Symmetry Breaking in the Alien Tiles Puzzle Ian Gent * , Steve Linton † , and Barbara Smith ‡ October, 2000 Report APES-22-2000 Abstract We describe an application of symmetry breaking in constraint programming to a combinatorial puz- zle based on the Alien Tiles game. We obtain a 40-fold run-time improvement over code with no symmetry breaking. We believe this is the first integration of an algebraic system like GAP and a constraint programming system like ILOG Solver. Available from http://www.cs.strath.ac.uk/˜apes/apesreports.html * School of Computer Science, University of St Andrews, St Andrews, Fife, KY16 9SS, UK. ipg@cs.st-and.ac.uk † School of Computer Science, University of St Andrews, St Andrews, Fife, KY16 9SS, UK. sal@cs.st-and.ac.uk ‡ School of Computing, University of Leeds, Leeds, LS2 9JT, UK. bms@comp.leeds.ac.uk 1