Finite satisfiability verification in UML class diagrams: a comparative study

Unified Modeling Language class diagrams are widely used for modeling, playing a key role in the analysis and design of information systems, especially in development contexts that use modeling oriented methodologies. Therefore, it is relevant to ensure the creation and maintenance of correct class diagrams. With the use of class diagrams it is possible to specify classes, relations and restrictions, however, such diagrams are subject to modeling errors made by their authors and may degenerate into incorrect diagrams. A common cause of incorrect diagrams refers to the definition of contradictory and inconsistent constraints, leading to finite satisfiability problems. Several approaches to the verification of finite satisfiability are currently available, supported by different tools. Through this work, we proceed with the identification and comparison of the existing approaches for the verification of finite satisfiability in class diagrams, determining the effectiveness and efficiency of the proposed tools

Testing Termination of Query Satisfiability Checking on Expressive Database Schemas

A query is satisfiable if there is at least one consistent instance of the database in which it has a non-empty answer. Defining queries on a database schema and checking their satisfiability can help the database designer to be sure whether the produced database schema is what was intended. The formulation of such queries may easily require the use of some arithmetic comparisons or negated expressions. Unfortunately, checking the satisfiability of this class of queries on a database schema that most likely have some integrity constraints (e.g., keys, foreign keys, Boolean checks) is, in general, undecidable. However, although the problem is undecidable for such a class of schemas and queries, it may not be so for a particular query satisfiability check. In this paper, we propose to perform a termination test as a previous step to query satisfiability checking. If positive, the termination test guarantees that the corresponding query satisfiability check will terminate. We assume the CQC method is the underlying query satisfiability checking method; to the best of our knowledge, it is the only method of this kind able to deal with schemas and queries as expressive as the ones we consider.Preprin

Providing explanations for database schema validation

We propose a new method for database schema validation that provides an explanation when it determines that a certain desirable property of a database schema does not hold. Explanations are required to give the designer a hint about the changes of the schema that are needed to fix the problem identified. Our method is an extension of the CQC method, which has been shown successful for testing such properties, and its contribution is twofold: Firstly, it is the first method that offers an explanation when the schema is not adequately defined. Secondly, the extension proposed here provides a significant efficiency improvement as far as the run-time performance of the method is concerned.Postprint (published version