Transposition table and Fine#70

[konsolas]

Hi

I'm trying to implement a transposition table and I'm using the Fine#70 position to see if it's working properly.

My engine successfully finds a1b1, but the pv suddenly disappears at depth 25 and for some reason there's a search tree explosion at depth 36:

Code: Select all

position fen 8/k7/3p4/p2P1p2/P2P1P2/8/8/K7 w - -
go
info depth 1 score cp 65 time 0 nodes 7 nps 7000 hashhit 0 hashcut 0 ebf 7 pv a1b2
info depth 2 score cp 65 time 2 nodes 29 nps 9000 hashhit 1 hashcut 0 ebf 4.14286 pv a1b2 a7a6
info depth 3 score cp 65 time 3 nodes 94 nps 23000 hashhit 7 hashcut 2 ebf 3.24138 pv a1b2 a7a6 b2c3
info depth 4 score cp 65 time 3 nodes 209 nps 52000 hashhit 33 hashcut 17 ebf 2.2234 pv a1b2 a7a6 b2c3 a6b6
info depth 5 score cp 65 time 4 nodes 412 nps 82000 hashhit 95 hashcut 54 ebf 1.97129 pv a1b2 a7a6 b2c3 a6b6 c3c4
info depth 6 score cp 65 time 5 nodes 680 nps 113000 hashhit 216 hashcut 133 ebf 1.65049 pv a1b2 a7a6 b2c3 a6b6 c3c4 b6a
6
info depth 7 score cp 65 time 6 nodes 1038 nps 148000 hashhit 402 hashcut 256 ebf 1.52647 pv a1b2 a7a6 b2c3 a6b6 c3c4 b6
a6 c4d3
info depth 8 score cp 65 time 9 nodes 1435 nps 143000 hashhit 671 hashcut 440 ebf 1.38247 pv a1b2 a7a6 b2c3 a6b6 c3c4 b6
a6 c4d3 a6b6
info depth 9 score cp 65 time 10 nodes 1923 nps 174000 hashhit 998 hashcut 664 ebf 1.34007 pv a1b2 a7a6 b2c3 a6b6 c3c4 b
6a6 c4d3 a6b6 d3c4
info depth 10 score cp 65 time 12 nodes 2495 nps 191000 hashhit 1412 hashcut 946 ebf 1.29745 pv a1b2 a7a6 b2c3 a6b6 c3c4
 b6a6 c4d3 a6b6 d3c4
info depth 11 score cp 65 time 13 nodes 3178 nps 227000 hashhit 1896 hashcut 1275 ebf 1.27375 pv a1b2 a7a6 b2c3 a6b6 c3c
4 b6a6 c4d3 a6b6 d3c4
info depth 12 score cp 65 time 14 nodes 3925 nps 261000 hashhit 2470 hashcut 1671 ebf 1.23505 pv a1b2 a7a6 b2c3 a6b6 c3c
4 b6a6 c4d3 a6b6 d3c4
info depth 13 score cp 65 time 15 nodes 4781 nps 298000 hashhit 3111 hashcut 2111 ebf 1.21809 pv a1b2 a7a6 b2c3 a6b6 c3c
4 b6a6 c4d3 a6b6 d3c4
info depth 14 score cp 65 time 17 nodes 5802 nps 322000 hashhit 3844 hashcut 2609 ebf 1.21355 pv a1b2 a7a6 b2c3 a6b6 c3c
4 b6a6 c4d3 a6b6 d3c4
