zxul767 / pawn

A chess engine and machine learning testbed
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3-fold repetition and 50-move rules are wrongly implemented #29

Open zxul767 opened 2 years ago

zxul767 commented 2 years ago

The 3-fold repetition rule is currently implemented as a forced draw, but in reality official chess rules (as established by FIDE) establish that it is in fact just a situation in which the player about to move can claim a draw. 5-fold repetition, on the other hand, does imply a forced draw.

repetition: 5.3.1. 1. A player may claim a draw if the same position occurs three times. 2. A game is drawn if the same position occurs five times.

The same issue is present with the 50-move rule, which in current rules only opens the possibility for a player to claim a draw, but does not automatically imply it. 75 moves is the correct limit for a forced draw.