First Release in 2024

Core Ontology, 202401 Release

What's Changed?

This is the second release of the IOF Core Ontology, but it is the first one of 2024, that the IOF makes available for public use. The main enhancement is the support for specifying temporal relations between occurrences such as events and processes. For that, the IOF Core team implemented the Allen Interval Algebra. This addition, not only offers a variety of temporal relations, but the formalizations given in OWL and SWRL also offer powerful constraint checking and inferencing capabilities as well. Along with that OWL Time is also supported (https://www.w3.org/TR/owl-time/). Through a provided mapping file, which can be imported into a deployment ontology, the user can express the values associated with ‘temporal instant’ and ‘temporal interval’, through durations and date-time information using either the conventional (Gregorian) calendar and clock, or using another temporal reference system such as Unix-time, geologic time, or different calendars.

Along with this new release of IOF Core ontology, the IOF Core team publishes a non-normative guideline document for using the Quantity, Unit, Dimension and Type (QUDT) Ontology with IOF ontologies. QUDT provides a rich vocabulary for quantity kinds and associated units of measure that can be used with the IOF Measurement and Measurement Process entities while the IOF is still working on its BFO-aligned version. In this way, the IOF user community has consistent and interoperable patterns when using IOF ontologies with QUDT. Another benefit of following the guidelines is that when the IOF has developed its quantity and unit ontology, an effort will be made to provide the content necessary to carry forward interoperability with the patterns. It should be noted that the IOF Core team has worked with the QUDT maintainers to fix several issues associated with opening QUDT in Protege 5.5 and with running a reasoner. The result is that QUDT versions 2.1.33 and 2.1.34 can be opened in Protege without error and have been tested to work with Hermit Reasoner version 1.4.

Another enhancement is the ability to represent the gain and loss of roles. Lastly, some terms in the Supply Chain Ontology were promoted to the Core; and some IOF Core terms got updated with more precise formal semantics primarily because of the new terms added in this release.

Validation

To ensure the axiomatic correctness and practical applicability of introduced changes, the IOF Core team has provided a set of comprehensive use cases that include competency questions. Each use case features a user story, instantiated data, competency questions, and SPARQL query results.

Allen Interval Algebra

IOF Core supports representing qualitative temporal information between 'processes' and between 'temporal intervals' (for detailed information about the exact properties created and rationale for choosing Allen Interval Algebra, see confluence page).

In an aim to guide and provide additional utilities of Allen’s temporal relations, two additional files: TemporalRelationChain.rdf and TemporalRelationsInference.rdf are supplied. They can be incorporated into a deployment environment that would result in more utility of the algebra. The former file contains property chain assertions, and the latter contains a set of SWRL rules. When applying appropriate reasoners, the former will bring about the effect of multiple, related Allen’s relations to data. The latter will infer possible Allen’s relations from data.

Temporal Interval and Temporal Instant Value Representation

IOF Core has introduced two new classes to quantify ‘temporal interval’ and ‘temporal instant’. These two classes: ‘temporal duration value expression’ and ‘temporal instant value expression’. IOF Core has also added a new data property 'hasDateTimeInstantValue', which may be used to relate a 'temporal instant value expression' to an XSD date-time.

Additionally, a mapping file MappingTimeToIOF.rdf contains mappings of ‘temporal duration value expression’ and ‘temporal instant value expression’ to corresponding classes in the OWL Time (https://www.w3.org/TR/owl-time/) ontology. If the user imports this file in their application files, they can use calendar date and clock time as well as measurement of duration with IOF Core entities to respectively express ‘time instant’ and ‘time interval’ based on various reference systems (e.g., calendar and clock systems) and units (e.g., hour, minute, second).

For more details about the usage of the new classes and the utilization of owl-time with IOF Core, see the confluence page.

Gaining and Losing Roles

BFO does not provide a way to express when the bearer has started or stopped bearing a role and for how long the role was held. To fill in these shortcomings, ‘gain of role’ and ‘loss of role’ were introduced to IOF Core as subclasses of ‘process’ (for more details about the usage and formalization of the two classes, see confluence page).

Guideline for using IOF Core with QUDT

Currently, the IOF Core Ontology contains key classes and properties for representing magnitude values as well as measurements. However, the IOF has not yet developed classes and properties for representing units of measure, systems of units, and quantity kinds. Developing this could take a long time; therefore, the IOF Core Working Group has taken a tactical step to provide an interim approach using the QUDT ontology. As a result, a non-normative guideline has been developed to establish a foundation for consistent representation of unit-value pairs with the QUDT ontology suite. QUDT was chosen due to its large coverage of units and systems of units as well as its additional provision for unit conversion, dimensional analysis as well as unit equivalence analysis.

It is important to point out that since the guideline is non-normative, the IOF user has the flexibility to use or incorporate other units' ontologies. However, in the event of leveraging QUDT, users are encouraged to adhere to the instructions outlined in the guideline as it will promote interoperability and ease of future transition to an IOF unit ontology.

