Unitii scm for engineering students knowledge

scm

1. Ontological Categories & Philosophical Background

2. Definition (Ontology). An ontology is a formal explicit specification of a shared conceptualization of a domain of interest.

3. Top-level Categories & Describing Physical Entities

4. A  T op-level ontology  provides a definition of  everything  at a very abstract level. The goal of a top-level ontology is to provide a useful categorization on which to base other ontologies. Making it explicit how domain ontologies fit into an upper-level ontology promises to facilitate the integration of these ontologies. The integration of ontologies is necessary to allow applications to refer to multiple knowledge bases, each of which may use different ontologies.

5. Here we present a top-level ontology based on  BFO , the  Basic Formal Ontology .  Figure provides a decision tree which can be used to categorize anything into a number of high-level categories.

6. At the top is  entity . OWL calls the top of the hierarchy  thing . Essentially, everything is an entity. Entities are divided into the disjoint classes of  continuants  and  occurrents . A  continuant  is something that exists at an instant in time and continues to exist through time. Examples include a person, a finger, a country, a smile, the smell of a flower, and an email. When a continuant exists at any time, so do its parts. Continuants maintain their identity through time. An  occurrent  is something that has temporal parts, for example, a life, infancy, smiling, the opening of a flower, and sending an email. One way to think about the difference is to consider the entity’s parts: a finger is part of a person, but is not part of a life; infancy is part of a life, but is not part of a person.

7. A continuant is an  independent continuant , or a  dependent continuant . An  independent continuant  is an entity that can exist by itself or is part of another entity. For example, a person, a face, a pen, a flower, a country, and the atmosphere are independent continuants. A dependent continuant only exists by virtue of another entity and is not a part of that entity. For example, a smile, the ability to laugh, or the inside of your mouth, or the ownership relation between a person and a phone, can only exist in relation to another object or objects. Note that something that is a part of another object is an independent continuant; for example, while a heart cannot exist without a body, it can be detached from the body and still exist. This is different from a smile; you cannot detach a smile from a cat.

8. An independent continuant is either a  material entity  or an  immaterial entity . A material entity has some matter as a part. Material entities are localized in space and can move in space. Examples of material entities are a person, a football team, Mount Everest, and Hurricane Katrina. Immaterial entities are abstract. Examples of immaterial entities are the first email you sent last Monday, a plan, and an experimental protocol. Note that you need a physical embodiment of an email to receive it (e.g., as text on your smartphone or spoken by a speech synthesizer), but the email is not that physical embodiment; a different physical embodiment could still be the same email. A material entity that is a single coherent whole is an  object . An object maintains its identity through time even if it gains or loses parts (e.g., a person who loses some hair, a belief, or even a leg, is still the same person). A person, a chair, a cake or a computer are all objects. The left leg of a person (if it is still attached to the person), a football team or the equator are not objects. If a robot were asked to find three objects, it would not be expected to bring a chair and claim the back, the seat and the left-front leg are three objects.

9. A  dependent continuant  depends on other objects. One type if dependent continuent is a  property . The following are subtypes of  properties : A  quality  is something that all objects of a particular type have for all of the time they exist – for example, the mass of a bag of sugar, the shape of a hand, the fragility of a cup, the beauty of a view, the brightness of a light, and the smell of the ocean. Although these can change, the bag of sugar always has a mass and the hand always has a shape. A  role  specifies a goal that is not essential to the object’s design but can be carried out. Examples of roles include the role of being a judge, the role of delivering coffee, and the role of a desk to support a computer monitor. A  disposition  is something that may happen to an object, for example, the disposition of a cup to break if dropped, the disposition of vegetables to rot if not refrigerated, and the disposition of matches to light if they are struck when not wet. A  function  is a disposition that is a purpose of an object. For example, the function of a cup may be to hold coffee; the function of the heart is to pump blood.

10. The other major category of entities is the occurrent. An  occurrent  is any of the following: A  temporal region  is a region of time. A temporal region is either connected (if two points are in the region, so is every point in between) or scattered. Connected temporal regions are either intervals or instants (time points). Sunday, March 1, 2026, is a temporal interval; 3:31 p.m. EST on that day is a temporal point. Tuesdays from 3:00 to 4:00 GMT is a scattered temporal region. A  spatio -temporal region  is a region of multidimensional space-time. Spatio -temporal regions are either scattered or connected. Some examples of spatio -temporal regions are the space occupied by a human life, the border between Canada and the United States in 1812, and the region occupied by the development of a cancer tumor. A  process  is something that happens over time, has temporal parts, and depends on a continuant. For example, Joe’s life has parts such as infancy, childhood, adolescence, and adulthood and involves a continuant, Joe. A holiday, writing an email, and a robot cleaning the lab are all processes. A  boundary of a process  is the instantaneous temporal boundary of a process, such as when a robot starts to clean up the lab, or a birth.

