Adjust futility margin in the child node based on whether the
static evaluation is improving.
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 15271 W: 3157 L: 2958 D: 9156
http://tests.stockfishchess.org/tests/view/
5a9f2f8c0ebc590297cb6216
LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 6617 W: 1053 L: 908 D: 4656
http://tests.stockfishchess.org/tests/view/
5a9f98390ebc590297cb6241
Ideas for future work:
- Tune the new margins.
- Try to get this idea to work for futility pruning in parent
nodes as well.
Bench:
5779242
// Razor and futility margins
const int RazorMargin1 = 590;
const int RazorMargin2 = 604;
// Razor and futility margins
const int RazorMargin1 = 590;
const int RazorMargin2 = 604;
- Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
+ Value futility_margin(Depth d, bool improving) {
+ return Value((175 - 50 * improving) * d / ONE_PLY);
+ }
// Futility and reductions lookup tables, initialized at startup
int FutilityMoveCounts[2][16]; // [improving][depth]
// Futility and reductions lookup tables, initialized at startup
int FutilityMoveCounts[2][16]; // [improving][depth]
ss->staticEval, TT.generation());
}
ss->staticEval, TT.generation());
}
+ improving = ss->staticEval >= (ss-2)->staticEval
+ /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */
+ ||(ss-2)->staticEval == VALUE_NONE;
+
if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move()))
goto moves_loop;
if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move()))
goto moves_loop;
// Step 8. Futility pruning: child node (skipped when in check)
if ( !rootNode
&& depth < 7 * ONE_PLY
// Step 8. Futility pruning: child node (skipped when in check)
if ( !rootNode
&& depth < 7 * ONE_PLY
- && eval - futility_margin(depth) >= beta
+ && eval - futility_margin(depth, improving) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval;
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval;