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Item Connection Subject Predicate Object

C D H I L M N O P R S T W X

Parent

A "parent" is an item that is in a parent-child relationship with one or more other items, the "children." Parent-child is a hierarchical relationship, and implies that the children are below or subsidiary-to the parent within the hierarchy. (If the hierarchy is a tree, the parent is closer to the "root" than the "leaves.") Being a parent in relationship with some items does not prevent the parent from having other relationships with other items, including also being a child. While the parent-child relationship would obviously be used in a wontology for expressing genealogy and family relationships between people, it is also commonly used to express more general hierarchical relations when other specific relationship types are not applicable.

Peer Relationship

Within a wontology, a peer relationship implies that the related items are at the same level in a hierarchy. That is, neither item is closer to the "root" (top, base, start, origin, etc.) than the other. Any relationship may be a peer relationship, regardless of the name used for it (the Name field of the Property-type item that is used to represent it). WontoMedia is told that a relationship denotes that items are peers by creating a connection using the sub_property_of type between the new property and another property that already indicates "peer-ship." (WontoMedia provides the built-in peer_relationship property to provide the base of a chain of peer properties.) Apart from any inferences that could be drawn from the peer nature of a relationship, WontoMedia takes into account whether items are peers when creating pages that display the relationships between items. A hierarchical relationship implies the opposite of a peer relationship, and is also treated specially for display by WontoMedia. A property item cannot represent both a peer and a hierarchical relationship, but can represent (be sub_property_of) neither.

Predecessor

A "predecessor" is an item that is in a predecessor-successor relationship with another item. Predecessor-successor implies that one item "comes before the other" when ordered relative to some criteria. It is also a peer relationship which implies that in addition to their relative order, the two related items are otherwise comparable (in position, in level, etc.) in any hierarchy that contains both.

Predicate

In an ontology, a predicate is the second item referred to by a connection, and specifies the type of relationship that the connection represents between its other two items (the first item, the subject, and the third item, the object). Each connection asserts a single fact within the ontology, and can be "read" by analogy with a sentence: "subject predicate object", like "vehicles include cars". Within WontoMedia, each item has a type, and the predicate item of a connection has to be a Property-type item. The other item's a connection references can be any type, Property, Category, or Individual.

Property

"Property" is one of the three types of items, along with Category and Individual. Property items are used exclusively to represent the types of relationships between (connections relating) other items. A property is not a particular relationship, but the definition of a type of relationship. Individual relationships are represented by connections: ordered triplets of items, a subject, a predicate, and an object. In a connection triplet, the predicate must by a Property-type item to determine the type of relationship the connection indicates, but the subject and object can be any kind of item. Note that Property-type items may also be subjects and objects, which allows the creation of connections that define the relationships of different properties to each other.

RDF

"RDF" is the "Resource Description Framework," a standard developed by the World Wide Web Consortium (W3C) for encoding information for automated consumption (as opposed to reading by humans) on the web. RDF provides for several standard representations of data "triples" (essentially the same as a connection in a wontology. The types of information that can be expressed in RDF is more restricted than is supported by the WontoMedia web application, but RDF is an important way to understand the fundamentals of capturing information in a set of items and connections, and it is the foundation on which the Web Ontology Language (OWL) is built. For more information, consider reading Practical RDF

RDFa

"RDFa" is the "Resource Description Framework in attributes," a standard developed by the World Wide Web Consortium (W3C) as a follow-on to RDF. RDFa is much like RDF, but where RDF addresses encoding information in stand-alone sets, RDFa addresses the interweaving of machine-readable information (as expressed by RDF) with human-readable information on the web. In some ways, RDFa can be thought of as "a microformat for RDF" or as an replacement for "RDF in HTML."

Relationship

In a wontology information is represented as a Wikipedia:Directed graph of items and connections. It is important to distinguish the items and connections stored from what they represent in the real world. An item is a representation of something, usually a physical entity or a concept. A connection is a representation of the relationship between two items. Connections can represent actual relationships ("head-bone is-connected-to [the] neck-bone"), or "relationships" between things and facts about them ("number-of-entries-in-list is 42"). When putting information into a wontology, it is important to keep in mind the difference between the real relationship and the connection (or multiple connections) created to represent it--after all, "the map is not the territory".

