#### Filter Results:

#### Publication Year

1981

2016

#### Publication Type

#### Co-author

#### Key Phrase

#### Publication Venue

#### Data Set Used

Learn More

We show that relational algebra calculations for incomplete databases, probabilistic databases, bag semantics and why-provenance are particular cases of the same general algorithms involving semirings. This further suggests a comprehensive provenance representation that uses semirings of polynomials. We extend these considerations to datalog and semirings… (More)

We investigate the properties of a simple programming language whose main computational engine is structural recursion on sets. We describe a progression of sublanguages in this paradigm that (1) have increasing expressive power, and (2) illustrate robust conceptual restrictions thus exhibiting interesting additional properties. These properties suggest… (More)

We state and solve the query reformulation problem for XML publishing in a general setting that allows mixed (XML and relational) storage for the proprietary data and exploits redundancies (materialized views, indexes and caches) to enhance performance. The correspondence between published and proprietary schemas is specified by views in both directions,… (More)

We present a method for providing semantic interpretations for languages with a type system featuring inheritance polymorphism. Our approach is illustrated on an extension of the language Fun of Cardelli and Wegner, which we interpret via a translation into an extended polymorphic lambda calculus. Our goal is to interpret inheritances in Fun via coercion… (More)

We present a new principle for the development of database query languages that the primitive operations should be organized around types. Viewing a relational database as consisting of sets of records, this principle dictates that we should investigate separately operations for records and sets. There are two immediate advantages of this approach, which is… (More)

We consider systems for data sharing among heterogeneous peers related by a network of schema mappings. Each peer has a locally controlled and edited database instance, but wants to ask queries over related data from other peers as well. To achieve this, every peer's updates propagate along the mappings to the other peers. However, this update exchange is… (More)

Personalized access and content syndication involving diverse conceptual representations of information resources are two of the key challenges of real-scale Semantic Web (SW) applications, such as e-Commerce, e-Learning or e-Science portals. RDF/S represents nowadays the core SW language for creating and exchanging resource descriptions worldwide.… (More)

We study combinations of many-sorted algebraic term rewriting systems and polymorphic lambda term rewriting. Algebraic and lambda terms are mixed by adding the symbols of the algebraic signature to the polymorphic lambda calculus, as higher-order constants. We show that if a many-sorted algebraic rewrite system R is strongly normalizing (terminating,… (More)

Let Σ<inf>1</inf>, Σ<inf>2</inf> be two schemas, which may overlap, <i>C</i> be a set of constraints on the joint schema Σ<inf>1</inf> ∪ Σ<inf>2</inf>, and <i>q</i><inf>1</inf> be a Σ<inf>1</inf>-query. An <b>(equivalent) reformulation</b> of <i>q</i><inf>1</inf> in the presence of <i>C</i> is a Σ<inf>2</inf>-query,… (More)