@InProceedings{AchHK08, author = {Tobias Achterberg and Stefan Heinz and Thorsten Koch}, title = {Counting solutions of integer programs using unrestricted subtree detection}, booktitle = {Integration of AI and OR Techniques in Constraint Programming for Combinatorial Optimization Problems}, pages = {278-282}, year = {2008}, editor = {Laurent Perron and Michael A.\ Trick}, volume = {5015}, series = {Lecture Notes in Computer Science}, publisher = {Springer} }