SOCoP/Ontology

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== Vocabularies, Specialized Terminologies and Ontologies {nid 2T8J} ==

== Vocabularies, Specialized Terminologies, Theories and Ontologies {nid 2T8J} ==

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Clearly vocabularies and ontologies are related. Ontologies use a lexical vocabulary and so you cant have an ontology without a vocabulary to express one's assertions. It is helpful to have vocabulary term for distinguishing concepts like river, stream, creek, brook, channel tributary and rivulet. These are related terms and one can generally distinguish them. When we have specialized vocabularies, such as in Science, we often call this a terminology and distinctions may be finer and more precise. A river is a pretty general concept for a natural watercourse. A canal is not natural. A river is usually freshwater, flowing towards an ocean, a lake, a sea, or another river. There seems to be there is no general agreed on rule that defines what can be called a river, although size involved in distinguishing it from other concepts. Small rivers may be called by several of the other special terms listed including stream, creek, brook, and as well as rill. {nid 2T8L}

Clearly vocabularies and ontologies are related. Ontologies use a lexical vocabulary and so you cant have an ontology without a vocabulary to express one's assertions. But ontologies are more than a collection of vocabulary terms. It is helpful to have vocabulary term for distinguishing concepts like river, stream, creek, brook, channel tributary and rivulet. These are related terms and one can generally distinguish them. When we have specialized vocabularies, such as in Science, we often call this a terminology. There distinctions may be finer and more precise. We may start with a general concept and become more specific as in a taxonomy or lattice. A river is terms for a pretty general concept for a natural watercourse. A canal is a term for a waterway but not a natural one. A river is usually freshwater, flowing towards an ocean, a lake, a sea, or another river (see http://miimr.com/1074795-River). {nid 2T8O}

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We may try to create an ontology from a vocabulary of terms like this, but to be an ontology it should organized about a theory about what exists in some domain. So river and stream ideas are organized along hydrological theory of what brings them into existence and what natural processes they follow. The theory specifies various classes of real objects and process , relations that may obtain among instances of such classes, and relationships among such classes and their instances. If we have a distinction between a stream class and a creek class then we need more than 2 terms. We need some organizing theory that explains why they are different. In England a creek is an inlet, an estuary, and the part of a river that goes down towards the sea. This provides enough of a theory to specify a difference since it relates a creek to a river and a sea concept. In Australia and the USA, however, the term is used differently. It's just a small river, so it's much the same as a brook or stream although brooks may flow more slowly than streams. We would have to make these distinctions on the terms clear in our ontology. We would have to explain why we use the term Gulf Stream, for example. This implies that stream is a very general concept of water flowing. The English point to the existence of part of a river that is called a creek on hydrological and locations terms. {nid 2T8M}

There seems to be no general agreed on rule that defines what can be called a river, although size involved in distinguishing it from other concepts. Small rivers may be called by several of the other special terms including stream, creek, brook, as well as rill. Analysis like this refines a vocabulary, but it also reveals some underlying concepts which we might say can be organized as a theory. {nid 2T8L}

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Likewise we vaguely divide tree reality into various types and use terms like: tree, bush, shrub sapling. Behind these we have a theory to organize these concepts. (Tree a woody perennial plant typically with a single stem or trunk growing to a considerable height and bearing lateral branches.) But as human conceptualization about what exists in the world, all of these concepts may have fuzzy, overlapping, inconsistent and dynamic boundaries. This arises in part because our theories of reality have a limited scope and different degrees of formalization . In this sense all ontologies are incomplete, although some are so sketchy with notable gaps and inconsistencies that they can be called informal ontologies. By analogy Newton's theory of gravitation may be considered formal but incomplete since it formalized what was understood. It was a theory that was completely formalized in mathematics, but we know it incompletely models reality. {nid 2T8N}

We may try to create an ontology from a vocabulary of terms like this, but to be an ontology it should organized into a theory that is relevant to the subject matter. By this we believe that it is more than a surface description. To be a quality ontology it should be able to make meaningful statements about what exists in its focused domain. So river and stream ideas are organized along an hydrological theory of what brings water collections into existence and what natural processes, such as downhill streaming flows, they follow. The hydrological concepts are more basic and underlie the real world phenomena at the river-stream level. Thus water within a river (or other watercourses) is generally collected from precipitation through surface runoff, groundwater recharge, springs, as well as the seasonal release of stored water. Stored water may include what is held by dams but usually is from from natural ice and snow packs (e.g., from glaciers). This theory specifies various classes of real objects (e.g. snow pack) and process (e.g. runoff), and relations (e.g. precipitates) that we assert applies among instances of such classes, as well as relationships among such classes and their instances. There is a technical use of theory in ontology to also mean model-theory which provides a basis for the semantics asserted in an ontology. The details of this are beyond the scope of material covered here and is left to the work ontologists. But the point to make is that a good ontology is able to express an organizing theory of concepts using a model-theoretic that is instantiated in an ontological language. {nid 2T8P}

