Marc Meister Khalil Djelloul Thom W. Frühwirth Complexity of a CHR Solver for Existentially Quantified Conjunctions of Equations over Trees. 139-153 2006 conf/csclp/2006 CSCLP http://dx.doi.org/10.1007/978-3-540-73817-6_9 db/conf/csclp/csclp2006.html#MeisterDF06