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21
Observational logic
 In Algebraic Methodology and Software Technology (AMAST'98
, 1999
"... Abstract. We present an institution of observational logic suited for statebased systems specifications. The institution is based on the notion of an observational signature (which incorporates the declaration of a distinguished set of observers) and on observational algebras whose operations are r ..."
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Cited by 53 (10 self)
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Abstract. We present an institution of observational logic suited for statebased systems specifications. The institution is based on the notion of an observational signature (which incorporates the declaration of a distinguished set of observers) and on observational algebras whose operations are required to be compatible with the indistinguishability relation determined by the given observers. In particular, we introduce a homomorphism concept for observational algebras which adequately expresses observational relationships between algebras. Then we consider a flexible notion of observational signature morphism which guarantees the satisfaction condition of institutions w.r.t. observational satisfaction of arbitrary firstorder sentences. From the proof theoretical point of view we construct a sound and complete proof system for the observational consequence relation. Then we consider structured observational specifications and we provide a sound and complete proof system for such specifications by using a general, institutionindependent result of [6]. 1
A Theory of Mixin Modules: Basic and Derived Operators
 Mathematical Structures in Computer Science
, 1996
"... Mixins are modules in which some components are deferred , i.e. their definition has to be provided by another module. Moreover, differently from parameterized modules (like ML functors), mixin modules can be mutually dependent and their composition supports redefinition of components (overriding). ..."
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Cited by 39 (13 self)
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Mixins are modules in which some components are deferred , i.e. their definition has to be provided by another module. Moreover, differently from parameterized modules (like ML functors), mixin modules can be mutually dependent and their composition supports redefinition of components (overriding). In this paper, we present a formal model of mixins and their basic composition operators. These operators can be viewed as a kernel language with clean semantics in which to express more complex operators of existing modular languages, including variants of inheritance in object oriented programming. Our formal model is given in an "institution independent" way, i.e. is parameterized by the semantic framework modeling the underlying core language. Introduction In object oriented languages, the definition of an heir class H from a parent class P takes usually the form H = extend P by M , where M denotes a collection of definitions of components (typically methods) which are either new, or re...
Behavioural Theories and The Proof of Behavioural Properties
, 1996
"... Behavioural theories are a generalization of firstorder theories where the equality predicate symbol is interpreted by a behavioural equality of objects (and not by their identity). In this paper we first consider arbitrary behavioural equalities determined by some (partial) congruence relation and ..."
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Cited by 33 (8 self)
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Behavioural theories are a generalization of firstorder theories where the equality predicate symbol is interpreted by a behavioural equality of objects (and not by their identity). In this paper we first consider arbitrary behavioural equalities determined by some (partial) congruence relation and we show how to reduce the behavioural theory of any class of algebras to (a subset of) the standard theory of some corresponding class of algebras. This reduction is the basis of a method for proving behavioural theorems whenever an axiomatization of the behavioural equality is provided. Then we focus on the important special case of (partial) observational equalities where two elements are observationally equal if they cannot be distinguished by observable computations over some set of input values. We provide general conditions under which an obvious infinite axiomatization of the observational equality can be replaced by a finitary one and we provide methodological guidelines for finding such...
On Behavioural Abstraction and Behavioural Satisfaction in HigherOrder Logic
, 1996
"... The behavioural semantics of specifications with higherorder logical formulae as axioms is analyzed. A characterization of behavioural abstraction via behavioural satisfaction of formulae in which the equality symbol is interpreted as indistinguishability, which is due to Reichel and was recently g ..."
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Cited by 25 (5 self)
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The behavioural semantics of specifications with higherorder logical formulae as axioms is analyzed. A characterization of behavioural abstraction via behavioural satisfaction of formulae in which the equality symbol is interpreted as indistinguishability, which is due to Reichel and was recently generalized to the case of firstorder logic by Bidoit et al, is further generalized to this case. The fact that higherorder logic is powerful enough to express the indistinguishability relation is used to characterize behavioural satisfaction in terms of ordinary satisfaction, and to develop new methods for reasoning about specifications under behavioural semantics. 1 Introduction An important ingredient in the use of algebraic specifications to describe data abstractions is the concept of behavioural equivalence between algebras, which seems to appropriately capture the "black box" character of data abstractions, see e.g. [GGM76], [GM82], [ST87] and [ST95]. Roughly speaking (since there ...
