Two different types of functional dependencies are compared: dependencies that are functional due to the laws of nature and dependencies that are functional if all involved agents behave rationally. The first type of dependencies was axiomatized by Armstrong. This paper gives a formal definition of the second type of functional dependencies in terms of strategic games and describes a sound and ...

In the temporal database literature, every fact stored in a database may be equipped with two temporal dimensions: the valid time, which describes the time when the fact is true in the modeled reality, and the transaction time, which describes the time when the fact is current in the database and can be retrieved. Temporal functional dependencies (TFDs) add valid time to classical functional de...

A relational database D is given with Ω as the set of attributes. We assume that the rows (tuples, data of one individual) are transmitted through a noisy channel (or, as many times in case of the datamining applications, the observed data is distorded from the real values in a manner which we cannot know). In case of low probability of the error it may be supposed that at most one data in a ro...

During the development of information systems there is a need to prototype the database which the applications will use when in operation. A prototype database can be built by sampling data from an existing database. Including relevant semantic information when extracting a sample from a database is considered invaluable to support the development of data-intensive applications. Functional depe...

Functional dependencies play an important role in relational database design. They are defined in the context of a single relation which a t all times must contain tuples with non-null entries. In this paper we examine an extension of the functional dependency interpretation t o handle null values, that is, entries in tuples that represent incomplete information in a relational database. A comp...

The dependency propagation problem is to determine, given a view defined on data sources and a set of dependencies on the sources, whether another dependency is guaranteed to hold on the view. This paper investigates dependency propagation for recently proposed conditional functional dependencies (CFDs). The need for this study is evident in data integration, exchange and cleaning since depende...

We study inference systems of weak functional dependencies in relational and complex-value databases. Functional dependencies form a very common class of database constraints. Designers and administrators proficiently utilise them in everyday database practice. Functional dependencies correspond to the linear-time decidable fragment of Horn clauses in propositional logic. Weak functional depend...