M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and FrameBased Languages, Journal of the ACM, 42, 1995.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....assigns to each relation name its arity. As said above, the definition considers the core elements of most languages for ontology representation only. It is possible to map the definition to most types of ontology representation languages. Our implementation, for instance, is based on Frame Logic [Kifer et al., 1995] . Frame Logic has a wellfounded semantics, but we do not refer to it in this paper. 2.2 Formal Concept Analysis We recall the basics of Formal Concept Analysis (FCA) as far as they are needed for this paper. A more extensive overview is given in [Ganter and Wille, 1999] To allow a ....

M. Kifer, G. Lausen, J. Wu: Logical foundations of object-oriented and frame-based languages. Journal of the ACM 42(4), 741--843.

....assigns to each relation name its arity. As said above, the de nition considers the core elements of most languages for ontology representation only. It is possible to map the de nition to most types of ontology representation languages. Our implementation, for instance, is based on Frame Logic [KLW95]. Frame Logic has a well founded semantics, but we do not refer to it in this paper. 3.2 Formal Concept Analysis We recall the basics of Formal Concept Analysis (FCA) as far as they are needed for this paper. A more extensive overview is given in [GW99] To allow a mathematical description of ....

M. Kifer, G. Lausen, J. Wu: Logical foundations of object-oriented and framebased languages. Journal of the ACM 42(4) 1995, 741-843

....one speci c ontology representation framework, and to a precise, detailed de nition. In a modular way we consider rst the common core of all ontologies, and then introduce di erent extensions. Our approach is independent of a speci c logical language. It can for instance be used with F Logic [KLW95], as it is e.g. implemented in Ontobroker [D 99] and OntoEdit [StaM00] but is open to other languages. De nition 1. A core ontology is a structure O : C; C ; R; R ) two disjoint sets C and R whose elements are called concept identi ers and relation identi ers, resp. a ....

M. Kifer, G. Lausen, J. Wu: Logical foundations of object-oriented and framebased languages, Journal of the ACM 42, 1995

....classes, class hierarchies, single and set valued attributes with domain and range restrictions, and multiple attribute inheritance for modelling terminological domain knowledge. The derivation of new object denotations can be expressed by functions. KARL uses O logic [KiW93] and F logic [KLW93] as a model for the integration of object orientation in a logical framework.The Horn clauses of L KARL are extended by stratified negation (cf. Prz88] and a richer logical language is provided for formulating constraints (necessary conditions for concepts and relationships) KARL ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, technical report 93/06, Department of Computer Science, SUNY at Stony Brook, NY, April 1993. To appear in Journal of the ACM.

....miles the epistemologically rich modeling primitives of frames, the formal semantics and efficient reasoning support of description logics and is mapped to the standard Web metaadata language proposals. Formal semantics for ontologies is a sine qua non, in our implementation we use Frame Logics [FL] and its concrete implementation in the SilRI inference engine [SILRI] to provide this for the above def mitions. Axioms are correspondingly given in Frame Logics. See section 3.2 for a more detailed description of Frame Logic. Further, a knowledge base consisting of instances of the concepts and ....

.... and 42 = a21, a22, a23 . A c att( r 1 ) and 42 c att( r 2 ) 1 4 I = 1 421 and type( a u ) type( a2i ) Ic denotes the transitive closure of I. 3.2 Frame Logics This is the target data model for the mapping approach. The resulting ontology is written in Frame Logic. Frame Logic [FL] was developed to combine the rich data modelling primitives of object oriented databases with logical languages as developed for deductive databases. Due to lack of space we can only briefly mention those properties that are important for our mapping procedure the interested reader can refer ....

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M. Kifer, G. Lausen, and J. Wu: Logical Foundations of ObjectOriented and Frame-Based Languages, Journal ACM, 42:741-843, 1995.

....to special purpose knowledge acquisition, representation and inference systems, that are easy to built, to maintain and to adjust to different tasks. In the following sections we illustrate the general approach through a kind of reengineering of two special representation languages: Frame Logic [KLW95], that is used to model object orientation, and Chronolog (see e.g. LiO96] OrM94] that realizes Linear Temporal Logic. Then the combination of both approaches is sketched and some interdependencies and limitations are analyzed. In the forthcoming examples we use standard syntax with the ....

....inference engines for standard horn logic. So the languages can be adapted to different purposes, can be combined, and techniques available for deductive databases are directly applicable. 3.1 Frame Logic We start with analyzing parts of the semantic structure of Frame Logic (abbr. F logic) see [KLW95]) F logic is designed as a declarative language, that accounts in a clean and declarative fashion for most of the structural aspects of object oriented and frame based languages ( StB86] RBP 91] F logic has its own model and proof theory and a specialized inference engine is available ....

