Perspectives AAAI Symposium on Agent Mediated Knowledge Management March 26, 2003 Sidney Bailin Knowledge Evolution, Inc. ( Walt Truszkowski NASA/Goddard Space Flight Center

Problem Scenario Agents must cooperate in some task They disagree about what must be done

A Possible Diagnosis and Treatment Ontology mismatch –Agents mean different things by the same terms –Agents view the world differently Solution: ontology negotiation –An incremental process for establishing shared understanding –Cf. Bailin & Truszkowski, “Ontology negotiation between intelligent information agents,” Knowledge Engineering Review, Volume 17, Issue 1, March 2002.

How do the agents know there’s an ontology mismatch?

Observer Interpretation Knowledge Base Message Stream Simple Model of an Observer

Update Problem Update a, b, c, d, e ? Interpretation p, q, r, s, t, u, v, w... Message Making Sense of an Observation Iterative KB Update

Examples of Observation Remote Sensing Auditory –Name that tune –“What does this mean?” Verbal –Intelligence analysis

Knowledge Representations Propositional –Assertions Ontological –Assertions about types Event sets –E.g., Probabalistic models Attribute sets –E.g., Neural net interpretations Lattice –States of knowledge

Observation TypePropositional InterpretationKB Contents Auditory · That’s Beethoven’s opus 110 · The tempo is too slow · The walls of this house are too thin · My neighbor is a pianist · My neighbor is an audio buff · Knowledge of classical music · Opinions about music performance · Opinions about house construction · Beliefs about a person Remote Sensing · A signature typical of iron compounds was recognized over this region · The asteroid surface is marked by large craters · The soil contains a high concentration of olivine · Spectral analysis · Topographic knowledge · Geo-chemical knowledge Verbal · The Prime Minister speaks in the capital today · Tanks are en route to the northern border · Preparations for an attack seem to be underway · Political events · Military maneuvers · Predictions and risk assessment Propositional Representation

Observation Type Propositional InterpretationPossible Event Space Auditory· That’s Beethoven’s opus 110 · The tempo is too slow · The walls of this house are too thin · My neighbor is a pianist · My neighbor is an audio buff · Musical compositions · Features of a musical performance · Architectural features · People’s skills · People’s hobbies Remote Sensing · A signature typical of iron compounds was recognized over this region · The asteroid surface is marked by large craters · The soil contains a high concentration of olivine · Spectral signatures of the elements · Topographic features · Chemical features Verbal · The Prime Minister speaks in the capital today · Tanks are en route to the northern border · Preparations for an attack seem to be underway · Political events · Military events · Military events Event Set Representation

Observer Interpretation Schema: - Type - Source - Capability - Threat... Position: 50  Velocity: 600 km/hr 70  Size: 3m Shape: oblong... Type: Missile Source: Adversary Capability: Evasive Threat level: High Auto-respond: Yes... Attribute Set Representation

Observation Type Observed AttributesInferred Attributes Auditory· Instrument: piano · Key: A-flat major · Tempo: slow · Volume: loud · Possible composer: Beethoven · Possible composition: opus 110 · Performance quality: sub- standard · Sound insulation: inadequate Remote Sensing · Spectral features · Visual features · Probable substance: iron · Topographic type: cratered Verbal· Activity: speech · Actor: Prime Minister · Location: capital · Goal: rally public · Risk: low · Activity: movement · Actor: tanks · Possible goal: launch attack · Risk: high Attribute Set Representation

Observation Type Propositional InterpretationClassification Performed Auditory· That’s Beethoven’s opus 110 · My neighbor is a pianist · My neighbor is an audio buff · Identification of a specific entity by its signature · Classification of an entity by inference from its behavior Remote Sensing · A signature typical of iron compounds was recognized over this region · Recognition of the presence of a type of substance by its signature Verbal· Preparations for an attack seem to be underway · Identification of a probable threat on the basis of associated signs OntologicalRepresentation

Initial Interpretation Type: Missile Source: Adversary Capability: Evasive Threat level: High Auto-respond: Yes... Message AttributesCategories Classification Uncertainty Method Ontology “Events” in the classification process are the possible categories to which the observed phenomenon can be assigned. “Events” in the initial interpretation process are the possible attribute-values that can be inferred about the observed phenomenon. Integrated Model

What is “Perspective” (1 of 2) Something that distinguishes one observation from another Must be a difference in input, interpretation process, or knowledge base

What is “Perspective” (2 of 2) Choice of input signal –Signal type –Wavelength State of observer, target of observation, and environment –E.g., time, position, angle of observation –As represented in the KB Interpretation function –Choice of significant info in input signal –Mapping of selected signal to KB ontology –This is like human’s “perspective on an issue:

When Observations Conflict Problem with signal? –Phenomenon: noise –Resolution method: calibration Difference in state? –Phenomenon: state-dependent events –Resolution method: correlate state with events Difference in interpretation? –Phenomenon: ontology conflict –Resolution method: ontology negotiation

Summary We’ve developed a model of observation and perspective Agents can explicitly represent and reason about perspective (theirs and others’) Agents can use perspective reasoning to determine how to resolve a conflict –In particular, to determine if and when an ontology conflict is occurring