J.A. Goguen and G. Malcom. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....results of the type theory, Bertino and Martino provided the Chimera object oriented database model [11] with formal foundations and typing. In [14] a novel logic was presented claiming capability to model all the aspects of the object oriented paradigm. Another promising approach is presented in [10]. It uses an algebraic specification and emphasizes proofs rather than models. The research done in these directions gives us the possibility to compare the set theoretic, logic based, algebraic and categorical approach. CT can be actually used in any of these approaches with the advantage of ....

GOGUEN, J. A., MALCOLM, G.: Extended Abstract of a Hidden Agenda. In Proceedings, Conference on Intelligent Systems: a Semiotic Perspective, J. Meystel, A. Meystel, and R. Quintero, Eds., 1996.

....invariant, bisimulation, refinement. Classification: 68Q60, 68Q65, 03B70 (AMS 91) F.3.1, F.3.2, D.1. 5 (CR 91) 1 Introduction This paper is part of a recent research line of applying coalgebraic and coinductive notions and techniques in the formalisation of object oriented concepts, see [25, 13, 10, 12, 14, 5, 6], building on earlier work [29, 2, 15] Coalgebras consist of a state space together with a transition function and can be used to describe various kinds of dynamical systems, including automata, transition systems and hybrid systems, see e.g. 27, 20, 11] A coalgebraic specification (as ....

....the behaviour that is specified in the abstract specification can be realised by the concrete specification. The latter often contains more details about how to realise this behaviour. Typically, it is more deterministic (i.e. less underspecified) than the abstract specification (as stressed in [6]) see the stack specification refining the store specification later in this section. We start with the definition of refinement, and with two associated proof principles, involving invariants and bisimulations. 5.1. Definition. Consider two coalgebraic specifications: A for abstract, and C for ....

J.A. Goguen and G. Malcom. An extended abstract of a hidden agenda. In J., A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

.... approaches to equational logics and even first order logic (for example [1, 29, 31] Coalgebra, as dual notion of categorical algebra, turned out to be appropriate to handle infinite data types and dynamic systems [25, 34, 30] A special but important case of coalgebra is basic hidden algebra [16, 18, 17], covering many of the practical situations of interest in computing. We call it basic because it was recently extended non coalgebraically [32, 10] Hidden algebra appeared as a generalization of many sorted algebra, in order to give algebraic semantics for the object paradigm. It allows hidden ....

Joseph Goguen and Grant Malcolm. Extended abstract of a hidden agenda. In James Albus, Alex Meystel, and Richard Quintero, editors, Proceedings, Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. National Inst. Standards and Technology, 1996. Gaithersberg MD, October 20--23.

....these mechanisms within the LOOP tool would lead too far, but they form of course essential ingredients of the object oriented paradigm whatever that may be. 3 LOOP on classes in CCSL Figure 1 gives the CCSL presentation of the flag example that is often used in hidden algebra (see e.g. [1]) A flag has an attribute for describing its status, and methods for setting it up or down and for reverting it. The type Self in this specification describes the state space, and is considered as a black box. The is up attribute gives some information about states (elements of Self) and the ....

J.A. Goguen and G. Malcolm. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

....bisimulations. Also, the proof principles are illustrated in examples (which are fully formalised and verified in pvs) 1 Introduction This paper is part of a recent research line of applying coalgebraic and coinductive notions and techniques in the formalisation of object oriented concepts, see [26, 14, 11, 13, 15, 5, 6], building on earlier work [30, 2, 17] Coalgebras consist of a state space together with a transition function and can be used to describe various kinds of dynamical systems, including automata, transition systems and hybrid systems, see e.g. 28, 22, 12] or [16] for an introduction to the ....

....the behaviour that is specified in the abstract specification can be realised by the concrete specification. The latter often contains more details about how to realise this behaviour. Typically, it is more deterministic (i.e. less underspecified) than the abstract specification (as stressed in [6]) see the stack specification refining the store specification later in this section. We start with the definition of refinement, and with two associated proof principles, involving invariants and bisimulations. 5.1. Definition. Consider two coalgebraic specifications: A for abstract, and C for ....

