Lmr at root (#15)

* Testing LMR at the root, again * Testing removing the 4 ply depth minimum for root lmr * LMR at root does not activate for the first few moves as we care more about what the best move is and less about the actual score * Updated version number Make also no longer calls clean by default
rosenthj · May 26, 2019 · e2a4144 · e2a4144
1 parent 0a0f1e6
commit e2a4144
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Showing 3 changed files with 15 additions and 10 deletions.
diff --git a/Makefile b/Makefile
@@ -8,20 +8,20 @@ SOURCES=$(wildcard src/general/*.cc src/learning/*.cc src/*.cc)
 OBJECTS=$(SOURCES:.cc=.o)
 EXECUTABLE:=Winter
 
-all: $(SOURCES) $(EXECUTABLE) clean
+all: $(SOURCES) $(EXECUTABLE)
 
 target no_bmi: CFLAGS += -DNO_BMI
 no_bmi: all
 
-target ancient: CFLAGS=-c -O3 -Wall -Wno-sign-compare -m64 -DNO_BMI -std=c++11 -Isrc -Isrc/general -Isrc/learning
+target ancient: CFLAGS=-c -DNDEBUG -O3 -Wall -Wno-sign-compare -m64 -DNO_BMI -std=c++11 -Isrc -Isrc/general -Isrc/learning
 target ancient: LDFLAGS=-Wall -static
 ancient: all
 
-target old: CFLAGS=-c -O3 -Wall -Wno-sign-compare -m64 -msse4.2 -DNO_BMI -std=c++11 -Isrc -Isrc/general -Isrc/learning
+target old: CFLAGS=-c -DNDEBUG -O3 -Wall -Wno-sign-compare -m64 -msse4.2 -DNO_BMI -std=c++11 -Isrc -Isrc/general -Isrc/learning
 target old: LDFLAGS=-Wall -static
 old: all
 
-target new: CFLAGS=-c -O3 -Wall -Wno-sign-compare -m64 -mavx2 -mbmi -mbmi2 -std=c++11 -Isrc -Isrc/general -Isrc/learning
+target new: CFLAGS=-c -DNDEBUG -O3 -Wall -Wno-sign-compare -m64 -mavx2 -mbmi -mbmi2 -std=c++11 -Isrc -Isrc/general -Isrc/learning
 target new: LDFLAGS=-Wall -static
 new: all
 

diff --git a/src/general/settings.h b/src/general/settings.h
@@ -33,7 +33,7 @@
 namespace settings {
 
 const std::string engine_name = "Winter";
-const std::string engine_version = "0.5.8";
+const std::string engine_version = "0.6";
 const std::string engine_author = "Jonathan Rosenthal";
 
 const int kNumClusters = 4;

diff --git a/src/search.cc b/src/search.cc
@@ -1108,6 +1108,7 @@ Score RootSearchLoop(Thread &t, Score original_alpha, Score beta, Depth current_
     }
     alpha = -1;
   }
+  const bool in_check = t.board.InCheck();
   for (size_t i = 0; i < moves.size(); ++i) {
     t.set_move(moves[i]);
     t.board.Make(moves[i]);
@@ -1124,11 +1125,15 @@ Score RootSearchLoop(Thread &t, Score original_alpha, Score beta, Depth current_
       lower_bound_score = std::max(score, lower_bound_score);
     }
     else {
-//      Depth reduction = 0;
-//      if (!in_check && !board.InCheck() && GetMoveType(moves[i]) <= kDoublePawnMove) {
-//        reduction = get_lmr_reduction<kPV>(current_depth, i) / 2;
-//      }
-      Score score = -AlphaBeta<NodeType::kNW, Mode>(t, -(alpha + 1), -alpha, current_depth - 1);
+      Depth reduction = 0;
+      if (!in_check && !t.board.InCheck() && i > 2) {
+        //Late Move Reduction factor
+        reduction = get_lmr_reduction<NodeType::kPV>(current_depth, i - 2);
+        if (GetMoveType(moves[i]) > kDoublePawnMove) {
+          reduction = (2 * reduction) / 3;
+        }
+      }
+      Score score = -AlphaBeta<NodeType::kNW, Mode>(t, -(alpha + 1), -alpha, current_depth - 1 - reduction);
       if (score > alpha) {
         score = -AlphaBeta<NodeType::kPV, Mode>(t, -beta, -alpha, current_depth - 1);
       }