R. J. Brachman. What IS-A is and isn't: An analysis of taxonomic links in semantic networks. IEEE Computer, 16(10):30--36, 1983.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... change [11] From the standpoint of semantics, Brachman describes several meanings of the isa relation that may exist between two generic concepts in semantic networks (subset superset, generalization specialization, kind of, conceptual containment, role value restriction, set prototype) [4]. He also suggests using those semantic subcomponents as the primitives of a representation system. In practice, taxonomic knowledge is complex and remains partially intuitive in many existing ontologies. This may lead to ruptures in knowledge representation, and thus impair the capability of ....

Brachman, R.J. What Is-a Is and Isn't - an Analysis of Taxonomic Links in Semantic Networks. Computer, 16 (10). 30-36.

....making models confusing and difficult to reuse or integrate. Clearly, insights into how to properly construct a taxonomy are useful. Many previous efforts at providing these insights have focused on the semantics of the taxonomic relationship (also called is a, class inclusion, subsumption, etc. [2], on different kinds of relations (generalization, specialization, subset hierarchy) according to the constraints involved in multiple taxonomic relationships (covering, partition, etc. 28] on the taxonomic relationship in the more general framework of data abstractions [7] or on structural ....

R. Brachman, What IS-A is and isn't: an analysis of taxonomic links in semantic networks, IEEE Computer 16 (10) (1983) 30-36.

....IRI 8819624 and in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014 86 K 0180. 1989 Massachusetts Institute of Technology. I Introduction relationships between classes [Bobrow and Winograd, 1977] Fahlman, 1979] [Brachman, 1983], Brachman et al. 1983] Taxonomic hierarchies without defaults or exceptions are semantically equivalent to a collection of formulas in first order predicate calculus. Designers of knowledge representation lan guages have argued that there are computational advantages to representing facts as ....

....and in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014 86 K 0180. 1989 Massachusetts Institute of Technology. I Introduction relationships between classes [Bobrow and Winograd, 1977] Fahlman, 1979] Brachman, 1983] [Brachman et al. 1983]. Taxonomic hierarchies without defaults or exceptions are semantically equivalent to a collection of formulas in first order predicate calculus. Designers of knowledge representation lan guages have argued that there are computational advantages to representing facts as taxonomic relationships ....

R. J. Brachman. What is-a is and isn't: An analysis of taxonomic links in semantic networks. IEEE Computer, 16(10):30-36, October 1983.

....we could also have that elephant mammal, leaving it under specified whether mammal animal or vice versa. each other, i.e. that there is a relation between concepts (which we denote ) and that this relation is a partial order. We don t say that such requirements shouldn t be stated (see e.g. [1, 7]) however, it is outside the scope of this paper where we focus on the mathematical properties of taxonomies. Actually, we are now able to specify taxonomies, simply by use of the subsumption relation. However, we prefer to introduce two operations on concepts, making the language far more ....

Ronald J. Brachman. What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks. IEEE Computer, 16(10):30--36, 1983.

....making models confusing and difcult to reuse or integrate. Clearly, insights into how to properly construct a taxonomy are useful. Many previous efforts at providing these insights have focused on the semantics of the taxonomic relationship (also called is a, class inclusion, subsumption, etc. [3], on different kinds of relations (generalization, specialization, subset hierarchy) according to the constraints involved in multiple taxonomic relationships (covering, partition, etc. 33] on the taxonomic relationship in the more general framework of data abstractions [9] or on structural ....

Brachman, R. 1983. What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks. IEEE Computer, 16(10): 30-36.

....within a Datalog framework. This paper deals with aspects that are complementary to type inferencing and method inheritance in that we concentrate on exploiting aggregation and classification knowledge. Generalization is seen as a logical implication between class membership predicates (see [BRAC83] and section 7) We therefore use an earlier and simpler object model that was first presented in [STAN86] and forms a subset of the knowledge representation language Telos [MBJK90] In this section, the formalization is briefly summarized as far as it is needed later on. 6 Definition 3 Let ....

Brachman,R.J. (1983). What IS-A is and isn't: an analysis of taxonomic links in semantic networks. IEEE Computer 16(10), Oct. 1983.

