Author: scott farrell
Date: 17:07:55 08/27/02
Guys,
I am playing around with IID.
Currently its implemented to do an IID search only where:
- its a PV node
- there is no best move already in the hash table
- (alpha != beta - 1) (this is from R.Hyatt as we both use PVS)
- its not a qsearch
- not a null move search
I am trying to see what using IDD at all nodes where (alpha != beta - 1) does
(other than just burn more nodes). A few things I found:
- it does go faster
- it seems to 'cover up' refutations until the next ply or so. Which seems in
line with playing around with PVS searches. I am judging this on a few test
positions, plus wac scores at 1 sec/position.
What I want to know is there anything inherently risky with IDD at PVS nodes -
or is it more like dumb luck that this happens (ie. interaction with something
else like null moves, or extensions or qsearch or something).
The test position below shows the new way takes until depth 9 to solve with
B6D7, and the standard IDD (not used at PVS nodes) finds it at depth 7. The
branching factor (bf) and average bf (avbf) are lower on IDD at all nodes, the
beta cuttoff on first move (bc%) is always higher, and the PV on first move(pv%)
is always higher also.
Here is one test position, and my analysis both ways, and crafty's analysis at
the end:
7k/pp3p1p/1np5/5N2/1P2P1NR/7P/3r2PK/2r5/ b - - 0 50
this is my analysis WITH IDD on PVS nodes as well (modified to
alpha=alpha-pawn/2 and research at alpha=alpha-pawn)
, D4.0(3): 4.34 : C1C2 , 0.44/99999.0 secs - NPS: 15827 AvCut: 1.3
itdeep:709/518, ks:6/-50, pp:0(0)/0(0), mateN: 1, mateNQ: 1, threatN: 1/1, N:
5190, nmN: 1221, nmNq: 45, qN: 508, cHit: 97%, cqHit: 0%, cUse%: 102, bc%:84,
pv%:55, pvs%:90,pc%:83,pv:C1C2 G4E3 C2A2 E3C2
, D5.0(3): 5.44 : C1C2 , 0.55/99999.0 secs - NPS: 26044 , bf:2.06, avbf:2.06
AvCut: 1.5 itdeep:1208/786, ks:6/-50, pp:0(0)/0(0), mateN: 1, mateNQ: 2,
threatN: 1/2, N: 9889, nmN: 3427, nmNq: 169, qN: 839, cHit: 90%, cqHit: 2%,
cUse%: 92, bc%:93, pv%:65, pvs%:95,pc%:66,pv:C1C2 H2G3 C2B2 G3F4 B2B4
, D6.0(5): 4.07 : C1C2 , 0.77/99999.0 secs - NPS: 48717 , bf:2.62, avbf:2.34
AvCut: 0.5 itdeep:2489/1705, ks:6/-50, pp:0(0)/0(0), mateN: 1, mateNQ: 2,
threatN: 6/8, N: 23059, nmN: 12629, nmNq: 414, qN: 1410, cHit: 81%, cqHit: 1%,
cUse%: 82, bc%:91, pv%:70, pvs%:96,pc%:96,pv:C1C2 G4E3 C2B2 E4E5 B2A2 E3C4
, D7.0(5): 4.69 : C1C2 , 1.7/99999.0 secs - NPS: 75524 , bf:3.42, avbf:2.7
AvCut: 0.7 itdeep:7605/4497, ks:6/-50, pp:0(0)/0(0), mateN: 38, mateNQ: 41,