info depth 15 score cp 65 time 19 nodes 6940 nps 347000 hashhit 4696 hashcut 3191 ebf 1.19614 pv a1b2 a7a6 b2c3 a6b6 c3c
4 b6a6 c4d3 a6b6 d3c4
info depth 16 score cp 65 time 21 nodes 9171 nps 416000 hashhit 6053 hashcut 4224 ebf 1.32147 pv a1b2 a7a6 b2c3 a6b6 c3c
4 b6a6 c4d3 a6b6 d3c4
info depth 17 score cp 65 time 23 nodes 11505 nps 479000 hashhit 7800 hashcut 5425 ebf 1.2545 pv a1b2 a7a6 b2c3 a6b6 c3c
4 b6a6 c4d3 a6b6 d3c4
info depth 18 score cp 65 time 25 nodes 15053 nps 578000 hashhit 10078 hashcut 7042 ebf 1.30839 pv a1b2 a7a6 b2c3 a6b6 c
3c4 b6a6 c4d3 a6b6 d3c4
info depth 19 score cp 65 time 28 nodes 19534 nps 673000 hashhit 13412 hashcut 9301 ebf 1.29768 pv a1b2 a7a6 b2c3 a6b6 c
3c4 b6a6 c4d3 a6b6 d3c4
info depth 20 score cp 152 time 32 nodes 34024 nps 1031000 hashhit 24192 hashcut 17044 ebf 1.74178 pv a1b1 a7b7 b1c1 b7c
7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5a5 h5g4 a5b6 g4f4 b6c7 f4e3
info depth 21 score cp 152 time 37 nodes 47390 nps 1247000 hashhit 33366 hashcut 23423 ebf 1.39284 pv a1b1 a7b7 b1c1 b7c
7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5a5 h5g4 a5b6 g4f4 b6c7 f4e3 c7d6
info depth 22 score cp 152 time 42 nodes 68059 nps 1582000 hashhit 47254 hashcut 32803 ebf 1.43615 pv a1b1 a7b7 b1c1 b7c
7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5a5 h5g4 a5b6 g4f4 a4a5 f4e3 b6c7 f5f4
info depth 23 score cp 177 time 48 nodes 98690 nps 2014000 hashhit 66281 hashcut 45390 ebf 1.45007 pv a1b1 a7b7 b1c1 b7c
7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5a5 h5g4 a5b6 g4f4 b6c7 f4e3 c7d6 e3d4 a4a5
info depth 24 score cp 152 time 56 nodes 133112 nps 2335000 hashhit 88038 hashcut 60144 ebf 1.34879 pv a1b1 a7b7 b1c1 b7
c7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5a5 h5g4 a5b6 g4f4 a4a5 f4e3 b6c7 e3d4 c7d6 f5f4
info depth 25 score cp 237 time 62 nodes 168192 nps 2669000 hashhit 108930 hashcut 74289 ebf 1.26354 pv a1b1 a7a6 b1c2
info depth 26 score cp 237 time 70 nodes 213801 nps 3011000 hashhit 137796 hashcut 93829 ebf 1.27117 pv a1b1 a7a6 b1c2
info depth 27 score cp 237 time 80 nodes 296886 nps 3665000 hashhit 185619 hashcut 126290 ebf 1.38861 pv a1b1 a7a6 b1c2

