1 citations · 3 across the 4 of their papers we have counts for
4 papers · 1 filter
On matrices and -relations
Robert Brijder, Marc Gyssens, Jan Van den Bussche
We show that the matrix query language corresponds to a natural fragment of the positive relational algebra on -relations. The fragment is defined by introduc…
Comparing Downward Fragments of the Relational Calculus with Transitive Closure on Trees
Jelle Hellings, Marc Gyssens, Yuqing Wu +4
Motivated by the continuing interest in the tree data model, we study the expressive power of downward navigational query languages on trees and chains. Basic navigational queries…
Structural characterizations of the navigational expressiveness of relation algebras on a tree
George H. L. Fletcher, Marc Gyssens, Jan Paredaens +2
Given a document D in the form of an unordered node-labeled tree, we study the expressiveness on D of various basic fragments of XPath, the core navigational language on XML docume…
On Typechecking Top-Down XML Tranformations: Fixed Input or Output Schemas
Wim Martens, Frank Neven, Marc Gyssens
Typechecking consists of statically verifying whether the output of an XML transformation always conforms to an output type for documents satisfying a given input type. In this gen…