Andrea Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13:141--176, 1994.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... capture the construct ONE OF, having the form fff 1 ; ff ng, denoting the concept made of exactly the enumerated individuals ff 1 ; ff n ; as well as the construct FILLS, having the form R : ff, denoting those individuals having the individual ff as a role filler of R (see [107] and references therein for further discussion on these constructs) The result in Section 7.1 can be generalized as follows: satisfiability in CNO knowledge bases can be polynomially reduced to satisfiability of CN formulae, hence is decidable, and EXPTIME complete. Similarly, the result in ....

A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994. 132

....operators that cannot be completely encoded using other operators. Using only transformations that preserve interpretation, we will often end up with a combination of operators that are hard to handle in reasoning. The use of instances in concept definitions for example is inherently intractable [Schaerf, 1994], especially if inverse roles are used. If we still want to reason about models encoded in these languages, we have to use transformations with weaker formal properties. 4.3.3 Weakening Transformations The applicability of semantics preserving transformations is somewhat restricted, because we ....

....preservation) A transformation # is said to be inconsistency preserving i# #= # =# #(#) #,A A practical example for the application of consistency preserving transformation is the use of individuals in concept definitions. Reasoning with individuals has been shown to be inherently intractable [Schaerf, 1994]. One solution to provide tractable inferences is to use weakening transformations like in the example given below: Example 4 (Reasoning in Instance OIL) The second layer of the OIL language called standard OIL provides an expressive language for building ontologies. Again, the language is ....

Schaerf, A. (1994). Reasoning with individuals in concept languages. Data Knowledge Engineering, 13(2):141--176.

....logics. extends the propositionally complete concept language AC [Schmidt SchauB and Smolka, 1991] with role con junction (7) Hollunder et a . 1990] inverse roles (Z) Donini et a . 1991] feature selection, agreement and disagreement ( nonunder and Nutt,1990] enumerated types (O) [Schaerf, 1994]. Section 4 describes the full CRACK language and some of its possible extensions. Figure 1 defines syntax and semantics of ACI Z y O. Knowledge base satisfiability is the basic reasoning task, since all the relevant reasoning tasks like concept satisfiability, concept subsumption, instance ....

Andrea Schaerf. Reasoning with individu- als in concept languages. Data and Knowledge Engineer- ing, 13(2):141 176, 1994.

....the case if I and I 0 satisfy A s pre and post conditions: conditions that must be satis ed for A to be carried out are described in pre. A condition of the form 8C requires that each individual in I is an instance of C. The other conditions correspond to ABox assertions in DLs; see, e.g. [18]. conditions that must be satis ed after A has been carried out (i.e. by I 0 ) are described in post. Since the state of the world before A may in uence the e ects of A, the post conditions di er slightly from pre conditions. The idea behind each =c is that, if each condition in holds in ....

A. Schaerf. Reasoning with individuals in concept languages. In Proceedings of the Third Conference of the Italian Association for Articial Intelligence (AI*IA-93), Lecture Notes in Articial Intelligence. Springer-Verlag, 1993.

....for an ontology specification language given that an ontology can be viewed as a kind of schema. Moreover, allowing individuals to occur in class definitions is equivalent to having extensionally defined classes, and this soon leads to very hard reasoning problems and even undecidability [8, 3, 1]. # The slot constraints numeric minimum and numeric maximum are not supported. Future extensions of OIL may support concrete data types (including numbers and numeric ranges) # Collection types other than set are not supported. # Slot inverse can only be specified in global slot definitions: ....

A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994.

....4.2 C(ALCO; S4 u ) Now imagine that you are employed by the EU parliament to develop a geographical information system about Europe. One part of the task is easy. You take the description logic ALCO (extending ALC with nominals, i.e. concept names which have to be interpreted as singleton sets [28, 20]) and, using concepts Country, Treaty, etc. nominals 10 EU, Schengen treaty, Spain, Luxembourg, UK, etc. and a role member, write Luxembourg v 9member:EU u 9member:Schengen treaty Iceland v 9member:Schengen treaty u :9member:EU Schengen treaty v Treaty 9member:Schengen treaty v Country ....

A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994.

....contain cycles and the 9 descriptive semantics given to S restrict the models of the corresponding knowledge base. Furthermore, it is well known that when individuals are permitted in the concept language as is our case the assertions in the World Description W do a ect the subsumption relation [23]. Formally, we are interested in the following reasoning services. De nition 3.4 Let = S; V; W) be a knowledge base, C and D concepts from VL(D) and a an individual. 1) logically implies C v S D ( j= C v S D) if every model I satis es C I D I . Hybrid subsumption is the problem of ....

A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13:141-176, 1994.

