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fix: remove attempt at quiescence search

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it does not help at all
This commit is contained in:
dogeystamp 2024-11-15 21:59:15 -05:00
parent d1506e4d6c
commit 69dfa98bef
1 changed files with 1 additions and 55 deletions
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56
src/search.rs
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@ -97,8 +97,6 @@ pub struct SearchConfig {
alpha_beta_on: bool,
/// Limit regular search depth
depth: usize,
/// Limit quiescence search depth (extra depth on top of regular depth)
quiesce_depth: usize,
}
impl Default for SearchConfig {
@ -106,7 +104,6 @@ impl Default for SearchConfig {
SearchConfig {
alpha_beta_on: true,
depth: 5,
quiesce_depth: 2,
}
}
}
@ -137,57 +134,6 @@ fn move_priority(board: &mut Board, mv: &Move) -> EvalInt {
eval
}
/// Search past the "horizon" caused by limiting the minmax depth.
///
/// We'll only search captures.
///
/// # Returns
///
/// Absolute (good for current side is positive) evaluation of the position.
fn quiesce(
board: &mut Board,
config: &SearchConfig,
depth: usize,
mut alpha: EvalInt,
beta: EvalInt,
) -> EvalInt {
if depth == 0 {
let eval = board.eval();
return eval * EvalInt::from(board.turn.sign());
}
let mut abs_best = None;
// sort moves by decreasing priority
let mut mvs: Vec<_> = board
.gen_moves()
.into_iter()
.collect::<Vec<_>>()
.into_iter()
.map(|mv| (move_priority(board, &mv), mv))
.collect();
mvs.sort_unstable_by_key(|mv| -mv.0);
for (_priority, mv) in mvs {
if move_get_capture(board, &mv).is_none() {
continue;
}
let anti_mv = mv.make(board);
let abs_score = -quiesce(board, config, depth - 1, -beta, -alpha);
anti_mv.unmake(board);
if let Some(abs_best_score) = abs_best {
abs_best = Some(max(abs_best_score, abs_score));
} else {
abs_best = Some(abs_score);
}
alpha = max(alpha, abs_best.unwrap());
if alpha >= beta && config.alpha_beta_on {
break;
}
}
abs_best.unwrap_or(board.eval() * EvalInt::from(board.turn.sign()))
}
/// Search the game tree to find the absolute (positive good) move and corresponding eval for the
/// current player.
///
@ -214,7 +160,7 @@ fn minmax(
let beta = beta.unwrap_or(EVAL_BEST);
if depth == 0 {
let eval = quiesce(board, config, config.quiesce_depth, alpha, beta);
let eval = board.eval() * EvalInt::from(board.turn.sign());
return (Vec::new(), SearchEval::Centipawns(eval));
}