The board game "lady" is solved: The computer program Chinook has calculated all possible and confirmed itself to be unbeatable

If your PC offers you a loose game of lady in the future – beat the invitation better, the computer wants to demonstrate you only his presentation. For at some point in the Fruhen Middle Ages in Sudfrankreich board game is now fully solved, as Canadian researchers of the University of Alberta describe in Edmonton in the current ie of the Science Magazine Science. The scientists did not hung themselves for months at the plaid lady board – they have been working on the computer for themselves. In mathematics, the computer guided, so calculated, evidence now no longer unusual – they are not so elegant as others, but quite solid.

Lady was played by the computer program Chinook, which already has a certain reputation in the Ladegemeinde and had already played in 1994 against human opponents to the world championship title. The problem (for the Chinook 1997 as an active player be sent in pension) was quite no small: 500 billion billion positions were to be paid out. The result: If both players always select the optimal allowance, the Damiel game is not to be gained.

This amption is not new to the lady base, but it was now confirmed. The scientists reached in three steps. First, they constructed an end game database that contains a maximum of ten stones remaining on the board all possible results. The database was already calculated in 2005.

It was about to evaluate that to the positions in the final database to evaluate. A program part designed a tree structure of the question in question, a second calculated the tree structure. Since 2004, a average of 50 computers around the clock has been working with this task – in real time, this will only be going to loose in a few years. However, the complete proof was stored, but only the search tree. The researchers violate the complete proof of a storage capacity of some ten terabytes required. But it can be reinstated at any time each branch of the tree.

Chinook played the British-American version of the game, checkers or also called Draghts. It uses an 8×8 board and differs from the lady variant known in this country by that the ladies (English "Kings") can not move anywhere, but always only one field diagonally. This affects them in the final: during a single "German" lady up to three enemy ladies always escape and thus a draw can achieve perfectly drawing US players usually also in the final two against one.

The story of the experiment, Lady to Losen is also a history of computer technology. When Chinook in 1989 began to avoid an end game database for a maximum of eight stones, the software needed on the then current computers still seven years. The same invoice was completed in 2001 during a month. The researchers also describe what practical problems their computer proof of lady solution was.

For example, hard disk manufacturers guarantee only one error frequency of 1 (10 high 13). Because of the enormous coarse of the final database (237 gigabytes for a ten-position database) therefore the so-called "bit-red" had to be excluded, the random tipping of bits. Therefore, there are always several copies of the database that are traced for correctness. Nevertheless, for example, the Chinook programmer can not complete transmission errors completely. The probability that one in the 40. TRAKE stored mistakes slippered to the end game, however, keep them low.

Heavier, there will be another program developed by the same team: Polaris, a poker software, wants to be 50 in the coming week against two human poker professionals.000 Dollar prize money.

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