- Addition of new scaling comments : official-stockfish/Stockfish@6db…

…47ed

 engine1 = YaneuraOuNNUE_V830_1024d.exe , eval = tanuki20240131
 engine2 = YaneuraOuNNUE_V830_1024e.exe , eval = tanuki20240131
 T2,b1000,1442 - 152 - 1406(50.63% R4.39[-6.32,15.1]) winrate black , white = 51.23% , 48.77%
 T2,b2000,1405 - 207 - 1388(50.3% R2.11[-8.7,12.93]) winrate black , white = 53.42% , 46.58%
 ⇨ 誤差なので採用する。

source/engine/yaneuraou-engine/yaneuraou-search.cpp

@@ -2577,8 +2577,11 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
  // then that move is singular and should be extended. To verify this we do
  // a reduced search on the position excluding the ttMove and if the result
  // is lower than ttValue minus a margin, then we will extend the ttMove.
- // Note: the depth margin and singularBeta margin are known for having non-linear
+ // Recursive singular search is avoided.
+ // Note: the depth margin and singularBeta margin are known for having non-linear
  // so changing them requires tests at these types of time controls.
+ // Generally, higher singularBeta (i.e closer to ttValue) and lower extension
+ // margins scale well.
 
  // (alpha-s,beta-s)の探索(sはマージン値)において1手以外がすべてfail lowして、
  // 1手のみが(alpha,beta)においてfail highしたなら、指し手はsingularであり、延長されるべきである。
@@ -2770,6 +2773,11 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
  // 指し手で1手進める
  pos.do_move(move, st, givesCheck);
 
+ // These reduction adjustments have proven non-linear scaling.
+ // They are optimized to time controls of 180 + 1.8 and longer so
+ // changing them or adding conditions that are similar
+ // requires tests at these types of time controls.
+
  // Decrease reduction if position is or has been on the PV (~5 Elo)
  // この局面がPV上にあり、fail lowしそうであるならreductionを減らす
  // (fail lowしてしまうとまた探索をやりなおさないといけないので)
@@ -2790,28 +2798,16 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
 
  // 【計測資料 18.】cut nodeのときにreductionを増やすかどうか。
 
- if (cutNode)
- r += 2 - (tte->depth() >= depth && ss->ttPv);
+ if (cutNode)
+ r += 2 - (tte->depth() >= depth && ss->ttPv)
+ + (!ss->ttPv && move != ttMove && move != ss->killers[0]);
 
  // Increase reduction if ttMove is a capture (~3 Elo)
  // 【計測資料 3.】置換表の指し手がcaptureのときにreduction量を増やす。
 
  if (ttCapture)
  r++;
 
- // Decrease reduction for PvNodes (~3 Elo)
- // PvNodeではreductionを減らす。
- if (PvNode && tte->bound() != BOUND_UPPER)
- r--;
-
-#if 0
- // Increase reduction on repetition (~1 Elo)
- // 千日手模様ならreductionを増やす。
- // →　4手前とmoveが同じであるケースのみ調べる。
- if (move == (ss-4)->currentMove && pos.has_repeated())
- r += 2;
-#endif
-
  // Increase reduction if next ply has a lot of fail high (~5 Elo)
  if ((ss + 1)->cutoffCnt > 3)
  r++;