Intelligent Agents: Technology and ApplicationsAgent Teamwork

IST 597B

Spring 2003

John Yen

Learning Objectives: Given an application that involves a group of agents, be

able to identify its major characteristics (e.g., adhoc vs structured team etc).

For a specific types of agent team applications, be able to identify major issues related to the design of such agent teams.

Given an agent team applications, be able to determine whether a particular agent teamwork model/architecture (i.e., CAST) is suitable for the application.

Problem 1

Consider the following five applications involving agent teams, identify several key characteristics that are important for these applications. Use a table to compare the similarities and differences of these applications along these characteristics.

1. A team of agents that play Robot Soccer together.2. A team including robots, soldiers, and software

agents (for information fusion/delivery) in the battle field.

3. A team of software agents that support/automate the information exchanges and/or transactions of business partners (e.g., supplier of parts, manufacturers of products, distributors, ...) in a supply chain.

4. A group of agents that assist the companies they each represent to form coalitions for business opportunities.

5. A group of agents, each represent a user, interacts in an e-auction marketplace.

Characteristics

Team membership: Static vs dynamic Shared goals vs individual goals Benevolent vs selfish Hierarchical vs Egalitarian Homogenous vs Heterogeneous Level of Trust Coordination vs competition

Key Characteristics for Agent Teamwork

Benevolent (shared goals) vs selfish (individual goals) Capabilities: Homogenous vs Heterogeneous Membership of the Team: Static vs dynamic Structure of the Team: Completely predefined, partially

defined by roles, completely unspecified. Types of the structure: Hierarchical vs Egalitarian Process of the Team: Completely predetermined, partially

specified, dynamically generated. Human agent-software agent relationship: boss-assistant,

peer, trainee-coach. Relationship between members of the Group:

Cooperative, partially cooperative, competitive. The level of trust

Homework 3 (15%, team assignment, due April 8th)

Compare the similarities and differences of the five agent teams using the key characteristics identified in class. Describe a (sixth) agent team application and characterize it using the characteristics.

Problem 2: (5%) What are important issues related to these

characteristics?

Related Issues - Team Structure How to form a team? How to determine the structure of

a team?– Important if the structure of the team is dynamically determined.

How to specify roles and assign responsibilities based on roles?

– Important if the team structure is partially specified by roles. How to reconfigure a team?

– Important if members of the team may die or be overloaded How to resolve conflicts in a team?

– Important if the team does not have a hierarchical structure.

Related Issues - Team Process

How to specify, coordinate, and execute a team process?– If the process is partially/fully specified.

How to generate a team process (through planning)?– If the process is dynamically generated.

How to make sure emergent behavior achieves expected effects?– If the process is not specified.

Related Issues - Human-agent Relationship

How to give human users adequate control of agents? – If agents are assistant to human

How to enable agents to understand the mental states of human and the context of the interactions?– If agents are peer; and (to some degree) assistant.

How much can users trust agents? How to design friendly interface to enables agents

and user interact more effectively? How to make agents human-like?

Related Issues - Cooperative/Competitive

How to enable agents to negotiate with others?– If agents are partially cooperative partially

competitive

How does an agent balance intentions of others with intentions of self when they are conflicting.

– If agents are not selfish less (I.e., partially self-centered).

Related Issues - Trust

How to establish/guarantee/revise trust?– Important if trust is important

Two Conflicting Objectives of Teamwork Models Efficiency

– Higher team performance– Reduced communications

Flexibility/Adaptability– Adapt the structure of the team– Adapt the process of the team– Adapt the responsibility assignment

Goals for CAST Teamwork Model

Achieves a high-level of efficiency with a reasonable degree of adaptability for applications with role-based structure and process.

Motivation

Psychological Studies about Effective Human Teamwork Indicated that

Team members can anticipate needs of team mates Team members can offer relevant information

proactively. These teamwork behaviors are based on an

overlapping shared mental model.

Shared Mental Model

Shared Ontology Shared Goals Shared Team Structure Shared Team Collaboration Process Shared Belief about the Team Shared Belief about the World

– Shared Hypotheses about the Enemy

CAST Agent Architecture

Use a high-level language to describe teamwork knowledge

Capture “shared mental model” about team structure and process

Infers information needs (from SMM) induces proactive information exchanges

Anticipating Information Needs of Teammates

Team PlanResponsibilities

of Tasks

Preconditions ofTasks

Information Needs

DynamicTask

Allocation

Who

needs what

Dynamic Task Allocation

Team Plan

Constraints for TaskAllocation

Roles of Agents in the Team

My Belief aboutThe World

My Belief aboutTeammates

DynamicTask

Allocation

Proactive Information Delivery

My Belief aboutTeammates

Information Needs

InformationMatch ?

CommunicationStrategy

Does he/sheknow ?

How toinform him/her?

CAST Agent Architecture

TeamKnowledge (MALLET)

Responsibilities(Petri Nets)

Belief

DomainKnowledge

ResponsibilitySelection

IdentifyInfo Needs

InformationNeeds

InformationBeliefUpdate

Act onInfo Needs

Shared Mental Model in CAST Prolog knowledge base: belief MALLET: High-level language for

representing team knowledge Petri Nets: An agent’s internal

representation of the dynamic teamwork processes and related information requirements

Relationships between SMM Components

MALLETKnowledge Base

PrologKnowledge Base

(belief)

MALLETCompiler

Petri Net(team process)

query

reply

CASTKernel

(team-plan T1 () (process (par (kill-wumpuses) (collect-gold))))

(team-plan kill-wumpuses () (agent-bind ?s (play-role ?s scout)) (agent-bind ?f (play-role ?f fighter)(closest ?

f wumpus)) (process (while ((wumpus ?x) (not (dead ?x)))) (seq (do ?s (find-wumpus ?x)) (do ?f (move-to-wumpus ?x)) (do ?f (shoot-wumpus ?x)))))(team-plan find-gold () (agent-bind ?c (play-role ?c carrier)) (process (while (true) (if (see ?any-agent

glitter) (do ?c (carrier-pickup gold))))

start find shootmove

wumpus exists

glitter

done

no wumpuses left

pickup

CAST Development Environ.

Circles are places and hold tokens denoting current execution state. Red indicates the presence of a token. Rectangles are transitions and are tested and executed when preceding places have tokens.

Circles are places and hold tokens denoting current execution state. Red indicates the presence of a token. Rectangles are transitions and are tested and executed when preceding places have tokens.

Two Types of Information needs

Action-performing information needs– enables an agent to perform certain (complex)

actions, which contributes to an agent's individual commitments to the whole team.

Goal-protection information needs– allows an agent to protect a goal from potential

threats that may result in a conflict with the goal.

Applications

Training for AWACS-like synthetic task (AFOSR MURI)

Support Agent-based Collaborative Mission Planning (Army Research Lab)

Simulating Digital TOC (STRICOM) Negotiation among Agent Teams for

Engineering Design (NSF)

Conclusion A computational shared mental model is critical for

developing agents that support a team involving both agents and human.

(PSU-TAMU) CAST enables proactive information delivery by anticipating needs of teammates.

MALLET facilitates the reuse of teamwork knowledge CAST achieves efficiency using shared team plans and

shared policy CAST achieves adaptability by dynamic assignment of

agent responsibility