Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86, 5th Conference of the American Association for Artificial Intelligence, pages 344--348, Philadelphia, PA, 1986.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... algorithm that tests the validity of # # # [32] Relevance description logics based on a 4 valued semantics have already been proposed by PatelSchneider for use in knowledge representation, and have been proven to possess a generally better computational behaviour than their 2 valued analogues[40, 41, 42, 43]. The semantics we adopt departs from Patel Schneider s, whose loss of inferential capabilities is too drastic for the needs of IR: in fact, that semantics sanctions the loss of modus ponens and, in general, of a great deal of conditional reasoning. In addition, the deduction algorithms and the ....

....every interpretation I. # 4 and # 4 are extended to roles in a straightforward way. Finally, a KB # entails an assertion # (# = 4 #) i# every interpretation satisfying the former also satisfies the latter. 8 For the motivations underlying this choice, see the discussion on t entailment in [40]. 12 3.3 Soundness and incompleteness One important property of Mirlog is that reasoning in it is sound with respect to classical semantics; that is, every inference that can be drawn within Mirlog can also be drawn within its corresponding 2 valued logic presented, for illustrative purposes, ....

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Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86, 5th Conference of the American Association for Artificial Intelligence, pages 344--348, Philadelphia, PA, 1986.

....by which formalisms, and of a common semantics to define the relationship between expressions of different formalisms in a semantically sound manner. The decidability of all algorithms involved is achieved by adopting a four valued semantics based on the works of Belnap [2] Patel Schneider [12] [13], Frisch [9] and Thomason et al. 14] The system supports four different knowledge representation formalisms first order logic, frames, semantic nets and production systems with their associated inference mechanisms assertional reasoning, terminological reasoning, inheritance with ....

....in section 7, some applications and conclusions are presented. 2 The Semantics One of the main characteristics of Mantra is the definition of a unified semantics for knowledge representation and reasoning methods and their interaction. This semantics is based upon a four valued logic [2] 12] [13] [9] 14] Many knowledge representation systems support standard first order logic due to its naturality and expressive power. However, when reasoning about some formulae, these systems may never stop due to the fact that first order logic is undecidable. This situation is higly unsatisfatory if ....

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P.F. Patel-Schneider, A four-Valued Semantics for Frame-Based Description Languages, Proceeding of AAAI-86, 1986.

....if a proof cannot be found within the time bound. But see [Horvitz et al. 1989] for an example of probabilistic inference, where confidence in the results increases with the amount of computation. Accounts of limited inference based on non traditional semantics [Levesque, 1984; Frisch, 1985; Patel Schneider, 1986] often provide only a very weak kind of inference. For example, in the four valued semantics approach of Levesque, given the statements p and p oe q, one cannot infer q. This paper presents a third alternative for obtaining efficient representation systems, which neither limits the expressive ....

Patel-Schneider, P.F. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86, Philadelphia, PA, 344--348.

.... be NP hard [7] In order to solve this problem we are currently working [12] on a variant of Mirtl based, rather than on classical logic, on relevance logic [1] early results in the field suggest that relevance TLs are in general computationally easier to handle than their classical equivalents [17]. An alternative solution to the complexity problem that we are considering is the investigation of probabilistic algorithms for subsumption checking. The answer that these algorithms would give to the question if concept C 1 subsumes concept C 2 would be accurate only with probability P 1; ....

Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86, 5th Conference of the American Association for Artificial Intelligence, pages 344-- 348, Philadelphia, PA, 1986.

.... is instance checking and amounts to verify whether the individual a is an instance of the concept C with respect to the knowledge base Sigma , i.e. in symbols Sigma j= C(a) Originally, four valued DLs have been proposed in order to develop expressively powerful DLs with tractable subsumption [21, 22, 23]. It has been shown that the four valued subsumption relation captures an important subset of twovalued subsumption relationships. More recently, DLs and their four valued versions have been proposed in the area of (multimedia) Document Retrieval (DR, for short) 12, 17, 18, 19, 26] In this ....

Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86, 5th Conference of the American Association for Artificial Intelligence, pages 344--348, Philadelphia, PA, 1986.

