M p singh agent communication languages rethinking the principles
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M.P. Singh - Agent Communication Languages: Rethinking the Principles. Alessandro Giusti March, 28 2006. Philips. Microsoft. Sony. Agent Communication Languages. Allow agents to communicate Interoperability (key feature) Other key agent features Autonomy Heterogeneity.

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M p singh agent communication languages rethinking the principles

M.P. Singh - Agent Communication Languages: Rethinking the Principles

Alessandro Giusti

March, 28 2006


Agent communication languages

Philips

Microsoft

Sony

Agent Communication Languages

  • Allow agents to communicate

    • Interoperability (key feature)

  • Other key agent features

    • Autonomy

    • Heterogeneity


Reality check 1998

Reality check (1998)

Verbatim:

“Theoretically, an ACL should let heterogeneous agents communicate.

However, none currently do.”

  • No interoperability

    Who to blame?

Philips

Microsoft


Thesis

Thesis

  • Blame current ACLs

    • Knowledge Query Management Language (KQML):

      based on wrong principles

    • France Telecom’s Arcol:

      based on wrong principles

    • FIPA ACL:

      based on wrong principles

       A paradigm shift is needed

FAILED

FAILED


What principles

What principles?

Analysis of communication dimensions:

  • Perspective

  • Type of meaning

  • Semantic / Pragmatic focus

  • Context

  • Coverage of communicative acts


1 perspective

1 - Perspective

  • Private

    • Sender’s perspective

    • Receiver’s perspective

  • Public

    • Multiagent system’s perspective

      Private perspectives are approximations of the public perspective


1 perspective1

1 - Perspective

  • Public perspective is needed:

    • ACLs must be normative

    • Agents must be tested for compliance

    • The ACL must have a public perspective (or compliance testing is not possible)

  • KQML and Arcol: private perspective


2 type of meaning

2 - Type of meaning

  • Personal

    • Meaning: intent or interpretation of receiver or sender

  • Conventional

    • Meaning: usage conventions

      Language is a system of conventions

      Different conventions need different communicative acts


2 type of meaning1

2 - Type of meaning

  • Conventional meaning is needed

  • KQML and Arcol: personal meaning

    • Different communicative acts do not capture different conventions


Dialects

Dialects

  • KQML failed because many dialects arose;

  • Blame private perspective and personal meaning:

    • Idiolects"When I use a word," Humpty Dumpty said, in rather a scornful tone, "it means just what I choose it to mean -- neither more nor less.“

      Lewis Carroll, “Through the Looking-Glass, and What Alice Found There” (1871)


3 semantics versus pragmatics

3 - Semantics versus pragmatics

Meaning =

Semantics + Pragmatics

  • Semantics

    • what symbols denote

  • Pragmatics

    • how syntactic symbols are interpreted and used

    • involves mental states and the environment

    • constrain how agents interact


3 semantics versus pragmatics1

3 - Semantics versus pragmatics

  • Semantics-focused language is needed

    • Pragmatics require fully-cooperative agents

    • Pragmatics fail where sincerity cannot be taken for granted

  • KQML and Arcol: Pragmatics-focused languages


4 context

4 - Context

Communication context: needed for understanding.

  • Fixed context

  • Flexible context

    Goal: flexible context


5 coverage of communicative acts

5 - Coverage of communicative acts

  • Seven categories:

    • Assertives

    • Directives

    • Commissives

    • Permissives

    • Prohibitives

    • Declaratives

    • Expressives

  • Limited coverage vs Full coverage

    • Full coverage is needed

  • KQML and Arcol have limited coverage


  • Opposing paradigms

    Opposing paradigms

    • Mental Agency

      • Focus on mental state (e.g. BDI)

      • Assumes intentional stance

      • How to determine the mental state of agents?

        • Introspection: unsatisfactory or impossible

        • “Mental state” is an abstract concept: only the agent designer warrants compliance.

    • Social Agency

      • Focus on agent behavior (external)

      • “Social creatures” (sic)

      • Compliance : obey conventions in society (self-evident)


    Autonomy

    Autonomy

    Design autonomy: agent designer’s freedom:

    • Promotes heterogeneity and applications

    • KQML and Arcol require that agents have BDI-based mental states

      Execution autonomy: agent’s freedom

    • Arcol assumes sincere, cooperative, benevolent agents

    • KQML is less strict


    Proposed solution

    Proposed solution

    • Social agency

      • Different from traditional ACLs

      • Goals:

        • Public perspective

        • Conventional meaning

        • Semantics over pragmatics

        • Flexible context

        • Full communicative acts coverage


    Protocols

    Protocols

    • Agents play different roles

    • Roles

      • Define commitments/obligations

        • Restrictions on behavior and communication

      • Agents can manipulate/cancel commitments

      •  Metacommitments (avoid chaos)

    • Protocol

      • Set of commitments

        • Testability without introspection; closed-source friendly.

    • Autonomy

      • Everything is allowed as soon as commitments are met

    • Context is society (“Social context”)

      • Context is better known and agreed on  better communication


    Dialects in societies

    Dialects in societies

    • Agent societies are free from idiolects

      • No private perspective nor personal meaning

    • Dialects  good

      • Allow “context sensitivity” and real-world applications

      • Do not involve introspection

      • No risk of Humpty Dumptyism


    Instantiation

    Instantiation

    • How is this translated into practice?

      • No clear answer

      • A purely behavior-based approach is not viable – too limiting.

      • The purely-mentalist approach has been criticized so far

    • Combine both solutions:

      • Define when a communicative act is satisfied

        • Assertive: if the world matches what is described

        • Directive: the receiver acts to ensure success

        • Commissive: the sender acts to ensure success

      • Coarse canonical set of objective definitions

      • Do not ascribe beliefs and intentions to agents


    Comments critique

    Comments / critique

    • Rewrite:

      • BDI-based languages have drawbacks:

        • Too strict

        • Require introspection for compliance testing

        • Limits autonomy

        • Requires full cooperation

          ... but many of the critiques are not adequately justified.

      • Behavior-Commitments based agencies sound good

        • Upon closer inspection, they have their limits as well: not powerful enough.

      • Proposed solution is a not-better defined mix between the two


    Conclusion

    Conclusion

    • FIPA ACL is based on wrong principles...

      • every possible communication dimension is wrong

    • ... but after 8 years FIPA ACL is the standard.

    • Some of the proposed concepts are intriguing, but they can not be easily translated into practice.


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