Jérôme Leroux Grégoire Sutre Flat counter automata almost everywhere!. 2006 Software Verification: Infinite-State Model Checking and Static Program Analysis http://drops.dagstuhl.de/opus/volltexte/2006/729 conf/dagstuhl/2006P6081 db/conf/dagstuhl/P6081.html#LerouxS06