providing updated contextual information for norm-aware agents in open mass carolina howard...

Providing Updated Contextual Information

for Norm-Aware Agents in Open MASs

Carolina Howard Felicíssimo

LES-PUC-Rio / LIP6-ParisVI

Advisor: Prof. Carlos José Pereira de Lucena

Co-Advisor: Prof. Jean-Pierre Briot

August 17, 2007 2/28Carolina Howard Felicíssimo © LES/PUC-Rio

Motivation

• Support the Development of Normative Open Multi-Agent Systems

• Support Norm-Aware Agents with Updated Contextual Information

• Our approach: DynaCROM

(dynamic contextual regulation

information provision in open MASs)


Agenda

• Introduction

• DynaCROM

• DynaCROM at Work

• Related Work

• Conclusion


Introduction

• We assume that MASs are open systems

• In Open MASs, agents can freely migrate among them in order to obtain resources or services not found locally

-> Open MASs are Extremely Dynamics !

• Key characteristics of open systems are:– Heterogeneity

– Conflicting Individual Goals

– Limited Trust

• Agents’ actions may deviate from the expected behavior

• Openness has led to software systems that have no centralized control


DynaCROM – Current Implemented Architecture

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DynaCROM

JADE Agent Architecture


Enabling Heterogeneous Agents to Perform in a DynaCROM MAS

(1) public class ExternalAgent extends Agent{...(2) protected void setup(){ (3) addBehaviour(new DynaCROM(this, “APintelSupplier”, “computer-supplier”)); (4) ... }

(1) public abstract class PlanForSuppliers extends APlanForASimpleFIPAContractNetIProtocol { ...(2) public abstract Object[] makeAProposal( String productItem, String productQuantity, String contextualCurrency); //Must return a collection of objects with // [String currency, String proposedPrice] (3) ... }

DynaCROM

makeAProposal()

ASupplierAgent


Enabling Heterogeneous Agents to Perform in a DynaCROM MAS

(1) public void action(){ ...

(2) receivedMsg = myAgent.receive(

MessageTemplate.MatchPerformative(ACLMessage.CFP));

(3) if (receivedMsg != null) {

(4) order = (Object[]) receivedMsg.getContentObject();

(5) String productItem = (String) order[0];

(6) String productQuantity = (String) order[1];

(7) Object[] proposal = ((PlanForSuppliers)

myPlan).makeAProposal(productItem,

productQuantity, contextualCurrency);

...

(8) sendObjMsg(ACLMessage.PROPOSE, proposal,

myAgent, receivedMsg.getSender());

(9) ... }


DynaCROM

• An Approach for Dynamic Contextual Regulation Information Provision in Open MASs

• It is based on:

– A Top-Down Classification of Contextual Norms

• Environment Norms

• Organization Norms

• Role Norms

• Interaction Norms

– A Contextual Normative Ontology

– An Inference Rule Engine to Automatically Compose Related Contextual Norms

Environment NormsOrganization Norms

Role Norms

Interaction Norms

LEGEND - Boundaries of:


DynaCROM at Work

• A Motivating Scenario:

– An American customer wants to built a computer;

– He sends a call for proposal (CFP) to suppliers;

– Suppliers answer the CFP with their proposed prices;

– The American customer chooses a proposal and informs his decision to the chosen supplier.

Organization Country State

Pintel USA Missouri

IMD USA Virginia

Basus Japan Osaka

BasusUSA USA California

Macrostar China Shanghai

MacrostarJapan Japan Hiroshima

Description Base price (in USD) Supplier

Pintel CPU 1500 Pintel

IMD CPU 1200 IMD

Pintel Motherboard 250 Macrostar

IMD Motherboard 300 Basus

Memory 2 GB 100 Macrostar

Memory 2 GB 200 Basus

Hard disk 500 GB 300 Macrostar

Hard disk 500 GB 400 Basus


DynaCROM – Top-Down Classification of Contextual Norms – Environment Norms

• Environment Norm for Payments: In all countries, negotiations are obliged to be paid in their national currency. Negotiations outside a country are obliged to have their values converted from its national currency to the national currency of the country where the seller is.

• Contextual Environment Norms for Payments:

– In USA, all negotiations are obliged to be paid in American dollars (USD);

– In Japan, all negotiations are obliged to be paid in Yen;

– In China, all negotiations are obliged to be paid in Chinese yuan (CNY).


