Formal languages
Decidability and expressiveness aspects of logic queries
PODS '87 Proceedings of the sixth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Foundations of logic programming; (2nd extended ed.)
Foundations of logic programming; (2nd extended ed.)
Expressiveness of restricted recursive queries
STOC '89 Proceedings of the twenty-first annual ACM symposium on Theory of computing
Inductive pebble games and the expressive power of datalog
PODS '89 Proceedings of the eighth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
On Datalog vs. polynomial time (extended abstract)
PODS '91 Proceedings of the tenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
On datalog linearization of chain queries
Theoretical studies in computer science
Proceedings of the 30th IEEE symposium on Foundations of computer science
On the expressive power of datalog: tools and a case study
PODS '90 Proceedings of the ninth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Indexed Grammars—An Extension of Context-Free Grammars
Journal of the ACM (JACM)
Programmed Grammars and Classes of Formal Languages
Journal of the ACM (JACM)
Universality of data retrieval languages
POPL '79 Proceedings of the 6th ACM SIGACT-SIGPLAN symposium on Principles of programming languages
ACM SIGMOD Record
Regulated Grammars with Leftmost Derivation
SOFSEM '98 Proceedings of the 25th Conference on Current Trends in Theory and Practice of Informatics: Theory and Practice of Informatics
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A chain query seeks, for each input database (viewed as directed graph), all pairs of start and end nodes of paths whose labels spell words in an associated (possibly non context-free) language over some binary predicates. We study the expressive power of Datalog for chain queries. Extending context-free productions with labels, we introduce a new tool called “indexed positive programmed grammarr” (IPPG). Three variations of IPPG are introduced to characterize chain queries computable (i) by linear Datalog, (ii) by “semi-linear Datalog”, and (iii) by general Datalog, respectively, under a natural “addressable” condition.