Pawel Pietrzak Jesús Correas Germán Puebla Manuel V. Hermenegildo A practical type analysis for verification of modular prolog programs. 61-70 2008 PEPM http://doi.acm.org/10.1145/1328408.1328418 conf/pepm/2008 db/conf/pepm/pepm2008.html#PietrzakCPH08