Law, Yat, Jimmy Lee, May Hiu Woo, and Toby Walsh. “A Comparison of Lex Bounds for Multiset Variables in Constraint Programming”. Proceedings of the AAAI Conference on Artificial Intelligence 25, no. 1 (August 4, 2011): 61–67. Accessed May 7, 2026. https://ojs.aaai.org/index.php/AAAI/article/view/7830.