Selected publications

• A decidable characterization of locally testable tree languages
  with Thomas Place.
  (presented at ICALP´09).
  
  
• Views and Queries: Determinacy and Rewriting
  with Alan Nash and Victor Vianu.
  (long abstracts were presented at PODS´05 and ICDT'07).
  
  
• XPath, transitive closure logic, and nested tree walking automata
  with Balder ten Cate.
  To appear in J. ACM (presented at PODS´08).
  
  
• Piecewise testable tree languages
  with Mikolaj Bojanczyk and Howard Straubing.
  (presented at LICS´08).
  
  
• Tree languages defined in first-order logic with one quantifier alternation
  with Mikolaj Bojanczyk.
  (a long abstract was presented at ICALP´08).
  
  
• Two-variable logic on words with data
  with Mikolaj Bojanczyk, Anca Muscholl, Thomas Schwentick and Claire David.
  (presented at LICS´06).
  
  
• Regular tree languages definable in FO and FOmod
  with Michael Benedikt.
  Trans. of Computational Logic (ToCL), 11(1), 2010 (a long abstract was presented at STACS´05, the proceeding version contains an important bug, please use this one instead).
  
  
• Future-looking logics on data words and trees
  with Diego Figueira.
  (presented at MFCS´09).
  
  
• Static Analysis of Active XML Systems
  with Serge Abiteboul and Victor Vianu.
  Trans. of Database Sysytems (ToDS), 34(4), 2009 (a long abstract was presented at PODS´08).
  
  
• Two-variable logic on data trees and applications to XML reasoning
  with Mikolaj Bojanczyk, Anca Muscholl, Thomas Schwentick.
  J. ACM 56(3), 2009 (a preliminary version was presented at PODS´06).
  
  
• Towards a Characterization of Order-Invariant Queries over Tame Structures
  with Michael Benedikt.
  J. of Symbolic Logic (JSL), 74(1), pp 168-186, 2009 (a preliminary version was presented at CSL´05).
  
  
• Complexity of pebble tree-walking automata
  with Mathias Samuelides.
  (presented at FCT 2007).
  
  
• Constant-memory validation of streaming XML documents against DTDs
  with Cristina Sirangelo.
  (a long abstract was presented at ICDT´07).
  
  
• Expressive power of pebble automata
  with Mikolaj Bojanczyk, Mathias Samuelides, and Thomas Schwentick.
  (presented at ICALP´06).
  
  
• Complementing deterministic tree-walking automata
  With Anca Muscholl and Mathias Samuelides.
  Information Processing Letters (IPL), 99(1), pp 33-39, 2006.
  
  
• Active Context-Free Games
  with Anca Muscholl and Thomas Schwentick.
  Theory of Computing Systems, 39(1), 2006 (a preliminary version was presented at STACS´04).
  
  
• Representing and Querying XML with Incomplete Information
  with Serge Abiteboul and Victor Vianu.
  Trans. Of Database Systems (TODS), 31(1), pp 208-254, 2006 (a preliminary version was presented at PODS´01).
  
  
• The Parallel Complexity of XML Typing and XPath Query Evaluation
  with Georg Gottlob, Christoph Koch, and Reinhard Pichler.
  J. ACM 52(2), pp 284-335, 2005 (this paper contains all the result presented in my PODS´03 paper, plus more).
  
  
• Order independent temporal properties
  with Sandra de Amo and Nicole Bidoit.
  Journal of Logic and Computation 14(2), pp 277-298, 2004.
  
  
• Definable Relations and First-Order Query Languages over Strings
  with Michael Benedikt , Leonid Libkin, and Thomas Schwentick.
  J. ACM 50, pp 694-751, 2003 (preliminary versions were presented in LICS´01, and in PODS´01).
  
  
• Reachability and Connectivity Queries in Constraint Databases
  with Michael Benedikt, Martin Grohe, and Leonid Libkin.
  JCSS, 66(1), pp 169-206, 2003 (a preliminary version was presented at PODS´00).
  
  
• Validating Streaming XML Documents
  with Victor Vianu
  Presented at PODS'02.
  
  
• On first-order topological queries
  with Martin Grohe.
  TOCL 3(3), pp 336-358, 2002 (presented at LICS'00).
  
  
• When is the evaluation of conjunctive queries tractable ?
  with Martin Grohe and Thomas Schwentick.
  Presented at STOC, 2001.
  
  
• Querying Spatial Databases via Topological Invariants
  with Victor Vianu.
  JCSS 61(2), pp 270-301, 2000 (a preliminary version was presented at PODS´98).
  
  
• I was also involved in the Dedale project. You can check the list of publication of Dedale.