Expected Utility Communication

A decision-theoretic framework for deciding whether and what to communicate: the utility of a message is the expected change in the hearer’s mental state (and thus their action) weighed against production cost. Central to the automated evolution of ACLs where new lexical items are adopted when their expected utility exceeds implementation cost.

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Summary

Instead of designing ACLs centrally (like KQML or FIPA), the authors propose letting rational, self-interested agents evolve a shared ACL on the fly when they encounter each other. Each agent has its own internal knowledge representation language (KRL) and decides, via Bayesian decision theory and expected-utility calculations, which messages are worth sending and which new ACL constructs are worth negotiating into the shared vocabulary.

Language creation is modeled as a negotiation game drawing on Rubinstein bargaining: agents propose grammatical rules and terminal labels, weigh them against translation/implementation costs and the value of faster communication, and reach Nash-equilibrium agreements. They illustrate with a Wumpus-world scenario, showing how pidgin ACLs grow into richer creole-like languages via unsupervised learning of transducers and negotiation of new lexicon/grammar productions.

Key Ideas

ACL emerges from pairwise negotiation instead of top-down standardization.

Rational agents use expected-utility gains from communication to drive language extension.

Translator modeled as a finite-state transducer between KRL and ACL.

Rubinstein bargaining gives closed-form agreement on new ACL constructs.

Evolution from pidgin to creole through repeated interaction.

Conceptual Contribution

Claim: Agent communication languages need not be standardised top-down (KQML, FIPA); rational agents can initiate, enrich, and evolve a shared ACL through game-theoretic negotiation driven by expected-utility gains from improved communication.

Mechanism: Each agent owns a private KRL and a finite-state transducer translating KRL ↔ ACL; decision-theoretic message selection (Bayesian, utility-maximising) identifies candidate new lexical/grammatical constructs; a Rubinstein-bargaining model with time discounting, implementation cost, and identity assumptions yields Nash-equilibrium agreements that extend the shared ACL grammar. Illustrated on a Wumpus-world example.

Concepts introduced/used: ACL Evolution, Knowledge Representation Language, Finite-State Transducer, Rubinstein Bargaining, Pidgin and Creole, Value of Communication, Unsupervised Grammar Induction, Mechanism Design

Stance: formal-semantic / engineering

Relates to: Offers a decentralised alternative to the standardisation stance of KQML Overview and FIPA-ACL; resonates with Emergence of Grounded Compositional Language in Multi-Agent Populations and Emergent Communication which study language emergence from interaction; the bargaining apparatus parallels commitment-based approaches in Agent Communication And Institutional Reality.

Summary

Gmytrasiewicz and Gopal propose a decision-theoretic framework for artificial agents to autonomously enrich and evolve their shared agent communication language. Each agent has a frame/object-based knowledge representation language (KRL) encoding beliefs about the world and nested beliefs about other agents. Decisions about which messages to send are grounded in expected-utility computations over the effect on the hearer’s mental state, so every well-defined message carries measurable value to the speaker.

When the ACL proves inadequate to express content the agent wishes to communicate, the agents engage in game-theoretic negotiation (after Rubinstein-style alternating offers) over new lexicon items and grammatical rules. Utilities trade off implementation cost, time-discounting, and communicative gain. The framework thus gives a concrete mechanism for pidgin-like emergence of shared ACLs among rational, knowledge-based agents.

Key Ideas

KRL as agents’ “language of thought”; ACL is a translation target.

Message value = expected-utility impact on hearer’s mental state.

Negotiation over lexicon and grammar when ACL is insufficient.

Nested agent models enable rational communication choices.

Decision-theoretic, game-theoretic grounding for language emergence.

Conceptual Contribution

Claim: The content and extension of an agent communication language can be derived from rational-decision principles: every message carries measurable expected utility, and when the current ACL is insufficient, agents rationally negotiate new lexicon and grammar.

Mechanism: Each agent has a frame-based KRL representing nested beliefs about others; message utility is computed as the expected change in the hearer’s mental state weighed against action value. When no existing ACL expression suffices, Rubinstein-style alternating-offers bargaining over new lexicon items and grammar rules trades off implementation cost, time-discount, and future communicative gain, producing a pidgin-like convergence path.

Concepts introduced/used: Knowledge Representation Language, Expected Utility Communication, Rubinstein Bargaining, Nested Beliefs, Lexicon Negotiation, Pidgin Emergence, Decision-Theoretic ACL

Stance: formal-semantic

Relates to: Provides a decision-theoretic counterpart to the situated emergence of Language Games for Autonomous Robots and the neural emergence studied in On the Pitfalls of Measuring Emergent Communication; its utility-grounded messages contrast with the mentalistic sincerity conditions of Agent-Oriented Programming and FIPA-ACL.

Expected Utility Communication

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