and THORSTEN HARTMANN Technische University Braunschweig and CRISTINA SERNADAS Instituto Superior T6cnicoTROLL is a language particularly suited for the early stages of information system development, when the universe of discourse must be described. In TROLL the descriptions of the static and dynamic aspects of entities are integrated into object descriptions. Sublanguages for data terms, for first-order and temporal assertions, and for processes, are used to describe respectively the static properties, the behavior, and the evolution over time of objects. TROLL organizes system design through object-orientation and the support of abstractions such as classification, specialization, roles, and aggregation. Language features for state interactions and dependencies among components support the composition of the system from smaller modules, as does the facility of defining interfaces on top of object descriptions,

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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 Obtog+-tanguage 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 taldng into account static and dynamic aspects of object interaction.