Author: Dann Corbit
Date: 13:32:43 03/28/00
Go up one level in this thread
On March 28, 2000 at 15:34:02, Peter McKenzie wrote:
>[D]3qkbr1/1b1n1p1p/4pp2/rB6/P2p1B2/5N2/1P3PPP/R2Q1RK1 b - -
>
>The above position is number 30 from the GMG2 test suite (positions from a
>Larsen book), and causes my program's search to explode.
>
>Node counts for Lambchop 9.50, without recapture extension:
>6ply: 82K, 7ply: 193K, 8ply 1262K
>
>Node counts for Lambchop 9.50, normal version with recapture extension:
>6ply: 186K, 7ply: 2997K, this is a branching factor of about 15!!
>
>Does anyone else have a similar problem with this position?
>
>I'm not exactly sure why the search explosion happens because the recapture
>extension fires at only about 0.7% of all nodes.
>I restrict it to the following conditions:
>- don't allow 2 recapture extensions in a row
>- previous move must have been a swap (eg. BxN, RxR etc)
>- current move must be a capture by a lesser piece, or piece
>being captured must be unguarded.
>- material balance after the current move must be between -2 pawns and
>+2 pawns.
>
>Note: the recapture extension extends a whole ply.
>Perhaps my recapture conditions aren't very good, or maybe I just have a bug...
>input welcome!
>
>I also hacked together a version of LambChop using partial ply.
>
>Node counts for Lambchop 9.50, using 0.75ply recapture extension:
>6ply: 68K, 7ply: 159K, 8ply 1328K
>
>So maybe partial play (crafty does similar I believe) is a good solution. More
>testing required...
Amy seems to do very well as far as quickly traversing a ply:
TC: 40 moves in 14400 secs
TL: 315/1260
GamePhase: Opening
It Time Score principal Variation
5 1.1 -0.880 1. .. Bc5 2. Bg3 Bxf3 3. Qxf3 Ke7
5 1.3 -0.880 1. .. Bc5 2. Bg3 Bxf3 3. Qxf3 Ke7
6 2.2 -1.000 1. .. Bc5 2. Rc1 Qc8 3. Bd2 Rxg2+ 4. Kxg2
6 3.3 -1.000 1. .. Bc5 2. Rc1 Qc8 3. Bd2 Rxg2+ 4. Kxg2
7 5.2 -1.024 1. .. Bc5 2. Bg3 Bxf3 3. Qxf3 Ke7 4. Rfc1 e5
7 6.7 +++ 1. .. Be7
7 7.9 -0.992 1. .. Be7 2. Bg3 e5 3. Rc1 Ba6 4. Bxa6 Rxa6
7 9.3 +++ 1. .. e5
7 9.8 -0.944 1. .. e5 2. Bd2 Ra8 3. Rc1 Rc8 4. Rxc8 Qxc8
7 11.4 -0.944 1. .. e5 2. Bd2 Ra8 3. Rc1 Rc8 4. Rxc8 Qxc8
8 18.0 -0.896 1. .. e5 2. Bg3 Qa8 3. Rc1 Bxf3 4. gxf3 Qd8 5. Re1
8 22.8 -0.896 1. .. e5 2. Bg3 Qa8 3. Rc1 Bxf3 4. gxf3 Qd8 5. Re1
9 39.4 -0.928 1. .. e5 2. Bg3 Ra8 3. Qe2 Be7 4. Rac1 Rc8 5. Qd3 e4
9 1:24 -0.928 1. .. e5 2. Bg3 Ra8 3. Qe2 Be7 4. Rac1 Rc8 5. Qd3 e4
10 2:39 -0.944 1. .. e5 2. Bg3 Qa8 3. Re1 Bxf3 4. gxf3 Qd5 5. Qd3 Rg6 6.
Rac1
10 4:17 -0.944 1. .. e5 2. Bg3 Qa8 3. Re1 Bxf3 4. gxf3 Qd5 5. Qd3 Rg6 6.
Rac1
11 7:06 -0.928 1. .. e5 2. Bg3 Be7 3. Nh4 Ra8 4. Qd3 Rh8 5. Rfc1 Rc8 6.
Nf5
Nodes = 18398992, QPerc: 73 %, time = 426.13 secs, 43.2 kN/s
Extensions: Check: 747335 DblChk: 2172 DiscChk: 37570 SingReply: 54398
Recapture: 175293 Passed Pawn: 31 Zugzwang: 0
Hashing: Trans: 218340/4840084 = 4 % Pawn: 9730705/9765254 = 99 %
Eval: 3792872/13558126 = 27 %
EGTB Hits/Probes = 0/0
Hashtable 1: entries = 1048576, use = 602529
not solved!
solved 0 out of 1 (BT2630 = 1730, LCT2 = 1900, BS2830 = 2830)
Crafty hits the wall crossing ply 10. Up to that point, it traversed the pile
quickly each time.
search time set to 999.00.
using cpu time
Crafty 17.10 vs ferret
pondering enabled.
