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 How to play with the applet of "goishi" (GO game marbles) example of proof animation.

  1.  [add] button adds a black marble in the bag.

  2.  Clicking a black marble turns it to a white marble.

  3.  [start] button starts the game.

  4.  [left] button selects the group A, the green group.

  5.  [right] button selects the group B, the yellow group.

An example of the game

  1. Add four marbles B W B B to the bag. B is a black marble and W is a white marble.
  2. This bag contradicts to the theorem. Thus something will be wrong with at least one of the two induction hypotheses.
  3. Actually, both are wrong for this case. Let's select right this time.
  4. For W B B, the induction hypothesis on group A (green) is wrong and the induction hypothesis on group B (yellow) is correct. A bug will be on group A hypothesis. Thus select left.
  5. Then you will see what's wrong!

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