Reversi (Othello) — Strategy
VOG — Vinco Online Games
Wedges
            Diag. 7: Black to play |
We have already seen that the corners are very important. This immediately
translates into a method by which edges must be played. Consider for
example the south edge in Diag. 7. If black plays c8, he can take
the corner a8 no matter what white does. The reason is that the disc at
c8 cannot be flipped back, since it is flanked by two white discs. One
says that the black disk is wedged. What about the east edge? If black
plays h6, he cannot wedge because white takes back with h5 (and similarly,
if black plays h5, white will respond h6). Now consider the north edge. If
black plays c1, white may take back with d1 to avoid losing the a1 corner.
However black may now wedge with e1, winning despite everything the corner
on his next move.
It seems clear therefore that whenever there are an odd number of empty squares between two discs of the same colour (here white), the other player may get a wedge (as in the south and north edges), while when there are an even number of empty squares, the wedge may be avoided (as in the east edge). From the principal that one should avoid playing C and X-squares, many beginning players deduce an incorrect strategy which consists of assigning to each square a fixed value in advance which does not take into consideration the position on the board. In this method, corners are the best squares, followed by edge squares other than C-squares, the central squares are given a neutral value, while the C-squares and especially X-squares are considered to be bad. At each move, they play to the square with the greatest value (assuming it is a legal move of course). Unfortunately, this strategy is badly flawed for reasons which will soon become apparent. |