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What we elevate to a formal ontology may provide detailed axioms and definitions to supplement and make an organizational theory more understandable to humans. To do this we add comments to "explain" terms using natural languages. Another distinction that some make between terminologies and formal ontologies is in terms of the use of logics as part of definitions. If a formal definition in some form of logic is not required, then we have an informal vocabulary or terminology collection. These may be well understood by humans but not processable by computer systems and thus less useful in the IT concept of ontologies. What is useful one one that is understandable to humans and yet capable of supporting automated deduction. In this view even detailed definitions such as have been captured in data dictionaries comments on terms in data models and in enterprise models are extended vocabulary-terminology collections and not ontologies because the definitions are only stated in natural language. They may however be useful starting points that can be formalized. See http://ontolog.cim3.net/forum/ontolog-forum/2011-05/msg00000.html for a discussion and debate of this idea. {nid 2T8K}

We can illustrated some ontological thinking that starts with a distinction between a stream class and a creek class. In a watercourse domain ontology we would need more than these 2 isolated terms or just a series of class words like them. We need some organizing theory that explains why they are different. Here is an example. In England a creek is an inlet, an estuary, and the part of a river that goes down towards the sea. This provides enough of a theory to specify a difference since it relates a creek to a river and a sea concept. The English point to the existence of part of a river that is called a creek based on organized hydrological and locations concepts. We can make this idea explicit in an ontology by making a commitment. This is an agreement to use a vocabulary ("creek") in a way that is consistent with respect to the theory specified by the ontology. In Australia the USA and elsewhere, however, the term is used differently. A creek can be just a small river, so it's much the same as a brook or stream, although brooks may flow more slowly than streams. We would have to make these distinctions on the terms clear in our ontology. We would have to explain why we use the term Gulf Stream, for example. This implies that there is a very general concept of a stream as water flowing. {nid 2T8M} == Simple Steps to Building an Ontology {nid 2T8Q} == There are practices for Ontological Engineering which are covered elsewhere, but a simple connection to vocaularies to start of on ontologies is outlined here. {nid 2T8R} * Listing terms and concepts {nid 2T8X} If we are starting from scratch we may just begin as data modelers often do by '''listing terms''' that denote the entities, events, qualities, relationships, etc. in a domain. We saw something like this in the previous discussion of rivers. The same would apply in a "Tree" domain. We vaguely divide tree reality into various types and use terms like: tree, bush, shrub sapling. Behind these we have a theory to organize these concepts: {nid 2T8S} - Tree are a woody perennial plant typically with a single stem or trunk growing to a considerable height and bearing lateral branches. {nid 2T8T} * Link them using one or more relations. These include: -structuring relations such as subsumption, located-in, near etc. -definitional relations -additional info relations {nid 2T8U} * Define axioms and properties rules that specify what must be true according to the applicable theory of reality {nid 2T8V} * Provide supporting information resources to help other people understand the model. These may include: -data dictionary lexicons, glossaries, supporting documentation, etc. {nid 2T8W} A caution is that as one starts on an ontology there are limits one must recognize. As human conceptualization about what exists in the world, all of our concepts may have fuzzy, overlapping, inconsistent and dynamic boundaries. This arises in part because our theories of reality have a limited scope and different degrees of formalization . In this sense all ontologies are incomplete simplifications. Some simplifications are so sketchy with notable gaps and inconsistencies that they can be called informal ontologies. By analogy Newton's theory of gravitation may be considered formal but incomplete since it formalized what was understood. It was a theory that was completely formalized in mathematics, but we know it incompletely models reality. {nid 2T8N} What we elevate to a formal ontology may provide detailed axioms and definitions to supplement and make an organizational theory more understandable to humans. To do this we add comments to "explain" terms using natural languages. Another distinction that some make between terminologies and formal ontologies is in terms of the use of logics to represent the previously mentioned model-theoretic as part of definitions. If a formal definition in some form of logic is not required, then we have an informal vocabulary or terminology collection. These may be well understood by humans but not processable by computer systems and thus less useful in the IT concept of ontologies. What is a useful ontology is one that has a theory and vocabulary that is understandable to humans and yet formalized in a language that is capable of supporting automated deduction. In this view even detailed definitions, such as have been captured in data dictionaries comments on terms in data models and in enterprise models are extended vocabulary-terminology collections and not ontologies because the definitions are only stated in natural language. They may however be useful starting points that can be formalized. See http://ontolog.cim3.net/forum/ontolog-forum/2011-05/msg00000.html for a discussion and debate of this idea. {nid 2T8K}