The problem with adjudication based on score

[Dann Corbit]

Try this one in your favorite chess engine and you will see the problem immediately (unless some engine scores it zero):
[d]7r/6p1/7P/p1r1p1k1/Pp1pPp2/1PpP1Pp1/2P3P1/K6R w - -

[Albert Silver]

Try this one in your favorite chess engine and you will see the problem immediately (unless some engine scores it zero):
[d]7r/6p1/7P/p1r1p1k1/Pp1pPp2/1PpP1Pp1/2P3P1/K6R w - -

I did not send this to an engine, but am wondering what the problem is. White is dead lost, no? 1.hxg7 Rxh1+ 2.Ka2 Ra1+ 3.Kxa1 Rc8 0-1

[jp]

White is dead lost, no?

Draws because of fortress with Kf1 or stalemate with Ke2 and R on first rank.

[Graham Banks]

1.hxg7, Rg8; 2.Kb1, Rc7; 3.Kc1, R8xg7; 4. Kd1, Rh7; 5.Rg1, Rh2; 6.Ke2, Rgh7; 7.Kf1, Rh1; 8.Rxh1, Rxh1+; 9.Ke2, Rh2; 10.Kf1, Kf6 seems to win?

[Graham Banks]

Sorry. Try this:

1.hxg7, Rg8; 2.Kb1, Rc7; 3.Kc1, R8xg7; 4. Kd1, Rh7; 5.Rg1, Rh2; 6.Ke2, Rgh7; 7.Kf1, Rxg2+

[konsolas]

Do any engines correctly score

[d]4k3/rr6/2p1p1p1/1pPpPpPp/pP1P1P1P/P7/8/3K4 w - - 0 1

to be a draw?

[Joerg Oster]

Do any engines correctly score

[d]4k3/rr6/2p1p1p1/1pPpPpPp/pP1P1P1P/P7/8/3K4 w - - 0 1

to be a draw?

Yes.
Just recently added a 1st blockade detection rule to my SF fork.
Patch is here: https://github.com/joergoster/Stockfish ... 020293f1ef

Code: Select all

position fen 4k3/rr6/2p1p1p1/1pPpPpPp/pP1P1P1P/P7/8/3K4 w - - 0 1
d

 +---+---+---+---+---+---+---+---+
 |   |   |   |   | k |   |   |   |
 +---+---+---+---+---+---+---+---+
 | r | r |   |   |   |   |   |   |
 +---+---+---+---+---+---+---+---+
 |   |   | p |   | p |   | p |   |
 +---+---+---+---+---+---+---+---+
 |   | p | P | p | P | p | P | p |
 +---+---+---+---+---+---+---+---+
 | p | P |   | P |   | P |   | P |
 +---+---+---+---+---+---+---+---+
 | P |   |   |   |   |   |   |   |
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   |
 +---+---+---+---+---+---+---+---+
 |   |   |   | K |   |   |   |   |
 +---+---+---+---+---+---+---+---+

Fen: 4k3/rr6/2p1p1p1/1pPpPpPp/pP1P1P1P/P7/8/3K4 w - - 0 1
PositionKey: 00FEC3309217ABF3
MaterialKey: FB26979F6BE2A3DB
PawnKey:     A90DE04509EB6C76
Checkers: 
eval
     Term    |     White     |     Black     |     Total    
             |   MG     EG   |   MG     EG   |   MG     EG  
 ------------+---------------+---------------+--------------
    Material |   4.69   6.52 |  14.57  16.83 |  -9.88 -10.31
   Imbalance |   0.57   0.57 |   0.52   0.52 |   0.05   0.05
  Initiative |   ----   ---- |   ----   ---- |   0.00  -0.07
       Pawns |   0.79   0.03 |   0.69  -0.06 |   0.10   0.09
     Knights |   0.00   0.00 |   0.00   0.00 |   0.00   0.00
     Bishops |   0.00   0.00 |   0.00   0.00 |   0.00   0.00
       Rooks |   0.00   0.00 |   0.00   0.00 |   0.00   0.00
      Queens |   0.00   0.00 |   0.00   0.00 |   0.00   0.00
    Mobility |   0.00   0.00 |   0.22   1.03 |  -0.22  -1.03
 King safety |  -0.36  -0.18 |  -0.41  -0.12 |   0.06  -0.06
     Threats |   0.05   0.05 |   0.00   0.00 |   0.05   0.05
      Passed |   0.00   0.00 |   0.00   0.00 |   0.00   0.00
       Space |   0.00   0.00 |   0.00   0.00 |   0.00   0.00
 ------------+---------------+---------------+--------------
       Total |   ----   ---- |   ----   ---- |  -9.83 -11.26

Total evaluation: 0.10 (white side)

info depth 31 seldepth 32 multipv 1 score cp -10 nodes 26051077 nps 2604847 hashfull 152 tbhits 0 time 10001 pv d1e2 b7g7 e2f1 a7f7 f1g1 f7b7 g1f2 e8f8 f2g2 b7f7 g2h2 f7c7 h2g2 f8g8 g2f1 c7f7 f1g1 g8h8 g1g2 f7b7 g2f1 h8h7 f1g1 g7d7 g1h2 d7c7 h2g2 c7f7 g2h1 h7g8 h1g1
bestmove d1e2 ponder b7g7

[konsolas]

Nice! Have you considered PR'ing that change to the main version?

[chrisw]

Try this one in your favorite chess engine and you will see the problem immediately (unless some engine scores it zero):
[d]7r/6p1/7P/p1r1p1k1/Pp1pPp2/1PpP1Pp1/2P3P1/K6R w - -

I did not send this to an engine, but am wondering what the problem is. White is dead lost, no? 1.hxg7 Rxh1+ 2.Ka2 Ra1+ 3.Kxa1 Rc8 0-1

The problem is you saw only half the problem. Correct was to see the rook sac on a1 to avoid stalemate, but the same situation arises in the centre if black tries to maneouvre to pick up the g2 pawn, or tries to occupy the back rank. In effect there is no way into the white position for the remaining black rook. It’s an unusual fortress which black can horizon away for many moves.

[chrisw]

1.hxg7, Rg8; 2.Kb1, Rc7; 3.Kc1, R8xg7; 4. Kd1, Rh7; 5.Rg1, Rh2; 6.Ke2, Rgh7; 7.Kf1, Rh1; 8.Rxh1, Rxh1+; 9.Ke2, Rh2; 10.Kf1, Kf6 seems to win?

nope. after 4 Rh7, white exchanges rooks and the impenetrable by stalemate fortress is on, as in the main line