ontology in model-based systems engineering

International Workshop28 Jan – 2 Feb 2011

Phoenix, AZ, USA

Ontology in Model-Based Systems Engineering

Henson Graves29 January 2011


Phoenix, AZ, USAPreview Of Monday Discussion Topics

• SysML and ontology in biomedical modeling• Ontology reuse in MBSE• Ontology for identifying and resolving model

ambiguity • Approaches to integrating SysML with logic

based frameworks, e.g., OWL• Overlap with other MBSE working groups

– Enterprise modeling (DoDAF, …– MBSE standards

• Issues, questions, what else is going on,…


Phoenix, AZ, USA

SysML and Ontology in Biomedical Modeling

Henson Graves

Yvonne Bijan30 January 2011


Phoenix, AZ, USAHuman Heart Use Case For Structural

Modeling

Focus of conceptual modeling is on structure


Phoenix, AZ, USAConceptual Modeling Objectives

• Construct a model that captures what is common to all (or at least) most human hearts

– corresponds to product model, or product line

• Perform general reasoning about effects of pathology and disease symptom propagation

– general properties of operation

• Use general case to analyze and reason about a specific heart

– fault detection


Phoenix, AZ, USAMBSE Interest

• Do the modeling principles used by Description Logic (OWL) community offer anything for MBSE?

• Will these examples and the DL models help us understand how to integrate formal reasoning with SysML?

• How do biomedical examples look in SysML?• Do the modeling principles used for air

vehicles and other systems work in biomedical domain?


Phoenix, AZ, USA

Ontology Reuse In MBSE

Henson GravesJanuary 2011


Phoenix, AZ, USAOntology Applications in MBSE

• Examples – Units and measures– Physical interactions (laws)– Material classification and properties– Enterprise concepts

• Levels of rigor– Vocabulary – Informal textual semantics of vocabulary– Formal (axiomatic) semantics


Phoenix, AZ, USAExample Opportunity: Analysis Result


Phoenix, AZ, USAApproaches To Achieving Ontology

Reuse

• Identify candidate ontologies, acquire and make available

• Start over with uniform modeling principles


Phoenix, AZ, USA

Common MBSE Modeling Questions and How Ontology Helps

Henson GravesConrad Bock

January 10, 2011


Phoenix, AZ, USAWhat Does a Model Describe

• Are the things described by a model all the same, or can they be different?– In particular, do they all have the same parts linked together

in the same way?

• The answer is no (perhaps intentionally) if– The model is incomplete.

• Does a car have more than engines and wheels?– Are there any specializations of the model? Is there more than one

model of the same car?

– The model is complete, but isn’t specific.• What kind of engine? What kind of wheel? Which goes with

which?– Parts aren’t distinguished or equated.

• Does the car roll on the driven wheels?


Phoenix, AZ, USAOntology Languages

• Ontology languages enable modelers to say how they want these questions to be answered

• Doesn’t mean system engineers need to learn ontology languages– Ontology languages can motivate and validate extensions to

SysML/UML and other modeling languages to address ambiguities

• Improves quality of communication between people, between people and machines, and between machines– Giving a model a descriptive name (“complete car model”)

does not mean that people or machines know exactly what you are talking about.


Phoenix, AZ, USA

Integrating SysML with OWL

(or other logic based formalisms)

Henson Graves Conrad Bock


Phoenix, AZ, USAWhy Integrate SysML With Logic

• Engineering has always been about • building models of real world domains,

– analyzing models and making measurements

– refining and modifying the models

• Integrating a modeling language with logic-based system enables

– Standardization of model semantics

– Checking that model integration does not lead to inconsistency

– Automated reasoning tools to perform tasks which outstrip manual capability

– formal derivations for justification of engineering decisions


Phoenix, AZ, USAHow Does Integration With Logic

Achieve Objectives

• Constructions in logical language are given (axiomatic and/or referential) semantics, e.g.,

– Codify expected properties of language constructions such as subclass, instance, part,…

– Allow users as they model systems to not be dependent on subject matter experts to convey their meaning

– Use automated reasoning, based on formal semantics, for consistency checking as models are developed and merged

– Formal derivations (proofs) can provide justification for assumptions and decisions made on basis of models


Phoenix, AZ, USASome Different Approaches To

Integration

• Learn some logic based language, say FOL, or OWL and use that

– recognizing that logic is primary

• Translate SysML into OWL and back in so far as is possible

– Switch back and forth

• Provide SysML with a formal logical foundation

– allow users to work within SysML and take advantage of reasoning tools


Phoenix, AZ, USA

A Stack of Semantic Standards for Ontologies

To enable semantic interoperability

Increasing use of standards

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Resource Identification Standards

Data Interchange Format Standards

Metadata Standards

Modeling Language Standards

OntologyStandards

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ontology in model-based systems engineering

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