In many computer-based applications, temporal information has to be stored, retrieved, and related to other temporal information. Several time models have been proposed to manage temporal knowledge in the fields of conceptual modeling, database systems, and artificial intelligence. In this paper we present TSOS, a system for reasoning about time that can be integrated as a time expert in environments designed for broader problem-solving domains. The main intended goal of TSOS is to allow a user to infer further information on the temporal data stored in the database through a set of deduction rules handling various aspects of time. For this purpose, TSOS provides the capability of answering queries about the temporal specifications it has in its temporal database. Distinctive time-modeling features of TSOS are the introduction of temporal modalitites , i.e., the possibility of specifying if a piece of information is always true within a time interval, or if it is only sometimes true, and the capability of answering about the possibility and the necessity of the validity of some information at a given time, the association of temporal knowledge both to instances of data and to types of data , and the development of a time calculus for reasoning on temporal data. Another relevant feature of TSOS is the capability to reason about temporal data specified at different time granularities.

Characteristics and requirements of systems for temporal data management in the areas of data and knowledge bases, artificial intelligence, and software engineering are investigated and discussed on the basis of a case study. Six representative approaches were selected for this analysis, with the goal of identifying particular features of systems proposed in different areas. The six approaches are: Allen's interval-based logic, Dean and McDermott's time map management, Kowalski and Sergot's event calculus, Maiocchi and Pernici's TSOS. Snodgrass' TQuel, and Hagelstein's ERAE. The characteristics of each system are classified and compared. On the basis of this analysis, a framework for the evaluation of temporal systems and for the specification of temporal data management systems is proposed.>

Designers of office information systems, which share various features with information systems and software development, need to carefully consider special issues such as document and communication flows, user roles, user interfaces, and available technology. The ESPRIT Project, Automatic TOols for Designing Office Information Systems (TODOS), proposes an integrated environment for office design with tools for requirements collection and analysis, conceptual design, rapid prototyping, and architecture selection. Conceptual design is a central phase of office system design: It provides correct and complete functional requirements from which the office prototype will be developed and the final architecture chosen. C-TODOS, the conceptual design support tool developed within TODOS, is presented in this paper. The purpose of C-TODOS is to give the designer tools for supporting conceptual modeling activities with the goal of obtaining correct, consistent, and good quality office-functional specifications. This paper presents C-TODOS within the TODOS development environment and describes the basic features of the tool: the TODOS Conceptual Model, the Specification Database, and the Modeling, Query and Consistency Checking Modules. The use of C-TODOS, through illustration of the development of a test case, and possible future research are discussed.