Departmental Papers (CIS)

Date of this Version

September 2001

Document Type

Conference Paper


Postprint version. Published in Lecture Notes in Computer Science, Volume 2397, Revised Papers of the 8th International Workshop on Database Programming Languages 2001 (DBPL 2001), pages 133-148.
Publisher URL:


We study absolute and relative keys for XML, and investigate their associated decision problems. We argue that these keys are important to many forms of hierarchically structured data including XML documents. In contrast to other proposals of keys for XML, these keys can be reasoned about efficiently. We show that the (finite) satisfiability problem for these keys is trivial, and their (finite) implication problem is finitely axiomatizable and decidable in PTIME in the size of keys.



Date Posted: 08 May 2005