Georg Gottlob Martin Grohe Nysret Musliu Marko Samer Francesco Scarcello Hypertree Decompositions: Structure, Algorithms, and Applications. 1-15 2005 conf/wg/2005 WG http://dx.doi.org/10.1007/11604686_1 db/conf/wg/wg2005.html#GottlobGMSS05