ATRACTOR

There is an empty position in the puzzle at all times. The pieces next to that position appear with a yellow border and it is possible to move them into the empty position by clicking or dragging. The pieces with the yellow border are the only ones which can be moved at any moment; we will call them "movable pieces".

If you move the mouse over the figures marked with , you will see an animated gif.

You can play on both of the pictures of the applet, since there is a correspondence between the figure on the plane (see one on the left) and the surface (see one on the right).

The way to move the movable pieces to the empty position depends on the choice made on the menu

:

If the option chosen is:

• , when you click on a movable piece it automatically moves into the empty position;

• , by dragging a movable piece it moves gradually into the empty position. By choosing a movable piece on the surface an arrow appears; this arrow indicates the direction in which you must drag the piece to reach the empty position. It is easier to drag the piece if you do it next to the arrow. If you have any difficulty move the piece on the plane or rotate the surface into a better position (to rotate choose the option "Rotate, Orbit" in the menu which you obtain by right clicking the right visualization window on a point not on the surface - for more information on how to manipulate the surface, click here ).

In some cases the movable pieces have a choice of two paths to move into the empty position. These situation occur:

• with the cylinder, if it has:
  • two columns;
• with the torus, if it has:
  • two columns, or,
  • two rows;
• with the Moebius strip and the Klein bottle, if they have:
• two columns, the number of rows is odd and the empty position is in the central row, or,
• two rows;
• with the projective plane, if it has:
  • two columns, the number of rows is odd and the empty position is in the central row, or;
  • two rows, the number of columns is odd and the empty position is in the central row, or;
  • the empty position is one of the four corners of the plane. The following pictures show the two possible paths of the movable piece 12 into the empty position:

In this cases, when the option chosen is:

• , an extra yellow line dividing the piece appears; click on the area which corresponds to the direction in which you wish the piece to move;

The movable piece 12 moves horizontally into the empty position.

The movable piece 12 moves vertically into the empty position.

• , drag the piece in the direction you want. If you drag on the surface an arrow appears showing the direction of dragging;

The movable piece 12 moves horizontally into the empty position.

The movable piece 12 moves vertically into the empty position.

Note: if a movable piece on the surface is "behind" the empty position then clicking on the surface next to that movable piece will not cause it to move (this is because the program "sees" the empty position as a transparent piece which "prevents" contact with the piece behind).

In this situation the movable piece 11 does not move when you click on it on the surface.

To move that piece click or drag the corresponding one on the plane or else rotate the surface so that the piece is now in front. (to rotate choose the option "Rotate, Orbit" in the menu which you obtain by right clicking the right visualization window on a point not on the surface - for more information on how to manipulate the surface, click here).

In this situation you can already click on the movable piece 11.

If you used the mouse to rotate the surface and you want to play on it again click:

To have a better perspective of the empty position:

click:

On the menu you can make several choices:

• : allows you to choose another surface;
• :
  • : Selecting the option or clicking CTRL + arrow the construction of the surface begins (you can stop it at any time). Clicking CTRL + arrow stops the process. Clicking CTRL + arrow / arrow the construction process goes one stepforward/backward;
  • : shows the initial rectangle;
  • : shows the surface as the final result of deformation and gluing;
• : allows you to choose another picture for the background of the puzzle. On the right visualization window of the applet the image may be deformed.
  • among the choices, allows the user to provide an image (more...).
• : shuffles the pieces of the puzzle with an:
  • 
  • 
• : allows you to choose the way of moving movable pieces into the empty position (more...). The options are:
  • 
  • 
• : allows you to choose the number of columns in the puzzle;
• : allows you to choose the number of rows in the puzzle;
• : if this option is on, the movable pieces are shown with a yellow border, otherwise they are similar to the others.

To see the image that you are supposed to obtain with the puzzle click:

The window* which opens meanwhile can be moved to the most convenient location.

The flag on the upper right hand corner of the applet shows the language chosen. If you wish click on it to choose another language:

By clicking the button, you can choose between:

• : shows this instruction page;
• : with this choice you can then reach localized help clicking where you have doubts. Instead of this you can just place the mouse where you have doubts (buttons, specific game situations, etc) and press Alt+F1. In this case if you want to clear up any question, the mouse must first pass over the right visualization area;
• : shows information about the version of the applet.

Return to the initial configuration by clicking:

---