Property:LogicalODPMotivation
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This is a property of type Text.
Pages using the property "LogicalODPMotivation"
Showing 15 pages using this property.
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| Adrian Walker 2 + | Enable government and other web sites to a … Enable government and other web sites to answer an open ended collection of English questions, and also to explain the answers in English. Support government folks and citizens socially networking, Wikipedia-style, to continually expand the range of questions that can be answered. e range of questions that can be answered. |
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| Change of Time Varying Entities + | This work is motivated by a project on urb … This work is motivated by a project on urban informatics, iCity \cite{miller2014}, in which our role is to develop an ontology capable of representing the urban system -- both the information that is collected, as well as information that is simulated and analyzed by various research groups. Such an ontology would not only provide valuable integration and inference capabilities for the research groups internally, it would support sharing of the results on the Semantic Web, in particular for reproducibility of simulations and analyses. Owing to its popularity, tool support, and role as the de facto standard for the Semantic Web, OWL was selected as the logical language for the formalization of the ontology. To capture the urban domain, the notion of change over time is a critical requirement: the population, family and household structures, transportation networks, and the locations of particular transportation vehicles (buses, household vehicles, and so on) are all subject to change. Change over time plays a role in many domains, and is by no means a new research topic. In fact, several approaches for capturing change in OWL have been proposed in the literature. Despite these solutions, we have found that Semantic Web practitioners currently lack clear and precise method for how to apply these approaches to capture change at a domain level, whether reusing an atemporal ontology or developing an ontology from scratch. gy or developing an ontology from scratch. |
| Context Slices + | Most information on the web is contextuali … Most information on the web is contextualized somehow, for example information may be believed by a person or organization, it may hold only for some time period, it may have been reported/observed by an individual, etc. There are myriad proposals and logics for context, but none are standards and few have even prototype implementations. In RDF and other binary relation languages (like object oriented languages and description logics), one typical way to represent that a binary relation holds in some context is to "reify" the relation-holding in the context as an node with a binary relations for the subject, object, and property, and a fourth binary relation to the object representing the context itself. The downside to this approach is the expressive ability of the language to describe the binary relation, especially in the case of description logics, is lost. For example, the ancestor relation is transitive. OWL allows one to express transitivity of a binary relation, but this expressiveness is lost if the statements of the relation are reified. The same would be true for symmetry, reflexivity, etc. One can get the effect of cardinality and range/domain restrictions by reifying a relation as an OWL class (instead of using RDF reification), with properties for the ''roles'' (as in the n-ary relations W3C note), but not transitivity etc. The motivation for context slices is to provide a logical pattern for encoding context information in standard RDF graphs that allows some of the expressiveness of OWL to be used in describing the relations that hold in contexts. This is a generaliztion of the four dimensional ontology for fluents published in [Welty & Fikes, 2006]. ts published in [Welty & Fikes, 2006]. |
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| Define Hybrid Class Resolving Disjointness due to Subsumption + | Problem : This pattern helps resolving a l … Problem : This pattern helps resolving a logical inconsistency triggered by a situation of disjoint classes subsuming a common sub-class. When we need to define – for some modeling issues related to domain of interest – a class as a sub-class of two disjoint classes, a disjointness inconsistency is caused. The problem can be illustrated by the following scenario: let’s consider a class Sub_Class defined as a sub-class of a class Disjoint_Class 2; and a class Disjoint_Class 1 disjoint with the Disjoint_Class 2 (see diagram in attached file). If we need to add a sub-class relation between the Sub_Class and the Disjoint_Class 1, this generates a disjointness inconsistency: - If the extension of the Sub_Class contains individuals instantiating this sub-class, the logical inconsistency will be extended to the knowledge base; - If the Sub_Class is not instantiated to individuals, it will be diagnosed as an unsatisfiable class. To solve this inconsistency, one can think about deleting the disjointness axiom. However, this can alter the semantics expressed in the ontology, and negatively affect consistency checking and automatic evaluation of existing individuals as explained in [1]. This pattern tackles the questions of how to resolve the inconsistency caused by such kind of subsumption while preserving existing knowledge. [1] Völker, J., Vrandecic, D., Sure, Y., Hotho, A.: Learning Disjointness. In F., Enrico, K., Michael, May. Wolfgang (Eds.). Proceedings of the 4th European Semantic Web Conference, ESWC 2007. LNCS: Vol. 4519 pp: 175-189. (2007) 2007. LNCS: Vol. 4519 pp: 175-189. (2007) |
| DisjointnessOfComplement (DOC) + | We have identified a set of patterns that … We have identified a set of patterns that are commonly used by domain experts in their DL formalisations and OWL implementations, and that normally result in unsatisfiable classes or modelling errors. As aforementioned all these antipatterns come from a misuse and misunderstanding of DL expressions by ontology developers. Thus they are all Logical AntiPatterns (LAP): they are independent from a specific domain of interest, but dependent on the expressivity of the logical formalism used for the representation. cal formalism used for the representation. |
