From: Stéphane Nicolet <cassio@free.fr>
Date: Mon, 5 Dec 2016 17:49:07 +0000 (+0100)
Subject: Pawn flank attacks
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=0d33466bcd84d9d58ea7049b224f375ba6a51221;ds=sidebyside

Pawn flank attacks

This patch tweaks some pawn values to favor flank attacks.

The first part of the patch increases the midgame psqt values of external pawns to launch more attacks (credits to user GuardianRM for this idea), while the second part increases the endgame connection values for pawns on upper ranks.

Passed STC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 34997 W: 6328 L: 6055 D: 22614

and LTC:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 13844 W: 1832 L: 1650 D: 10362

Bench: 5884767
---

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 71ec3443..6e564c9d 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -197,7 +197,7 @@ void init() {
   {
       int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
       v += (apex ? v / 2 : 0);
-      Connected[opposed][phalanx][apex][r] = make_score(v, v * 5 / 8);
+      Connected[opposed][phalanx][apex][r] = make_score(v, v * (r-2) / 4);
   }
 }
 
diff --git a/src/psqt.cpp b/src/psqt.cpp
index 41a9b499..3addc288 100644
--- a/src/psqt.cpp
+++ b/src/psqt.cpp
@@ -39,12 +39,12 @@ const Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
   { },
   { // Pawn
    { S(  0, 0), S(  0, 0), S(  0, 0), S( 0, 0) },
-   { S(-16, 7), S(  1,-4), S(  7, 8), S( 3,-2) },
-   { S(-23,-4), S( -7,-5), S( 19, 5), S(24, 4) },
-   { S(-22, 3), S(-14, 3), S( 20,-8), S(35,-3) },
-   { S(-11, 8), S(  0, 9), S(  3, 7), S(21,-6) },
-   { S(-11, 8), S(-13,-5), S( -6, 2), S(-2, 4) },
-   { S( -9, 3), S( 15,-9), S( -8, 1), S(-4,18) }
+   { S(-11, 7), S(  6,-4), S(  7, 8), S( 3,-2) },
+   { S(-18,-4), S( -2,-5), S( 19, 5), S(24, 4) },
+   { S(-17, 3), S( -9, 3), S( 20,-8), S(35,-3) },
+   { S(- 6, 8), S(  5, 9), S(  3, 7), S(21,-6) },
+   { S(- 6, 8), S(- 8,-5), S( -6, 2), S(-2, 4) },
+   { S( -4, 3), S( 20,-9), S( -8, 1), S(-4,18) }
   },
   { // Knight
    { S(-143, -97), S(-96,-82), S(-80,-46), S(-73,-14) },