Subject

A "subject," in the context of an individual connection in a wontology, is the first item that the connection references. A connection's subject item is named that way by analogy, from viewing a connection as a sentence making a statement about the relationship between items. Thus, a connection is composed "subject predicate object" like the sentence fragment "ball is red". Virtually all items will be both subjects and objects of different connections. Note that, unlike the object of a connection, the subject will always be an item. Some connections make factual statements about the subject in which the object is not another item. For example, in the statement "Fred was-born-on December 14, 1919", "Fred" is the subject and refers to an item (which itself presumably represents an individual in the real world, or even a fictional world if that's what the current wontology describes). However, in this example, "December 14, 1919" is simply a constant value, rather than an item itself. This may be the case for objects, but never for subjects.

Successor

A "successor" is an item that is in a predecessor-successor relationship with another item. Predecessor-successor implies that one item "comes before the other" when ordered relative to some criteria. It is also a peer relationship which implies that in addition to their relative order, the two related items are otherwise comparable (in position, in level, etc.) in any hierarchy that contains both.

Symmetric

A relationship is symmetric when creating a connection from a subject to an object has exactly the same meaning as making the same connection in the opposite direction (e.g., from the first potential connection's object back to its subject). "spouse of" and "sibling of" are both examples of symmetric relationships: there is no way for Dick to be Jane's sibling without Jane also being Dick's sibling. It doesn't matter which item is selected as a symmetric connection's subject and which as the object; each symmetric connection implies another connection with the same predicate in the opposite direction.

Thesaurus

A thesaurus is a model for an information categorization scheme that, in terms of complexity and expressiveness, falls between a controlled vocabulary and an ontology. Typically a thesaurus is used to express the organization of and relationships between words in a language. Thesauri may be created for an entire language, or for a subset of one. Thesauri may also be created to represent the relationships between words in two different languages, providing simple mappings between synonyms or otherwise-related words. (Although a thesaurus is not expressive enough to capture the full semantic differences between related words in different languages that would be needed for translation.) Having been designed to express ontologies, WontoMedia can be used to store and maintain any thesaurus.

Title

In the context of a wontology, a "Title" is a data field associated with an item. All items have a Title, which should be a brief, meaningful (to a person) description for that item. Items also have a required data field called "Name", which serves a purpose similar to Title. Names must be shorter than titles, and are restricted to a narrower set of text characters. In WontoMedia a Title may be no more than 255 characters and can only be a single line. When formatting a page that refers to an item, WontoMedia will show the item's Title, the item's Name, or both, depending on the amount of space available. In addition, less-important information in a title can be placed in a parenthetical—pairs of parentheses and their content within Titles will not be displayed in places with less space. An item's Title should be an accurate enough reference to what the item represents that anyone who's read the item's Description will know exactly what the item means, and most other people will have a good guess.

Tree

In the context of information organization, a tree is a structure in which elements (items in an ontology) are arranged so that each has one parent item (containing, more general, larger, more important, etc.) and zero or more child items (contained, more specific, less important, controlled-by, etc.). For the purposes of the WontoMedia web application, "tree" can be considered a synonym of "hierarchy."

Wontology

A wontology is an ontology created or maintained by a community. The word was coined by borrowing the "w" from "Wikipedia:Wiki", which has come to be a generic term for a community-maintained collection of articles or other documents. This glossary is part of the documentation of the WontoMedia web application software, a Wikipedia:Free Software package implementing a wontology for web sites, and information about WontoMedia's development and use is separate.

WontoMedia

WontoMedia is a Wikipedia:Free software package that implements a wontology as web site. WontoMedia is intended to allow anyone to set up their own wontology, with information about any topic or topics, and to inter-reference their information with wontologies created and published by others. WontoMedia can be installed to provide a large public repository of information, like http://wontology.org, or as a small component of another web site or application, providing easy management of lists or category hierarchies for the containing system.

XML

XML is the "eXtensible Markup Language", standardized by the World Wide Web Consortium. It is a derivation of the earlier SGML standard. XML has become widely used for encoding information in text documents that can be read by both people and computers. XML is important to the wontology web application WontoMedia because the most important general standards for the exchange of ontological information, RDF and OWL, have mechanisms for capturing information as XML. If you're interested in more information on XML in general, consider the books XML in a Nutshell, Third Edition and Learning XML, Second Edition. If you're interested in more about how XML is used in ontologies, consider the books referenced in the RDF and OWL glossary entries above.