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Composing Hidden Information Modules over Inclusive Institutions
 In From ObjectOrientation to Formal Methods: Essays in Honor of JohanOle Dahl
, 2003
"... This paper studies the composition of modules that can hide information, over a very general class of logical systems called inclusive institutions. Two semantics are given for composition of such modules using five familiar operations, and a property called conservativity is shown necessary and suf ..."
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Cited by 18 (3 self)
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This paper studies the composition of modules that can hide information, over a very general class of logical systems called inclusive institutions. Two semantics are given for composition of such modules using five familiar operations, and a property called conservativity is shown necessary and sufficient for these semantics to agree. The first semantics extracts the visible properties of the result of composing the visible and hidden parts of modules, while the second uses only the visible properties of the components; the semantics agree when the visible consequences of hidden information are enough to determine the result of the composition. A number of "laws of software composition" are proved relating the composition operations. Inclusive institutions simplify many proofs.
Presheaves as Configured Specifications
"... The paper addresses a notion of configuring systems, constructing them from specified component parts with specified sharing. This notion is independent of any underlying specification language and has been abstractly identified with the taking of colimits in category theory. Mathematically it is kn ..."
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Cited by 2 (0 self)
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The paper addresses a notion of configuring systems, constructing them from specified component parts with specified sharing. This notion is independent of any underlying specification language and has been abstractly identified with the taking of colimits in category theory. Mathematically it is known that these can be expressed by presheaves and the present paper applies this idea to configuration. We interpret the category theory informally as follows. Suppose C is a category whose objects are interpreted as specifications, and for which each morphism u : X ! Y is interpreted as contravariant "instance reduction", reducing instances of specification Y to instances of X . Then a presheaf P : Set C op represents a collection of instances that is closed under reduction. We develop an algebraic account of presheaves in which we present configurations by generators (for components) and relations (for shared reducts), and we outline a proposed configuration language based on the techniques. Oriat uses diagrams to express colimits of specifications, and we show that Oriat's category Diag(C) of finite diagrams is equivalent to the category of finitely presented presheaves over C.
Morphisms and Semantics for Higher Order Parameterized Programming
, 2002
"... Parameterized programming is extended to higher order modules, by extending views, which fit actual parameters to formal parameters in a flexible way, to morphisms, with higher order module expressions to compose modules into systems. A category theoretic semantics is outlined, and examples in BOBJ ..."
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Cited by 1 (0 self)
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Parameterized programming is extended to higher order modules, by extending views, which fit actual parameters to formal parameters in a flexible way, to morphisms, with higher order module expressions to compose modules into systems. A category theoretic semantics is outlined, and examples in BOBJ show the power of morphisms.
Putting Synchronous and Asynchronous Object Modules together: an EventBased Model for Concurrent Composition
, 1997
"... In this paper we show how by means of a categorical framework we can compose systems of concurrent object modules satisfying some interaction rules given by a specification. Module interaction can be either synchronous or asynchronous and both cases are considered separately. The behaviour of object ..."
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In this paper we show how by means of a categorical framework we can compose systems of concurrent object modules satisfying some interaction rules given by a specification. Module interaction can be either synchronous or asynchronous and both cases are considered separately. The behaviour of object modules is modelled by labelled prime event structures. The category of labelled prime event structures has (co)products. A product in the category of labelled prime event structures is given accordingly to Winskel and Nielsen but denotes parallel composition in a sense that does not have much practical interest. For synchronously communicating modules, by applying to the product a restriction on the allowed life cycles by means of the categorical concept of a functor induced by a co bration and a morphism on labels, we achieve the desired joint behaviour. A way to model asynchronous composition of modules is to construct a coproduct and extend it by their interaction rules. At the end of ...
Perspective Switching Using Theories and Interpretations
"... William M. Farmer The MITRE Corporation An important aspect of intelligence is the ability to switch perspectives. In the course of reasoning about a particular subject matter, it can be convenient to change from one perspective of the subject matter to another perspective, which is often at a die ..."
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William M. Farmer The MITRE Corporation An important aspect of intelligence is the ability to switch perspectives. In the course of reasoning about a particular subject matter, it can be convenient to change from one perspective of the subject matter to another perspective, which is often at a dierent level of abstraction. For example, in some situations it may be advantageous to view a building as a collection of oors and in other situations as a collection of wings. If the arrangement of the rooms is not important for the task at hand, the building might be viewed as simply an unstructured collection of rooms. These are three perspectives on how a building can be decomposed. Utilizing multiple perspectives and freeing moving from one to another is a powerful method for both managing complexity and organizing knowledge. The key idea behind this method is to always employ the \right" perspective for each reasoning task. This talk will address the following two questions: (1) What ...
Composition of Modules with Hidden Information over Inclusive Institutions
"... This paper studies the composition of modules that can hide information, over a very general class of logical systems called inclusive institutions. Two semantics are given for compositions using five familiar operations, and a property called conservativity is shown necessary and sufficient for the ..."
Abstract
 Add to MetaCart
This paper studies the composition of modules that can hide information, over a very general class of logical systems called inclusive institutions. Two semantics are given for compositions using five familiar operations, and a property called conservativity is shown necessary and sufficient for these semantics to agree. The first semantics extracts the visible properties of the result of composing both the visible and hidden parts of modules, while the second uses only the visible properties of the components. Several "laws of software composition" are given, which demonstrate the power of inclusive institutions to simplify proofs.