ON CORE XPATH WITH INFLATIONARY FIXED POINTS

摘要

We prove the undecidability of Core XPath 1.0 (CXP) [G. Gottlob and C. Koch, in Proc. of 17th Ann. IEEE Symp. on Logic in Computer Science, LICS '02 (Copenhagen, July 2002). IEEE CS Press (2002) 189-202.] extended with an Inflationary Fixed Point (IFP) operator. More specifically, we prove that the satisfiability problem of this language is undecidable. In fact, the fragment of CXP+IFPcontaining only the self and descendant axes is already undecidable.