Rina Dechter Kalev Kask Javier Larrosa A General Scheme for Multiple Lower Bound Computation in Constraint Optimization. 346-360 2001 conf/cp/2001 CP http://link.springer.de/link/service/series/0558/bibs/2239/22390346.htm db/conf/cp/cp2001.html#DechterKL01