IBM Research "Ponder This" challenge

This month's official IBM challenge is based on a model suggested by Harry Buhrman, Serge Fehr, Christian Schaffner, and Florian Speelman, who described the garden-hose model in their paper "The Garden-Hose Game: A New Model of Computation, and Application to Position-Based Quantum Cryptography" ( http://arxiv.org/abs/1109.2563).

For more information, see http://domino.research.ibm.com/Comm/wwwr_ponder.nsf/Challenges/April2012.html