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M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the A CM, vol 42, 1995.

....[Berners Lee Fischetti, 1999] for 227 the vision of the latter) for the Semantic Web. UPML is language neutral in the sense that different formal languages can be plugged in to describe the elementary slots defined by UPML. We already used order sorted logic [Fensel et al. 1998] frame logic [Kifer et al. 1995], and OCML [Motta, 1999] successfully for adding formal semantics to UPML specifications (cf. Fensel et al. to appear] We also tried to use the OIL language [Fensel et al. 2001] which has been developed within the Ontoknowledge 22 project (cf. Fensel et al. 2000(b) as a Web based ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the ACM, 42(4):741-843, 1995.

....in Section 4 we will discuss XOL, a proposal for an XML based standard for expressing ontologies. 2 Ontology Languages For our discussion we have chosen: CycL and KIF [Gene 1991] as representatives for enriched first order predicate logic languages. Ontolingua [FFR 1997] and Frame Logic [KLW 1995] as representatives for framebased approaches. Both incorporate frame based modeling primitives in a first order logical framework, however they apply very different strategies for this. Description Logics that describe knowledge in terms of concepts and role restrictions used to automatically ....

....for (they are typed) and the same attribute (i.e. the same attribute name) may be associated with different range and value restrictions when defined for different classes. In the following we will discuss two frame oriented approaches: Ontolingua (cf. Grub 1993] FFR 1997] and Frame logic [KLW 1995]. Ontolingua 4 was designed to support the design and specification of ontologies with a clear logical semantics based on KIF. Ontolingua extend KIF using additional syntax to include the intuitive bundling of axioms into definitional forms with ontological significance and a Frame Ontology to ....

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M. Kifer, G. Lausen, and J. Wu: Logical Foundations of ObjectOriented and Frame-Based Languages, Journal of the ACM, 42, 1995. Ontology Languages and Web Standards

....assigns to each relation name its arity. As said above, the definition considers the core elements of most languages for ontology representation only. It is possible to map the definition to most types of ontology representation languages. Our implementation, for instance, is based on Frame Logic [Kifer et al., 1995] . Frame Logic has a wellfounded semantics, but we do not refer to it in this paper. 3.2 Formal Concept Analysis We recall the basics of Formal Concept Analysis (FCA) as far as they are needed for this paper. A more extensive overview is given in [Ganter and Wille, 1999] To allow a ....

M. Kifer, G. Lausen, J. Wu: Logical foundations of object-oriented and frame-based languages. Journal of the ACM 42(4), 741--843.

....the structure of the problem domain, i.e. its entities and their interrelationships. The domain model is made up of the concepts defined in the dictionary. # O e : axioms about the concepts of O are specified in a body of rules. Following [2] this can be efficiently accomplished using Frame Logic [10] but DAML OIL [15] may proof itself feasible as well. # E: application semantics are modeled using laws. It is still an open question how laws should be formalized for practical purposes but Frame Logic and various description logic languages offer a promising starting point for further ....

M. Kifer, G. Lausen, J. Wu: Logical Foundations of Object-Oriented and FrameBased Languages, Journal of the ACM, 42, 1995.

....RDF schema. Still the work we report failed in an important aspect. We did not define an object language as part of UPML version 2, to support the definition of elementary attributes of UPML. In UPML version 1, we proposed either first order logic with sorts [Blsius et al. 1990] or Frame logic [Kifer et al. 1995] as a language for defining declarative specifications elements, and MCL [Fensel et al. 1998] for describing the procedural part of a complex PSM. In UPML version 2.0 we weakened these commitments. There are some serious reasons for this: 1. UPML should fulfil contradictory requirements. Library ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the ACM, vol 42, 1995.

....ontologies is syntactically enriched. First, ideas of [Lloyd Topor, 1984] were used to get rid of some of the limitations of Horn logic without requiring a new inference mechanism. Second, languages with richer epistemological primitives than predicate logic are provided. Frame logic [Kifer et al. 1995] is used as the representation language for ontologies. It incorporates objects, relations, attributes, classes, and subclass of and element of relationships within a first order semantic framework. To improve the accessibility of our service we are currently realizing a translator to Ontolingua ....

....both shortcomings. 4.1.1 Elementary Expressions Usually, ontologies are defined via concepts or classes, is a relationships, attributes, further relationships, and axioms. Therefore an adequate language for defining the ontology has to provide modeling primitives for these concepts. Frame Logic [Kifer et al. 1995] provides such modeling primitives and integrates them into a logical framework providing a Horn logic subset. Furthermore, in contrast to most Description Logics 2 , expressing the ontology in 2. Badea, 1997] recently proposed to extend Description Logics a step into the direction of ....

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M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the ACM, 42, 1995.