info depth 28 score cp 237 time 96 nodes 409046 nps 4216000 hashhit 253032 hashcut 172841 ebf 1.37779 pv a1b1 a7a6 b1c2

info depth 29 score cp 237 time 116 nodes 574502 nps 4910000 hashhit 337249 hashcut 230069 ebf 1.40449 pv a1b1 a7a6 b1c2

info depth 30 score cp 237 time 146 nodes 789112 nps 5368000 hashhit 457585 hashcut 312476 ebf 1.37356 pv a1b1 a7a6 b1c2

info depth 31 score cp 237 time 194 nodes 1244199 nps 6380000 hashhit 645997 hashcut 444448 ebf 1.57671 pv a1b1 a7a6 b1c
2
info depth 32 score cp 237 time 294 nodes 1933203 nps 6553000 hashhit 967112 hashcut 661558 ebf 1.55377 pv a1b1 a7a6 b1c
2
info depth 33 score cp 237 time 428 nodes 3275981 nps 7636000 hashhit 1415270 hashcut 966488 ebf 1.69459 pv a1b1 a7a6 b1
c2
info depth 34 score cp 237 time 714 nodes 5334728 nps 7461000 hashhit 2214888 hashcut 1526138 ebf 1.62844 pv a1b1 a7a6 b
1c2
info depth 35 score cp 381 time 1069 nodes 8852241 nps 8273000 hashhit 3109260 hashcut 2169696 ebf 1.65936 pv a1b1 a7a6
b1c2
info depth 36 score cp 381 time 7720 nodes 62571450 nps 8104000 hashhit 27631420 hashcut 23571161 ebf 7.06843 pv a1b1 a7
a6 b1c2
info depth 37 score cp 1275 time 22895 nodes 267105035 nps 11666000 hashhit 72212330 hashcut 59508136 ebf 4.2688 pv a1b1
 a7b7 b1c1 b7c7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5c6 h5g4 c6d6 g4f4 d6e6 f4g4 d5d6 f5f4 d6d7 f4f3 d7d8
 f3f2 d8f6 g4g3 d4d5 g3g2 f6g6 g2h1 g6e4 h1h2 e4e5 h2g1 d5d6
info depth 38 score cp 1334 time 48249 nodes 466954019 nps 9677000 hashhit 176566121 hashcut 147604506 ebf 1.7482 pv a1b
1 a7b7 b1c1 b7c7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5c6 h5g4 c6d6 g4f4 d6e6 f4g4 d5d6 f5f4 d6d7 f4f3 d7d
8 f3f2 d8g8 g4f3 g8f8 f3e2 f8f2 e2f2
info depth 39 score cp 1334 time 90212 nodes 980831619 nps 10872000 hashhit 306610481 hashcut 252610993 ebf 2.10049 pv a
1b1 a7b7 b1c1 b7c7 c1d1 c7d7 d1c2 d7e7 c2d3 e7f6 d3c4 f6g6 c4b5 g6h5 b5c6 h5g4 c6d6 g4f4 d6e7 f4e3 d5d6 f5f4 d6d7 f4f3 d
7d8 f3f2 d8f8 e3e2 d4d5 f2f1 f8f1 e2f1 d5d6 f1e1 d6d7 e1f1 d7d8 f1g2

I'm also getting the same strange behaviour with the pv getting cutoff in other positions now, such as the following:

