Eriksson, Salomé, and Malte Helmert. “Certified Unsolvability for SAT Planning With Property Directed Reachability”. Proceedings of the International Conference on Automated Planning and Scheduling 30, no. 1 (June 1, 2020): 90-100. Accessed March 28, 2024. https://ojs.aaai.org/index.php/ICAPS/article/view/6649.