The Reified Requirements Ontology
An upper ontology for requirements in OWL

For a typical application of the ontology, a requirement is represented as an individual: as a member of the Requirement class, or any subclass of Requirement that may be introduced. The requirement source, which will typically be an organisation, is given by the posited by object property. The material “if–then” rule of the requirement is given by an SCD Clause. The antecedent of the SCD Clause is related by has scope, with an optional qualifier by has condition; and the consequent by has demand.

The following diagram illustrates the pattern. Classes defined by the ontology are represented by blue nodes, while white nodes indicate types from the OWL specification.

For example, take a (fictional) Requirement no. 123 on welder qualifications issued by company ACME, that “welders shall be certified to the ISO 9606 standard”. We have

• The organisation issuing the requirement: ACME
• The scope class: Welder
• There is no condition – the requirement applies to any Welder
• The demand class: ISO 9606 certified [professional]

Expressed in semi-formal terms, we may state the requirement as, "it shall be case that every Welder is a ISO 9606 certified. The pattern will then be instantiated as in the following diagram, where purple nodes indicate individuals, amber nodes indicate classes defined for the use case. The annotation property requirement statement is provided for the natural language expression of the requirement.

The representation relies on the punning capability of OWL 2 to allow for the treatment of classes – here, Welder and ISO 9606 certified – as individuals. The following diagram adds types to the previous illustration to indicate this.

As represented according to the pattern of this ontology, a requirement lacks the logical force of a rule: when represented as (punned) individuals, there is no semantic relationship between members of Welder and the required membership in ISO 9606 certified.

To apply requirements to an existing ontology, a transformation is needed so that the rule, “every Welder shall be certified”, has semantic weight. Such a transformation can, for example, be applied using a SPARQL construct query.

In a naive interpretation, we may choose to represent the rule of the requirement as an OWL axiom stating, Welder is a subclass of ISO 9606 certified. Note that this will be too rigid as a proper interpretation of a requirement – it will yield an inconsistency if any welder individual is known not to be certified. (Because OWL DL has no support for defeasible rules, other transformations or rule mechanisms may be required, depending on the use case.)

To preserve a link from this axiom back to the requirement, it may be reified (using owl:Axiom, cf. https://www.w3.org/TR/owl2-syntax/#Axioms), then linked using the provided OWL annotation property from requirement.

The ontology provides the object property violates provision for representing that an individual is in violation of a requirement. Continuing on the example above, assume that J. Doe is a non-certified Welder individual; the following diagram illustrates how this may be applied.

The ontology document in OWL employs the namespace prefixes of table 1.

owl:versionInfo

A02B

dcterms:title

“Reified Requirements Ontology”@en

dcterms:title

“Ontologi for reifiserte krav”@no

pav:lastUpdateOn

“2025-03-05T14:30:33Z”^^xsd:dateTime

dcterms:license

https://creativecommons.org/licenses/by-sa/4.0/

dcterms:creator

https://orcid.org/0000-0002-7167-7321

dcterms:contributor

https://orcid.org/0000-0002-6228-1317

dcterms:modified

“2025-03-05”^^xsd:date

dcterms:publisher

https://www.dnv.com

dc:rights

Copyright DNV Performance and Assurance Solutions

dcterms:description

The Reified Requirements Ontology provides classes and relations for representing requirements as OWL individuals. The intended use relies on punning to handle classes as individuals.

rdfs:comment

The Reified Requirements Ontology provides classes and relations for representing requirements as OWL individuals. The intended use relies on punning to handle classes as individuals.

This ontology contains no owl:DatatypeProperty.

This ontology contains no owl:NamedIndividual.