Code: Select all

position fen 4k3/8/8/8/8/8/4P3/4K3 w - - 0 1
go
info depth 1 score cp 127 time 0 nodes 13 nps 13000 hashhit 0 hashcut 0 ebf 13 pv e2e4
info depth 2 score cp 127 time 1 nodes 50 nps 25000 hashhit 1 hashcut 0 ebf 3.84615 pv e2e4 e8d7
info depth 3 score cp 152 time 2 nodes 172 nps 57000 hashhit 13 hashcut 5 ebf 3.44 pv e2e4 e8d7 e4e5
info depth 4 score cp 152 time 3 nodes 420 nps 105000 hashhit 51 hashcut 26 ebf 2.44186 pv e2e4 e8d7 e4e5 d7c6
info depth 5 score cp 127 time 5 nodes 1266 nps 211000 hashhit 189 hashcut 98 ebf 3.01429 pv e2e4 e8d7 e1f2 d7d6 f2g3
info depth 6 score cp 127 time 6 nodes 2704 nps 386000 hashhit 578 hashcut 332 ebf 2.13586 pv e2e4 e8d7 e1f2 d7d6 f2g3 d
6c5
info depth 7 score cp 127 time 8 nodes 5573 nps 619000 hashhit 1339 hashcut 830 ebf 2.06102 pv e2e4 e8d7 e1f2 d7c6 f2g3
c6d6 g3h4
info depth 8 score cp 127 time 10 nodes 10289 nps 935000 hashhit 2870 hashcut 1840 ebf 1.84622 pv e2e4 e8d7 e1f2 d7c6 f2
g3 c6d6 g3h4 d6c5
info depth 9 score cp 152 time 13 nodes 24471 nps 1747000 hashhit 7411 hashcut 4879 ebf 2.37837 pv e1f2 e8d7 f2g3 d7c6 e
2e4 c6c5
info depth 10 score cp 152 time 16 nodes 37917 nps 2230000 hashhit 12312 hashcut 8090 ebf 1.54947 pv e2e4 e8d7 e1f2 d7c6
 f2g3 c6c5 e4e5 c5d5 g3f4 d5c4
info depth 11 score cp 152 time 19 nodes 59588 nps 2979000 hashhit 20916 hashcut 13843 ebf 1.57154 pv e2e4 e8d7 e1f2 d7c
6 f2g3 c6b5 e4e5 b5c5 g3g4 c5d5 g4f5
info depth 12 score cp 152 time 24 nodes 93998 nps 3759000 hashhit 34578 hashcut 22783 ebf 1.57747 pv e2e4 e8d7 e1f2 d7c
6 f2g3 c6b5 e4e5 b5c5 g3g4 c5d5 g4f5 d5c4
info depth 13 score cp 182 time 34 nodes 179797 nps 5137000 hashhit 69378 hashcut 46708 ebf 1.91277 pv e1f2 e8d7 f2g3 d7
c6 e2e4 c6b5
info depth 14 score cp 182 time 41 nodes 248942 nps 5927000 hashhit 102264 hashcut 69527 ebf 1.38457 pv e2e4 e8d7 e1f2 d
7c6 f2g3 c6b5 e4e5 b5c5 g3g4 c5d5 g4f5 d5c4 e5e6 c4b3
info depth 15 score cp 182 time 53 nodes 357140 nps 6613000 hashhit 150205 hashcut 102662 ebf 1.43463 pv e2e4 e8d7 e1f2
d7c6 f2g3 c6b5 e4e5 b5c5 g3g4 c5b5 e5e6 b5c6 g4g5 c6d6 g5f6
info depth 16 score cp 182 time 68 nodes 488872 nps 7085000 hashhit 221902 hashcut 153610 ebf 1.36885 pv e2e4 e8d7 e1f2
d7c6 f2g3 c6b5 e4e5 b5c5 g3g4 c5b5 e5e6 b5c6 g4g5 c6d6 g5f6 d6c5
info depth 17 score cp 182 time 95 nodes 822022 nps 8562000 hashhit 368171 hashcut 261222 ebf 1.68147 pv e2e4 e8d7 e1f2
