Let consider a 2-dim tor as square on plane with equal opposite sides. Consider also metrics on this square as distance between 2 points A, B as: d(A,B)=min{L(f(A), g(B))| f,g-any replicas of square}, where L - usual metrics on plane. What will be space of isometries of such tor? Yeah, what about 3-dim cube with equal opposite sides and same metrics? ============= Such task have origin in simulations with so called boundrary conditions.