Syzygy question

[ernst]

I wonder how I can check that the syzygy dtz tablebases are working correctly, as it seems that an engine doesn't report them being used.

[ernst]

Nobody?

[zullil]

Here's something to try, inspired by a recent thread at the Rybka Forum.

I'm assuming you have 6-man syzygy tables?

With tablebases enabled, enter and search the following FENS:

8/8/8/6k1/3R2Pp/2b5/6K1/8 w - - 75 176

8/8/8/6k1/3R2Pp/2b5/6K1/8 w - - 1 176

The second search should show a win for White, but not the first.

Here's Stockfish from the command line:

Code: Select all

position fen 8/8/8/6k1/3R2Pp/2b5/6K1/8 w - - 75 176
go depth 5
info depth 1 seldepth 1 multipv 1 score cp 45 nodes 72 nps 36000 tbhits 1 time 2 pv d4e4
info depth 2 seldepth 2 multipv 1 score cp 45 nodes 85 nps 42500 tbhits 1 time 2 pv d4e4 c3a1
info depth 3 seldepth 3 multipv 1 score cp 45 nodes 118 nps 59000 tbhits 1 time 2 pv d4e4 c3b2 e4e2 g5g4 e2b2
info depth 4 seldepth 4 multipv 1 score cp 45 nodes 291 nps 145500 tbhits 1 time 2 pv d4e4 c3d2 e4c4 h4h3 g2h3
info depth 5 seldepth 5 multipv 1 score cp 45 nodes 482 nps 241000 tbhits 1 time 2 pv d4e4 c3d2 e4c4 d2e1 c4a4
bestmove d4e4 ponder c3d2

position fen 8/8/8/6k1/3R2Pp/2b5/6K1/8 w - - 1 176     
go depth 5
info depth 1 seldepth 1 multipv 1 score cp 12353 nodes 73 nps 36500 tbhits 1 time 2 pv d4e4
info depth 2 seldepth 2 multipv 1 score cp 12353 nodes 81 nps 40500 tbhits 1 time 2 pv d4e4 c3d2
info depth 3 seldepth 3 multipv 1 score cp 12353 nodes 95 nps 47500 tbhits 1 time 2 pv d4e4 c3d2 e4e2
info depth 4 seldepth 4 multipv 1 score cp 12353 nodes 129 nps 64500 tbhits 1 time 2 pv d4e4 c3d2 e4a4 d2c1
info depth 5 seldepth 5 multipv 1 score cp 12353 nodes 265 nps 132500 tbhits 1 time 2 pv d4e4 c3d2 e4c4 d2e1 c4a4
bestmove d4e4 ponder c3d2

[ernst]

Thank you, that was most helpful.