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Interoperability in Agentspace: proposal of agent interface to environment

Stanisław Ambroszkiewicz IPI PAN, Warsaw,

Poland

Supported by ESPRIT project CRIT2September 2000

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FOCUS OF OUR RESARCH: Agent organizations in Cyberspace

Autonomous, heterogeneous agents are supposed to form organizations!

The key issues:•Infrastructure

• Interactions: mobility, communication, services, ...

•Semantic interoperability• Understanding: negotiation, cooperation, …

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Interoperability

agent communities A1, A2, A3, … in a world (AGENTSPACE)

a community Ai consists of homogeneous agents perceiving the world, interacting and speaking their own language Li

interoperability between heterogeneous communities: heterogeneous agents can interact and understand each other

A3A1 A2

AGENTSPACE:

L1 L2

L3

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Interoperability continued

Fix agent community A1 What does it mean: perceiving the world, interacting,

speaking language L1, and understanding each other ??? perfect (interaction and semantic) interoperability

inside A1:common interaction infrastructure is NOT necessaryexplicit meaning (ontology) of L1 is not needed !

A1

L1

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Interoperability continued

interoperability between heterogeneous communities: heterogeneous agents can interact and understand each other interaction interoperability: common interaction

infrastructure; semantic interoperability, explicit semantics is

necessary: language for ontology interchange + interpretation

of O2 into O3 and vice versameaning of concepts is reduced to common generic

representation of the world structure

A2L2,O2

A3L3, O3

Common interaction infrastructure

OIL or generic representation of the world

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Generic MAP architecture as Interaction Infrastructure

PEGAZ - our MAP for agents, services, and agent

organizations development

Java Virtual MachineJava Virtual Machine

Win 95/98

Internet/Intranet/WAN/LAN (TCP,UDP)

LINUX SunOS MS Win NT

Mobile Agent Platform - a uniform view of Cyberspace

place place placeservice

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AGENT ARCHITECTURE

Environment:

Agent memory, i.e. local states

situations

Perception

Communic-ation

LearningRoutine execution

Decision mechanism

Goal

Library of routines

KNOW

agent or service

Action: communicate

communicate

event

Interface

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Proposal of agent interface to environment

Responsible for interactions. Based on MASIF / FIPA standard. It assures interaction interoperability: migration, communication, using services, etc.

The goal: means to achieve semantic interoperability

Representation layer

Agent interface:

Communication Language

Functionality layer

Language layer

Representation of the world (Agentspace) structure. Local event structure is the basis for the representation. Agents perceive the environment in the same way

Communication Language: simple query language for homogenous agents and Meaning Interchange Language (MIL to be constructed) for heterogeneous agents

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The idea behind

The reason for common interface: nothing in common = no understanding, i.e. no semantic interoperability

Functionality layer: MASIF / FIPA standard are not sufficient; still work in progress

Our proposal: Representation layer as formal representation of the

structure determined by the functionality level : generic MAP environment & mechanisms for acquiring knowledge from perception (already done!)

Language layer - MIL (Meaning Interchange Language) - work in progress

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ENVIRONMENT of a Mobile Agent Platform

place place placeservice

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FORMAL SPECIFICATION OF GENERIC MAP ENVIRONMENT

Primitive entities:

places, agents, services, resources

Primitive actions: migrate, use service, take (give) resource, communicate with agent (service)

Events: each event represents an action execution - local interaction of agents, services and places involved in the execution

communicate

place placemigrate

take / give

use service

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FORMAL SPECIFICATION OF GENERIC MAP ENVIRONMENT

Partial order of events

service......

service

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AGENT MEMORY

Agent’s memory: collection of variables V1 , V2, … , Vk (abstraction of database) standing for concepts.

concept vi = ( name , carrier , meaning )

variable vi = (identifier, type, modification way)

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ACQUIRING KNOWLEDGE 1: FROM PERCEPTION

place placemove

where the current location is stored

where names of services are stored

where the info on contents is saved

Update variable: at event:

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ACQUIRING KNOWLEDGE 2: FROM COMMUNICATION

Query

Answer

Query: what is your Vi ? Answer: my Vi=10. Agent: revision of Vi; preserve Vi, change Vi to 10 or compute new value

Vi is used in the same way by the homogeneous agents !!!

Homogeneous agents:

Agents’ databases are of the same type, i.e., V1 , V2, … , Vk (of blue agent) and V1,V2, ... ,Vk (of green agent) , and Vi and Vi are of the same type for i=1,2,...,k

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CONCEPT MEANING is the way the

concept is used (Wittgenstein)

meaning of Vi = the way Vi is used in updating and revision updating and revision mechanisms are the same for all homogeneous agents !!! The same interfaces !!!

Vi

update

agent

revise

Agent’s database

Agent’s interface:

Funct

ionalit

y layer

Repre

senta

tion layer

Language layer

Vi

a homogeneous agent

Environment:Perceptio

nevent

sambrosz:

meaning of concept is defined inside a community of homogeneous agents; sharing the same ontology

sambrosz:

meaning of concept is defined inside a community of homogeneous agents; sharing the same ontology

Communication

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Meaning Interchange Language: MIL

Ontology of society A1

Concepts: v1; vi

Functionality layer

Representation layer

Language layerReduction of concept meaning Concept formation

from / to a heterogeneous agent

generic meaning of v1 (in RDFS ?)

generic meaning of vi (in RDFS ?)

? ?

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Conclusion

What has been done: Specification of the representation layer;

What not: The rest of the interface;

Future work: Construction of MIL, generic rules

(primitive constructors) for concept formation;

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SEMANTIC INTEROPERABILITY:agents can identify, communicate and understand each other

to understand each other they must agree on the meaning of concepts they use!

KEY ISSUE: meaning, semantics (ontology) represented in a machine-readable way

Natural language: Can we represent the meaning of concepts (we use) explicitly, i.e. in a machine-readable way? A fundamental problem !!!

Kant , Husserl, Wittgenstein, …

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Formal approaches to semantics and semantic interoperability

Tarskian semantics: semantics of a theory is given by interpretation in a model. The model is another theory !!!

Ontolingua: Gruber, Guarino et al.: meaning of concept is constrained by logical axioms.

OKBC - Open Knowledge Base Connectivity, exchange standard for ontologies chosen by FIPA

XML and RDF web standards for information exchange

OIL - Ontology Interchange Language, a European project

DAML project - DARPA Agent Markup Language: a semantic language that ties the information on page to machine-readable semantics