d7c6 f2g3 c6c5 e4e5 c5d5 g3f4 d5e6 f4e4 e6e7 e4f5 e7f7 e5e6 f7e7 f5e5
info depth 18 score cp 203 time 134 nodes 1217362 nps 9017000 hashhit 615761 hashcut 452111 ebf 1.48094 pv e1f2 e8d7 f2g
3 d7c6 e2e4 c6b5
info depth 19 score cp 203 time 191 nodes 2114701 nps 11014000 hashhit 929595 hashcut 695079 ebf 1.73712 pv e2e4 e8d7 e1
f2 d7c6 f2g3 c6b5 e4e5 b5c5 g3g4 c5b5 e5e6 b5c6 g4g5 c6d6 g5f6 d6c6 e6e7 c6d7 f6f7
info depth 20 score cp 203 time 470 nodes 5007761 nps 10632000 hashhit 3022525 hashcut 2451773 ebf 2.36807 pv e2e4 e8d7
e1f2 d7c6 f2g3 c6b5 e4e5 b5c5 g3g4 c5b5 e5e6 b5c6 g4g5 c6d6 g5f6 d6c6 e6e7 c6d7 f6f7 d7c6
info depth 21 score cp 203 time 1005 nodes 13319412 nps 13239000 hashhit 6208562 hashcut 5091262 ebf 2.65975 pv e2e4 e8d
7 e1f2 d7c6 f2g3 c6c5 e4e5 c5b5 e5e6 b5c6 g3g4
info depth 22 score cp 182 time 2392 nodes 27922160 nps 11668000 hashhit 18051103 hashcut 15056157 ebf 2.09635 pv e2e4 e
8d7 e1f2 d7c6 f2g3 c6d6 g3g4 d6e5 g4f3 e5d6 f3g4 d6e5 g4f3 e5d6 f3f4 d6e6 e4e5 e6d7 f4g5
info depth 23 score cp 1148 time 4412 nodes 59401766 nps 13460000 hashhit 32203649 hashcut 27162533 ebf 2.12741 pv e1f2
e8d7 f2f3 d7c6 f3g4 c6c5 e2e4 c5c6
info depth 24 score cp 1160 time 5850 nodes 74808901 nps 12785000 hashhit 45701515 hashcut 38905451 ebf 1.25937 pv e1f2
e8d7 f2g3 d7c6 g3g4 c6c5 e2e4 c5c6
info depth 25 score cp 1160 time 7543 nodes 100138137 nps 13273000 hashhit 58209711 hashcut 49553734 ebf 1.33859 pv e1f2
 e8f8 f2g3 f8e7 g3g4 e7e6 g4f4
info depth 26 score cp 1285 time 9954 nodes 125201880 nps 12576000 hashhit 80219905 hashcut 68661728 ebf 1.25029 pv e1f2
 e8f8 f2g3 f8e7 g3g4 e7e6 g4f4
info depth 27 score cp 1338 time 11656 nodes 149375023 nps 12814000 hashhit 93297469 hashcut 79863555 ebf 1.19307 pv e1f
2 e8d7 f2g3 d7c6 e2e3 c6b5 e3e4 b5a4 e4e5 a4b5 g3h4 b5c5 h4g5 c5b5 e5e6 b5c6 g5g6 c6b5 e6e7 b5c6 e7e8 c6c5 e8h8 c5b4 h8h
5 b4a3 h5e5
info depth 28 score cp 1338 time 14003 nodes 173777683 nps 12409000 hashhit 115362362 hashcut 99169710 ebf 1.16337 pv e1
f2 e8d7 f2g3 d7c6 e2e3 c6b5 e3e4 b5a4 e4e5 a4b5 g3h4 b5c5 h4g5 c5b5 e5e6 b5c6 g5g6 c6d6 g6f7 d6c5 e6e7 c5b4 e7e8 b4a3 e8
h8 a3a2 h8e5 a2b1
info depth 29 score cp 1338 time 24096 nodes 322730828 nps 13392000 hashhit 196387382 hashcut 168577137 ebf 1.85715 pv e
1f2 e8d7 f2g3 d7c6 e2e3 c6b5 e3e4 b5c5

