Oded Goldreich. Finding the Shortest Move-Sequence in the Graph-Generalized 15-Puzzle Is NP-Hard. In Oded Goldreich, editor, Studies in Complexity and Cryptography. Miscellanea on the Interplay between Randomness and Computation - In Collaboration with Lidor Avigad, Mihir Bellare, Zvika Brakerski, Shafi Goldwasser, Shai Halevi, Tali Kaufman, Leonid Levin, Noam Nisan, Dana Ron, . Volume 6650 of Lecture Notes in Computer Science, pages 1-5, Springer, 2011. [doi]
Abstract is missing.