2 papers
cs.DB2004
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…
cs.DB2003
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…