....from already existing ones. It will offer union, intersection, and difference as basic operations for such an algebra. Various kind of formal languages are used for representing ontologies, among others description logics (see e.g. LOOM [MacGregor, 1991] or CYCL [Lenat Guha, 1990] Frame Logic [Kifer et al. 1995], and Ontolingua [Gruber, 1993] which is based on KIF (Knowledge Interchange Format) Genesereth Fikes, 1992] It is basically a first order predicate logic extended with meta capabilities to reason about relations. Languages for expressing ontologies and their relationships to arising web ....

....the terminology (i.e. signature) and may introduce further rules (i.e. axioms) that allow the derivation of additional facts that are not stated as extensions. 3.2.1.2 The Representation Languages A representation language is used to formulate an ontology. This language is based on Frame logic [Kifer et al. 1995]. F Logic is a language for specifying object oriented databases, Frame systems, and logical programs. Its main achievement is to integrate conceptual modeling constructs (classes, attributes, domain and range restrictions, inheritance, axioms) into a coherent logical framework. Basically it ....

[Article contains additional citation context not shown here]

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of ObjectOriented and Frame-Based Languages, Journal of the ACM, 42, 1995.

....assigns to each relation name its arity. As said above, the definition considers the core elements of most languages for ontology representation only. It is possible to map the definition to most types of ontology representation languages. Our implementation, for instance, is based on Frame Logic [Kifer et al., 1995] . Frame Logic has a wellfounded semantics, but we do not refer to it in this paper. 2.2 Formal Concept Analysis We recall the basics of Formal Concept Analysis (FCA) as far as they are needed for this paper. A more extensive overview is given in [Ganter and Wille, 1999] To allow a ....

M. Kifer, G. Lausen, J. Wu: Logical foundations of object-oriented and frame-based languages. Journal of the ACM 42.

....domain ontology 4 itself classes, their attributes, their interrelationships (generalization, part of relation) and the relationships should be accessible within rules. For this purpose signature atoms, i.e. atoms which allow to access the attributes of classes and their range restrictions (cf. [Kifer, Lausen, and Wu, 1995]) are introduced. For instance given the following class definition: CLASS elevator car capacity range: REAL ; speed: REAL ; 3. The syntax of atoms in L KARL differs from the syntax of atoms in predicate logic, because L KARL is based on F logic [Kifer, Lausen, and Wu, 1995] 4. At ....

....(cf. Kifer, Lausen, and Wu, 1995] are introduced. For instance given the following class definition: CLASS elevator car capacity range: REAL ; speed: REAL ; 3. The syntax of atoms in L KARL differs from the syntax of atoms in predicate logic, because L KARL is based on F logic [Kifer, Lausen, and Wu, 1995]. 4. At the domain layer there is no separation of structure information (types) and the extension. END; Used in rules signature formulae together with variables for the attributes allow the attributes and the range restrictions of the attributes of the classes and relationships to be ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages. In: Journal of the ACM, vol. 42, 1995, 741-843.

....for the verification of procedural programs, for specifying the task layer. The language KARL was developed as part of the MIKE project [AFL 93] and provides a formal and executable specification language for the KADS model of expertise by combining two types of logic: A variant of Frame Logic [KLW93] is used to specify domain and inference layers. It combines first order logic with semantical data modeling primitives. A restricted version of dynamic logic is provided to specify a task layer. Executability is achieved by resticting Frame logic to Horn logic with stratified negation and by ....

....It provides predicates, classes, class hierarchies, single and set valued attributes with domain and range restrictions, and multiple attribute inheritance for modelling terminological domain knowledge. The derivation of new object denotations can be expressed by functions. KARL uses F logic [KLW93] as a model for the integration of object orientation in a logical framework. The Horn clauses of L KARL are extended by stratified negation [Prz88] The domain layer of our running example is given in figure 2. 2.3.2 Inference layer The same language L KARL which is used at the domain layer is ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages. In Technical Report 93/06, Department of Computer Science, SUNY at Stony Brook, NY, April 1993. To appear in Journal of ACM.

....for the verification of procedural programs, for specifying the task layer. The language KARL was developed as part of the MIKE project [AFL 93] and provides a formal and executable specification language for the KADS model of expertise by combining two types of logic: A variant of Frame Logic [KLW93] is used to specify domain and inference layers. It combines first order logic with semantical data modeling primitives. A restricted version of dynamic logic is provided to specify a task layer. Executability is achieved by restricting Frame logic to Horn logic with stratified negation and by ....

