Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Browse files

Decrease NullMoveMargin and adjust razoring

Also retire razoring margins vector and use
a simpler formula instead.

Now that we use a more accurate static evaluation
try to avoid useless null searches when we are well
below beta. And for teh same reason increase a bit
the razoring.

After 972 games at 1+0
Mod vs Orig +224 =558 -190 +12 ELO

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
  • Loading branch information...
commit e817a55bc6cc60b831f74ce5c180ec8b07c41d8a 1 parent 638f3d3
@mcostalba authored
Showing with 4 additions and 11 deletions.
  1. +4 −11 src/search.cpp
View
15 src/search.cpp
@@ -172,9 +172,9 @@ namespace {
// best move from the previous iteration, Problem is set back to false.
const Value NoProblemMargin = Value(0x14);
- // Null move margin. A null move search will not be done if the approximate
+ // Null move margin. A null move search will not be done if the static
// evaluation of the position is more than NullMoveMargin below beta.
- const Value NullMoveMargin = Value(0x300);
+ const Value NullMoveMargin = Value(0x200);
// If the TT move is at least SingleReplyMargin better then the
// remaining ones we will extend it.
@@ -190,13 +190,6 @@ namespace {
// Depth limit for razoring
const Depth RazorDepth = 4 * OnePly;
- // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
- const Value RazorMargins[6] = { Value(0x180), Value(0x300), Value(0x300), Value(0x3C0), Value(0x3C0), Value(0x3C0) };
-
- // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
- const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) };
-
-
/// Variables initialized by UCI options
// Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes
@@ -1453,12 +1446,12 @@ namespace {
// Null move search not allowed, try razoring
else if ( !value_is_mate(beta)
&& depth < RazorDepth
- && staticValue < beta - RazorApprMargins[int(depth) - 2]
+ && staticValue < beta - (depth > OnePly ? NullMoveMargin + 16 * depth : 2*NullMoveMargin)
&& ss[ply - 1].currentMove != MOVE_NULL
&& ttMove == MOVE_NONE
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{
- Value rbeta = beta - RazorMargins[int(depth) - 2];
+ Value rbeta = beta - (NullMoveMargin + 16 * depth);
Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
if (v < rbeta)
return v;
Please sign in to comment.
Something went wrong with that request. Please try again.