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| Enlarge Class Definition for Resolving Disjointness due to Subsomption + | Problem : This pattern helps resolving a … Problem : This pattern helps resolving a logical inconsistency triggered by a situation of disjoint classes subsuming a common sub-class. When we need to define – for some modeling issues related to domain of interest – a class as a sub-class of two disjoint classes, a disjointness inconsistency is caused. The problem can be illustrated by the following scenario: let’s consider a class Sub_Class defined as a sub-class of a class Disjoint_Class 2; and a class Disjoint_Class 1 disjoint with the Disjoint_Class 2 (see diagram in attached file). If we need to add a sub-class relation between the Sub_Class and the Disjoint_Class 1, this generates a disjointness inconsistency: - If the extension of the Sub_Class contains individuals instantiating this sub-class, the logical inconsistency will be extended to the knowledge base; - If the Sub_Class is not instantiated to individuals, it will be diagnosed as an unsatisfiable class. To solve this inconsistency, one can think about deleting the disjointness axiom. However, this can alter the semantics expressed in the ontology, and negatively affect consistency checking and automatic evaluation of existing individuals as explained in [1]. This pattern tackles the questions of how to resolve the inconsistency caused by such kind of subsumption while preserving existing knowledge. [1] Völker, J., Vrandecic, D., Sure, Y., Hotho, A.: Learning Disjointness. In F., Enrico, K., Michael, May. Wolfgang (Eds.). Proceedings of the 4th European Semantic Web Conference, ESWC 2007. LNCS: Vol. 4519 pp: 175-189. (2007) 2007. LNCS: Vol. 4519 pp: 175-189. (2007) |
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| Summarization of an inverse n-ary relation + | An n-ary relationship should be used to ad … An n-ary relationship should be used to address any of the following situations: (a) a binary relationship that really needs a further argument. For example, to represent the distance between two places. (b) two binary relationships that always go together and should be represented as one n-ary relation. For example, to represent the value of an observation (e.g. temperature in a patient) and its trend. (c) a relationship that is really amongst several things. For example, to represent the spatial location of a person in a given point of time. On the one hand, the motivation of this pattern is to express the inverse relationship of an n-ary relation where there are distinguished participants. This means that the relationship exists mainly between two entities and the rest of entities involved in the relationship can be considered as additional arguments. This situation can also mean that there is a single individual standing out as the subject or the "owner" of the relation. On the other hand, the motivation is to provide a shorcut for queries that involve the distinguished participants in the n-ary relationship. This pattern is inspired on the third consideration shown in http://www.w3.org/TR/swbp-n-aryRelations/#choosingPattern1or2. The difference in our case is that there are at least two distinguished participants in the relationship. Therefore, this pattern could be considered as an extension of the third consideration shown in http://www.w3.org/TR/swbp-n-aryRelations./#choosingPattern1or2 applied to the use case of n-ary relationships described in http://www.w3.org/TR/swbp-n-aryRelations/#useCase1. w.w3.org/TR/swbp-n-aryRelations/#useCase1. |
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| N-Ary Relation Pattern (OWL 2) + | OWL does not support N-Ary relations. This means that an n-ary relation can only be represented in its reified form in OWL. This is problematic, as the relational character is then completely lost. |
| NegativePropertyAssertions + | The motivation of this pattern is to model … The motivation of this pattern is to model ''negative property assertions'' (NPAs) in ontology languages such as OWL 1 [1] that do not provide a special constructor for expressing it. It is worth mentioning that not all knowledge base systems can be migrated to OWL 2 [2] for several reasons. On the other hand, NPAs modeled according to this pattern can be migrated to OWL 2 using the newly introduced constructor. A negative property assertion as defined in the upcoming OWL 2 states that a given individual ''i'' is never connected to a given individual ''j'' by a given property expression ''P''. In other words, asserting that ''i'' is connected to ''j'' by ''P'' results in an inconsistent ontology. In this sense this assertion can be considered as a constraint that should not be violated. In contrast, considering an ontology where it cannot be inferred that ''i'' is connected to ''j'' by ''P'' does not necessarily mean that there cannot be such a connection - in fact, it is merely not modeled. [1] Patel-Schneider, P.F., Hayes, P., Horrocks, I.: OWL Web Ontology Language Semantics and Abstract Syntax, W3C Recommendation 10 February 2004. [2] Motik, B., Patel-Schneider, P.F., Parsia, B.: OWL 2 Structural Specification and Functional-Style Syntax. W3C Candidate Recommendation 11 June 2009, 2009. ndidate Recommendation 11 June 2009, 2009. |
| Normalization + | There are ontologies where a given class c … There are ontologies where a given class can have plenty of superclasses, building a polyhierarchy. If all those subsumption relationships are directly stated by the ontology maintainer, two main problems rise: (i) the ontology becomes very difficult to maintain: whenever a subsumption must be deleted (because a class has changed) or created (because a new class has been created) it has to be done by hand; in a polyhierarchy the process becomes very inefficient and error-prone. (ii) the semantics are implicitly stated, not explicitly: any other ontologist or reasoner only knows that a class is a subclass of its superclasses, without knowing why. of its superclasses, without knowing why. |
