Simplify LMR condition

Apply LMR on captures the same way it is applied on quiets

Hit rate of removed condition (!ss->ttPv || !capture || (cutNode && (ss - 1)->moveCount > 1))
Total 1253801 Hits 1228904 Hit Rate (%) 98.0143

Hit rate of previous LMR (depth >= 2 && moveCount > 1 + rootNode && ...)
Total 1253801 Hits 727234 Hit Rate (%) 58.0023

Hit rate of simplified LMR (depth >= 2 && moveCount > 1 + rootNode)
Total 1201839 Hits 713540 Hit Rate (%) 59.3707

.github/workflows/pikafish.yml

@@ -23,14 +23,14 @@ jobs:
             shell: bash
             sde: /home/runner/work/Pikafish/Pikafish/.output/sde-temp-files/sde-external-9.27.0-2023-09-13-lin/sde -future --
           - name: MacOS
-            os: macos-14
+            os: macos-latest
             shell: bash
           - name: Windows
             os: windows-latest
             shell: msys2 {0}
             ext: .exe
             sde: /d/a/Pikafish/Pikafish/.output/sde-temp-files/sde-external-9.27.0-2023-09-13-win/sde.exe -future --
-        arch: ["-vnni512", "-avx512", "-avx512f", "-avxvnni", "-bmi2", "-avx2", "-sse41-popcnt", "-ssse3", "apple-silicon"]
+        arch: ["-vnni512", "-avx512", "-avx512f", "-avxvnni", "-bmi2", "-avx2", "-sse41-popcnt", "-ssse3"]
         exclude:
           - arch: -avxvnni
             config: {os: ubuntu-20.04}

src/search.cpp

@@ -1031,11 +1031,7 @@ Value Search::Worker::search(
         r -= ss->statScore / 12254;
 
         // Step 16. Late moves reduction / extension (LMR, ~117 Elo)
-        // We use various heuristics for the sons of a node after the first son has
-        // been searched. In general, we would like to reduce them, but there are many
-        // cases where we extend a son if it has good chances to be "interesting".
-        if (depth >= 2 && moveCount > 1 + rootNode
-            && (!ss->ttPv || !capture || (cutNode && (ss - 1)->moveCount > 1)))
+        if (depth >= 2 && moveCount > 1 + rootNode)
         {
             // In general we want to cap the LMR depth search at newDepth, but when
             // reduction is negative, we allow this move a limited search extension