rootAlpha & +1% window for each depth increase

Passed f20 nonregressive: Book: f20-100M-40k TC: 60+0.6 Total/Win/Draw/Lose: 13742 / 6913 / 26 / 6803 PTNML: 1340 / 9 / 4114 / 17 / 1391 WinRate: 50.40% ELO: 1.95[-4.23, 7.99] LOS: 73.45 LLR: 3.01[-2.94, 2.94] Passed s15: Book: s15-100M-40k TC: 60+0.6 Total/Win/Draw/Lose: 13292 / 3137 / 7229 / 2926 PTNML: 267 / 1460 / 3026 / 1581 / 312 WinRate: 50.79% ELO: 4.93[0.56, 9.20] LOS: 98.63 LLR: 3.19[-2.94, 2.94] Passed r15: Book: r15-100M-40k TC: 60+0.6 Total/Win/Draw/Lose: 7150 / 2589 / 2177 / 2384 PTNML: 318 / 661 / 1476 / 738 / 382 WinRate: 51.43% ELO: 9.21[2.25, 16.09] LOS: 99.51 LLR: 2.97[-2.94, 2.94] bench dc9cb330 bench (msvc) 16f94416
dhbloo · Aug 29, 2023 · bdec238 · bdec238
1 parent 8a824ab
commit bdec238
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Showing 2 changed files with 15 additions and 2 deletions.
diff --git a/Rapfi/search/ab/search.cpp b/Rapfi/search/ab/search.cpp
@@ -494,6 +494,8 @@ void aspirationSearch(Rule rule, Board &board, SearchStack *ss, Value prevValue,
 
     // Loop until we got a search value that lies in the aspiration window.
     while (true) {
+        searchData->rootAlpha = alpha;
+
         // Decrease search depth if multiple fail high occurs
         Depth adjustedDepth = std::max(1.0f, depth - failHighCnt / 4);
 
@@ -533,8 +535,11 @@ void aspirationSearch(Rule rule, Board &board, SearchStack *ss, Value prevValue,
         // In case of failing low/high increase aspiration window and re-search,
         // otherwise exit the loop.
         if (value <= alpha) {
-            beta        = (alpha + beta) / 2;
-            alpha       = std::max(value - delta, -VALUE_INFINITE);
+            // Increase beta by 1% for each increase in depth
+            int   completedDepth  = searchData->completedDepth.load(std::memory_order_relaxed);
+            float alphaPercentage = std::min(0.5f + 0.01f * completedDepth, 0.99f);
+            beta  = Value((double)alpha * alphaPercentage + (double)beta * (1 - alphaPercentage));
+            alpha = std::max(value - delta, -VALUE_INFINITE);
             failHighCnt = 0;
         }
         else if (value >= beta) {
@@ -1126,6 +1131,10 @@ Value search(Board &board, SearchStack *ss, Value alpha, Value beta, Depth depth
             if (ss->ttPv && !likelyFailLow)
                 r -= 1.0f;
 
+            // Increase reduction for nodes that does not improve root alpha
+            if (!RootNode && (ss->ply & 1) && bestValue >= -searchData->rootAlpha)
+                r += 1.0f;
+
             // Increase reduction for cut nodes if is not killer moves
             if (cutNode && !(!oppo4 && ss->isKiller(move) && ss->moveP4[self] < H_FLEX3))
                 r += 1.7f;
@@ -1282,6 +1291,9 @@ Value search(Board &board, SearchStack *ss, Value alpha, Value beta, Depth depth
                 if (PvNode && value < beta) {
                     alpha = value;  // Update alpha, make sure alpha < beta
 
+                    if (RootNode)
+                        searchData->rootAlpha = alpha;
+
                     // Reduce other moves if we have found at least one score improvement
                     if (depth > 2 && depth < 12 && beta < 2000 && value > -2000)
                         depth -= 1;

diff --git a/Rapfi/search/ab/searcher.h b/Rapfi/search/ab/searcher.h
@@ -36,6 +36,7 @@ struct ABSearchData : SearchData
     uint32_t         pvIdx;            /// Current searched pv index
     int              rootDepth;        /// Current searched depth
     Value            rootDelta;        /// Current window size of the root node
+    Value            rootAlpha;        /// Current alpha value of the root node
     bool             singularRoot;     /// Is there only a single response at root?
     std::atomic<int> completedDepth;   /// Previously completed depth
     std::atomic<int> bestMoveChanges;  /// How many time best move has changed in this search