Dennis Shasha. Upstart Puzzles: Ice Trap. Communications of the ACM, 59(1):136, 2016. [doi]
@article{Shasha16, title = {Upstart Puzzles: Ice Trap}, author = {Dennis Shasha}, year = {2016}, doi = {10.1145/2851212}, url = {http://doi.acm.org/10.1145/2851212}, researchr = {https://researchr.org/publication/Shasha16}, cites = {0}, citedby = {0}, journal = {Communications of the ACM}, volume = {59}, number = {1}, pages = {136}, }