11. Describing Physical Entities

12. In ontology, a physical entity refers to any object or substance that has a material existence and can be observed or measured through the senses or scientific instruments. Physical entities are often classified into different categories based on their properties, functions, and relationships with other entities. Some common categories of physical entities in ontology include: Object: Objects are physical entities that have a defined shape, size, and boundaries. They can be further classified into subcategories such as living and non-living objects, natural and artificial objects, and so on. Substance: Substances are physical entities that have mass and occupy space. They can be further classified into subcategories such as pure substances and mixtures, chemical elements, compounds, and so on. Event: Events are physical entities that occur at a specific time and place and involve a change or transformation in the physical world. They can be further classified into subcategories such as natural events and human-made events, physical and chemical events, and so on. Property: Properties are physical entities that describe the characteristics or attributes of other physical entities. They can be further classified into subcategories such as qualitative and quantitative properties, intrinsic and extrinsic properties, and so on. Process: Processes are physical entities that involve a sequence of events or changes that occur over time and lead to a specific outcome. They can be further classified into subcategories such as natural and artificial processes, physical and chemical processes, and so on.

13. Describing Abstractions, sets & Collection

14. In ontology, abstractions, sets, and collections are used to represent concepts and entities that do not have a physical existence, but exist only as ideas or mental constructs. These entities are used to organize and classify knowledge and information, and to provide a foundation for reasoning and inference. Abstractions are general concepts that are derived from specific instances or examples. They represent a higher level of understanding that captures the essential features of a group of related entities or phenomena. Examples of abstractions in ontology include concepts such as "justice," "happiness," "freedom," and "equality." Sets are collections of objects or entities that share a common property or attribute. In ontology, sets are used to group similar entities together based on their properties or relationships. Examples of sets in ontology include the set of all prime numbers, the set of all mammals, and the set of all living things. Collections are groups of objects or entities that are not necessarily related based on their properties or attributes. In ontology, collections are used to group together entities that have been arbitrarily selected for a specific purpose or task. Examples of collections in ontology include a collection of books, a collection of paintings, and a collection of scientific data. Overall, abstractions, sets, and collections are essential tools in ontology for organizing and representing knowledge and information in a systematic and structured way. They allow for the identification of similarities and differences among entities, and provide a framework for reasoning and inference based on shared properties and relationships.

15. Common components of ontologies include: Individuals : instances or objects (the basic or "ground level" objects; the tokens). Classes : sets, collections, concepts, types of objects, or kinds of things.[1] Attributes : aspects, properties, features, characteristics, or parameters that objects (and classes) can have. [2] Relations : ways in which classes and individuals can be related to one another.[3] Function terms : complex structures formed from certain relations that can be used in place of an individual term in a statement. Restrictions : formally stated descriptions of what must be true in order for some assertion to be accepted as input. Rules : statements in the form of an if-then (antecedent-consequent) sentence that describe the logical inferences that can be drawn from an assertion in a particular form. Axioms : assertions (including rules) in a logical form that together comprise the overall theory that the ontology describes in its domain of application.[4] This definition differs from that of "axioms" in generative grammar and formal logic. In these disciplines, axioms include only statements asserted as a priori knowledge. As used here, "axioms" also include the theory derived from axiomatic statements.[citation needed] Events : the changing of attributes or relations. Actions : types of events.

16. Individuals Individuals (instances) are the basic, "ground level" components of an ontology. The individuals in an ontology may include concrete objects such as people, animals, tables, automobiles, molecules, and planets, as well as abstract individuals such as numbers and words (although there are differences of opinion as to whether numbers and words are classes or individuals). Strictly speaking, an ontology need not include any individuals, but one of the general purposes of an ontology is to provide a means of classifying individuals, even if those individuals are not explicitly part of the ontology. In formal extensional ontologies, only the utterances of words and numbers are considered individuals – the numbers and names themselves are classes. In a 4D ontology, an individual is identified by its spatio -temporal extent. Examples of formal extensional ontologies are  BORO ,  ISO 15926  and the model in development by the  IDEAS Group .

