Agent Mediated Grid Services in e-Learning Chun Yan, Miao School of Computer Engineering Nanyang Technological University (NTU) Singapore April, 2004

2 Singapore

3 Preface: Agent Agent is an emerging new paradigm for next generation e-Systems in various domains. Agent technology is identified by “MIT Technology Review” as one of the technologies that will change the world”. It is predicted that in 10 years time, most new software developments will contain embedded agent systems.

Vision: How People Learn The familiar “world to the desktop” “Alice in Wonderland”: computer based agents assist learners in diverse ways “ubiquitous learning”: embedded agents in handheld wireless devices and in real objects i.e. intelligent objects

5 Preface: Goal Orientation An agent is defined as the one who acts on behalf of human beings. By nature, a human being does things based on goals. Goal orientation is a key character of agents. A large majority of the current efforts on agent modeling and development still employ object- oriented methodologies, which model an agent as an extended object Agents are goal oriented, which necessitates a shift in modelling paradigm, from object-oriented modeling to goal-oriented modeling.

6 Agenda Agent Mediate Service Oriented Grid Goal Net: A Goal oriented modeling approach to agent oriented systems Goal Selection and Action Selection Modeling of MAS with Goal Net Goal Autonomous Agent Agent Mediate Grid Service in e-Learning

7 Agent’s Goal Model Task Oriented: Task Oriented: an agent lives in a task- oriented domain; the goal of an agent is a set of tasks to perform. State Oriented: State Oriented: an agent lives in the state- oriented domain. The agent’s environment is evolved with a finite set of states. A goal of an agent is a desired state that the agent tries to reach from its current state by going through a sequence of states.

8 Characterizing Agent’s Goal To model the complex goals of agents, a characterization of an agent’s goal with different properties such as composite goal, fuzzy goal, partial goal, sub goal etc. is highly needed. To model the complex goals of agents, a characterization of an agent’s goal with different properties such as composite goal, fuzzy goal, partial goal, sub goal etc. is highly needed. To enable agents to present such goal characters, new goal models are demanded. To enable agents to present such goal characters, new goal models are demanded.

9 Goal Net: Overview A Goal Net is composed of five basic objects: states, transitions, arcs, branches, and tokens. composite state transition atomic state transition composite state arc token branch

10 Goal Net: State State State is a system situation at a time during agent running State is a system situation at a time during agent running Atomic, Composite Atomic, Composite Goal is a desired state that an agent intents to reach. Goal is a desired state that an agent intents to reach. In a Goal Net, a composite state is a goal. In a Goal Net, a composite state is a goal.

11 Goal Net: Transition Transition Defines actions to transit from one state to another state. Defines actions to transit from one state to another state. Defines action selection mechanism Defines action selection mechanism Direct, Conditional, Probabilistic, Fuzzy Direct, Conditional, Probabilistic, Fuzzy Direct Transition Probabilistic Transition Conditional Transition Fuzzy Cognitive Transition

12 Goal Net: Transition Transitions can represent four basic relationships between states: sequence, conflict, concurrency, and synchronization. SiSi Concurrency Synchronization Sequence Choice SjSj SiSi SiSi SiSi SkSk SjSj SkSk SjSj SkSk SjSj

13 Goal Net: Arc,Token,Branch An arc is used to connect a state to a transition or a transition to a state. It indicates the relationship between the state and the transition it connects. A token is used to indicate agent’s current activities in different states. It presents dynamic behaviors of the goal model. It indicates the progress of the goal pursuit process. The branches are used to represent the decomposition of a composite state.

14 Goal Net: Measurement Goal Measurement Achievement: represents a recognizable benefit of reaching a goal; Achievement: represents a recognizable benefit of reaching a goal; Distance: indicates how close the current state is to a composite state or a sub goal; Distance: indicates how close the current state is to a composite state or a sub goal; Completeness: represents a percentage of the entire goal fulfillment; Completeness: represents a percentage of the entire goal fulfillment; Cost: means the time, memory, money, etc. spent or required to be spent from one state to another. Cost: means the time, memory, money, etc. spent or required to be spent from one state to another.

