Schema design for XML repositories: complexity and tractability
Proceedings of the twenty-ninth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Simplifying XML schema: single-type approximations of regular tree languages
Proceedings of the twenty-ninth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Generating, sampling and counting subclasses of regular tree languages
Proceedings of the 14th International Conference on Database Theory
The complexity of text-preserving XML transformations
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Journal of Computer and System Sciences
Succinctness of the Complement and Intersection of Regular Expressions
ACM Transactions on Computational Logic (TOCL)
The complexity of evaluating path expressions in SPARQL
PODS '12 Proceedings of the 31st symposium on Principles of Database Systems
Foundations of regular expressions in XML schema languages and SPARQL
PhD '12 Proceedings of the on SIGMOD/PODS 2012 PhD Symposium
Foundations of XML based on logic and automata: a snapshot
FoIKS'12 Proceedings of the 7th international conference on Foundations of Information and Knowledge Systems
Fast learning of restricted regular expressions and DTDs
Proceedings of the 16th International Conference on Database Theory
Learning queries for relational, semi-structured, and graph databases
Proceedings of the 2013 Sigmod/PODS Ph.D. symposium on PhD symposium
Simplifying XML Schema: Single-type approximations of regular tree languages
Journal of Computer and System Sciences
The complexity of regular expressions and property paths in SPARQL
ACM Transactions on Database Systems (TODS) - Invited papers issue
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We study the complexity of the inclusion, equivalence, and intersection problem of extended chain regular expressions (eCHAREs). These are regular expressions with a very simple structure: they basically consist of the concatenation of factors, where each factor is a disjunction of strings, possibly extended with “$*$”, “$+$”, or “$?$”. Though of a very simple form, the usage of such expressions is widespread as eCHAREs, for instance, constitute a super class of the regular expressions most frequently used in practice in schema languages for XML. In particular, we show that all our lower and upper bounds for the inclusion and equivalence problem carry over to the corresponding decision problems for extended context-free grammars, and to single-type and restrained competition tree grammars. These grammars form abstractions of document type definitions (DTDs), XML schema definitions (XSDs) and the class of one-pass preorder typeable XML Schemas, respectively. For the intersection problem, we show that obtained complexities only carry over to DTDs. In this respect, we also study two other classes of regular expressions related to XML: deterministic expressions and expressions where the number of occurrences of alphabet symbols is bounded by a constant.