17. Classes Classes – concepts that are also called  type ,  sort ,  category , and  kind  – can be defined as an extension or an intension. According to an extensional definition, they are abstract groups, sets, or collections of objects. According to an intensional definition, they are abstract objects that are defined by values of aspects that are constraints for being member of the class. The first definition of class results in ontologies in which a class is a subclass of collection. The second definition of class results in ontologies in which collections and classes are more fundamentally different. Classes may classify individuals, other classes, or a combination of both. Some examples of classes: [5] Person , the class of all people, or the abstract object that can be described by the criteria for being a person. Vehicle , the class of all vehicles, or the abstract object that can be described by the criteria for being a vehicle. Car , the class of all cars, or the abstract object that can be described by the criteria for being a car. Class , representing the class of all classes, or the abstract object that can be described by the criteria for being a class. Thing , representing the class of all things, or the abstract object that can be described by the criteria for being a thing (and not nothing).

18. Ontologies vary on whether classes can contain other classes, whether a class can belong to itself, whether there is a universal class (that is, a class containing everything), etc. Sometimes restrictions along these lines are made in order to avoid certain well-known  paradoxes . The classes of an ontology may be  extensional  or  intensional  in nature. A class is extensional if and only if it is characterized solely by its membership. More precisely, a class C is extensional if and only if for any class C', if C' has exactly the same members as C, then C and C' are identical. If a class does not satisfy this condition, then it is intensional . While extensional classes are more well-behaved and well understood mathematically, as well as less problematic philosophically, they do not permit the fine grained distinctions that ontologies often need to make. For example, an ontology may want to distinguish between the class of all creatures with a kidney and the class of all creatures with a heart, even if these classes happen to have exactly the same members. In most  upper ontologies , the classes are defined intensionally . Intensionally defined classes usually have necessary conditions associated with membership in each class. Some classes may also have sufficient conditions, and in those cases the combination of necessary and sufficient conditions make that class a fully  defined  class.

19. Importantly, a class can subsume or be subsumed by other classes; a class subsumed by another is called a  subclass  (or  subtype ) of the subsuming class (or  supertype ). For example,  Vehicle  subsumes  Car , since (necessarily) anything that is a member of the latter class is a member of the former. The subsumption relation is used to create a hierarchy of classes, typically with a maximally general class like  Anything  at the top, and very specific classes like  2002 Ford Explorer  at the bottom. The critically important consequence of the subsumption relation is the inheritance of properties from the parent (subsuming) class to the child (subsumed) class. Thus, anything that is necessarily true of a parent class is also necessarily true of all of its subsumed child classes. In some ontologies, a class is only allowed to have one parent ( single inheritance ), but in most ontologies, classes are allowed to have any number of parents ( multiple inheritance ), and in the latter case all necessary properties of each parent are inherited by the subsumed child class. Thus a particular class of animal ( HouseCat ) may be a child of the class  Cat  and also a child of the class  Pet . A partition is a set of related classes and associated rules that allow objects to be classified by the appropriate subclass. The rules correspond with the aspect values that distinguish the subclasses from the superclasses . For example, to the right is the partial diagram of an ontology that has a partition of the  Car  class into the classes  2-Wheel Drive Car  and  4-Wheel Drive Car . The partition rule (or subsumption rule) determines if a particular car is classified by the  2-Wheel Drive Car  or the  4-Wheel Drive Car  class. If the partition rule(s) guarantee that a single  Car  cannot be in both classes, then the partition is called a disjoint partition. If the partition rules ensure that every concrete object in the super-class is an instance of at least one of the partition classes, then the partition is called an exhaustive partition.

20. Attributes Objects in an ontology can be described by relating them to other things, typically  aspects  or  parts . These related things are often called  attributes , although they may be independent things. Each attribute can be a class or an individual. The kind of object and the kind of attribute determine the kind of relation between them. A relation between an object and an attribute express a fact that is specific to the object to which it is related. For example, the  Ford Explorer  object has attributes such as: ⟨has as name⟩ Ford Explorer ⟨as by definition as part⟩  6-speed transmission ⟨as by definition as part⟩  door  (with as minimum and maximum cardinality: 4) ⟨as by definition as part one of⟩  {4.0L engine, 4.6L engine} The value of an attribute can be a complex  data type ; in this example, the related engine can only be one of a list of subtypes of engines, not just a single thing. Ontologies are only true ontologies if concepts are related to other concepts (the concepts do have attributes). If that is not the case, then you would have either a  taxonomy  (if  hyponym  relationships exist between concepts) or a  controlled vocabulary . These are useful, but are not considered true ontologies.