threatN: 65/73, N: 75246, nmN: 46335, nmNq: 2902, qN: 3907, cHit: 88%, cqHit:
3%, cUse%: 91, bc%:91, pv%:53, pvs%:97,pc%:83,pv:C1C2 G4E3 C2B2 E4E5 F7F6 E5F6
B2B4
, D8.0(4): 3.9 : C1C2 , 3.57/99999.0 secs - NPS: 87529 , bf:2.43, avbf:2.63
AvCut: 0.6 itdeep:16294/10245, ks:6/-50, pp:0(0)/0(0), mateN: 69, mateNQ: 72,
threatN: 82/155, N: 152362, nmN: 143325, nmNq: 8053, qN: 8738, cHit: 136%,
cqHit: 3%, cUse%: 142, bc%:87, pv%:63, pvs%:95,pc%:93,pv:C1C2 G4E3 C2C3 H4G4
B6C4 G4G7 C4E3 F5E3
, D9.0(5): 4.54 : B6D7 , 12.41/99999.0 secs - NPS: 94122 , bf:3.74, avbf:2.85
AvCut: 0.8 itdeep:63875/39147, ks:-94/-50, pp:0(0)/0(0), mateN: 617, mateNQ:
456, threatN: 1104/1259, N: 611739, nmN: 469479, nmNq: 37541, qN: 49297, cHit:
104%, cqHit: 5%, cUse%: 112, bc%:86, pv%:63, pvs%:95,pc%:85,pcc:2,pv:B6D7 F5H6
F7F5 E4F5 C1E1 F5F6 E1E2 H6F7 H8G8
, D10.0(5): 3.85 : B6D7 , 22.46/99999.0 secs - NPS: 96397 , bf:1.85, avbf:2.69
AvCut: 0.8 itdeep:108994/69136, ks:-94/-50, pp:0(0)/0(0), mateN: 1147, mateNQ:
583, threatN: 1124/2383, N: 965575, nmN: 1049738, nmNq: 70242, qN: 79514, cHit:
124%, cqHit: 5%, cUse%: 132, bc%:79, pv%:51, pvs%:93,pc%:93,pcc:15,pv:B6D7 F5H6
F7F6 H6F7
, D11.0(6): 4.14 : B6D7 , 45.7/99999.0 secs - NPS: 99338 , bf:2.1, avbf:2.6
AvCut: 0.9 itdeep:232115/140136, ks:-94/-50, pp:0(0)/0(0), mateN: 3492, mateNQ:
1537, threatN: 3679/6062, N: 1995167, nmN: 2213245, nmNq: 159329, qN: 171992,
cHit: 106%, cqHit: 6%, cUse%: 114, bc%:81, pv%:60, pvs%:94,pc%:93,pcc:84,pv:B6D7
H4H6 C1C2 G4E3 C2B2 H6D6 D7E5
, D12.0(6): 3.99 : B6D7 , 157.2/99999.0 secs - NPS: 95890 , bf:3.32, avbf:2.69
AvCut: 0.8 itdeep:769624/426178, ks:-94/-50, pp:0(0)/0(0), mateN: 6731, mateNQ:
3315, threatN: 9844/15906, N: 5544572, nmN: 8396397, nmNq: 641691, qN: 491247,
cHit: 91%, cqHit: 3%, cUse%: 95, bc%:81, pv%:62, pvs%:93,pc%:95,pcc:441,pv:B6D7
H4H6 C1E1
This is WITHOUT IDD at PVS
, D5.0(3): 5.44 : C1C2 , 0.55/99999.0 secs - NPS: 23151 , bf:2.1, avbf:2.1
AvCut: 1.5 itdeep:120/82, ks:6/-50, pp:0(0)/0(0), mateNQ: 4, threatN: 4/5, N:
8428, nmN: 3606, nmNq: 179, qN: 520, cHit: 52%, cqHit: 2%, cUse%: 54, bc%:92,
pv%:54, pvs%:94,pc%:65,pv:C1C2 H2G3 C2B2 G3F4 B2B4
, D6.0(5): 4.07 : C1C2 , 0.77/99999.0 secs - NPS: 42208 , bf:2.55, avbf:2.33
AvCut: 0.6 itdeep:139/99, ks:6/-50, pp:0(0)/0(0), mateNQ: 5, threatN: 15/20, N:
18982, nmN: 12457, nmNq: 457, qN: 604, cHit: 35%, cqHit: 0%, cUse%: 36, bc%:90,
pv%:54, pvs%:96,pc%:97,pv:C1C2 G4E3 C2B2 E4E5 B2A2 E3C4
, D7.0(5): 4.52 : B6D7 , 2.15/99999.0 secs - NPS: 79259 , bf:5.24, avbf:3.3
AvCut: 0.7 itdeep:717/536, ks:-94/-50, pp:0(0)/0(0), mateN: 9, mateNQ: 88,
