4 papers
Pushing Blocks without Fixed Walls via Checkable Gizmos: Push-1 is PSPACE-Complete
MIT Hardness Group, Josh Brunner, Lily Chung +4
We prove PSPACE-completeness of Push-1: given a rectangular grid of 1 x 1 cells, each possibly occupied by a movable block, can a robot move from one specified location to another,…
ASP-Completeness of Hamiltonicity in Grid Graphs, with Applications to Loop Puzzles
MIT Hardness Group, Josh Brunner, Lily Chung +4
We prove that Hamiltonicity in maximum-degree-3 grid graphs (directed or undirected) is ASP-complete, i.e., it has a parsimonious reduction from every NP search problem (including…
Tetris is Hard with Just One Piece Type
MIT Hardness Group, Josh Brunner, Erik D. Demaine +2
We analyze the computational complexity of Tetris clearing (determining whether the player can clear an initial board using a given sequence of pieces) and survival (determining wh…
Undecidability of Tiling with a Tromino
ULB CompGeom Group, Zachary Abel, Hugo Akitaya +6
Given a periodic placement of copies of a tromino (either L or I), we prove co-RE-completeness (and hence undecidability) of deciding whether it can be completed to a plane tiling.…