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Object Specification Logic
 Journal of Logic and Computation
, 1995
"... A logic for specifying and reasoning about object classes and their instances (aspects) is presented and illustrated. This logic is an extension of a rather standard linear temporal, manysorted, firstorder predicate logic with equality. The extensions where designed to be as simple as possible whi ..."
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Cited by 65 (13 self)
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A logic for specifying and reasoning about object classes and their instances (aspects) is presented and illustrated. This logic is an extension of a rather standard linear temporal, manysorted, firstorder predicate logic with equality. The extensions where designed to be as simple as possible while supporting the envisaged locality of arguments, object specialization and object aggregation. Objects are specified through their aspects. Each aspect establishes a local vocabulary (signature). The logic works at two levels: first, we can specify and prove assertions about a given object aspect in isolation (local reasoning), eg persons, or patients, or cars; second, we can specify interaction constraints and make inferences between aspects within the same community of objects (global reasoning), eg carry the theorems of persons onto patients (specialization inheritance), or carry the theorems of persons onto the aggregations of persons and cars (incorporation inheritance). Some reflecti...
Defaults and Revision in Structured Theories
 In Proceedings of the IEEE Symposium on Logic in Computer Science (LICS'91
, 1991
"... Starting from a logic which specifies how to make deductions from a set of sentences (a `flat theory'), a way to generalise this to a partially ordered bag of sentences (a `structured theory') is given. The partial order is used to resolve conflicts. If OE occurs below / then / is accepted ..."
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Cited by 35 (16 self)
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Starting from a logic which specifies how to make deductions from a set of sentences (a `flat theory'), a way to generalise this to a partially ordered bag of sentences (a `structured theory') is given. The partial order is used to resolve conflicts. If OE occurs below / then / is accepted only insofar as it does not conflict with OE. We start with a language L, a set of interpretations M and a satisfaction relation fl ` M \Theta L. The key idea is to define, for each structured theory, a preorder on interpretations. Models of the structured theory are defined to be maximal interpretations in the ordering. They are shown to exist if the logic hL; M; fli is compact. A revision operator is defined, which takes a structured theory and a sentence and returns a structured theory. The consequence relation has the properties of weak monotonicity, weak cut and weak reflexivity with respect to this operator, but fails their strong counterparts. 1 Introduction Ordering sentences in a theo...
What is an Object, After All?
, 1991
"... The envisaged notion of object is presented as corresponding to the basic, universal building block of (information) systems. A simple mathematical model for fully concurrent objects (actors) is adopted that extends a suitable model for sequential processes. An object is defined as a process possibl ..."
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Cited by 33 (4 self)
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The envisaged notion of object is presented as corresponding to the basic, universal building block of (information) systems. A simple mathematical model for fully concurrent objects (actors) is adopted that extends a suitable model for sequential processes. An object is defined as a process possibly endowed with initiative and tracedependent attributes. Transactional requirements are analysed within this framework as liveness requirements. Object aggregation is explained using the general notion of object morphism. The basic inheritance, overriding and reification mechanisms are also presented, as well as a suitable notion of objecttype. The computational model is shown through examples to provide a sound basis for (information) systems design, including abstract conceptual modeling and layered implementation of both passive (recordlike) and active (procedurelike) objects. The model establishes a suitable semantic domain for the envisaged broad spectrum specification/design languag...
Equational Specification of Dynamic Objects
 ObjectOriented Databases: Analysis, Design & Construction (DS4), Proc. IFIP WG 2.6 Working Conference, Windermere (UK
, 1990
"... An equational language to specify objectoriented conceptual models is defined. Objects are considered to be characterized by a unique object identifier and have static and dynamic structure. Examples of static structure are classification, aggregation, generalization and grouping, examples of dynam ..."
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Cited by 31 (6 self)
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An equational language to specify objectoriented conceptual models is defined. Objects are considered to be characterized by a unique object identifier and have static and dynamic structure. Examples of static structure are classification, aggregation, generalization and grouping, examples of dynamic structure are events, processes, local (intraobject) and global (interobject) and communication. The language, called CMSL, has a declarative (algebraic) semantics, which is divided into two. The part of CMSL that can be used to specify static structures has an initial algebra semantics, in which the data elements are object versions. The part dealing with process has a larger algebra as semantics; in this paper we use an algebra of graphs modulo bisimulation equivalence. About both models can be reasoned using standard equational logic. Apart from the combination of static and dynamic features of objects in an algebraic framework, and the joint specification of this in an equational la...
Local Specification of Distributed Families of Sequential Objects
 Recent Trends in Data Types Specification, Proc. 10th Workshop on Specification of Abstract Data Types joint with the 5th COMPASS Workshop, S.Margherita, Italy, May/June 1994, Selected papers
, 1995
"... . Fully concurrent models of distributed object systems are specified using linear temporal logic that does not per se cope with concurrency. This is achieved by employing the principle of local sequentiality: we specify from local viewpoints assuming that there is no intraobject concurrency but ful ..."