....0 s 1 (Y) s 0 (X) 8Zsuch that Z 6= Y s 0 (Z) s 1 (Z)g 2. 3 KARL The language KARL provides a formal and executable specification language for the KADS model of expertise by combining two types of logic: Logical KARL (L KARL) and ProceduralKARL (P KARL) L KARL, a variant of Frame Logic [KLW93], is provided to specify domain and inference layers. It combines first order logic with semantic data modeling primitives (see [Bro84] for an introduction to semantic data models) A restricted version of dynamic logic is provided by P KARL to specify a task layer. Executability is achieved by ....

[Article contains additional citation context not shown here]

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages. In Technical Report 93/06, Department of Computer Science, SUNY at Stony Brook, NY, April 1993. To appear in Journal of ACM.

....we developed a system called Ontobroker (Fensel et al. 98a) Ontobroker) with the following core elements (see Figure 1) Gamma The most central part are the ontologies. They are used in several components of the system. They are expressed in a representation language based on Frame Logic (Kifer et al. 95) rdf3.tex; 25 09 1998; 12:41; p.2 3 RDF Maker Inference Engine Query Interface Facts Ontologies Extract Annotation Wrapper Ontocrawler Annotated Documents Similarly Structured Documents HTML HTML HTML HTML Query Knowledge RDF Descriptions Query Language Representation Language ....

....both shortcomings. 2.1.1. Elementary Expressions Usually, ontologies are defined via concepts or classes, is a relationships, attributes, further relationships, and axioms. Therefore an adequate language for defining the ontology has to provide modeling primitives for these notions. Frame Logic (Kifer et al. 95) provides such modeling primitives and integrates them into a logical framework providing a Horn logic subset. Furthermore, in contrast to Description Logic, expressing the ontology in Frame Logic allows queries that directly use parts of the ontology as first class citizens. That is, not only ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of ObjectOriented and Frame-Based Languages, Journal of the ACM, 42, 1995.

....the successor step, these variable substitutions are appended to the list of already computed input output pairs. 2.2. KARL The language KARL provides a formal and executable specification language for the KADS model of expertise by combining two types of logic. L KARL, a variant of Frame Logic [10], is provided to specify domain and inference layers. It combines first order logic with semantic data modelling primitives. A restricted version of dynamic logic is provided by P KARL to specify a task layer. L KARL is provided for specifying inference actions and knowledge roles. The ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the ACM, vol 42, 1995.

....derived query. 9 4.1 Elementary Expressions Usually, ontologies are defined via concepts or classes, is a relationships, attributes, further relationships, and axioms. Therefore an adequate language for defining the ontology has to provide modeling primitives for these concepts. Frame Logic [Kifer et al. 1995] provides such modeling primitives and integrates them into a logical framework providing a Horn logic subset. Furthermore, in contrast to most Description Logics, expressing the ontology in Frame Logic allows for queries that directly use parts of the ontology as first class citizens. That is, ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the ACM, 42, 1995.

....[KIF] and CommonKADS [Schreiber et al. 1994] Ontologies are consensual and formal specification of a vocabulary used to describe a specific domain. Frame based languages enriched by logical axioms are often used to formulate them (cf. LOOM [MacGregor, Introduction 2 1990] and Frame Logic [Kifer et al. 1995]) Roughly, ontologies correspond to generalized database schemata. However, ontologies can be used to describe the semantic structure of much more complex objects than common databases and are therefore wellsuited for describing heterogeneous, distributed and semistructured information sources. ....

....string provides the name of a researcher. We will later show that this is a significant difference between our approach and approaches like SHOE, RDF, and annotations used in information retrieval. A representation language is used to formulate an ontology. This language is based on Frame logic [Kifer et al. 1995]. Basically it provides classes, attributes with domain and range definitions, is a hierarchies with set inclusion of subclasses and multiple attribute inheritance, and logical axioms that can be used to further characterize relationships between elements of an ontology and its instances. The ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the ACM, 42, 1995. 6 Conclusions 22

....language only. KARL is a customization of first order logic consisting of the two sublanguages LKARL that represents static knowledge and P KARL that represents dynamic knowledge. It has a declarative semantics [Fen93a] as well as an operational semantics [Ang93] L KARL is based on Frame logic [KLW93], which integrates objectorientation into a declarative framework. P KARL is based on dynamic logic [Koz90] which integrates the representation of procedural knowledge into a declarative framework. The modelling primitives of KARL reflect the structure of the model of expertise of KADS (i.e. the ....

M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages. In Technical Report 93/06, Department of Computer Science, SUNY at Stony Brook, NY, April 1993. To appear in Journal of ACM.

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M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and FrameBased Languages, Journal of the ACM, 42, 1995.

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M. Kifer, G. Lausen, and J. Wu: Logical Foundations of Object-Oriented and Frame-Based Languages, Journal of the ACM, 42, 1995.

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M. Kifer, G. Lausen, J. Wu: Logical foundations of object-oriented and framebased languages, Journal of the ACM 42, 1995

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