Author: Ratko V Tomic
Date: 07:56:08 10/16/99
Go up one level in this thread
> Of course, the effective branching factor will vary with the position.
> For some positions it will simply be fairly low. Others, higher. Or
> it can be low for many ply, and then suddenly be high at certain depths
> in the search.
Yes, I know it can vary. But B=3, with typical Crafty's nps (200 kN/s on Celeron
400Mhz) which I get in Fritz UI (which came with Crafty 16.6) didn't fit at all
the depths I saw it reach in the 15-30 seconds when I was trying it out. So I
took a position which had exactly 38 branching factor and measured the exact B
for depths 10, 11 and 12 plies, and indeed B was 4.5-4.7. Yes it varied with
depth, but just a little bit and nowhere near to bring the B down to 3. Now this
is in Fritz UI and what gets displayed as Nodes may not be the same what Crafty
diagnostics show as nodes, i.e. we're dealing with different definitions of
"total nodes." The position I tested is the from the game below, after black's
6th move (6 ...Nc6) and while white is thinking for 7th move (7. Bb5). What do
you get with your Crafty for B here (and what are the exact "node totals" from
which B was computed) at depths 10, 11 and 12?
[Event "Level=30"av. "]
[Site "Lexington, MA"]
[Date "1999.09.11"]
[Round "?"]
[White "Tomic, Ratko"]
[Black "Hiarcs 7.32"]
[Result "1-0"]
[ECO "B41"]
[PlyCount "105"]
[EventDate "1999.09.07"]
{16384kB, HIARCS.ctg. C400
} 1. e4 {0} 1... c5 {0} 2. Nf3 {9} 2... e6 {0} 3.
d4 {2} 3... cxd4 {0} 4. Nxd4 {2} 4... a6 {0} 5. c4 {3} 5... Nf6 {0} 6. Nc3 {3}
6... Bb4 {0} 7. Bd3 {12} 7... Nc6 {0} 8. Nxc6 {6} 8... dxc6 {0} 9. e5 {6} 9...
Qa5 {0} 10. exf6 {5} 10... Bxc3+ {0} 11. bxc3 {4} 11... Qxc3+ {0} 12. Bd2 {8}
12... Qxd3 {0} 13. fxg7 {4} 13... Rg8 {0} 14. Bh6 {9} 14... Qc3+ {0} 15. Kf1 {3
} 15... Qxc4+ {0} 16. Kg1 {3} 16... Qh4 {0} 17. Qd2 {24} 17... e5 {-0.59/10 110
} 18. Rd1 {7} 18... Be6 {-0.59/9 68} 19. Bg5 {3} 19... Qd4 {-0.23/10 102} 20.
Bf6 {10} 20... Bxa2 {-0.38/9 52} 21. Qxd4 {5} 21... exd4 {-0.30/11 45} 22. Rxd4
{6} 22... c5 {-0.30/12 51} 23. Rd2 {24} 23... Be6 {3.02/12 195} 24. f4 {3}
24... c4 {3.02/12 32} 25. Kf2 {4} 25... c3 {3.08/12 35} 26. Rc2 {13} 26... Rd8
{2.71/9 161} 27. Rxc3 {46} 27... Rd2+ {3.40/8 53} 28. Ke3 {4} 28... Rxg7 {
3.41/9 16} 29. Bxg7 {7} 29... Rxg2 {3.81/10 11} 30. Bf6 {16} 30... Rg6 {
3.87/9 23} 31. Bh4 {22} 31... Bg4 {3.87/9 6} 32. Rc7 {11} 32... Rh6 {3.89/9 31}
33. Bg5 {38} 33... Re6+ {3.91/9 0} 34. Kd4 {24} 34... h6 {4.34/8 35} 35. Bh4 {3
} 35... b5 {4.95/9 95} 36. Re1 {11} 36... a5 {5.20/9 91} 37. Rb7 {14} 37...
Rxe1 {5.03/9 27} 38. Bxe1 {3} 38... b4 {5.13/9 13} 39. Ra7 {6} 39... Bd1 {
5.26/8 8} 40. Rxa5 {4} 40... b3 {5.66/8 38} 41. Ra7 {23} 41... Kf8 {5.52/8 22}
42. Kc3 {9} 42... Kg7 {5.44/10 32} 43. Rb7 {6} 43... Kg6 {5.51/9 20} 44. Rxb3 {
11} 44... Bxb3 {3.66/11 11} 45. Kxb3 {3} 45... Kf5 {3.74/13 14} 46. Bd2 {4}
46... Kg4 {3.56/14 41} 47. Kc4 {4} 47... Kh3 {4.18/15 82} 48. f5 {5} 48... Kg4
{4.73/14 37} 49. f6 {3} 49... Kf5 {5.98/15 61} 50. Bc3 {2} 50... Ke6 {
6.97/15 29} 51. Kc5 {6} 51... Kd7 {14.54/16 48} 52. Kd5 {3} 52... Kc7 {
18.09/17 38} 53. h4 {18.19/16 5} 1-0
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