.... Owsnicki, 1986] back [von Luck et al. 1987; Nebel and von Luck, 1988] loom [MacGregor, 1988] classic [Brachman et al. 1989; Borgida et al. 1989] and sb one [Kobsa, 1989] and the formal properties of these systems were investigated [Schmolze and Israel, 1983; Brachman and Levesque, 1984; Patel Schneider, 1986; Levesque and Brachman, 1987; Nebel, 1988; Schild, 1988; Patel Schneider, 1989a; PatelSchneider, 1989b; Schmidt Schau , 1989; Schmidt Schau and Smolka, 1990; Nebel and Smolka, 1990; Nebel, 1990; Donini et al. 1990; Hollunder et al. 1990] When studying the above mentioned papers, one notes ....

Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of the 5th National Conference of the American Association for Artificial Intelligence, pages 344--348, Philadelphia, Pa., August 1986.

....be easily detected. That is certainly not the kind of behaviour we expect from a knowledge representation system. Although it is clear that we have to live with incomplete reasoners, this incompleteness should be systematic, perhaps even describable by a systematic, model theoretic approach (cf. [18]) In conclusion, if we claim to integrate the reasoning of two formalisms, a minimal requirement is that the inferences are independent of the order of input. The only solution to this problem is to employ some sort of symbolic constraint propagation. 11 After a new MSG is determined for some ....

Peter F. Patel-Schneider, "A Four-Valued Semantics for Frame-Based Description Languages," Proc. AAAI-86, Philadelphia, Pa., August 1986, pp. 344--348.

....if a proof cannot be found within the time bound. But see [Horvitz et al. 1989] for an example of probabilistic inference, where confidence in the results increases with the amount of computation. Accounts of limited inference based on non traditional semantics [Levesque, 1984; Frisch, 1985; Patel Schneider, 1986] often provide only a very weak kind of inference. For example, in the four valued semantics approach of Levesque, given the statements p and p oe q, one cannot infer q. This paper presents a third alternative for obtaining efficient representation systems, which neither limits the expressive ....

Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86, pages 344-- 348, Philadelphia, PA, 1986.

....in many areas: logic design, switching theory, programming languages, pattern recognition, artificial intelligence and many others. Our concern here is the decidable four valued logic introduced by Belnap [4] and extended to a version suitable for knowledge representation by Patel Schneider [30, 31]. 2.1.4.1 Why Four Valued Logic There are several reasons behind the need to use four valued logic: Firstly, there is a trade off between expressive power and computational tractability in knowledge representation formalisms [24] When the formalism is very expressive like first order logic, ....

Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86 5th International Conference on AI, Philadelphia, USA, August 11--15 1986. Springer-Verlag.

....is provided if a proof cannot be found in the time bound. But see [Horvitz et al. 1989] for an example of probabilistic inference, where confidence in the results increases with the amount of computation. Accounts of limited inference based on non traditional semantics [Frisch, 1985; Patel Schneider, 1986] often provide only a very weak kind of inference. For example, in the four valued semantics approach of Patel Schneider, given the statements p and p oe q, one cannot infer q. This paper presents a third alternative for obtaining efficient representation systems, which neither limits the ....

Peter F. Patel-Schneider. A four-valued semantics for frame-based description languages. In Proceedings of AAAI-86, pages 344-- 348, Philadelphia, PA, 1986.

....subrole introduction and role value maps (another popular concept forming operator) Alternatively, instead of general number restrictions, a limited set of restricted operators could be used, e.g. some, none and unique 11 . Another way out of this dilemma, pursued by Patel Schneider in [17] and [18] could be to use a different semantics based on a four valued logic, for which a complete and tractable subsumption algorithm even for very expressive FDLs can be specified. Another view of this solution is that it provides a sound algorithm for standard semantics and gives a precise ....

Patel-Schneider, P. F., A Four-Valued Semantics for Frame-Based Description Languages, in: Proc. AAAI-86, Philadelphia, Pa. (1986) 344--348.

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Peter F. Patel-Schneider, A Four-Valued Semantics for Frame-Based Description Languages, in: Proc. AAAI-86, Philadelphia (Pa.), August 1986, 344--348.

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