@string{cons="Constraints"} @article{SamerSzeider11, author = {Marko Samer and Stefan Szeider}, title = {Tractable cases of the extended global cardinality constraint}, journal = Cons, volume = {16}, number = {1}, pages = {1-24}, year = {2011}, doi = {10.1007/s10601-009-9079-y}, }