EGTB cache memory = 6M bytes.
hash table memory = 24M bytes.
pawn hash table memory = 8M bytes.
EGTB access enabled
using tbpath=e:/crafty/release/tb,F:/KBP
4 piece tablebase files found
1302kb of RAM used for TB indices and decompression tables
search nodes set to 100000000.
PFGA: EPD record: 1
middle-game phase
clearing hash tables
time surplus 0.00 time limit 16:39 (16:39)
nss depth time score variation (1)
Black(0): exit
5-> 1.55 -0.89 1. ... Bb4 2. Bg3 e5 3. Qd3 Rg6
6 2.49 -1.12 1. ... Bb4 2. Rc1 e5 3. Rc4 Qe7 4.
Rc7 Bxf3 5. Bxd7+
6 4.58 -1.05 1. ... Bc5 2. Bd2 Ra8 3. Re1 Bd6 4.
Nxd4 Rxg2+
6-> 8.71 -1.05 1. ... Bc5 2. Bd2 Ra8 3. Re1 Bd6 4.
Nxd4 Rxg2+
7 11.18 -1.03 1. ... Bc5 2. Bd2 Ra8 3. Re1 Qb6 4.
Bxd7+ Kxd7 5. b3 Ke8
7 16.81 -1.02 1. ... Bb4 2. Nh4 e5 3. Bd2 Bxd2 4.
Qxd2 Bc8 5. Rac1
7 37.24 -1.01 1. ... e5 2. Bd2 Ra7 3. Re1 Rg4 4.
Be2 Bc5
7-> 38.56 -1.01 1. ... e5 2. Bd2 Ra7 3. Re1 Rg4 4.
Be2 Bc5
8 44.22 -0.96 1. ... e5 2. Bd2 Qa8 3. Kh1 Ra7 4.
Bxd7+ Kxd7 5. Re1 Ke8 6. b4 <HT>
8-> 57.38 -0.96 1. ... e5 2. Bd2 Qa8 3. Kh1 Ra7 4.
Bxd7+ Kxd7 5. Re1 Ke8 6. b4 <HT>
9 1:16 -0.95 1. ... e5 2. Bd2 Qa8 3. Kh1 Ra7 4.
Rc1 Bxf3 5. gxf3 Qd8 6. Re1
9-> 1:10 -0.95 1. ... e5 2. Bd2 Qa8 3. Kh1 Ra7 4.
Rc1 Bxf3 5. gxf3 Qd8 6. Re1
10 3:48 -1.06 1. ... e5 2. Bg3 Rg7 3. Nh4 Bb4 4.
Qb3 Bc5 5. Nf5 Rg4 6. Qd3
10-> 12:33 -1.06 1. ... e5 2. Bg3 Rg7 3. Nh4 Bb4 4.
Qb3 Bc5 5. Nf5 Rg4 6. Qd3
time=12:59 cpu=97% mat=0 n=100037690 fh=90% nps=125173
ext-> checks=4362417 recaps=422158 pawns=14357 1rep=276875 thrt:45
00
predicted=0 nodes=100037690 evals=23625987
endgame tablebase-> probes done=0 successful=0
ColChess (which does not do any NULL move or tricky pruning) gives the following
result:
Please Input Name:-epd
epd.epd loaded OK!
Set Time Limit [5] :- 800
Log to File epd.out [YES/NO]? YES
Appending to output file!
Test #1 : Black to play
Current Position
----------------
. . . q k b r .
. b . n . p . p pP=Pawn
. . . . p p . . rR=Rook
r B . . . . . . nN=Knight lower=Black
P . . p . B . . bB=Bishop CAPS=White
. . . . . N . . qQ=Queen
. P . . . P P P kK=King
R . . Q . R K .
Thinking 2 114 30 1878 b7f3 d1f3
3 22 1762 55451 e6e5 f1e1 f8c5
4 1 4116 154370 e6e5 f4d2 a5a7 d1b3
5 26 12428 463863 e6e5 f4g3 d8a8 f3d4 b7g2
6 8 33738 1778747 e6e5 f4d2 a5a7 d1b3 f8d6 f1e1
7 11 130768 5493845 e6e5 f4g3 d8a8 f3d4 b7g2 d4e6 g2c6
8 -1 644727 35315152 e6e5 f4g3 f8c5 d1c2 b7f3 g2f3 d8c7 c2h7
9 -1 890360 43982781
---Answer: Rxb5 ~Incorrect-??
Correct So Far: 0[0]/1
Result: 0[0]/1 (0%)[0%]
This does not seem to indicate the same extremely high branching factor that you
have found. Quite likely, the extensions you have added are contributing to the
very high totals.
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.