PerspectivesAAAI Symposium on Agent Mediated Knowledge

Management

March 26, 2003

Sidney BailinKnowledge Evolution, Inc. (www.kevol.com)

Walt TruszkowskiNASA/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

InterpretationKnowledge

Base

Message Stream

Simple Model of an Observer

Update Problem

Update a, b, c,d, e ?

Interpretationp, q, r,

s, t,u, v, w

...

Message

Making Sense of an ObservationIterative 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 Type

Propositional Interpretation KB 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 Interpretation Possible 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: 50Velocity: 600 km/hr 70Size: 3mShape: oblong...

Type: Missile

Source: Adversary

Capability: Evasive

Threat level: High

Auto-respond: Yes

...

Attribute Set Representation

Observation Type

Observed Attributes Inferred 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 Interpretation Classification 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

InitialInterpretation

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