1. OVERVIEW OF AGENTS AND AGENT ENVIRONMENTS

2. Categories of Agent Research

3. What Is an Agent? In general, an agent is an active computational entity with a persistent identity that can perceive, reason about, and initiate activities in its environment that can communicate (with other agents)

4. Roles of Agents Agents can serve several roles in information systems. Each role can have different variants As client –does everything itself –tells a server how to do something –tells a server what the client would like to have done As server –does nothing –does exactly as told –satisfies high-level requests –preserves self-interest As contents of messages –embodies all of client's functionality –is a procedural script –is a declarative specification

5. Agent Characteristics/1 Locality: local or remote Uniqueness: homogeneous or heterogeneous Granularity: fine- or coarse-grained Persistence: transient or long-lived Level of Cognition: reactive or deliberative Sociability: autistic, aware, responsible, team player Friendliness: cooperative or competitive or antagonistic Construction: declarative or procedural Semantic Level: communicate what or how Mobility: stationary or itinerant

6. Agent Characteristics/2 Autonomy: independent or controlled Adaptability: fixed or teachable or autodidactic Sharing: degree and flexibility with respect to –communication: vocabulary, language, protocol –intellect: knowledge, goals, beliefs, specific ontologies –skills: procedures, "standard" behaviors, implementation languages Interactions: direct or via facilitators, mediators, or “nonagents” Interaction Style/Quality/Nature: with each other or with “the world”, or both? Do the agents model their environment, themselves, or other agents?

7. A Rational Agent Rationality depends on... The performance measure for success What the agent has perceived so far What the agent knows about the environment The actions the agent can perform An ideal rational agent: for each possible percept sequence, it acts to maximize its expected utility, on the basis of its knowledge and the evidence from the percept sequence

8. A Simple Reactive Agent Agent Environment Sensors Effectors What the world is like now What action I should do now Condition-action rules

9. A Simple Reactive Agent function Simple-Reactive-Agent(percept) static: rules, a set of condition-action rules state  Interpret-Input(percept) rule  Rule-Matching(state, rules) action  Rule-Action(rule) return action

10. A Reactive Agent with State Agent Environment Sensors Effectors What the world is like now What action I should do now Condition-action rules State How the world evolves What my actions do

11. function Reactive-Agent-with-State(percept) static: rules, a set of condition-action rules state, a description of the current world state  Update-State(state, percept) rule  Rule-Matching(state, rules) action  Rule-Action(rule) state  Update-State(state, action) return action A Reactive Agent with State

12. A Goal-Based Agent Agent Environment Sensors Effectors What the world is like now What action I should do now Goals State How the world evolves What my actions do What it will be like if I do action A

13. A Utility-Based Agent Agent Environment Sensors Effectors What the world is like now What action I should do now Utility State How the world evolves What my actions do What it will be like if I do action A How happy I will be in such a state

14. A Utility-Based Agent function Utility-Based-Agent(percept) static: a set of probabilistic beliefs about the state of the world Update-Probs-for-Current-State(percept,old-action) Update-Probs-for-Actions(state, actions) Select-Action-with-Highest-Utility(probs) return action

15. Agent Environments Communication Infrastructure –Shared memory (blackboard) –Connected or Connectionless (email) –Point-to-Point, Multicast, or Broadcast –Directory Service Communication Protocol –KQML –HTTP and HTML –OLE, CORBA, DCOM, etc. Interaction Protocol Mediation Services Security Services (timestamps/authentication/currency) Remittance Services Operations Support (archiving/billing/redundancy/restoration/accounting)

16. Agent Environments Accessible vs. Inaccessible Deterministic vs. Nondeterministic Episodic vs. Nonepisodic Static vs. Dynamic Discrete vs. Continuous Open information environments (e.g., InfoSleuth) are inaccessible, nondeterministic, nonepisodic, dynamic, and discrete

17. Mediators Modules that exploit encoded knowledge about data to create information for higher-level applications. Mediators, thus, provide logical views of the underlying information reside in an active layer between applications and resources are small, simple, and maintainable independently of others are declaratively specified, where possible, and inspectable by users come in a wide range of capabilities, from database and protocol converters, to intelligent modules that capture the semantics of the domain and learn from the data

18. Mediator Architecture Application Programs Information Resources User Interfaces Networks Network Interfaces and Mediators

19. Mediator Interfaces Mediators should be separate from databases –mediators contain knowledge beyond the scope of a database –mediators contain abstractions that are not part of a database –mediators must deal with uncertainty –mediators access multiple databases to combine disjoint data Mediators should be separate from applications –their functions are different in scope than those of applications –separate mediators are easier to maintain Because mediators are stable and small, they can be mobile –they can be shipped to sites where large volumes of data must be processed

20. Learning in Mediators Learning can be driven by feedback from performance measures explicit induction over information resources Result of learning can be modifications to certainty parameters augmented tabular knowledge new symbolic concepts

21. Type Brokers A means to manage structure and semantics of information and query languages. Define standard types by which computations can communicate. Most of this work pertains to lower level issues than CIS Typically these involve a set of type servers or brokers and a way to distribute type information. An application uses the broker to find a service, and then communicates directly with the desired service Brokers give slightly more semantics than directories--the type signature of methods, not just their names With more sophisticated notions of service semantics, these could be more useful

22. Protocol Handlers Mediators [Wiederhold] Aides [Carnot DCA] Database and Protocol Agents [Carnot ESS] Heads [Steiner] Brokers [OMNI] Knowledge handlers [COSMO] Intelligent information agents [Papazoglou] Front-end processors [Hecodes] Integrating agents, routers, and wrappers [Gray] Facilitators [ARPA Knowledge Sharing Effort]