• Publications
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Efficient Memory Representation of XML Documents
A technique is presented that allows to represent the tree structure of an XML document in an efficient way by “compressing” their tree structure, which allows to directly execute queries without prior decompression. Expand
Efficient memory representation of XML document trees
A technique is presented that allows to represent the tree structure of an XML document in an efficient way by compressing their tree structure, and the functionality of basic tree operations, like traversal along edges, is preserved under this compressed representation. Expand
The submonoid and rational subset membership problems for graph groups
It is shown that the membership problem in a finitely generated submonoid of a graph group is decidable if and only if the independence graph (commutation graph) is a transitive forest. Expand
XML tree structure compression using RePair
A new linear time algorithm for computing small SLCF tree grammars, called TreeRePair, is presented and it is shown that it greatly outperforms the best known previous algorithm BPLEX. Expand
Word Problems and Membership Problems on Compressed Words
  • Markus Lohrey
  • Mathematics, Computer Science
  • SIAM J. Comput.
  • 1 May 2006
A fixed deterministic context-free language with a PSPACE-complete compressed membership problem for finitely presented monoids and completeness results for complexity classes in the range from P to EXPSPACE are obtained. Expand
Safe Realizability of High-Level Message Sequence Charts
It is proved that safe realizability is EXPSPACE-complete for bounded HMSCs but undecidable for the class of all HMSCs, which solves two open problems from [2]. Expand
Branching-Time Model Checking of One-Counter Processes and Timed Automata
It is proved that already over some fixed OCA, model checking is${\mathsf{PSPACE}}$-hard, i.e., expression complexity is ${\m... Expand
Algorithmics on SLP-compressed strings: A survey
  • Markus Lohrey
  • Computer Science
  • Groups Complex. Cryptol.
  • 1 December 2012
Results on algorithmic problems on strings that are given in a compressed form via straight-line programs are surveyed and applications in combinatorial group theory and computational topology and to the solution of word equations are discussed. Expand
The complexity of tree automata and XPath on grammar-compressed trees
The complexity of various membership problems for tree automata on compressed trees is analyzed and the evaluation problem for (structural) XPath queries on trees that are compressed via straight-line context-free tree grammars is investigated. Expand
First-order and counting theories of ω-automatic structures
Abstract The logic extends first-order logic by a generalized form of counting quantifiers (“the number of elements satisfying … belongs to the set C”). This logic is investigated for structures withExpand