Key aspects covered by the guideline include the proper instantiation of quantitative and semi-quantitative values. This involves the combination of IOF Core Classes (such as 'value expression' and its subclasses) and IOF Core object and data properties ('has value expression at some time' and its subproperties, and 'has simple expression value') with QUDT classes ('quantity value', 'unit', 'quantity kind') and their instances, including specific units within the QUDT unit vocabulary (e.g., Celsius). Furthermore, the guideline provides explicit instructions on combining QUDT object and data properties ('unit', 'has quantity kind', 'upper bound', and 'lower bound').

To aid understanding, the guideline is enriched with illustrative examples. These examples demonstrate the representation of measured values, physical constant values, specified value ranges, and the integration of the 'measurement process' in which particular values are obtained.

The guideline also equips users with instructions on introducing new units when unavailable within the QUDT framework. Finally, the guideline explains the underlying reasons for the adopted design patterns.

Incorporation of terms from the Supply Chain Ontology (SCO)

Several terms in SCO that are applicable beyond the supply chain domain have been identified and moved to IOF Core. They are then marked deprecated in SCO. With the current IRI specification, these terms now have the IOF Core namespace. The IOF annotation rules also require that all annotations on the deprecated terms be deleted. The following terms are moved:

1. Designed Function (was Artifact Function)
   As part of the move of the term ‘artifact function’, both its label and definition were improved to respect the BFO definition of ‘function’, and align with the definitions of ‘artifact’ and ‘engineered system’. Rather than a function of some material artifact, it is now defined as a function prescribed by some design specification.
2. Gain of Role
   As part of the move of the term ‘gain of role’, the definition was expanded to make extensive use of Allen’s Time Intervals. Specifically, additional axioms indicate that the process produces a role that does not exist prior to the process. For more information, see Gaining and Losing Roles above.
3. Group of Persons
   As part of the move, the principle of identity for this term was changed to strengthen the semantics and make it more widely applicable, such that...

First release in 2023

Core Ontology, Version 1, January 2023 Release

What's Changed?

This is the first "formal release" of the IOF Core Ontology that the IOF makes available and will support for public use. The focus of the release was to adjust the definitional content of all terms to conform with the evolving IOF Annotation Property rules – the latest version of which is also released herewith. Additionally, the release expands our treatment of measurements and identifiers and adds "provisional formalizations" for the notions of 'event' and the 'state'. Lastly, a key objective was to formalize the infrastructure and processes the IOF uses for managing ontologies in development and during pre- and post-release, and to implement the necessary tooling to automate source code management, testing and deployment. The new processes, tools and infrastructure have been implemented in this release of Core for the first time and will apply to the all other ontologies the IOF will release going forward.

Measurements & Measurement Processes

Several new classes and object properties (relations) have been introduced in this release including measurement process, the ability of a thing to be measured, and the resulting measurement results and measurement value expressions (both information content entity types). Many of these are at a “provisional maturity” level and will be refined in the forthcoming release, including better alignment with ISO standards prevailing in this topic area.

Identifiers

The classes and properties related to the notion of identifier have been aligned with and allow for the eventual adoption of the Identifiers Ontology from the OMG Commons Library of Ontologies. The provision for interoperability with the Identifiers Ontology includes the mappings and equivalence expressions captured in a separate mapping file included in this release. Please note that the extended set of terms appearing in the Commons ontologies are not available in the standalone Core. The guidance to users of this release desiring to use IOF ontology along with the Commons ontologies is to import the mapping ontology.

Provisional Definitions for Terms Event and State

Terms Event and State (that latter as in "the particular condition someone or something is in at a particular time) have been introduced as primitive terms in this release along with provisional formalizations. These terms will be further formalized in the coming release and may well involve the introduction of related terms. The intent behind introducing the terms in this is to solicit feedback and to provide "hook classes" from which more specialized types of events and states can be asserted within the domain-specific ontologies of the IOF.

Updates to IOF IRI Construction and Annotation Rules and Vocabulary

Rules have been refined concerning both IRI construction and annotations.

The new rules provide normative requirements related to the IRIs used by an IOF ontology and any linked meta OWL/RDF documents. The requirements were introduced to facilitate consistency and improve usability and apply to both versioned and non-versioned forms of IRIs used by an IOF ontology, as well as during the development phase and upon release. For details, please refer to IRI Structure and Format V2.1, accessible in the IOF member portal.

An updated IOF Annotation Vocabulary is included in this release of Core and may be found under the “meta" category or folder of the ontology resource hierarchy and this source code repository. Updates include the introduction of various maturity properties to aid in managing maturity levels both for IOF ontologies and individual “constructs” – meaning for an individual class, object property or other ontological term. Substantial revisions were made to the annotation properties and rules governing how terms are formalized using the semi-formal and first-order logic expressions, and whether the term is a primitive or a defined term (i.e., has a set of both necessary and sufficient conditions). For details, please consult the Annotation Vocabulary OWL file included in this GitHub repository, or consult the IOF Annotation Property Guide V2.1, accessible in the IOF member portal.