Saturday, February 12, 2005

Checkers Variants

One of the problems of checkers is that it is played in a bazillion different variants in different countries. Chess is played with the same rules in all countries, and I strongly believe that this is one of the reasons that it is much more popular than checkers. In Europe, you cannot go from one country to another without changing rules: the board size (8x8 or 10x10), the capture rules (men can or cannot capture kings, men can or cannot capture backwards), the king movement (chess-king-like, flying in two different forms), the board orientation and the side to start the game can change. The last two items are essentially irrelevant, since they are just a convention - the game itself doesn't change if you change these rules, but of course it will appear unfamiliar to a player accustomed to another playing style.
Now, even without changing the possible moves, we can generate checkers variants: I'll take a closer look at two specific changes. The first is Kingscourt: the first side to make a king wins. If one player loses all pieces or cannot move, he loses. Another variant is Losing Checkers (also called suicide checkers): The side which loses according to normal rules wins.
The first thing to note is that Kingscourt cannot end in a draw; it must be a win either for black or for white. Losing checkers on the other hand has many drawn endgame positions, some of them are quite surprising! I'll return to this topic in my next post.


Kestutis said...

Losing checkers or give-away checkers ? In Russian language -
poddavki.I have poddavki engine
from Yuri Sorkin. How much I know
from Russian checkers web sites
this variant is more complicated
than traditional russian shashki.
Almost all Russian checkers programs supports this variant.
Apparently programmers loves it.
Here in Lithuania who plays checkers almost certainly plays only Russian checkers ( shashki )and in all former USSR teritory
Russian checkers is #1.I even initially was surprised that
there exists another forms of checkers except Russian and International.

Martin Fierz said...

As far as I know, losing checkers and giveaway checkers are just two different names for the same thing. For humans, the giveaway variant is much tougher than the normal variant IMO, because the game is extremely tactical. There are often moves that lead to a loss by force because the opponent can force you to capture all his pieces with the right sacrifice sequence. Since this is a matter of pure calculation, human intuition doesn't help all that much. For programmers too it is a special challenge - I'll write more about that later.