Minimax and Othello

Hi,

I've used MiniMax trees in the past, but I have run into a kink while
applying them to the game of Othello (Reversi).

Othello differs, from a game like chess, in that you can leave your opponent
ZERO moves and yet the game is not over. I am not sure how to represent
this "forced pass" in the game tree.

For example I am building the tree and run into a situation where it is
Player B's turn to move, but he has no moves and yet Player A DOES have
moves from this position.

Any help would be appreciated!

BT

Tom Jones wrote:
> Hi,
>
> I've used MiniMax trees in the past, but I have run into a kink while
> applying them to the game of Othello (Reversi).
>
> Othello differs, from a game like chess, in that you can leave your opponent
> ZERO moves and yet the game is not over. I am not sure how to represent
> this "forced pass" in the game tree.
>
> For example I am building the tree and run into a situation where it is
> Player B's turn to move, but he has no moves and yet Player A DOES have
> moves from this position.
>
> Any help would be appreciated!
>
> BT

I ran into this problem also when I wrote an Othello
program. My solution was to have a no operation move for passing. The
board doesn't change (You just copy it to the next level in the tree)
but the turn switches from one oponent to the next. In my game moves
where indicated by a row and col number of a legal move. So a pass move
was simply indicated by zero zero ("00").
Beware of a special case where both oponents have to pass. It's
possible before all 64 squares are used and when this occurs the game
is over.

HTH,
Tom Z.