{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/139145"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/139145","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Subway Shuffle, 1 × 1 Rush Hour, and Cooperative Chess Puzzles: Computational Complexity of Puzzles","abstract":"Oriented Subway Shuffle is a game played on a directed graph with colored edges and colored tokens present on some vertices. A move consists of moving a token across an edge of the matching color to an unoccupied vertex and reversing the orientation of that edge. The goal is to move a token across a target edge. We show that it is PSPACE-complete to determine whether a particular target edge can be moved across through a sequence of Oriented Subway Shuffle moves. We show how this can be interpreted in the context of the motion-planning-through-gadgets framework, thus showing PSPACE-completeness of certain motion planning problems. In contrast, we show that polynomial time suffices to determine whether a particular token can ever move. This hardness result is motivated by three applications of proving other puzzles hard. A fairly straightforward reduction shows that the puzzle game Rush Hour is PSPACE-complete when all of the cars are 1 × 1 and there are fixed immovable cars. We show that two classes of cooperative Chess puzzles, helpmates and retrograde Chess, are also PSPACE-complete by reductions from Oriented Subway Shuffle.","abstract_html":"Oriented Subway Shuffle is a game played on a directed graph with colored edges and colored tokens present on some vertices. A move consists of moving a token across an edge of the matching color to an unoccupied vertex and reversing the orientation of that edge. The goal is to move a token across a target edge. We show that it is PSPACE-complete to determine whether a particular target edge can be moved across through a sequence of Oriented Subway Shuffle moves. We show how this can be interpreted in the context of the motion-planning-through-gadgets framework, thus showing PSPACE-completeness of certain motion planning problems. In contrast, we show that polynomial time suffices to determine whether a particular token can ever move. This hardness result is motivated by three applications of proving other puzzles hard. A fairly straightforward reduction shows that the puzzle game Rush Hour is PSPACE-complete when all of the cars are 1 × 1 and there are fixed immovable cars. We show that two classes of cooperative Chess puzzles, helpmates and retrograde Chess, are also PSPACE-complete by reductions from Oriented Subway Shuffle.","abstract_has_math":false,"creators":["Brunner, Josh"],"institution":"Massachusetts Institute of Technology","degree_name":"Master","degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science","school":null,"contributors":[],"advisors":["Demaine, Erik"],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-06","date_published":"2021-06","updated_at":"2026-07-22T22:21:37Z","subjects":[],"languages":[],"rights":["In Copyright - Educational Use Permitted","Copyright MIT"],"rights_urls":["http://rightsstatements.org/page/InC-EDU/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/1721.1/139145","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Demaine, Erik"]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. 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A move consists of moving a token across an edge of the matching color to an unoccupied vertex and reversing the orientation of that edge. The goal is to move a token across a target edge. We show that it is PSPACE-complete to determine whether a particular target edge can be moved across through a sequence of Oriented Subway Shuffle moves. We show how this can be interpreted in the context of the motion-planning-through-gadgets framework, thus showing PSPACE-completeness of certain motion planning problems. In contrast, we show that polynomial time suffices to determine whether a particular token can ever move. This hardness result is motivated by three applications of proving other puzzles hard. A fairly straightforward reduction shows that the puzzle game Rush Hour is PSPACE-complete when all of the cars are 1 × 1 and there are fixed immovable cars. We show that two classes of cooperative Chess puzzles, helpmates and retrograde Chess, are also PSPACE-complete by reductions from Oriented Subway Shuffle."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.Eng."]},{"key":"dc:title","label":"Title","values":["Subway Shuffle, 1 × 1 Rush Hour, and Cooperative Chess Puzzles: Computational Complexity of Puzzles"]}]}],"canonical_facts":{"dc:contributor.advisor":["Demaine, Erik"],"dc:contributor.department":["Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science"],"dc:creator":["Brunner, Josh"],"dc:date.accessioned":["2022-01-14T14:52:37Z"],"dc:date.available":["2022-01-14T14:52:37Z"],"dc:date.issued":["2021-06"],"dc:description.abstract":["Oriented Subway Shuffle is a game played on a directed graph with colored edges and colored tokens present on some vertices. A move consists of moving a token across an edge of the matching color to an unoccupied vertex and reversing the orientation of that edge. The goal is to move a token across a target edge. We show that it is PSPACE-complete to determine whether a particular target edge can be moved across through a sequence of Oriented Subway Shuffle moves. We show how this can be interpreted in the context of the motion-planning-through-gadgets framework, thus showing PSPACE-completeness of certain motion planning problems. In contrast, we show that polynomial time suffices to determine whether a particular token can ever move. This hardness result is motivated by three applications of proving other puzzles hard. A fairly straightforward reduction shows that the puzzle game Rush Hour is PSPACE-complete when all of the cars are 1 × 1 and there are fixed immovable cars. We show that two classes of cooperative Chess puzzles, helpmates and retrograde Chess, are also PSPACE-complete by reductions from Oriented Subway Shuffle."],"dc:description.degree":["M.Eng."],"dc:identifier.uri":["https://hdl.handle.net/1721.1/139145"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["In Copyright - Educational Use Permitted","Copyright MIT"],"dc:rights.uri":["http://rightsstatements.org/page/InC-EDU/1.0/"],"dc:title":["Subway Shuffle, 1 × 1 Rush Hour, and Cooperative Chess Puzzles: Computational Complexity of Puzzles"],"dc:type":["Thesis"],"thesis:degree_name":["Master","Master of Engineering in Electrical Engineering and Computer Science"]},"updated_at":"2026-07-22T22:21:37Z"}