The AlignmentOntology (AO)

The AlignmentOntology aims for a formalisation of the concept of an alignment and the relations it is based on. It is defined by an RDFSchema file. A corresponding Protégé 3.1.1 project is also available. Be aware that this ontology is under development and may be subject to changes.


  • [04.07.06] EXTENSION: Benjamin Horak added DiscreteAttachments and Acknowledgements.
  • [04.07.06] CHANGE: Retyped the xsd:anyURI datatype references to the ontology entities. rdf:resource is better.
  • [30.06.06] The first version of an im-/exporter tool is now available, allowing to export PhaseLibs alignments to an AO rdf file, and to import such a file by an PhaseLibs alignment implementation.
  • [29.06.06] The AO has been created by Benjamin Horak and Björn Endres. The draft is now subject to discussion.

Feature/Change Requests

not yet

License Issues

The Alignment Ontology is published under the GNU Lesser General Public License (LGPL).

Integration/Alignment with other alignment ontologies

Lockheed Martin Alignment

An alignment between our AlignmentOntology and the Lockheed Martin ATL alignment specification is given by the file LMCOAlignment.rdf. This file specifies the alignment using both schemes at the same time.

SKOS Mapping

The SKOS Mapping Vocabulary defines mappings between topic maps. However, their scheme is not semantically equivalent to our alignment concept, since they use a set theory based approach on the documents attached to their concepts. Thus, the transformation of a SKOS mapping into a PhaseLibs alignment or vice versa is semantically questionable.

In order to transform a set of simple (one-to-many) SKOS mappings you can do the following:

  • the various degrees of matches can be mapped to the confidence property
  • flat AND bag constructs can be transformed to refer instead to an artificial subclasse of the given class conjunction.
  • flat OR bag constructs can be expressed by a number of Superordination/Subsumption relations.
  • NOT constructs can be expressed by a number of Distinctions.

Ontology Description

The AlignmentOntology basically defines relations between ontology entities, e.g. classes, properties, instances. The semantic of a basic, untyped relation is a connection of any kind, a cooccurrence. There are also further specifications of a realtion:

  • Subsumption defines a relation like subclass_of or subproperty_of
  • Superordination is the opposite of Subsumption
  • Equivalence defines the two entities as semantically equivalent. In particular, this is the case if it is a supsumtion AND a superordination at the same time.
  • Classification defines a type_of relationship, e.g. that an instance belongs to a class.
  • Distinction states, that neither of the above holds for the relation

Each relation defines

  • the two entities to relate
  • a confidence value which expresses the confidence that the producer has of the correctness of the relation
  • an arbitrary number of attachments, that supply additional information but are formally not important.

Finally, an Alignment is defined as a set of such Relations. Since the consistency of an alignment is controversial, this is not taken care of here. Further specialisations of Alignment will adress such issues.

In order to store additional information with the Relations, an RelationAttachment resource can be provided. A subtype, the DiscreteRelationAttachment, additionally defines a backlink to the relation resource being attached to, as well as an optional creator property. The following types of attachments have been included so far:

  • Similarity - Describes the type and value of a similarity, that has led to the creation of this Relation.
  • Acknowledgement - Describes an external review of the Relation, e.g. user confirmation.

Last modified 11 years ago Last modified on 09/25/06 18:03:53

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