....A , respectively. In the last example, the duplicate key will open the door only if it is well made, and so the conclusion seems less certain than in the rst example. According to Brachman, understanding what is on either end of the link is also the key to understanding the import of the link [9]. This is where Aristotelian logic has something to o er to conceptual integrity over and above rigorous formalism. 1.1 Overview of Aristotelian Logic Aristotle s logical works are commonly referred to as the Organon (Greek, for tool and reason is the tool of tools) The Organon is divided by ....

....This type of is a relation that carries structure between structured descriptions is one of the most radical departures from representation schemes based on standard predicate logic. Almost all of the other is a relations are easily expressed in standard quanti cational languages. [9] This type of is a relation is at the core of Aristotelian logic, and here we wish to investigate how the object oriented programming notion of class is similar to the notion of species . Now, to say the notion of species , without quali cation of context, could easily lead us to an ....

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Brachman, R. J. What is-a Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks. IEEE Computer 16, 10 (October 1983), pp. 30 - 36.

....structured taxonomies have the opposite effect, making models confusing and difficult to reuse or integrate. Many previous efforts at providing some clarity in organizing taxonomies have focused on the semantics of the taxonomic relationship (also called is a, class inclusion, subsumption, etc. [3], on different kinds of relations (generalization, specialization, subset hierarchy) according to the constraints involved in multiple taxonomic relationships (covering, partition, etc. 23] on the taxonomic relationship in the more general framework of data abstractions [7] or on structural ....

Brachman, R. 1983. What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks. IEEE Computer, 16(10): 30-36.

....eds. http: sunsite.informatik.rwth aachen.de Publications CEUR WS Vol 18 I will focus here on a single design practice, which is the main responsible of most semantic difficulties: IS A overloading. Notice that I do not refer with this expression to the old debate about the semantics of IS A (Brachman, 1983), since I assume a standard set inclusion semantics for it. Rather, I will discuss the cases where this standard semantics turns out to be violated, if we carefully analyze the ontological nature of the arguments. I will consider a number of bad practice cases, proposing a way to simplify the ....

Brachman, R. 1983. What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks. IEEE Computer, 16(10): 30-36.

....more attributes on the elements of the subclass. It is more difficult to define inheritance concepts on bit strings whose interpretation is environment dependent. In mathematics, the integers are a subset of the reals; an integer is a real #################################### 26 Brachman [Bra83] correctly notes that inheritance as defined by the IS A construct is really little more than a convenient syntactic shorthand for incrementally creating subclasses. We, too, will treat it in just this fashion. This way of incrementally creating subclasses has also been called specialization ....

R. J. Brachman, What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks, COMPUTER 16,10 (Oct. 1983), 30-36.

....programming, and non monotonic reasoning systems. An unsatisfactory way of achieving this is to allow instances to be maximally specific (or leaf) sorts. The problems of mixing class and instance (i.e. subset vs. element) links in hierarchies were clearly identified by Woods [18] and Brachman [4]. Another unsatisfactory solution is to create new sorts which denote single elements, because sorts are declarative in nature whereas individuals are assertional. We propose an elegant generalization of equality constraints as a formal means of specifying and maintaining instance level ....

....set of individuals (the subset of the universe which contains the individual) If the exact individual denoted is unknown, the set represented by a variable is neither empty nor a singleton. The distinctions between sorts and individuals (or declarational vs. assertional relations) is described in [4], and the need to distinguish between subsort (i.e. isa subsort of) relations and member (i.e. isa instance of) relations is justified. Thus, we cannot intermix the sort hierarchy and individuals (where individuals might be seen as minimal sorts or leaves of the hierarchy) In a sense, our ....

R. J. Brachman. What IS-A is and isn't: An analysis of taxonomic links in semantic networks. IEEE Computer, 16:30--36, 1983.

....more rigorous and at the same time more understandable upperlevel ontologies. I will focus here on a single design practice, which is the main responsible of most semantic difficulties: IS A overloading. Notice that I do not refer with this expression to the old debate about the semantics of IS A [Brachman 1983], since I assume a standard set inclusion semantics for it. Rather, I will discuss the cases where this standard semantics does not reflect the ontological nature of the arguments. I will consider a number of bad practice cases, proposing a way to simplify the domain s hierarchical structure by ....

Brachman, R. 1983. What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks. IEEE Computer, 16(10): 30-36.