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Cited by 28 (11 self)
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. Fully concurrent models of distributed object systems are specified using linear temporal logic that does not per se cope with concurrency. This is achieved by employing the principle of local sequentiality: we specify from local viewpoints assuming that there is no intraobject concurrency but full interobject concurrency. Local formulae are labelled by identity terms. For interaction, objects may refer to actions of other objects, e.g., calling them to happen synchronously. A locality predicate allows for making local statements about other objects. The interpretation structures are global webs of local life cycles, glued together at shared communication events. These interpretation structures are embedded in an interpretation frame that is a labelled locally sequential event structure. Two initiality results are presented: the category of labelled locally sequential event structures has initial elements, and so has the full subcategory of those satisfying given temporal axioms. As...
A Formalization of Objects Using Equational Dynamic Logic
, 1991
"... Ordersorted equational logic is extended with dynamic logic to a specification language for dynamic objects. Special attention is paid to different concepts of encapsulation that play a role in objectorientation. It is argued that the resulting language, CMSL, meets those requirements of the ob ..."
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Cited by 28 (11 self)
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Ordersorted equational logic is extended with dynamic logic to a specification language for dynamic objects. Special attention is paid to different concepts of encapsulation that play a role in objectorientation. It is argued that the resulting language, CMSL, meets those requirements of the objectoriented database system manifesto [6] that are applicable to objectoriented conceptual models (as opposed to OO databases).
A Logical Theory of Interfaces and Objects
, 1995
"... In this paper we motivate and describe a logicbased specification framework for objects and interfaces based on Abstract Data Views, a formal model for specifying interfaces. Abstract Data Views (ADVs) are Abstract Data Objects (ADOs) or objects that have been specifically augmented to support the ..."
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Cited by 13 (9 self)
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In this paper we motivate and describe a logicbased specification framework for objects and interfaces based on Abstract Data Views, a formal model for specifying interfaces. Abstract Data Views (ADVs) are Abstract Data Objects (ADOs) or objects that have been specifically augmented to support the specification of interfaces: interfaces between application components (ADOs) or between application components and an "external" environment such as a user or a network. The central mathematical tools used for this purpose are temporal logic (or deontic action logic) and some tools from category theory (institutions). Essentially, temporal logic is used to represent the individual ADVs or ADOs and the tools from category theory are used to represent the amalgamation of these components into a structure. Both ADVs and ADOs will basically be represented by tuples ! DT ; AT ; AC; AX ?, where DT is a data signature, AT is a set of attributes (state memory), AC is a set of actions that can quer...
Gaining a Uniform View of Different Integration Aspects in a Prototyping Environment
, 1995
"... : Prototyping based on formal specification should satisfy the requirements of engineers and users equally. The support of both groups requires a formalization of all activities as contract base and an increase of experience by experimental strategies. Contrary to these requirements several problems ..."
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Cited by 10 (3 self)
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: Prototyping based on formal specification should satisfy the requirements of engineers and users equally. The support of both groups requires a formalization of all activities as contract base and an increase of experience by experimental strategies. Contrary to these requirements several problems rest with existing software development environments, which result in complex systems becoming easily unmanageable. Our approach to develop a prototyping environment integrates former results of our project "Implementation of Information Systems". We propose the objectoriented specification language Troll as core of the integrated software development environment TBench. Troll is used for conceptual modeling of structural and behavioral aspects of the universe of discourse by offering a formal framework. Moreover the TBench utilizes Troll to realize relationships between the various graphical representations and the different stages of development. Especially Troll specification documents ...
Conceptual Data Modeling from a Categorical Perspective
 The Computer Journal
, 1996
"... For successful information systems development, conceptual data modeling is essential. Nowadays many techniques for conceptual data modeling exist. Indepth comparisons of concepts of these techniques are very difficult as the mathematical formalizations of these techniques, if they exist at all, ar ..."
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Cited by 9 (4 self)
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For successful information systems development, conceptual data modeling is essential. Nowadays many techniques for conceptual data modeling exist. Indepth comparisons of concepts of these techniques are very difficult as the mathematical formalizations of these techniques, if they exist at all, are very different. As such there is a need for a unifying formal framework providing a sufficiently high level of abstraction. In this paper the use of category theory for this purpose is addressed. Wellknown conceptual data modeling concepts, such as relationship types, generalization, specialization, collection types, and constraint types, such as the total role constraint and the uniqueness constraint, are discussed from a categorical point of view. An important advantage of this framework is its "configurable semantics". Features such as null values, uncertainty, and temporal behavior can be added by selecting appropriate instance categories. The addition of these features usually requir...
A Categorical Framework for Conceptual Data Modeling: Definition, Application, and Implementation
, 1995
"... For successful information systems development, conceptual data modeling is essential. Nowadays a plethora of techniques for conceptual data modeling exist. Many of these techniques lack a formal foundation and a lot of theory, e.g. concerning updates or schema transformations, is highly data model ..."
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Cited by 9 (4 self)
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For successful information systems development, conceptual data modeling is essential. Nowadays a plethora of techniques for conceptual data modeling exist. Many of these techniques lack a formal foundation and a lot of theory, e.g. concerning updates or schema transformations, is highly data model specific. As such there is a need for a unifying formal framework providing a sufficiently high level of abstraction. In this paper the use of category theory for this purpose is addressed. Wellknown conceptual data modeling concepts, such as relationship types, generalization, specialization, and collection types are discussed from a categorical point of view. An important advantage of this framework is its "configurable semantics". Features such as null values, uncertainty, and temporal behavior can be added by selecting appropriate instance categories. The addition of these features usually requires a complete redesign of the formalization in traditional setbased approaches to semantics...