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Scale singular extension margin by tt_move history #1114

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Scale singular extension margin by tt_move history #1114

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19 changes: 5 additions & 14 deletions src/search.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -693,8 +693,9 @@ fn search<NODE: NodeType>(
if !NODE::ROOT && !excluded && potential_singularity {
debug_assert!(is_valid(tt_score));

let singular_margin = if tt_bound == Bound::Exact { (depth as u32).div_ceil(4) as i32 } else { depth }
+ depth * (tt_pv && !NODE::PV) as i32;
let singular_margin = (if tt_bound == Bound::Exact { (depth as u32).div_ceil(4) as i32 } else { depth }
+ depth * (tt_pv && !NODE::PV) as i32)
+ (td.move_history(ply, tt_move) / 1024).clamp(-depth / 4, depth / 4);
let singular_beta = tt_score - singular_margin;
let singular_depth = (depth - 1) / 2;

Expand Down Expand Up @@ -766,12 +767,7 @@ fn search<NODE: NodeType>(
let is_quiet = mv.is_quiet();
let is_direct_check = td.board.is_direct_check(mv);

let history = if is_quiet {
td.quiet_history.get(td.board.all_threats(), stm, mv) + td.conthist(ply, 1, mv) + td.conthist(ply, 2, mv)
} else {
let captured_type = td.board.type_on(mv.to());
td.noisy_history.get(td.board.all_threats(), td.board.moved_piece(mv), mv.to(), captured_type)
};
let history = td.move_history(ply, mv);

if !NODE::ROOT && !is_loss(best_score) {
// Late Move Pruning (LMP)
Expand Down Expand Up @@ -1191,7 +1187,6 @@ fn qsearch<NODE: NodeType>(td: &mut ThreadData, mut alpha: i32, beta: i32, ply:
}
}

let stm = td.board.side_to_move();
let in_check = td.board.in_check();

if NODE::PV {
Expand Down Expand Up @@ -1295,11 +1290,7 @@ fn qsearch<NODE: NodeType>(td: &mut ThreadData, mut alpha: i32, beta: i32, ply:
while let Some(mv) = move_picker.next::<NODE>(td, skip_quiets(best_score), ply) {
move_count += 1;

let history = if mv.is_quiet() {
td.quiet_history.get(td.board.all_threats(), stm, mv) + td.conthist(ply, 1, mv) + td.conthist(ply, 2, mv)
} else {
td.noisy_history.get(td.board.all_threats(), td.board.moved_piece(mv), mv.to(), td.board.type_on(mv.to()))
};
let history = td.move_history(ply, mv);

if !is_loss(best_score) {
// Late Move Pruning (LMP)
Expand Down
15 changes: 15 additions & 0 deletions src/thread.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -295,6 +295,21 @@ impl ThreadData {
self.continuation_history.get(self.stack[ply - index].conthist, self.board.piece_on(mv.from()), mv.to())
}

pub fn move_history(&self, ply: isize, mv: Move) -> i32 {
if mv.is_quiet() {
self.quiet_history.get(self.board.all_threats(), self.board.side_to_move(), mv)
+ self.conthist(ply, 1, mv)
+ self.conthist(ply, 2, mv)
} else {
self.noisy_history.get(
self.board.all_threats(),
self.board.moved_piece(mv),
mv.to(),
self.board.type_on(mv.to()),
)
}
}

pub fn print_uci_info(&mut self, depth: i32) {
if self.root_moves.is_empty() {
self.print_uci_no_move();
Expand Down