Deciding equivalence of finite tree automata
SIAM Journal on Computing
One-unambiguous regular languages
Information and Computation
DTD inference for views of XML data
PODS '00 Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Normal form algorithms for extended context-free grammars
Theoretical Computer Science
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
Everything You Ever Wanted to Know About DTDs, But Were Afraid to Ask (Extended Abstract)
Selected papers from the Third International Workshop WebDB 2000 on The World Wide Web and Databases
Word problems requiring exponential time(Preliminary Report)
STOC '73 Proceedings of the fifth annual ACM symposium on Theory of computing
Taxonomy of XML schema languages using formal language theory
ACM Transactions on Internet Technology (TOIT)
Expressiveness and complexity of XML Schema
ACM Transactions on Database Systems (TODS)
On the minimization of XML Schemas and tree automata for unranked trees
Journal of Computer and System Sciences
Inferring XML schema definitions from XML data
VLDB '07 Proceedings of the 33rd international conference on Very large data bases
Simplifying XML schema: effortless handling of nondeterministic regular expressions
Proceedings of the 2009 ACM SIGMOD International Conference on Management of data
Journal of Computer and System Sciences
Complexity of Decision Problems for XML Schemas and Chain Regular Expressions
SIAM Journal on Computing
Succinctness of pattern-based schema languages for XML
Journal of Computer and System Sciences
Succinctness of the Complement and Intersection of Regular Expressions
ACM Transactions on Computational Logic (TOCL)
CSL'07/EACSL'07 Proceedings of the 21st international conference, and Proceedings of the 16th annuall conference on Computer Science Logic
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XML Schema Definitions (XSDs) can be adequately abstracted by the single-type regular tree languages. It is well known that these form a strict subclass of the robust class of regular unranked tree languages. Sadly, in this respect, XSDs are not closed under the basic operations of union and set difference, complicating important tasks in schema integration and evolution. The purpose of this paper is to investigate how the union and difference of two XSDs can be approximated within the framework of single-type regular tree languages. We consider both optimal lower and upper approximations. We also address the more general question of how to approximate an arbitrary regular tree language by an XSD and consider the complexity of associated decision problems.