An Extension of Data Automata that Captures XPath

We define a new kind of automata recognizing properties of data words or data trees and prove that the automata capture all queries definable in Regular XPath. We show that the automata-theoretic approach may be applied to answer decidability and expressibility questions for XPath. Finally, we use the newly introduced automata as a common framework to classify existing automata on data words and trees, including data automata, register automata and alternating register automata.

[1]  Stéphane Demri,et al.  LTL with the Freeze Quantifier and Register Automata , 2006, 21st Annual IEEE Symposium on Logic in Computer Science (LICS'06).

[2]  Thomas Schwentick,et al.  Two-Variable Logic on Words with Data , 2006, 21st Annual IEEE Symposium on Logic in Computer Science (LICS'06).

[3]  Diego Figueira,et al.  Forward-XPath and extended register automata on data-trees , 2010, ICDT '10.

[4]  Wenfei Fan,et al.  Satisfiability of XPath Queries with Sibling Axes , 2005, DBPL.

[5]  Diego Figueira,et al.  Satisfiability of downward XPath with data equality tests , 2009, PODS.

[6]  Thomas Colcombet,et al.  A Combinatorial Theorem for Trees , 2007, ICALP.

[7]  Ernst W. Mayr,et al.  An algorithm for the general Petri net reachability problem , 1981, STOC '81.

[8]  Floris Geerts,et al.  XPath satisfiability in the presence of DTDs , 2008, JACM.

[9]  Thomas Schwentick,et al.  Finite state machines for strings over infinite alphabets , 2004, TOCL.

[10]  Luc Segoufin.  Automata and Logics for Words and Trees over an Infinite Alphabet , 2006, CSL.

[11]  Thomas Schwentick,et al.  Two-variable logic on data words , 2011, TOCL.

[12]  Christof Löding,et al.  Deterministic Automata on Unranked Trees , 2005, FCT.

[13]  Thomas Schwentick,et al.  Two-variable logic on data trees and XML reasoning , 2009, JACM.

[14]  Nissim Francez,et al.  Finite-Memory Automata , 1994, Theor. Comput. Sci..

[15]  Tony Tan,et al.  On pebble automata for data languages with decidable emptiness problem , 2009, J. Comput. Syst. Sci..