31 citations · 46 across the 4 of their papers we have counts for
4 papers
Relative Expressive Power of Navigational Querying on Graphs
George H. L. Fletcher, Marc Gyssens, Dirk Leinders +5
Motivated by both established and new applications, we study navigational query languages for graphs (binary relations). The simplest language has only the two operators union and…
Similarity and bisimilarity notions appropriate for characterizing indistinguishability in fragments of the calculus of relations
George H. L. Fletcher, Marc Gyssens, Dirk Leinders +3
Motivated by applications in databases, this paper considers various fragments of the calculus of binary relations. The fragments are obtained by leaving out, or keeping in, some o…
The semijoin algebra and the guarded fragment
Dirk Leinders, Jerzy Tyszkiewicz, Jan Van den Bussche
The semijoin algebra is the variant of the relational algebra obtained by replacing the join operator by the semijoin operator. We discuss some interesting connections between the…
On the expressive power of semijoin queries
Dirk Leinders, Jerzy Tyszkiewicz, Jan Van den Bussche
The semijoin algebra is the variant of the relational algebra obtained by replacing the join operator by the semijoin operator. We provide an Ehrenfeucht-Fraissé game, characterizi…