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Add improving to a condition of NMP #5813

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Add improving to a condition of NMP #5813

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7d0ff51
Adjust margin for attempting null-move pruning
pkrisz99 Jan 18, 2025
1e10959
Use the classical definition of improving there
pkrisz99 Jan 18, 2025
66773b7
Tweak values
pkrisz99 Jan 19, 2025
ed13905
Update AUTHORS
pkrisz99 Jan 20, 2025
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1 change: 1 addition & 0 deletions AUTHORS
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Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,7 @@ Kian E (KJE-98)
kinderchocolate
Kiran Panditrao (Krgp)
Kojirion
Krisztián Peőcz
Krystian Kuzniarek (kuzkry)
Leonardo Ljubičić (ICCF World Champion)
Leonid Pechenik (lp--)
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6 changes: 3 additions & 3 deletions src/search.cpp
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Expand Up @@ -799,11 +799,9 @@ Value Search::Worker::search(
&& eval >= beta && (!ttData.move || ttCapture) && !is_loss(beta) && !is_win(eval))
return beta + (eval - beta) / 3;

improving |= ss->staticEval >= beta + 97;

// Step 9. Null move search with verification search (~35 Elo)
if (cutNode && (ss - 1)->currentMove != Move::null() && eval >= beta
&& ss->staticEval >= beta - 20 * depth + 440 && !excludedMove && pos.non_pawn_material(us)
&& ss->staticEval >= beta - 20 * depth + 470 - 60 * improving && !excludedMove && pos.non_pawn_material(us)
&& ss->ply >= thisThread->nmpMinPly && !is_loss(beta))
{
assert(eval - beta >= 0);
Expand Down Expand Up @@ -842,6 +840,8 @@ Value Search::Worker::search(
}
}

improving |= ss->staticEval >= beta + 97;

// Step 10. Internal iterative reductions (~9 Elo)
// For PV nodes without a ttMove as well as for deep enough cutNodes, we decrease depth.
// This heuristic is known to scale non-linearly, current version was tested at VVLTC.
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