....concepts and their analytic interrelations, while the assertions stored in the ABox state contingent facts about what is true of the world. The TBox and ABox each have their own language. These are called the terminological language and the assertional language, respectively. Brachman and Levesque [7, 4] argue that these two components should be separately designed and optimized for their respective tasks. In particular, they insist on a strict separation of the inferential mechanisms each employs, in that neither component can change or manipulate the information contained in the other. ....

.... knowledge representation researchers since the latter part of 1988 (primarily as MIT LCS TM 387 and 387b) Our concern in this paper is solely with the restricted language and restricted classification theses, which have continued to exert influence on the field since their first appearances in [4, 6, 7, 19]. Subsequent to these articles and the writing of our paper, however, work by a number of authors (including Brachman, Levesque, and their students) has been concerned with improving the utility of knowledge representation systems in some of the directions we urge in our discussion, for example, ....

R. J. Brachman. What IS-A is and isn't: An analysis of taxonomic links in semantic networks. IEEE Computer, 16(10):30--36, October 1983.

....or their instances may even be totally unrelated. The set of given class derivations and their semantics ultimately determine how type and set relationships interact within a given data model as will be shown in Section 4. The term is a relationship has been misused to mean many different things [4]. We can now define the is a relationship in terms of the two just defined class relationships. Definition 5 C1 is a C2 ( C1 C2 and C1 C2. Informally, we say that C1 is a C2 if (1) every member of C1 is an member of C2 (the subset relationship) and (2) every property defined for C2 is also ....

R. J. Brachman, "What IS-A is and isn't: An Analysis of Taxonomic Links in Semantic Networks," in IEEE Computer, pp. 30 -- 36, Oct. 83.

....[16, 18] Therefore each tentative characterisation of OOL with regard to OBKR is contradicted by some non typical system. On the other hand, in the last ten years, there has been fundamental work concerning the semantics attached to the notions of objects, classes, specialisation and so on [3, 2]. There are roughly three ways for establishing the semantics of object based systems: designing an operational semantics which models the behaviour of the system without referring to the modelled domain [21] designing a denotational semantics given by an interpretation function ranging from ....

Ronald Brachman, What is-a is and isn't: an analysis of taxonomic link in semantic networks, IEEE Computer 16(10):30-36, 1983

....does not lie solely in its name [13] but rather in its constraint satisfaction and inheritance mechanisms. In this light, our ownership relationship can be viewed as a modeling primitive of an OODB system with built in semantics. In previous research, the IS A (or SUBCLASS) relationship [2, 12] and the PART OF relationship [6, 7, 8, 10, 11] have been modeled as semantic relationships. The remainder of this paper is organized as follows. In Section 2, we discuss the legal definition of ownership. In Section 3, we formally define the ownership relationship and describe its characteristic ....

R. J. Brachman. What IS-A is and isn't: An analysis of taxonomic links in semantic networks. Computer, 16(10):30--36, Oct. 1983.

....class, for example the class PERSON, will share common properties, such as name, home address, age, and social security number. We will also assume the existence of subclasses. Most semantic and object oriented databases use an IS A construct to support the concept of class and subclass. Brachman [Bra83] correctly notes that inheritance as defined by the IS A construct is really little more than convenient syntactic shorthand for incrementally creating subclasses, so we will ignore actual inheritance mechanisms per se. The important feature that is abstracted in the entity database model is the ....

R. J. Brachman, What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks, COMPUTER 16,10 (Oct. 1983), 30-36.

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R. J. Brachman. What IS-A is and isn't: An analysis of taxonomic links in semantic networks. IEEE Computer, 16(10):30--36, 1983.

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R. J. Brachman, "What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantic Networks", IEEE Computer, vol. 16, pp. 30-36, 1983.

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R.J. Brachman. What IS-A is and isn't: An analysis of taxonomic links in semantic networks. IEEE Computer, 16(10), 1983.

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Brachman RJ. What IS-A is and isn't: an analysis of taxonomic links in semantic networks. Computer 1983;16(10):30-6.

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R.J. Brachman. What IS-A Is and Isn't: An Analysis of Taxonomic Links in Semantics Networks. IEEE Computer, 16(10):30-36, 1983.

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Ronald J. Brachman. What is-a is and isn't: An analysis of taxonomic links in semantic networks. Computer, 16(10):30--36, October 1983.

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Brachman, Ronald J. 1983. What IS-A is and isn't: An analysis of taxonomic links in semantic networks. IEEE Computer, 30-36.

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