threatN: 111/131, N: 97531, nmN: 63382, nmNq: 5029, qN: 4464, cHit: 63%, cqHit:
3%, cUse%: 66, bc%:87, pv%:47, pvs%:95,pc%:83,pv:B6D7 G4E3 D2E2 E3F1 C1C2 F1E3
C2D2
, D8.0(4): 3.88 : B6D7 , 5.0/99999.0 secs - NPS: 94497 , bf:2.77, avbf:3.17
AvCut: 0.5 itdeep:1305/930, ks:-94/-50, pp:0(0)/0(0), mateN: 9, mateNQ: 152,
threatN: 272/403, N: 238190, nmN: 212218, nmNq: 14846, qN: 7229, cHit: 110%,
cqHit: 3%, cUse%: 116, bc%:87, pv%:55, pvs%:96,pc%:94,pv:B6D7 H4H6 C6C5 B4B5
C5C4 H6D6 D2D6
, D9.0(5): 4.35 : B6D7 , 9.67/99999.0 secs - NPS: 98060 , bf:2.01, avbf:2.93
AvCut: 0.7 itdeep:1619/1099, ks:-94/-50, pp:0(0)/0(0), mateN: 28, mateNQ: 388,
threatN: 662/1065, N: 458553, nmN: 437865, nmNq: 33063, qN: 18755, cHit: 53%,
cqHit: 3%, cUse%: 55, bc%:84, pv%:60, pvs%:96,pc%:84,pcc:2,pv:B6D7 F5H6 C1F1
H4H5 D7F6 H6F7
, D10.0(6): 3.85 : B6D7 , 22.14/99999.0 secs - NPS: 98781 , bf:2.31, avbf:2.83
AvCut: 0.7 itdeep:1907/1296, ks:-94/-50, pp:0(0)/0(0), mateN: 29, mateNQ: 591,
threatN: 2058/3123, N: 897346, nmN: 1174774, nmNq: 81462, qN: 33440, cHit: 84%,
cqHit: 3%, cUse%: 86, bc%:79, pv%:44, pvs%:95,pc%:94,pcc:21,pv:B6D7 F5H6 F7F6
H6F7
, D11.0(6): 4.18 : B6D7 , 69.87/99999.0 secs - NPS: 101529 , bf:3.24, avbf:2.89
AvCut: 0.8 itdeep:2017/1351, ks:-94/-50, pp:0(0)/0(0), mateN: 29, mateNQ: 3115,
threatN: 8706/11829, N: 3192200, nmN: 3428197, nmNq: 298184, qN: 175260, cHit:
55%, cqHit: 2%, cUse%: 57, bc%:80, pv%:52, pvs%:97,pc%:92,pcc:199,pv:B6D7 H4H6
C6C5 B4C5
, D12.0(6): 3.9 : B6D7 , 249.58/99999.0 secs - NPS: 101829 , bf:3.58, avbf:2.98
AvCut: 0.8 itdeep:4407/2572, ks:-94/-50, pp:0(0)/0(0), mateN: 107, mateNQ: 7623,
threatN: 26643/38472, N: 9955212, nmN: 13709870, nmNq: 1249453, qN: 499897,
cHit: 60%, cqHit: 2%, cUse%: 61, bc%:77, pv%:54,
pvs%:94,pc%:-38,pcc:1261,pv:B6D7
this is craftys analysis of the position
(Ra2 was the move my program played in a bullet game - pretty dumb huh!! - hence
why I use this position to test)
({10:Mat06} 35. ... Ra2 36. Nf6 Rxg2+ 37. Kxg2 Rc2+ 38. Kg3 Rc3+ 39. Kg4 Rxh3
40. Rxh3 Nc4 41. Rxh7# +-)
({10:-5.14} 35. ... Nd7 36. Rh6 Rb1 37. Rd6 Rxd6 38. Nxd6 Kg7 39. Nxb7 h5 40.
Ne3 Rxb4 -+)
({10:-1.74} 35. ... Rcc2 36. Nf6 Rxg2+ 37. Kh1 Rh2+ 38. Kg1 Rcg2+ 39. Kf1 Rg7
40. Nxg7 Kxg7 41. Ne8+ Kg8 42. Nd6 Rb2 43. Rf4 Rb1+ 44. Kg2 Rb2+ 45. Kf3 -+)
({10:+2.46} 35. ... Nd5 36. exd5 Rcc2 37. Nge3 Rb2 38. Re4 h5 39. dxc6 bxc6 40.
Ng3 c5 41. bxc5 +-)
Thanks
Scott
sfarrell@icconsulting.com.au
sfarrellc@icc
(you read this far ?)
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.