Lecture Notes in Computer Science

The papers in this volume represent the technical program of the 8th Biennial Workshop on Data Bases and Programming Languages (DBPL 2001), that was held during September 8-10, 2001, in Frascati, located on the beautiful hills surrounding Rome, in an area favored by the ancient Roman patricians who built their summer residences there. DBPL 2001 continued the tradition of - cellence initiated by its predecessors in Rosco?, Finist` ere (1987), Salishan, O- gon (1989), Nafplion, Argolida (1991), Manhattan, New York (1993), Gubbio, Umbria (1995), Estes Park, Colorado (1997), and Kinloch Rannoch, Scotland (1999). Databases grew out of a separation between physical and logical data, thus enabling high-level query languages. Database query languages have evolved in expressive power and structural capabilities. Programming languages have seen a development from assembly languages to high-level declarative paradigms. Thus the two areas approach each other as they mature. Earlier successful cro- fertilizationsbetweenthe?eldsincludethecombinationofrelationaltheory,type theory and object-oriented languages, resulting in object-oriented databases, object-relational databases and persistent programming languages. The com- nation of database logic programming and constraint programming p- duceddeductiveandconstraintdatabases.Recently,withtheemergenceofse- structured data models, there is a renewed synergy between databases and p- gramminglanguages,inparticularinthedesignoflanguagestomanipulateXML data. The DBPL 2001 Program Co-Chairs were Giorgio Ghelli (Pisa) and G¨ osta Grahne(Montr´ eal).TheProgramCommitteeMemberswereCatrielBeeri(Je- salem),DiegoCalvanese(Rome),RichardConnor(Glasgow),AlonHalevy(Se- tle), Leonid Libkin (Toronto), Gianni Mecca (Potenza), Frank Neven (Limburg), Benjamin Pierce (Philadelphia), Chris Ramming (Menlo Park), J´ erË ome Sim´ eon (Murray Hill), Victor Vianu (San Diego), and Philip Wadler (Basking Ridge).