Why Letter Substitution Puzzles are Not Hard to Solve: A Case Study in Entropy and Probabilistic Search-Complexity Eric Corlett author Gerald Penn author 2013-08 text Proceedings of the 13th Meeting on the Mathematics of Language (MoL 13) András Kornai editor Marco Kuhlmann editor Association for Computational Linguistics Sofia, Bulgaria conference publication corlett-penn-2013-letter https://aclanthology.org/W13-3009/ 2013-08 83 92