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Playing chess against the computer can be very frustrating. He always wins while computing the next four or even more moves completely.

This small article shows how to set the computation level down, so that the computer plays more predictable.

Small background introduction

Computers are still very stupid. This knowledge isn't that old. In older times (ancient times in computer related scale) the common opinion was that computers are intelligent when they beat humans in playing chess. In the last few years some grand masters in chess played and lost!

Why? First there are in the left corner the computers with their great amount of computing power and in the right corner the humans with their strategic logic and experience in rating the positions of the chess figures. This is not the same! So the (old) definition of intelligence can't be right, too. Still computers are not able to imitate human behavior, which is the second argument against the definition.

A computer tries to find the best move in a chess game by computing the next moves based on the current positions of the figures on the board. He is building up a so called tree in which he considers that you are trying the best possible move for yourself. The full tree can't be computed because that would require a tree size (each node represents a board position) greater than the number of atoms available in the whole universe. So he computes and rates only a few moves away from the current board position, which is so called "search depth".

The search depth is the key to lower the chess intelligence.

The command

Here is the basic command:

bash:~$ xboard -searchDepth 0 -clockMode false -boardSize Big

The core is the searchDepth argument. The two other ones disable the clock (I want to play without time pressure) and display the board in an appropriate scale on the screen.

It is not said that now I'm always winning a game (in fact, im losing almost every game), but now the computer plays a lot fairer according to my skills...

Further Information

The ability of today's computers in playing efficient chess is based on a simple algorithm which relies on computation power. However, there exist some games for which this is not that simple, for example the board game Go. It has even simpler rules than chess but the combination of them and the great board size (common is 19x19 in tournaments) makes it very difficult to provide an efficient algorithm so that the human is still unbeaten in this section.

Author: Christoph Hermes, published: 2007-02-28 16:38:05