Discussion of chess software programming and technical issues.
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MahmoudUthman
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Post
by MahmoudUthman » Thu Jun 06, 2019 4:28 pm
Stockfish used to do this for captures:
Code: Select all
for (auto& m : *this)
if (type_of(m) == ENPASSANT)
m.value = PieceValue[MG][PAWN] - Value(PAWN);
else if (type_of(m) == PROMOTION)
m.value = PieceValue[MG][pos.piece_on(to_sq(m))] - Value(PAWN)
+ PieceValue[MG][promotion_type(m)] - PieceValue[MG][PAWN];
else
m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
- Value(type_of(pos.moved_piece(m)));
resulting in the following order for captures & promotions:
Code: Select all
From/Pr To
Queen Queen Promotion
Rook Queen Promotion
Queen Rook Promotion
Bishop Queen Promotion
Queen Bishop Promotion
Knight Queen Promotion
Queen Knight Promotion
Pawn Queen
Queen Pawn Promotion
Knight Queen
Bishop Queen
Rook Queen
Queen Queen
King Queen
Rook Rook Promotion
Queen Null Promotion
Bishop Rook Promotion
Rook Bishop Promotion
Knight Rook Promotion
Rook Knight Promotion
Bishop Bishop Promotion
Knight Bishop Promotion
Bishop Knight Promotion
Knight Knight Promotion
Pawn Rook
Rook Pawn Promotion
Knight Rook
Bishop Rook
Rook Rook
Queen Rook
King Rook
Rook Null Promotion
Pawn Bishop
Bishop Pawn Promotion
Knight Bishop
Bishop Bishop
Rook Bishop
Queen Bishop
King Bishop
Pawn Knight
Knight Pawn Promotion
Knight Knight
Bishop Knight
Rook Knight
Queen Knight
King Knight
Bishop Null Promotion
Knight Null Promotion
Pawn Pawn
Knight Pawn
Bishop Pawn
Rook Pawn
Queen Pawn
King Pawn
but searching this forum I found multiple posts with different ordering schemes, some of which place all promotions after all non losing captures to reduce the search tree size,...etc.
which one is better in general & do you use different schemes in the main search than in Qsearch ?
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Ras
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Post
by Ras » Thu Jun 06, 2019 6:43 pm
MahmoudUthman wrote: ↑Thu Jun 06, 2019 4:28 pm
do you use different schemes in the main search than in Qsearch ?
You can drop underpromotion from quiescence.
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Dann Corbit
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- Location: Redmond, WA USA
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by Dann Corbit » Thu Jun 06, 2019 10:37 pm
Ras wrote: ↑Thu Jun 06, 2019 6:43 pm
MahmoudUthman wrote: ↑Thu Jun 06, 2019 4:28 pm
do you use different schemes in the main search than in Qsearch ?
You can drop underpromotion from quiescence.
Including underpromotion to knight?
Taking ideas is not a vice, it is a virtue. We have another word for this. It is called learning.
But sharing ideas is an even greater virtue. We have another word for this. It is called teaching.
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Ras
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by Ras » Fri Jun 07, 2019 12:51 pm
Dann Corbit wrote: ↑Thu Jun 06, 2019 10:37 pm
Including underpromotion to knight?
Yes, it's not worth the effort in QS. In main search however, underpromotions should be searched.
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Joost Buijs
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- Location: Almere, The Netherlands
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by Joost Buijs » Fri Jun 07, 2019 1:48 pm
Ras wrote: ↑Fri Jun 07, 2019 12:51 pm
Dann Corbit wrote: ↑Thu Jun 06, 2019 10:37 pm
Including underpromotion to knight?
Yes, it's not worth the effort in QS. In main search however, underpromotions should be searched.
Even in main search you can omit under-promotions to bishop, at least I've never seen a game where under-promotion to bishop led to anything useful.
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elpapa
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- Location: Sweden
- Full name: Patrik Karlsson
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by elpapa » Fri Jun 07, 2019 3:01 pm
Joost Buijs wrote: ↑Fri Jun 07, 2019 1:48 pm
Ras wrote: ↑Fri Jun 07, 2019 12:51 pm
Dann Corbit wrote: ↑Thu Jun 06, 2019 10:37 pm
Including underpromotion to knight?
Yes, it's not worth the effort in QS. In main search however, underpromotions should be searched.
Even in main search you can omit under-promotions to bishop, at least I've never seen a game where under-promotion to bishop led to anything useful.
It happens once in 33,000 games according to Wikipedia.
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Dann Corbit
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- Location: Redmond, WA USA
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by Dann Corbit » Fri Jun 07, 2019 3:07 pm
Joost Buijs wrote: ↑Fri Jun 07, 2019 1:48 pm
Ras wrote: ↑Fri Jun 07, 2019 12:51 pm
Dann Corbit wrote: ↑Thu Jun 06, 2019 10:37 pm
Including underpromotion to knight?
Yes, it's not worth the effort in QS. In main search however, underpromotions should be searched.
Even in main search you can omit under-promotions to bishop, at least I've never seen a game where under-promotion to bishop led to anything useful.
It happens quite a bit in chess puzzles because it gets deliberately designed into some problems.
Taking ideas is not a vice, it is a virtue. We have another word for this. It is called learning.
But sharing ideas is an even greater virtue. We have another word for this. It is called teaching.