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check for depth > 3, less aggressive reductions #73

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check for depth > 3, less aggressive reductions #73

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7 changes: 2 additions & 5 deletions src/alpha_beta.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,7 @@ pub fn alpha_beta<const PV_NODE: bool>(
} else {
#[allow(clippy::useless_let_if_seq)]
let mut reduction = 1;
if settings::LMR && moves_visited >= settings::MOVES_BEFORE_LMR && depth > 2 {
if settings::LMR && moves_visited >= settings::MOVES_BEFORE_LMR && depth > 3 {
// ensure we always reduce less than `depth`, otherwise we run into overflows and search until the end of the universe
reduction += LMP_REDUCTION[depth][moves_visited.clamp(0, 63)].min(depth as u32);
}
Expand Down Expand Up @@ -210,8 +210,6 @@ pub fn alpha_beta<const PV_NODE: bool>(
break;
}
}
// TODO try whether it gains to punish ALL quiet moves (including TT and killers)
// instead of just the one generated
if mv.decode().is_quiet() {
quiets_tried.push(mv);
}
Expand Down Expand Up @@ -285,7 +283,6 @@ const LMP_REDUCTION: [[u32; 64]; 64] = {
let mut moves_visited = 1;
while moves_visited < 64 {
out[depth][moves_visited] = lmr_reduction(depth, moves_visited);
// assert!(lmr_reduction(depth, moves_visited) != 0, "we have a non-zero value");
moves_visited += 1;
}
depth += 1;
Expand All @@ -299,7 +296,7 @@ const fn lmr_reduction(depth: usize, moves_visited: usize) -> u32 {
// false => 20 * int_ln(depth) * int_ln(moves_visited) / 335,
// true => 135 * int_ln(depth) * int_ln(moves_visited) / 275
// };
135 * int_ln(depth) * int_ln(moves_visited) / 275
99 * int_ln(depth) * int_ln(moves_visited) / 260
}

#[allow(
Expand Down
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