It is rare to give a semantic definition of a full-scale programming language, despite the many potential benefits. Partly this is because the available metalanguages for expressi...
Peter Sewell, Francesco Zappa Nardelli, Scott Owen...
We study relations on trees defined by first-order constraints over a vocabulary that includes the tree extension relation Ì Ì ¼, holding if and only if every branch of Ì ex...
In this paper we study the expressive power of query languages for nested bags. We de ne the ambient bag language by generalizing the constructs of the relational language of Brea...
The XML support in relational databases and the SQL/XML language are still relatively new as compared to purely relational databases and traditional SQL. Today, most database user...
Angelic nondeterminism can play an important role in program development. It simplifies specifications, for example in deriving programs with a refinement calculus; it is the form...