Cees Witteveen Wiebe van der Hoek Nico Roos Concurrently Decomposable Constraint Systems. 153-164 2009 MATES http://dx.doi.org/10.1007/978-3-642-04143-3_14 conf/mates/2009 db/conf/mates/mates2009.html#WitteveenHR09