My search is just a simple PVS implementation without any forward pruning/anything else: https://gist.github.com/konsolas/33a940 ... 9a3bca7aba

Could anyone have a quick look to see if they can spot the problem? It's probably something obvious but I can't see it.

[JVMerlino]

I haven't taken the time to look at your code. But unless you have specific code to recreate the full PV, then this is not unexpected behavior after implementing a transposition table. At some point down your main PV branch, you'll get a hash hit that will end the search on that branch. If that branch turns out to be best, then that's as far as you needed to search to get a best move, so that's all you have to print.

Some engines write code to walk the transposition table from the root to the end of the PV branch when it comes time to print their PV. I never bothered with it.

As for your explosion at depth 36, this is also not unexpected. That could be about the time the engine starts to spot potential checkmates. If you haven't implemented aspiration windows, then it could take a long time to resolve your full-width search at the root. If you have implemented aspiration windows, then it is trivial to print out the results from a reduced window search to see if it ended with a fail-high or fail-low.

Here's some of Myrddin's output on the same position to show you what I mean:

Code: Select all

42    799    346      4916191 a1b1 a7b7 b1c1 b7c7 c1d1 c7b7 d1e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f7 h4g5 f7g7 g5f5 g7f7 f5e4 f7f8 f4f5 f8f7 e4d3 f7f6 d3c4 f6f5 c4b5 f5e4 b5a5 e4d5 a5b6 d5d4 a4a5 d6d5 a5a6 d4e5 a6a7 d5d4 a7a8Q d4d3 a8e8 e5d5 e8c6 d5d4 (1417 KNPS)
43    802    362      5147122 a1b1 a7b7 b1c1 b7c7 c1d1 c7b7 d1e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f7 h4g5 f7g7 g5f5 g7f7 f5e4 f7f8 f4f5 f8f7 e4d3 f7f6 d3c4 f6f5 c4b5 f5e4 b5a5 e4d5 a5b6 d5d4 a4a5 d6d5 a5a6 d4e3 a6a7 d5d4 a7a8Q d4d3 a8e8 e3d4 (1419 KNPS)
44    808    389      5552173 a1b1 a7b7 b1c1 b7c7 c1d1 c7b7 d1e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f7 h4g5 f7g7 g5f5 g7f7 f5e4 f7f8 f4f5 f8f7 e4d3 f7f6 d3c4 f6f5 c4b5 f5e4 b5a5 e4d5 a5b6 d5d4 a4a5 d6d5 a5a6 d4e3 a6a7 d5d4 a7a8Q d4d3 a8e8 e3d4 e8d7 d4e4 d7e6 e4d4 b6b5 (1427 KNPS)
45    811    450      6365113 a1b1 a7b7 b1c1 b7c7 c1d1 c7b7 d1e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f7 h4g5 f7g7 g5f5 g7f7 f5e4 f7f8 f4f5 f8f7 e4d3 f7f6 d3c4 f6f5 c4b5 f5e4 b5a5 e4d5 a5b6 d5d4 a4a5 d6d5 a5a6 d4e3 a6a7 d5d4 a7a8Q d4d3 a8e8 e3d4 e8d7 d4e3 d7e7 e3d4 e7f6 (1414 KNPS)
46    820    525      7361146 a1b1 a7b7 b1c1 b7c7 c1d1 c7b7 d1e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f7 h4g5 f7g7 g5f5 g7f7 f5e4 f7f8 f4f5 f8f7 e4d3 f7f6 d3c4 f6f5 c4b5 f5e4 b5a5 e4d5 a5b6 d5d4 a4a5 d6d5 a5a6 d4e3 a6a7 d5d4 a7a8Q d4d3 a8e8 e3d4 e8d8 d4e3 d8e7 (1402 KNPS)
47    820    559      7835869 a1b1 a7b7 b1c1 b7c7 c1d1 c7b7 d1e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f7 h4g5 f7g7 g5f5 g7f7 f5e4 f7f8 f4f5 f8f7 e4d3 f7f6 d3c4 f6f5 c4b5 f5e4 b5a5 e4d5 a5b6 d5d4 a4a5 d6d5 a5a6 d4e3 a6a7 d5d4 a7a8Q d4d3 a8e8 e3d4 e8d8 d4e3 d8e7 e3d4 e7c5 d4e4 c5f2 e4d5 f2f5 d5d4 (1400 KNPS)
48    820    628      8779082 a1b1 a7b7 b1c1 b7c7 c1d1 c7b7 d1e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f7 h4g5 f7g7 g5f5 g7f7 f5e4 f7f8 f4f5 f8f7 e4d3 f7f6 d3c4 f6f5 c4b5 f5e4 b5a5 e4d5 a5b6 d5d4 a4a5 d6d5 a5a6 d4e3 a6a7 d5d4 a7a8Q d4d3 a8e8 e3f2 e8f7 f2e3 f7e7 d3d2 (1397 KNPS)
49    836    796     11104044 a1b1! (1393 KNPS)
49    852   1257     17468958 a1b1! (1388 KNPS)
49    884   1512     20865850 a1b1! (1379 KNPS)
49    932   1695     23473400 a1b1! (1384 KNPS)
49    996   2234     30957819 a1b1! (1385 KNPS)
49   1076  16100    171935468 a1b1! (1067 KNPS)
49   1076  16435    176286339 a1b1 a7b7 b1c1 b7b6 c1d2 b6b7 d2e2 b7c7 e2f2 c7d8 f2g3 d8e7 g3h4 e7f6 h4h5 f6f7 h5g5 f7g7 g5f5 g7f7 f5e4 f7e7 e4d3 e7f6 d3c4 f6f5 c4b5 f5f4 b5a5 f4e4 a5b5 e4d5 a4a5 d5d4 a5a6 d4d5 a6a7 d5d4 a7a8Q d4e3 a8a3 e3e2 a3b2 e2f3 b5c6 d6d5 c6d5 f3g3 d5d6 g3h4 d6e6 (1072 KNPS)

So, about six seconds to get to depth 48, then close to three minutes to get to depth 49.

Make sense?

jm