This paper offers two main contributions. On the one hand, it establishes a general formal framework for developing a foundational ontology of socially constructed entities, in the broadest sense of this notion; on the other hand, it further contributes to understanding the ontological nature of roles. The key choice here is to put all social entities in the domain of discourse: besides social individuals, we also consider ‘reified ’ social concepts and roles, as well as their descriptions, i.e, the ‘social conventions ’ or ‘contexts ’ that define them. This allows us to formally characterize in a first-order theory the relationships among all these entities. 1

In this report we present the language TROLL . It is a language particularly suited to be used in the early stages of information system design where the problem domain or Universe of Discourse must be described. In TROLL , the description of the static and dynamic aspects of entities is integrated in object descriptions. TROLL is based on sublanguages for data terms, for first-order and temporal assertions and for processes. These sublanguages are the tools to describe static properties, behavior and evolution over time of objects. Object descriptions can be related in many ways. The abstraction mechanisms provided by TROLL are classification, specialization, generalization, roles, and aggregation. Abstraction mechanisms together with the basic structuring in objects help in organizing the system design. In order to support the composition of system descriptions from component description TROLL provides language features to state interactions and dependencies between components ...

An equational language to specify object-oriented 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 (intra-object) and global (inter-object) 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...

Data Types (ADT's) in the framework of order sorted algebraic specifications, in a way similar to the specification languages OBJ[6] and ASF[2]. The syntactical construct for defining ADTs in LCM is the hValueBlocki, in which you bind a name to a set of values, and define the appearance of functions and constants related to that set. The meaning of the expressions using values from that set is expressed by giving equations. As a simple example, a value block for specifying a sort representing the colors of a traffic light, together with a function nextcolor might look like this: begin value type TRAFFICLIGHTCOLOR functions -- Constants are viewed as functions without parameters. red : TRAFFICLIGHTCOLOR; orange : TRAFFICLIGHTCOLOR; green : TRAFFICLIGHTCOLOR; -- A function to return the next color to be displayed, -- given the current color of a traffic light. nextcolor(TRAFFICLIGHTCOLOR) : TRAFFICLIGHTCOLOR; predicates continue(TRAFFICLIGHTCOLOR); axioms nextcolor(red) = ...

Order-sorted 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 object-orientation. It is argued that the resulting language, CMSL, meets those requirements of the object-oriented database system manifesto [6] that are applicable to object-oriented conceptual models (as opposed to OO databases).

this paper is to show how a collection of specification constructs may be formally defined that supports the former effort. We should stress that we shall not attempt to provide a full and practical specification language that can be used for object-oriented design. We shall have to limit ourselves to concentrate on the definition of our main primitive of specification (formalising the notion of object) together with two well known specification constructs: inheritance and aggregation (complex objects). However, we do not see deep problems in extending our results to other useful constructs such as class/type grouping and parameterisation.

In this paper we investigate several concepts that are known in database research for some time but which are still surrounded by some confusion. We start with the concepts of object identifier, surrogate and key and list the differences between these concepts, which in practice are often ignored. Sharpening these differences allows us to analyze the distinction between objects and roles that recently surfaced in the literature. Distinguishing objects from roles helps to avoid migration of objects between classes and thus the problems associated with it. We show that this distinction requires the use of role identifiers that, just as object identifiers, should be globally unique and unchangeable. We next show that using role identifiers requires a distinction between two essentially different kinds of inheritance relationships, is-a inheritance and played-by inheritance. These are often both treated as if they were one and the same kind of is-a relationship. The result of the discussio...

The conceptual modeling of the Universe of Discourse (UoD) is an important phase for the development of information systems because the conceptual model is the basis for system development. Conceptual model specifications must be formal in order to be precise and unambiguous and to support consistency and completeness checks. The object-oriented paradigm is suitable for providing an integrated formal description of all relevant static and dynamic aspects of the UoD structured in objects. In this paper we introduce a formal concept of object suitable to represent the UoD by a collection of concurrent interacting objects. The Oblog-language for object-oriented UoD-specification based on this concept supports the integrated description of data about objects, the development of objects through time and of various relationships between objects taking into account static and dynamic aspects of object interaction. 1 Introduction Information systems are data-intensive software systems which ...

The logic of norms, called deontic logic, has been used to specify normative constraints for information systems. For example, one can specify in deontic logic the constraints that a book borrowed from a library should be returned within three weeks, and that if it is not returned, the library should send a reminder. Thus, the notion of obligation to perform an action arises naturally in system specification.

One of the key issues of object-oriented modeling and design is inheritance. It allows for the definition of subclasses that inherit features of some superclass. Inheritance is well defined for static properties of classes such as attributes and methods. However, there is no general agreement on the meaning of inheritance when considering the dynamic behavior of objects, captured by their life cycles. This paper studies inheritance of behavior both in a simple process-algebraic setting and in a Petri-net framework. Process algebra is chosen, because it concentrates on behavior, while abstracting from the internal states of processes. The result of the algebraic study is a clear conceptual understanding of inheritance of behavior. It can be expressed in terms of blocking and hiding method calls. The results in the algebraic framework inspire the development of the concept of inheritance of behavior in the Petri-net framework. The Petri-net formalism allows for a graphical representation...