21. Relations Relations  (also known as relationships) between objects in an ontology specify how objects are related to other objects. Typically a relation is of a particular type (or class) that specifies in what sense the object is related to the other object in the ontology. For example, in the ontology that contains the concept Ford Explorer and the concept  Ford Bronco  might be related by a relation of type ⟨is defined as a successor of⟩. The full expression of that fact then becomes: Ford Explorer  is defined as a successor of  : Ford Bronco This tells us that the Explorer is the model that replaced the Bronco. This example also illustrates that the relation has a direction of expression. The inverse expression expresses the same fact, but with a reverse phrase in natural language. Much of the power of ontologies comes from the ability to describe relations. Together, the set of relations describes the  semantics  of the domain: that is, its various  semantic relations , such as  synonymy ,  hyponymy and hypernymy ,  coordinate  relation, and others. The set of used relation types (classes of relations) and their subsumption hierarchy describe the expression power of the language in which the ontology is expressed.

22. An important type of relation is the  subsumption  relation ( is-a- superclass -of , the converse of  is-a ,  is-a-subtype-of  or  is-a- subclass -of ). This defines which objects are classified by which class. For example, we have already seen that the class Ford Explorer  is-a-subclass-of  4-Wheel Drive Car, which in turn  is-a-subclass-of  Car. The addition of the is-a-subclass-of relationships creates a  taxonomy ; a tree-like structure (or, more generally, a  partially ordered set ) that clearly depicts how objects relate to one another. In such a structure, each object is the 'child' of a 'parent class' (Some languages restrict the is-a-subclass-of relationship to one parent for all nodes, but many do not). Another common type of relations is the  mereology  relation, written as  part-of , that represents how objects combine to form composite objects. For example, if we extended our example ontology to include concepts like Steering Wheel, we would say that a "Steering Wheel is-by-definition-a-part-of-a Ford Explorer" since a steering wheel is always one of the components of a Ford Explorer. If we introduce meronymy relationships to our ontology, the hierarchy that emerges is no longer able to be held in a simple tree-like structure since now members can appear under more than one parent or branch. Instead this new structure that emerges is known as a  directed acyclic graph .

23. As well as the standard is-a-subclass-of and is-by-definition-a-part-of-a relations, ontologies often include additional types of relations that further refine the semantics they model. Ontologies might distinguish between different categories of relation types. For example: relation types for relations between classes relation types for relations between individuals relation types for relations between an individual and a class relation types for relations between a single object and a collection relation types for relations between collections Relation types are sometimes domain-specific and are then used to store specific kinds of facts or to answer particular types of questions. If the definitions of the relation types are included in an ontology, then the ontology defines its own ontology definition language. An example of an ontology that defines its own relation types and distinguishes between various categories of relation types is the  Gellish  ontology. For example, in the domain of automobiles, we might need a  made-in  type relationship which tells us where each car is built. So the Ford Explorer is  made-in   Louisville . The ontology may also know that Louisville is-located-in  Kentucky  and Kentucky is-classified-as-a state and is-a-part-of the  U.S.  Software using this ontology could now answer a question like "which cars are made in the U.S.?"

24. Types and Categories

25. Formal ontology: Formal ontology refers to the use of mathematical and logical techniques to develop a formal representation of the concepts and relationships in a particular domain. Formal ontology is often used in knowledge representation, artificial intelligence, and the Semantic Web. Domain ontology: Domain ontology refers to the development of a formal representation of the concepts and relationships within a specific domain or area of knowledge. Domain ontology is used to represent knowledge in fields such as biology, chemistry, physics, and engineering. Top-level ontology: Top-level ontology refers to the development of a formal representation of the most general concepts and relationships that are common across all domains. Top-level ontology is used to represent knowledge that is shared across multiple domains and to provide a foundation for more specialized ontologies. Task ontology: Task ontology refers to the development of a formal representation of the tasks, activities, and processes that are performed within a particular domain or context. Task ontology is used to represent knowledge related to workflow management, business process modeling, and other applications. Social ontology: Social ontology refers to the development of a formal representation of the social entities, relationships, and interactions that exist within a particular social context. Social ontology is used to represent knowledge related to social networks, social media, and other social applications.

26. Time and Space

27. Time and space are fundamental concepts in ontology, physics, and philosophy. They are used to describe the physical world and the relationships between objects and events. Time refers to the progression of events from the past, through the present, and into the future. It is often described as a dimension that can be measured and quantified using units such as seconds, minutes, and hours. Time is also relative to the observer's frame of reference, which means that time can appear to move faster or slower depending on the observer's position and velocity. Space refers to the physical dimensions of the universe and the relationships between objects within that universe. Space is often described as a three-dimensional continuum that can be measured and quantified using units such as meters, feet, and miles. Space is also relative to the observer's frame of reference, which means that the position and movement of objects can appear different depending on the observer's perspective. The relationship between time and space is described by the concept of spacetime, which combines the dimensions of space and time into a single four-dimensional continuum. Spacetime is the foundation of Einstein's theory of relativity, which describes how the laws of physics are affected by the relative motion of observers and the curvature of spacetime.