Reification

What is reification in artificial intelligence?

Reification is the process through which an abstract idea regarding a computer application is converted into an object or explicit data model or another object created in a programming language. A computable or addressable object (a resource) gets created in a system as a proxy for a non-computable or non-addressable object. Reification makes it possible for something that was implicit, unexpressed, and maybe even inexpressible to be formulated explicitly and made available for conceptual (logical or computational) manipulation. 

The process of reification is informally known as turning something into a first-class citizen within the scope of a specific system.

It is possible to reify certain aspects of the system at language design time. This is related to reflection in programming languages. You can apply this as stepwise refinement during system design time. Reification is a very widely used technique of conceptual analysis and knowledge representation.

It assists in converting an unexpressed, implicit idea into a conceptual or logical one.

How is data reification different from data refinement?

Data reification has some similarities with data refinement, but the reification process concentrates more on concretizing the idea and the abstract data types than it does on refining it. 

In data reification, the refinement is made up of steps to get more concrete representations of abstract data types. It achieves this through the use of standard specifications. Data reification is pretty much the terminology used by the Vienna Development Method (VDM) for what most people would consider being data refinement. The VDM community favors the term reification because the process concentrates more on concretizing ideas than on refining them.

Data reification aids in reducing the level of abstract data types and the abstraction involved in operation modeling.

How is reification used in conceptual modeling?

The process of reification is used very extensively in conceptual modeling. To reify a relationship essentially means to view it as an entity. The whole objective of reification is to make the relationship explicit when more information must be added to it. 

Take the example of the relationship type IsMemberOf(member:Person, Committee). An instance of IsMemberOf happens to be a relationship representing the fact that a person is a member of a committee. The figure displayed below depicts an example population of the IsMemberOf relationship in the form of a table. The Person P1 is shown to be a member of the committees C1 and C2. The person P2 is solely a member of the committee C1 and no other committee.

This fact could also be viewed as an entity. If you view a relationship as an entity, you could say that the entity reifies the relationship. This phenomenon is known as the reification of the relationship. Like all other entities, it has to be an instance of an entity type. 

How is Reification used in Unified Modeling Language (UML)?

Unified Modeling Language (UML) gives you an association class construct which you can use for the purpose of defining reified relationship types. The association class will always be a single model element that happens to be a type of association as well as a type of a class.

The association as well as the entity type that reifies both happen to be the same model element. 

You should keep in mind that it is not possible for attributes to be reified.

How is Reification used on semantic web?

RDF and OWL

In Semantic Web languages, like Resource Description Framework (RDF) and Web Ontology Language (OWL), statements happen to be binary relations. These binary relations are used for the purpose of linking two individuals or an individual and a value. 

There are situations in which applications are required to describe other RDF statements. These circumstances could include information like the time at which statements were made or even who made them. This information can be referred to as provenance information. For example, you might intend to represent some properties of of a relation, like your certainty about it, the severity or strength of a relation, the relevance of a relation, and other such properties.

Topic Maps

In XML Topic Maps, (XTMs), only topics can possess names or play roles in an association. You could also make use of an assertion about a topic but it won’t be possible for you to directly make assertions about that assertion.

Inspite of that, it is possible for you to create a topic that can reify a non-topic construct in a map. This would enable you to name the association to be named and treat it as a topic itself.

n-ary relations

In Semantic Web languages like RDF and OWL, properties are binary relations that are used to  two individuals or an individual and a value. But, in certain situations, the natural and convenient way to represent certain concepts involves making use of relations for the purpose of linking an individual to more than just a single individual or value. 

Examples include representing relations among multiple individuals, like a committee, a committee member and another person who nominated the first person to become a committee member, or a buyer, a seller, and an object that was bought when describing a purchase of a book.

A more general approach to reification involves making an explicit new class and n new properties to represent an n-ary relation, making an instance of the relation linking the n individuals an instance of this class. You can also use this approach for the purpose of representing provenance information and other properties for an individual relation instance.

Vs. quotation

The reification that is described here isn’t the same as quotation that can be found in other languages. Rather, the reification explains the relationship between a specific instance of a triple and the resources that the triple refers to.

Reification pretty much says something like “this RDF triple talks about these things" rather than "this RDF triple has this form."