diff options
Diffstat (limited to 'src/board/engine.rs')
| -rw-r--r-- | src/board/engine.rs | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/src/board/engine.rs b/src/board/engine.rs index 1516784..7f2fef3 100644 --- a/src/board/engine.rs +++ b/src/board/engine.rs @@ -343,6 +343,7 @@ impl Board { let mut principal_variation = Vec::new(); let mut killer_moves = Vec::new(); let color = self.color(); + let is_in_check = self.is_king_in_check(color); match self.transposition() { Some(transposition) => { @@ -377,7 +378,7 @@ impl Board { return (self.quiscence(alpha, beta), principal_variation); } - let mut should_pv_search = true; + let mut should_pv_search = true; // = !should_apply_LMR let mut legal_move_found = false; for mov in moves { let ep_target_before = self.ep_target.clone(); @@ -392,10 +393,22 @@ impl Board { // Assume PV-node is high in the list (if move ordering is good) self.negamax_search(-beta, -alpha, depth_left - 1, &mut killer_moves, deadline) } else { + // Apply late move reductions + let reduction = if + depth_left > 2 && + !is_in_check && + !mov.is_tactical() + { + 1 + } else { + 0 + }; + // After we have PV-node (that raised alpha) all other nodes will be searched - // with zero-window first to confirm this assumption + // with zero-window first to confirm this assumption. + // Also (optionally) apply Late Move Reductions // TODO: changing 0.001 -> 0.0001 leads to a weird bug - let result = self.negamax_search(-(alpha + 0.001), -alpha, depth_left - 1, &mut killer_moves, deadline); + let result = self.negamax_search(-(alpha + 0.001), -alpha, depth_left - 1 - reduction, &mut killer_moves, deadline); // In case some of the other nodes raises alpha, then it's true PV node now, // let's research with full window to find its exact value if -result.0 > alpha { @@ -459,7 +472,7 @@ impl Board { } if !legal_move_found { - if self.is_king_in_check(color) { + if is_in_check { return (-VALUE_WIN, principal_variation); } } |