J.A. Goguen and G. Malcolm. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

.... to equational logics and even first order logic (for example [1, 26, 28] Coalgebra, as dual notion of categorical algebra, turned out to be appropriate to handle infinite data types and dynamic systems [23, 31, 27] A special but very important case of coalgebra is basic hidden algebra [16, 18, 17], covering most of the practical situations of interest in computing. We call it basic because it was recently extended non coalgebrically [29, 10] Hidden algebra appeared as a generalization of many sorted algebra, in order to give algebraic semantics for the object paradigm. It allows hidden ....

Joseph Goguen and Grant Malcolm. Extended abstract of a hidden agenda. In James Albus, Alex Meystel, and Richard Quintero, editors, Proceedings, Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. National Inst. Standards and Technology, 1996. Gaithersberg MD, October 20--23.

....construct its elements) but only something about what can be observed (via the attributes) about an arbitrary state (i.e. inhabitant of X) Objects may be identified with such inhabitants. This coalgebraic state space X corresponds to the (product of the) hidden sorts in hiddensorted algebra, see [6, 5, 18, 7, 1, 8]. In this setting we define what it means for a concrete class to refine an abstract class. The idea is that every object of the concrete class (when considered with appro To appear in the Proceedings of TAPSOFT FASE 1997 (in the Springer LNCS series) 1 In this paper we shall be ....

....is different from automata theoretic specification in that it does not describe states explicitly (e.g. in transition diagrams) but only implicitly via their observable behaviour 2 . This work is inspired by the earlier work on refinement in automata theory and in hidden sorted algebra (notably [6, 7]) What makes the (coalgebraic) notion of refinement particularly useful is that it comes with a certain coinductive proof technique. It allows us to answer the question of whether we have indistinguishable behaviour (for objects of the concrete and abstract classes) by giving an appropriate ....

[Article contains additional citation context not shown here]

J.A. Goguen and G. Malcom. An extended abstract of a hidden agenda. In J., A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

....accepted formal computational model for object oriented programming. Such a model is needed as domain of reasoning. One such formal model has recently emerged in the form of coalgebras (explicitly e.g. in [21] It should be placed in the tradition of behavioural specification, see also [6, 8, 4]. Coalgebras are the formal duals of algebras, see [14] for background information. They consist of a (hidden) state space typically written as Self in this context together with several operations (or methods) acting on Self. These operations may be attributes giving some information about ....

J.A. Goguen and G. Malcolm. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

....accepted formal computational model for object oriented programming. Such a model is needed as domain of reasoning. One such formal model has recently emerged in the form of coalgebras (explicitly e.g. in [21] It should be placed in the tradition of behavioural specification, see also [6, 8, 4]. Coalgebras are the formal duals of algebras, see [14] for background information. They consist of a (hidden) state space typically written as Self in this context together with several operations (or methods) acting on Self. These operations may be attributes giving some information about ....

J.A. Goguen and G. Malcolm. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

....results of the type theory, Bertino and Martino provided the Chimera object oriented database model [11] with formal foundations and typing. In [14] a novel logic was presented claiming capability to model all the aspects of the object oriented paradigm. Another promising approach is presented in [10]. It uses an algebraic specification and emphasizes proofs rather than models. The research done in these directions gives us the possibility to compare the set theoretic, logic based, algebraic and categorical approach. CT can be actually used in any of these approaches with the advantage of ....

GOGUEN, J. A., MALCOLM, G.: Extended Abstract of a Hidden Agenda. In Proceedings, Conference on Intelligent Systems: a Semiotic Perspective, J. Meystel, A. Meystel, and R. Quintero, Eds., 1996.

....operational semantics of some language, by giving the transition rules by induction on the structure of the terms of the language. The latter means that the set of terms of the language is used as (initial) algebra. See [64, 67] for an investigation of this perspective. Hidden sorted algebras, see [23, 22, 14, 24, 44] can be seen as other examples: they involve algebras with invisible sorts, playing a (coalgebraic) role of a state space. Coinduction is used to reason about such hidden state spaces, see [24] 3 Inductive and coinductive definitions In the previous section we have seen that constructor ....

....See [64, 67] for an investigation of this perspective. Hidden sorted algebras, see [23, 22, 14, 24, 44] can be seen as other examples: they involve algebras with invisible sorts, playing a (coalgebraic) role of a state space. Coinduction is used to reason about such hidden state spaces, see [24]. 3 Inductive and coinductive definitions In the previous section we have seen that constructor and destructor observer operations play an important role for algebras and coalgebras, respectively. Constructors tell us how to generate our (algebraic) data elements: the empty list constructor ....