15 Goal Net: Goal/Action Selection Goal Selection – Goal Autonomy Take future goals/stats into consideration Take future goals/stats into consideration Achievement, Cost, Constraint, Trust, Index Achievement, Cost, Constraint, Trust, Index Action Selection – Behavior Autonomy Sequential execution Sequential execution Situation Action: Rule-based inference Situation Action: Rule-based inference Probabilistic inference Probabilistic inference Fuzzy Cognitive Inference Fuzzy Cognitive Inference

16 Goal Net: Action Selection Sequential execution: This is the simplest situation. There is no action selection needed. Agents can move from one state to the next state by the execution of the fixed sequence of actions. Sequential execution: This is the simplest situation. There is no action selection needed. Agents can move from one state to the next state by the execution of the fixed sequence of actions. Rule-based inference: In this situation, complete information for action selection is present. Agents can make decision according to the rules and current values of all the factors or states. Rule-based inference: In this situation, complete information for action selection is present. Agents can make decision according to the rules and current values of all the factors or states.

17 Goal Net: Action Selection Probabilistic inference: In this situation, information for action selection is not complete. A Bayesian network that represents the relationships between factors and actions can be constructed. An agent then reasons its actions through the Bayesian network inference. Probabilistic inference: In this situation, information for action selection is not complete. A Bayesian network that represents the relationships between factors and actions can be constructed. An agent then reasons its actions through the Bayesian network inference. Fuzzy Cognitive Inference: A Fuzzy Cognitive map that represents the relationships between factors and actions can be constructed. An agent reasons its actions through fuzzy cognitive inference. Fuzzy Cognitive Inference: A Fuzzy Cognitive map that represents the relationships between factors and actions can be constructed. An agent reasons its actions through fuzzy cognitive inference.

18 Modeling MAS with Goal Net In addition to an agent goal model, Goal Net also serves as a goal-oriented requirement and modeling tool, and a multi-agent identification, organization and coordination model. From Goal Hierarchy to Agent Hierarchy Agent Identification Agent Identification Agent Coordination Agent Coordination Goal Net is able to assist in whole life cycle for development of agent-oriented applications

19 Agent Mediated Service Oriented Grid 7. End Users 6.Consumer Applications 5. Service Agents 4. Information Service Center 3. Marketing Service Agents 2. Grid Services 1. Provider Applications Applications A A A AA A A A A A A Services Applications

20 Marketing Agents in Agent Grid Provide Service Received Request Process Request Sent Results Negotiated Job Dispatched Exception Processed

21 Service Agents in Agent Grid Serviced Request Received Obtain Service Service Located Services Discovered Search Service Broadcast Service Selected NegotiatedRequest Sent Services Found Query Prepared

22 From Goal Hierarchy to Agent Hierarchy: MAS Derivation X Y Z Marketing agent Process request agent Negotiate agent D B A Negotiation agent Look up agent Locate service agent Service agent C

23 Goal Autonomous Agent The agent whose goal is modeled with the Goal Net is able to present both behavior autonomy and goal autonomy in a dynamic changing environment. We call this type of agents goal autonomous agents.

24 Goal Autonomous Agent Life Cycle PR 2 A Perceive: The agent perceives its environment continuously to sense any new situations. Perceive: The agent perceives its environment continuously to sense any new situations. Reason for goal selection: The agent infers the next goal, based on its goal model, knowledge, and the perception of its environment. Reason for goal selection: The agent infers the next goal, based on its goal model, knowledge, and the perception of its environment. Reason for action selection: The agent infers actions based on the selected goal, knowledge, and the perception of its environment. Reason for action selection: The agent infers actions based on the selected goal, knowledge, and the perception of its environment. Act: The selected actions are executed. Act: The selected actions are executed.

25 Goal Autonomous Agent Agent Model Database Knowledge Base Data Goal Knowledge Inference Engine controller communication perception action Environment

26 E-Learning System E-learning service Learner preparation Learning Role Selected Pre- Assessment Learning Path Generated Learning Object Delivery Teaching Post- Assessment

27 E-Learning Grid Services System Learning agent Courseware servers in a Grid environment Learning service agent Learner preparation agent

28 E-Learning Grid Services System Learning agent Courseware servers in a Grid environment Learning service agent Learner preparation agent

29 Conclusion Goal Net serves as a goal-oriented modeling and analysis tool, an agent goal model, and a multi- agent modeling, identification and organization model. As a new agent goal model, Goal Net enables the agents to present both behavior autonomy and goal autonomy. The modeling and design of goal autonomous multi-agent systems using Goal Net have demonstrated a promising approach for designing and developing intelligent, open distributed agent systems in grid service in e- Learning.

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