An Algebraic Approach to Mixins and Modularity
 ALP '96  5th Intl. Conf. on Algebraic and Logic Programming, number 1139 in Lecture Notes in Computer Science
, 1996
"... . We present an algebraic formalization of the notion of mixin module, i.e. a module where the definition of some components is deferred . Moreover, we define a set of basic operators for composing mixin modules, intended to be a kernel language with clean semantics in which to express more complex ..."
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Cited by 22 (4 self)
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. We present an algebraic formalization of the notion of mixin module, i.e. a module where the definition of some components is deferred . Moreover, we define a set of basic operators for composing mixin modules, intended to be a kernel language with clean semantics in which to express more complex operators of existing modular languages, including variants of inheritance in object oriented programming. The semantics of the operators is given in an "institution independent" way, i.e. is parameterized on the semantic framework modeling the underlying core language. Introduction One of the major contributions of object oriented programming has been the discover of inheritance as primary mean for incremental software development. In object oriented languages, an heir class can extend the definition of the parent class adding new methods, as well as redefining old methods, overriding their preceding definitions (sometimes the precedence is given to the parent, see [7]). Note that, since ...
General logics
 In Logic Colloquium 87
, 1989
"... theory, categorical logic. model theory that emerged in computer science studies of software specification and semantics. To handle proof theory, our institutions use an extension of traditional categorical logic with sets of sentences as objects instead of single sentences, and with morphisms repre ..."
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Cited by 9 (3 self)
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theory, categorical logic. model theory that emerged in computer science studies of software specification and semantics. To handle proof theory, our institutions use an extension of traditional categorical logic with sets of sentences as objects instead of single sentences, and with morphisms representing proofs as usual. A natural equivalence relation on institutions is defined such that its equivalence classes are logics. Several invariants are defined for this equivalence, including a Lindenbaum
Global Development via Local Observational Construction Steps
, 2002
"... The way that refinement of individual "local" components of a specification relates to development of a "global" system from a specification of requirements is explored. Observational interpretation of specifications and refinements add expressive power and flexibility while bringing in some subtle ..."
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Cited by 8 (5 self)
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The way that refinement of individual "local" components of a specification relates to development of a "global" system from a specification of requirements is explored. Observational interpretation of specifications and refinements add expressive power and flexibility while bringing in some subtle problems. The results are instantiated in the context of Casl architectural specifications.
Context Institutions
, 1996
"... . The paper introduces a notion of a context institution. The notion is explicitly illustrated by two standard examples. Morphism between context institutions are introduced, thus yielding a category of context institutions. Some expected constructions on context institutions are presented as functo ..."
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Cited by 7 (2 self)
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. The paper introduces a notion of a context institution. The notion is explicitly illustrated by two standard examples. Morphism between context institutions are introduced, thus yielding a category of context institutions. Some expected constructions on context institutions are presented as functors from this category. The potential usefulness of these notions is illustrated by one such a construction, yielding a Hoare logic for an arbitrary small context institution satisfying mild extra assumptions. 1 Introduction The theory of institutions ([4], [6]) has proved its usefulness in the area of foundations of software specification and development. The modeltheoretic view of logical systems advocated in the theory of institutions captures very well the idea that in computer science applications of logic what we are really interested in are models. We always try to specify (logical) properties of concrete objects standard examples can be programs, database management systems or ...
A Formal Framework for Modules With State
, 1996
"... this paper, we address the problem of formal foundations for module manipulation within an imperative context. A module in a programming language is a part of a program viewed as a whole (often a compilation unit), having an ..."
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Cited by 5 (4 self)
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this paper, we address the problem of formal foundations for module manipulation within an imperative context. A module in a programming language is a part of a program viewed as a whole (often a compilation unit), having an