Porting syzgy/tb to an old version chess (shatranj)

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syzygy
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Joined: Tue Feb 28, 2012 11:56 pm

Re: Porting syzgy/tb to an old version chess (shatranj)

Post by syzygy »

syzygy wrote: Sun Sep 29, 2024 6:56 pm Unfortunately, simply changing DRAW_RULE in the generator from (2 * 50) to (2 * 70) does not work.

The problem is that the values stored in the table no longer fit in a byte, so a "reduction" step has to be done before the "N-move rule" is reached. Not a major problem but it needs some work.
It took a while, but it seems to work now.

The only cursed positions with 5 pieces or less are in KQBvKB (using a 70-move rule).

And this still seems to be the longest win (DTZ=766 ply):
[d]Q7/7k/8/3Q4/8/8/1K4n1/6Q1 b - -