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| OnlynessIsLoneliness (OIL) + | Our work is based on the debugging process … Our work is based on the debugging process of real ontologies that have been developed by domain experts, who are not necessarily too familiar with DL, and hence can misuse DL constructors and misunderstand the semantics of some OWL expressions, leading to unwanted unsatisfiable classes. Our patterns were first found during the debugging process of a medium-sized OWL ontology (165 classes) developed by a domain expert in the area of hydrology called HydrOntology. The first version of this ontology had a total of 114 unsatisfiable classes. The information provided by the debugging systems used on (root) unsatisfiable classes was not easily understandable by domain experts to find the reasons for their unsatisfiability. And in several occasions during the debugging process the generation of justifications for unsatisfiability took several hours, what made these tools hard to use. Using this debugging process and several other real ontologies debugging one, we found out that in several occasions domain experts were just changing axioms from the original ontology in a somehow random manner, even changing the intended meaning of the definitions instead of correcting errors in their formalisations. We have identified a set of patterns that are commonly used by domain experts in their DL formalisations and OWL implementations, and that normally result in unsatisfiable classes or modelling errors. Thus they are antipatterns. A Koenig define antipatterns as patterns that appear obvious but are ineffective or far from optimal in practice, representing worst practice about how to structure and build software. We also have made an effort to identify common alternatives for providing solutions to them, so that they can be used by domain experts to debug their ontologies. All these antipatterns come from a misuse and misunderstanding of DL expressions by ontology developers. Thus they are all Logical AntiPatterns (LAP): they are independent from a specific domain of interest, but dependent on the expressivity of the logical formalism used for the representation. cal formalism used for the representation. |
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| Partition + | The Partition Pattern is a logical pattern … The Partition Pattern is a logical pattern that introduces axioms which model a partition of concepts. A partition is a general structure which is divided into several disjoint parts. With respect to ontologies the structure is a concept which is divided into several pair-wise disjoint concepts. This pattern reflects the simplest case where a named concept is defined as a partition of concepts. ept is defined as a partition of concepts. |
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| Stub Metapattern + | When modeling an ontology, one of the issu … When modeling an ontology, one of the issues to be addressed is that of granularity: To what detail should the ontology represent the notions it captures? Traditionally, this issue is resolved by looking at a concise definition of the use cases, e.g. by means of competency questions. As a result of this, some parts of the ontology may be modeled in a rather fine-grained manner, while other parts remain relatively coarse. A straightforward handling of differing granularity requirements in different parts of an ontology can make it more difficult to repurpose or extend the ontology, or to use it in an ontology-driven data integration setting. The reason is that because one is often faced with a situation where (s)he has to decide whether to represent a notion as a string literal value or an ontology entity such as a class. Choosing one over the other introduces a commitment that one may regret later on. For example, when modeling a location, one could use the location name as a string or model it as a possibly full-blown pattern for the notion of Place. Choosing the former may prevent future use case of data enrichment, e.g., for expressing co-location (as one cannot use owl:sameAs relation between two strings). Choosing the latter means committing to a particular way of modeling Place, which may not necessarily be desirable in the future. This pattern provides a way to solve this problem is to essentially keep both in the model, i.e., by including the literal value in the model, while employing a very minimalistic pattern for the notion. The latter is realized only as a single class. latter is realized only as a single class. |
| Symmetric n-ary relationship + | The symmetric n-ary relationship pattern e … The symmetric n-ary relationship pattern emerged from the need of modelling distances among two points. This problem is a clear case of an n-ary relationship where the relation between two points needs a further argument to represent the distance between such points. Once we have applied the n-ary pattern for this use case (http://www.w3.org/TR/swbp-n-aryRelations/#useCase1), we can realize that the origin and the destination of the n-ary relation belong to the same class. In addition, the value for the relationship is the same to represent the distance from A to B and vice-versa. Then, if we want to represent both distances we should instanciate the pattern twice, from A to B and vice-versa, resulting in a redundant representation. , resulting in a redundant representation. |
| SynonymOrEquivalence (SOE) + | We have identified a set of patterns that … We have identified a set of patterns that are commonly used by domain experts in their DL formalisations and OWL implementations, and that normally result in unsatisfiable classes or modelling errors. As aforementioned all these antipatterns come from a misuse and misunderstanding of DL expressions by ontology developers. Thus they are all Logical AntiPatterns (LAP): they are independent from a specific domain of interest, but dependent on the expressivity of the logical formalism used for the representation. We have categorized them into three groups: e have categorized them into three groups: |