DynaCROM – Top-Down Classification of Contextual Norms – Environment Norms

• Environment Norm for Calculating Prices: In North America, a finished good from every organization is obliged to have its price increased by a fixed percentage (dependent of the seller location) as taxes, for immediate delivery or if the deliver address is in North America.

• Contextual Environment Norms for Calculating Prices:

– In California, a state corporate income tax rate of 8.84 is obliged to be imposed on all sales;

– In Virginia, a state corporate income tax rate of 6.00 is obliged to be imposed on all sales;


DynaCROM – Top-Down Classification of Contextual Norms – Organization Norms

• Organization Norm for Providing Warranty: Organizations are obliged to give a limited lifetime warranty.

• Contextual Organization Norms for Providing Warranty:

– Basus organizations are obliged to give one year limited lifetime warranty;

– Macrostar organizations are obliged to give six months limited lifetime warranty;

– MacrostarJapan organizations are permitted to make an offer of two years limited lifetime warranty if a plus tax of 5% is accepted to be paid.


DynaCROM – Top-Down Classification of Contextual Norms – Role Norms

• Role Norm for Providing Discounts: Suppliers are permitted to give up to a limited percentage of discounts.

• Contextual Role Norms for Providing Discounts:

– Pintel suppliers are permitted to give up to 5% discount;

– IMD suppliers are permitted to give up to 8% discount on orders paid in cash.


DynaCROM – Top-Down Classification of Contextual Norms – Interaction Norms

• Interaction Norm for Providing Discounts: Suppliers are permitted to give up to a limited percentage of discounts if their products are bought in bundles.

• Contextual Interaction Norms for Providing Discounts:

– IMD and BasusUSA suppliers are permitted to offer 15% discount if their products are bought in bundles.


DynaCROM – Top-Down Classification of Contextual Norms – Politic / Economic Norms

• Politic Norm for Operating in the Market: When USA and Japan are under political crisis, American organizations are prohibited to deal with Japanese organizations.

• Contextual Politic Norm for Operating in the Market– Mintor organizations are permitted to increase 10% of their prices when

Watergate organizations are not operating in the American market.

• Economic Norms for Operating in the Market: An organization is obliged to make price fixing for, at least, six months when its competing organizations are not operating in the market.

• Contextual Economic Norm for Operating in the Market– Pintel organizations are obliged to make price fixing for six months

when IMD organizations are not operating in the market.


DynaCROM – Contextual Normative Ontology


DynaCROM – Inference Rule Engine

(1) Rule1- [ruleForEnvWithOEnvNorms:(2) hasNorm(?Env,?OEnvNorms)(3) <- hasNorm(?OEnv,?OEnvNorms),(4) belongsTo(?Env,?OEnv)]

(5) Rule2- [ruleForOrgWithMOrgNorms:(6) hasNorm(?Org,?MOrgNorms)(7) <- hasNorm(?MOrg,?MOrgNorms),(8) hasMainOrganization(?Org,?MOrg)]

(9) Rule3- [ruleForOrgWithEnvNorms:(10) hasNorm(?Org,?OrgEnvNorms)(11) <- hasNorm(?OrgEnv,?OrgEnvNorms),(12) isIn(?Org,?OrgEnv)]

(13) Rule4- [ruleForRoleWithOrgNorms:(14) hasNorm(?Role,?OrgNorms)(15) <- hasNorm(?Org,?OrgNorms),(16) isPlayedIn(?Role,?Org)]


DynaCROM – Reasoning in a DynaCROM MAS

• Purchase Criteria: Minimize Costs

– Buy the bundle IMD/BasusUSA

• In IMD: 1,200.00 (IMD CPU) + 300.00 (IMD Motherboard) + 200.00 (Memory) + 400.00 (Hard Disk) = 2,100.00 – 15% (IMD/BasusUSA bundle discount) = 1,785.00 + 6% (Virginia’s corporate income tax).

– In BasusUSA, then, the corporate income tax of 8.84% from California should be applied instead of the 6% from Virginia

• Purchase Criteria: Maximize the Warranty Period

– Buy in MacrostarJapan for getting two years limited lifetime warranty. However, there, orders should be paid in Yen.

– If he decides to buy in Pintel, suppliers can give 5% discount and the corporate income tax of 6.25% from Missouri should be applied.

