Walking through Doors is Hard, even without Staircases: Universality and PSPACE-hardness of Planar Door Gadgets

MIT Gadgets Group, Jeffrey Bosboom, Erik D. Demaine +4

An open-close door gadget has two states and three tunnels that can be traversed by an agent (player, robot, etc.): the "opening" and "closing" tunnels set the gadget's state to op…