J.A. Goguen and G. Malcom. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

....is closed under common operations, such as subalgebra, quotient algebra and product algebra. He called such a class a variety. Later, his results were abstracted categorically to catch other modern approaches to equational logics and even first order logic (for example [1,17,18] Hidden algebra [10,12,11] appeared as a generalization of many sorted algebra, in order to give algebraic semantics for the object paradigm. It allows On leave from Fundamentals of Computer Science, Faculty of Mathematics, University of Bucharest, Romania. c fl1998 Published by Elsevier Science B. V. Ros u hidden ....

Joseph Goguen and Grant Malcolm. Extended abstract of a hidden agenda. In James, Alex Meystel, and Richard Quintero, editors, Proceedings, Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. National Inst. Standards and Technology, 1996. Gaithersberg MD, October 20--23.

.... [Rei95] and continued in [Jac96c, Jac95, Jac96b, Jac97] In [HHJT98] a formal language CCSL for coalgebraic class speci cations is described, together with a translation tool for generating logical theories for the proof tool PVS [ORSvH95] Connections with (speci cations in) hidden algebra (see [GM96] are investigated in [Mal96, C r98] Coalgebraic program veri cation Coalgebras can provide a basis for Java program veri cation, in the style described in Section 3. An elaboration of such a semantics, together with an associated Hoare logic, is described in [HJ99b] A tool that translates ....

J.A. Goguen and G. Malcolm. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159-167. Nat. Inst. Stand. & Techn., 1996.

....tradition in that it is concerned with generating systems, rather than just specifying them, i.e. it is constructive as well as descriptive. Another unusual feature is the use of information hiding in specifications and the resulting behavioral (i.e. black box ) notion of satisfaction for views [22, 20]) The version of parameterized programming in this paper, like that in LIL, provides both horizontal and vertical composition. Vertical composition concerns the structuring of a system into layers, each providing services to higher layers, while horizontal composition concerns the structure of ....

....only appear to be consequences of the axioms in M 0 ; i.e. we are dealing with what is called behavioral satisfaction, as is appropriate to the black box notion of module used in this paper. Techniques for proving this kind of satisfaction have been developed in hidden sorted algebra; see [22, 20, 19]. For example, in the example of a STACK module with type Stack hidden, the equation pop(push(I,S) S is not satisfied by the standard implementation using an array and a pointer, but all of its visible consequences are. So a view from M as this STACK specification module to another more ....

Joseph Goguen and Grant Malcolm. Extended abstract of a hidden agenda. In James Albus, Alex Meystel, and Richard Quintero, editors, Proceedings, Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. National Inst. Standards and Technology, 1996. Gaithersberg MD, October 20--23.

....The second system, called CafeOBJ [4] is being implemented at JAIST (Japan Advanced Institute of Science and Technology) in Horuriku, Japan, under the direction of Professor Kokichi Futatsugi. This system includes features to handle both rewriting logic (as in Maude) and hidden sorted algebra [12], which provides powerful proof techniques for behavioral specification and verification. This project is supported on a large scale by MITI, the Japanese Ministry of Industry and Technology. 1.5 OBJ is not the Last Word The case studies in this book show that OBJ can be used to specify, ....

....and provides facilities for prototyping at the system design level. It also provides support for reuse of code and designs [9] Current research is directed to unifying the functional, logic, constraint and object paradigms in a way that takes better account of the situatedness of software [12]. Although some elements of this paradigm are already prefigured in the use of foops in toor [25] an object oriented environment for requirements tracing, much exciting work remains to be done. 2 These quotations from Leibniz are taken from a fascinating discussion of mathematical formalism in ....

Joseph Goguen and Grant Malcolm. Extended abstract of a hidden agenda. In James Albus, Alex Meystel, and Richard Quintero, editors, Proceedings, Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. National Inst. Standards and Technology, 1996. Gaithersberg MD, October 20--23.

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J.A. Goguen and G. Malcom. An extended abstract of a hidden agenda. In J. Meystel, A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

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J.A. Goguen and G. Malcom. An extended abstract of a hidden agenda. In J., A. Meystel, and R. Quintero, editors, Proceedings of the Conference on Intelligent Systems: A Semiotic Perspective, pages 159--167. Nat. Inst. Stand. & Techn., 1996.

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