multiagent system communication

Agent CommunicationBy: Ahsan Rahim

Introduction

An agent is a computer system capable of autonomous action in some

environment in order to meet its design objectives

Agent communication is essential for facilitating cooperation,

coordination, negotiation, and other aspects of agent interaction

Agent Communication Languages (ACLs)

Agents Communication Language (ACL) provides agents with a means

of exchanging information and knowledge.

Number of languages have been developed specifically for agent

communication.

Knowledge Sharing Effort (KSE)

In the early 1990s, Knowledge Sharing Effort (KSE) was formed &

sponsored by the Advanced Research Projects Agency (ARPA)

The Knowledge-Sharing Effort (KSE) is an initiative to develop the

technical infrastructure to support the sharing of knowledge among

autonomous information systems

The goal of this effort is to develop a technology that will enable

researchers to develop new systems

Participation by dozens of researchers in academia and industry

Knowledge Sharing Effort (KSE)

The KSE generated two main deliverables as follows:

i. The Knowledge Query and Manipulation Language (KQML)

ii. The Knowledge Interchange Format (KIF)

Knowledge Interchange Format (KIF)

KIF is a computer-oriented language for the interchange of knowledge

This language was originally developed with the intent of being a

common language for expressing properties & representing knowledge

of a particular domain

It was not intended to be a language in which messages themselves

would be expressed

KIF is a Langauge for expressing message content


KIF is used to state:

i. Properties of things in a Domain (e.g. ‘John is a Chairman‘)

ii. Relationships between things in a Domain (e.g. 'Michael is Janine’s

Boss')

iii. General properties of a Domain (e.g. 'everybody has a mother')


“The temperature of m1 is 83 Celsius”:

(= (temperature m1) (scalar 83 Celsius))

“An object is a bachelor if the object is a man and is not married”:(defrelation bachelor (?x) :=

(and (man ?x) (not (married ?x))))

“Any individual with the property of being a person also has the property

of being a mammal”:(defrelation person (?x) :=> (mammal ?x))

Knowledge Query and Manipulation Language (KQML)

KQML is a message-based language for agent communication. Thus

KQML defines a common format for messages

It was developed by the ARPA-supported Knowledge Sharing Effort and

independently implemented by several research groups

KQML is a language that is designed to support interaction among

intelligent software agents

The KQML language simplifies its implementation by allowing KQML

messages to carry useful information:

Such as the names and addresses of the sending and receiving agents,

a unique message identifier, and notations by agents

Knowledge Query and Manipulation Language (KQML)

KQML is a language that defines various acceptable ‘communicative

verbs’, or Performatives (such as: ask, reply)

Example Performatives:

• ask-if (‘is it true that. . . ’)

• perform (‘please perform the following action. . . ’)

• tell (‘it is true that. . . ’)

• reply (‘the answer is . . . ’)

KQML: The 3 Layers

Communication Layer

Mechanics of communication, e.g. Sender, receiver

Performatives (Message Layer)

Specifies the actual content of the messagee.g. a KIF expression

Content Layer

Logic of communication, The set of performatives provided by the language e.g. ask, tell

KQML Example

(ask-one

: content (PRICE IBM ?price)

: receiver stock-server

: language LPROLOG

: ontology NYSE-TICKS 1

)

The intuitive interpretation of this message is that the sender is asking

about the price of IBM stock

The Foundation for Intelligent Physical Agents (FIPA) In 1995, the Foundation for Intelligent Physical Agents (FIPA) began its work

on developing standards for agent systems

The Foundation for Intelligent Physical Agents (FIPA) is a non-profit

association

FIPA’s purpose is to promote the success of emerging agent-based

applications, services and equipment

FIPA operates through the open international collaboration of member

organisations: companies, universities and government organisations

The most important difference between the KQML & FIPA is in the

collection of performatives they provide

FIPA

Here is an example of a I FIPA ACL message

( inform

:sender agent1

: receiver agent2

:content (price good2 150)

:language sl

: onto1ogy hpl –auction

)

multiagent system communication

Education