Author: scott farrell
Date: 18:07:47 09/06/02
Go up one level in this thread
On September 06, 2002 at 16:10:56, Robert Hyatt wrote:
>On September 06, 2002 at 05:17:01, David Dory wrote:
>
>>On September 05, 2002 at 21:46:41, scott farrell wrote:
>>
>>>Hi guys,
>>>
>>>I hope someone can give me some ideas, or can understand this pattern.
>>>
>>>this is the fen position
>>>
>>>[D]7k/pp3p1p/1np5/5N2/1P2P1NR/7P/3r2PK/2r5 b - - 0 50
>>>
>>>clearly the best move is Nd7 (aka B6D7)
>>>Rcc2 (aka c1c2) is not too bad either
>>>The rest pretty much lead to mate.
>>>My program works that out pretty quickly, but changes its mind during depth 10
>>>to D2C2.
>>>When searching depth 11 - its sees that D2C2 leads straight to being mated (in 2
>>>plies - mate in 1 - I think). The move ordering obviously gets screwed up, and
>>>it does an almost reverse alpha-beta search.
>>>I assume this is a bug somewhere in my search, does anyone have any ideas?
>>>
>>>this is my programs analysis:
>>>
>>>d6/8(3) 4.28 0.38secs 6820 C1C2 G4E3 C2A2 H4G4 B6D7 G4G7
>>>->6/10(3) 4.28 0.71secs 38971 C1C2 G4E3 C2A2 H4G4 B6D7 G4G7
>>>d7/12(3) 4.59 0.88secs 55850 C1C2 F5E3 C2B2 G4F6 H8G7 F6H7 B2B4
>>>d7/12(4) 4.85 1.7secs 137123 B6D7 F5H6 F7F6 G4E3 H8G7 H6F5
>>>->7/12(4) 4.85 1.7secs 137141 B6D7 F5H6 F7F6 G4E3 H8G7 H6F5
>>>d8/12(3) 4.22 1.98secs 162918 B6D7 F5H6 F7F6 H4H5 C1C2 H6F7
>>>->8/14(4) 4.22 4.01secs 364580 B6D7 F5H6 F7F6 H4H5 C1C2 H6F7
>>>d9/16(4) 4.69 6.87secs 654405 B6D7 H4H6 C1C2 G4E3 C2B2 H6D6 D2D6
>>>->9/16(4) 4.69 7.36secs 711939 B6D7 H4H6 C1C2 G4E3 C2B2 H6D6 D2D6
>>>d10/18(4) 3.86 12.3secs 1292913 B6D7 H4H6 C6C5 B4B5 C1E1 F5D6 E1F1 D6C4 D2C2
>>>H6D6
>>>d10/18(4) 3.9 19.17secs 1941731 D2C2 H2G3 C6C5 B4C5
>>>->10/24(4) 3.9 30.43secs 3164993 D2C2
>>>d11/19(2) -501.99 30.59secs 3178776 PV miss at root:D2C2
>>>d11/20(3) -1.03 41.52secs 4470207 D2G2 H2G2 C1C2 G2F3 C2C3 F3E2 B6D7 F5D6
>>>H8G7 D6B7 C3G3 G4F2 G7F6
>>>d11/20(3) 3.89 43.01secs 4611313 C1C2 F5E3 C2B2 G4F6 H8G7 E4E5 G7F8 F6H7
>>>d11/22(4) 4.59 116.28secs 11658630 B6D7 G4E3 D7E5
>>>
>>>This is from crafty:
>>>
>>>({10:Mat06} 35. ... Ra2 36. Nf6 Rxg2+ 37. Kxg2 Rc2+ 38. Kg3 Rc3+ 39. Kg4 Rxh3
>>>40. Rxh3 Nc4 41. Rxh7# +-)
>>>(yes beleive it or not, my engine played Ra2 - a few months back without
>>>extensions)
>>>({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 +-)
>>>
>>>
>>>normal moves:
>>>C1H1,C1G1,C1F1,C1E1,C1D1,C1B1,C1A1,C1C2,C1C3,C1C4,C1C5,D2D1,D2G2,D2F2,D2E2,D2C2,
>>>D2B2,D2A2,D2D3,D2D4,D2D5,D2D6,D2D7,D2D8,C6C5,B6C4,B6A4,B6D5,B6D7,B6C8,B6A8,H7H5,
>>>H7H6,F7F6,A7A5,A7A6,H8G7,H8G8,
>>>OUT OF CHECK moves:
>>>C1H1,C1G1,C1F1,C1E1,C1D1,C1B1,C1A1,C1C2,C1C3,C1C4,C1C5,D2D1,D2G2,D2F2,D2E2,D2C2,
>>>D2B2,D2A2,D2D3,D2D4,D2D5,D2D6,D2D7,D2D8,C6C5,B6C4,B6A4,B6D5,B6D7,B6C8,B6A8,H7H5,
>>>H7H6,F7F6,A7A5,A7A6,H8G7,H8G8,
>>>qsearch moves:
>>>D2G2,
>>>sideotmove token:
>>>7k/pp3p1p/1np5/5N2/1P2P1NR/7P/3r2PK/2r5/ b - - 0 50
>>>searchProbeThread starting
>>>start search from 6 to 30
>>>
>>>Scott
>
>
>I don't see this as a "pattern" problem. It looks like you need to check
>two things:
>
>(1) your search extensions. IE are you extending on checks at least? and
>a whole ply?
>
>(2) are you sure your checkmate detection is working? Allowing a short mate
>with a 10 ply search suggests you are overlooking something. The question is,
>what? and why?
>
>Are you doing any odd stuff like futility pruning, razoring, null-move, etc?
Robert,
No futility code - other than 'stand-pat' in the Qsearch.
yes, adaptive null move.
I still cant find it.
Scott
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