • yj.(binary) decision variable on for the submitted bids • 0≤wj≤1 degree of importance assigned by the buyer to item i-th • V1, , ........ Vmbid valuation functions per item • qijdecision variable on the number of units selected from j-th offer for i-th item • pijunitary prices per item • Δij = <δi1j,…, δ ikj> bid values offered by j-th bid for i-th item • Realised as a variation of MDKP (multi-dimensional knapsack problem).
Model SIDE CONSTRAINTS FORMALISATION • Units allocated to each provider falls within his offer • Allocated units per bid multiple of bid’s batch • Aggregation of selected bids’ units lies within requested ranges of units • Units allocated to a single provider do not exceed his capacity • Percentage of units allocated to a single provider does not exceed safety constraints
Model SIDE CONSTRAINTS FORMALISATION • Homogeneous combinatorial bids must be satisfied • Providers per item must comply with saftey constraints • AND bids must be satisfied • XOR bids must be satisfied • Intra-item constraints must be satisfied • Inter-item constraints must be satisfied
Agenda Motivation Requirements Model Implementation Demo
Service Architecture RFQ RFQ’ RFQ’ RFQ’
Service Architecture SOLUTION SOLUTION PROBLEM PROPOSE (BIDS) PROPOSE (BIDS)
AUML Interaction protocol IP-CFP IP-RFQ IP Request Solution Protocols implemented as JADE behaviours (extensions of the FSMBehaviour class) IP-AWARD
Service Ontology (I) RFQ ProviderResponse Buyer’s Constraints Providers’ Constraints
Service Ontology (II) Bid Solution Problem
Implementation features • All agents in the agency implemented in JADE • FIPA as ACL (agent communication language) • Two implementations of SOLVER • ILOG CPLEX + SOLVER • MIP modeller based on GNU GLPK library • Ontology editor: Protegé2000 • Ontology generator: The Beangenerator Protege2000 plugin to generate ready-to-use Java classes
iBundler @ work TRANSLATOR BUYER RFQ ProviderResponse
iBundler @ work TRANSLATOR BUYER Problem Solution
Agenda Motivation & Goal Requirements Model Agent Service Description Demo
PART NUMBER DESCRIPTION UNITS 1 FRONT HUB 2 7 LOWER CONTROL ARM BUSHINGS 3 8 STRUT 4 9 COIL SPRING 2 14 STABILIZER BAR 1 Demo Parts acquisition FRONT SUSPENSION, FRONT WHEEL BEARING GOAL: BUY PARTS TO PRODUCE 200 CARS
Demo Contract Allocation. Unconstrained RFQ Ignoring business rules may lead to inefficient allocations of products/services!!! Unbalanced allocation Unsafe allocation Unsafe allocation
Demo Contract Allocation. Constrained RFQ Balanced allocation Safe allocation Safe allocation
Demo Conclusion iBundler helps buyers & providers to reach better agreeements
Summary and future works • iBundler is an agent-aware negotiation service to help buying agents to determine the optimal bundle of offers based on a large variety of constraints and preferences. It provides: • assistance to buyers in one-to-many negotiations; and • automated winner-determination in combinatorial auctions. • What happens if all constraints cannot be met? • Empirical evaluation of the agentified service vs web service • How to support bidders?