....so there is no mechanism for reasoning with this part of the language. Secondly, realistic ontologies typically contain references to named individuals within class descriptions. e.g. Italians might be described as persons who are citizens of Italy , where Italy is a named individual [Schaerf, 1994] . The required functionality can be partially simulated by treating such individuals as pairwise disjoint atomic classes (this is the approach taken in the existing OIL FaCT mapping) but this can result in incorrect inferences. In this paper we will present a new DL that overcomes 2 In fact ....

.... additional expressive power that is useful in many applications; nominals (as such individuals can be called) are a prominent feature of hybrid logics [Blackburn and Seligman, 1998] and various extensions of modal and description logics with nominals have already been investigated (see, e.g. [Schaerf, 1994; De Giacomo, 1995; Areces et al. 2000] As we have seen, nominals occur naturally in ontologies as names for specific persons, companies, countries etcetera. From a semantic point of view, it is important to distinguish between a nominal and an atomic concept simple class, since the nominal ....

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A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994.

....so there is no mechanism for reasoning with this part of the language. Secondly, realistic ontologies typically contain references to named individuals within class descriptions. e.g. Italians might be described as persons who are citizens of Italy , where Italy is a named individual [Schaerf, 1994] . The required functionality can be partially simulated by treating such individuals as pairwise disjoint atomic classes (this is the approach taken in the existing OIL # FaCT mapping) but this can result in incorrect inferences. 2 In fact they can be viewed as syntactic variants of such a ....

.... additional expressive power that is useful in many applications; nominals (as such individuals can be called) are a prominent feature of hybrid logics [Blackburn and Seligman, 1998] and various extensions of modal and description logics with nominals have already been investigated (see, e.g. [Schaerf, 1994; De Giacomo, 1995; Areces et al. 2000] As we have seen, nominals occur naturally in ontologies as names for specific persons, companies, countries etcetera. From a semantic point of view, it is important to distinguish between a nominal and an atomic concept simple class, since the nominal ....

[Article contains additional citation context not shown here]

A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994.

....results on the computational complexity of more powerful DLs, we had deemed Mirtl the best compromise between expressivity and tractability for our purposes. Somehow encouraged by the fact that the standard reasoning problems in the related logics ALCNR [ Buchheit et al. 1993 ] ALCO [ Schaerf, 1994 ] and ALNI (also known as PL 1 ) Donini et al. 1991 ] are all decidable, and considering that the wellknown algorithms based on constraint propagation for reasoning on them tend to be easily customizable to a # This work has been carried out in the context of the project FERMI 8134 ....

Andrea Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13:141--176, 1994.

.... (Schmiedel, 1990) and of Weida and Litman (Weida Litman, 1992) Advantages of using description logics are their high expressivity combined with desirable computational properties such as decidability, soundness and completeness of reasoning procedures (Buchheit, Donini, Schaerf, 1993; Schaerf, 1994; Donini Era, 1992; Donini, Lenzerini, Nardi, Schaerf, 1994; Donini, Lenzerini, Nardi, Nutt, 1995) To represent the temporal dimension classical description logics are extended with temporal constructors; 1. Description Logics have been also called Frame Based Description Languages, Term ....

.... 1992) Advantages of using description logics are their high expressivity combined with desirable computational properties such as decidability, soundness and completeness of reasoning procedures (Buchheit, Donini, Schaerf, 1993; Schaerf, 1994; Donini Era, 1992; Donini, Lenzerini, Nardi, Schaerf, 1994; Donini, Lenzerini, Nardi, Nutt, 1995) To represent the temporal dimension classical description logics are extended with temporal constructors; 1. Description Logics have been also called Frame Based Description Languages, Term Subsumption Languages, Terminological Logics, Taxonomic Logics, ....

Schaerf, A. (1994). Reasoning with individuals in concept languages. Data & Knowledge Engineering, 13 (2), 141--176.

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Andrea Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13:141--176, 1994.

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Andrea Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994.

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A. Schaerf. Reasoning with individuals in concept languages. Data Knowledge Engineering, 13(2):141--176, 1994.

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A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13:141-176, 1994.

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A. Schaerf. Reasoning with Individuals in Concept Languages. DKE, 13(2):141--176, 1994.

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A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994.

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A. Schaerf. Reasoning with individuals in concept languages. In Proceedings of the Third Conference of the Italian Association for Artificial Intelligence (AI*IA-93), Lecture Notes in Artificial Intelligence. Springer-Verlag, 1993.

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Andrea Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141-176, 1994.

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Andrea Schaerf. Reasoning with individuals in concept languages. Data Knowledge Engineering, 13(2):141--176, 1994.

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A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13:141-176, 1994.

No context found.

Andrea Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141-176, 1994.

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A. Schaerf. Reasoning with individuals in concept languages. Data and Knowledge Engineering, 13(2):141--176, 1994.

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Andrea Schaerf. Reasoning with individuals in concept languages. Data Knowledge Engineering, 13(2):141--176, 1994.

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A. Schaerf. Reasoning with individuals in concept languages. Data Knowledge Engineering, 13(2):141--176, 1994.

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