• (1,500.00 (Pintel CPU) – 5% (Pintel suppliers’ discount) + 6,25% (Missouri’s corporate income tax)) + 250.00 (Pintel Motherboard) + 100.00 (Memory) + 300.00 (Hard Disk) + 32.50 (plus tax for extending warranty).


Enforcing DynaCROM Contextual Norms

Agent Contexts

abcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcd

obligation

Contextual Norms

Agent Actions

abcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcd

obligation

Agent Contextual

Norms

Agent Contexts

Norm Enforcement

MOSES / SCAAR

Agent Contextual Norms

abcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd abcdabcd

DynaCROM


Enforcing DynaCROM Contextual Norms With LGI

public void sent(…) { if (message.startsWith("CFP")) { … doForward(); return;}

1

public void arrived(…) { if (message.startsWith("CFP")) { doAdd(“manufacturerCurrency(" + getMessageContent(message) + ")"); … doDeliver(); return;}

CFP(currency,USD)

ACalifornianManufacturer AMacrostarSupplier

AMacrostarSupplierPolice

CFP(currency,USD)

ACalifornianManufacturerPolice

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1

2

3

5

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CFP(currency,USD)

manufacturerCurrency = USD

4

5


Enforcing DynaCROM Contextual Norms With LGIpublic void sent(…) { if (message.startsWith(“PROPOSE")) { doAdd(“currency(“ + getMessageContent(message) + ")"); doImposeObligation("checkCurrency", 1, "sec"); return; }

ACalifornianManufacturer

AMacrostarSupplier

AMacrostarSupplierPolice

currency = USDmanufacturerCurrency = USD

“Ok!”

PROPOSE(USD,26157.5)


public void arrived(…) { if (message.startsWith("PROPOSE")) { doDeliver(); return; }


ACalifornianManufacturerPolice

1

1

2

2

3

4 3

if (obligationTerm.equals("checkCurrency")) { … if (currency.equals(manufacturerCurrency) ) { doForward(); doDeliver(CS.toString(), "Ok!", sourceAddress); } else { doDeliver(CS.toString(), "NOk!", sourceAddress); } …}

3

45

5

6

6


Enforcing DynaCROM Contextual Norms With SCAAR

(1) SCAARNorm1- (2) [(agt: aGenericAgent)(3) OBLIGED (agt do PayWithNationalCurrency with environment.hasCurrency = "USD")(4) IF (agt be environment with environment = "USA")(5) OR IF (agt be environment with environment.belongsTo = "USA")]

(6) SCAARNorm2- (7) [(agt: aMintorSupplierAgent)(8) OBLIGED (agt do GiveALimitedLifeTimeWarranty with organization.hasLimitedLifeTimeWarranty = "SixMonths")(9) IF (agt be organization with organization = "Mintor")(10) OR IF (agt be organization with organization.hasMainOrganization = "Mintor")]


Related Work

• Important works concerning regulations in the domain of MASs have been proposed recently (e.g., OMNI, XMLaw,…). However, these solutions seem to lack the necessary flexibility and dynamics for norm evolution in open systems.

• The use of contexts permits a more precise mechanism to deal with norm evolution

• The use of ontologies and ontology-driven rules provides a reasonable dynamics for norm evolution, at system run-time, and also a meaningful way for heterogeneous agents to interpret precise contextual norm information in open MASs.


Conclusion

• The motivating question of my research is how to easily implement regulation in open MASs permitting heterogeneous agents to perform efficiently and coherently.

• The thesis we held here is that the complexity of norm management in open MAS can be decreased by decoupling information in contexts.

• DynaCROM aims to be a straightforward method to smoothly apply and manage regulations in open MASs, enforcing customized compositions of contextual norms.

• The main goal of DynaCROM is not specifically the enforcement mechanism, but how to provide a dynamic solution for regulating open MASs.


Conclusion

• DynaCROM is still a work in progress, but we agree that it already has important contributions for the domain of regulation in open MASs. Its main contributions are:

– Definition of a top-down classification for contextual norms which facilitates the tasks of elucidation, organization and management of norm information;

– Definition of a contextual normative ontology to explicitly represent the semantic of classified norms in a meaningful way (i.e., with a common understanding) for heterogeneous agents;

– Definition of a norm composition process, based on ontology-driven rules, that permits easily update in the system regulation by evolving norms in a unique resource (an ontology) and/or by activating rules for different customized compositions of contextual norms;

– A solution for enforcing contextual norms

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