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Subject: Re: a couple of hard positions -- CM8000 results

Author: John Merlino

Date: 19:43:28 06/12/01

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On June 12, 2001 at 10:22:52, Jon Dart wrote:

>Here are a couple of positions from recent Arasan games:
>
>[D] 1n2r3/5Nk1/p4b2/2Qp3p/6p1/P5P1/P1B1q1PP/6RK b - -
>
>Here taking the piece with Kxf7 is fatal. It appears
>however that after Be7! Black doesn't have anything better
>than a draw.

It takes CM8000, on a PIII-600, 52 seconds to see the draw with Be7:

Time	Depth	Score	Positions	Moves
0:00	1/4	-0.69	8273		1...Kxf7 2. Qxd5+ Qe6 3. Qxh5+
					Kg8 4. Qh7+ Kf8 5. Rf1
0:00	2/5	-0.79	23576		1...Kxf7 2. Qxd5+ Kg7 3. Qxh5 Kf8
					4. Qh6+ Bg7 5. Qf4+ Kg8
0:00	2/6	-0.46	50737		1...Kxf7 2. Qxd5+ Kg7 3. Qxh5 Kf8
					4. Bf5 Qxa2 5. Qxg4 Qxa3
0:02	3/7	0.00	201443		1...Kxf7 2. Qxd5+ Qe6 3. Qxh5+
					Kf8 4. Bb3 Qd7 5. Rf1 Qg7 6. Qc5+
					Re7 7. Qc8+ Re8 8. Qc5+
0:07	3/8	0.00	523948		1...Kxf7 2. Qxd5+ Qe6 3. Qxh5+
					Kf8 4. Bb3 Qd7 5. Rf1 Qg7 6. Qc5+
					Re7 7. Qc8+ Re8 8. Qc5+
0:21	4/9	0.60	1707969		1...Kxf7 2. Qxd5+ Kg7 3. Qxh5 Kf8
					4. Bb3 Qe7 5. Qxg4 Qh7 6. Rf1 Nd7
					7. Be6
0:52	4/9	0.00	4072392		1...Be7 2. Qd4+ Bf6 3. Qxd5 Qxc2
					4. Nd6 Rf8 5. Qxh5 Qg6 6. Nf5+
					Kf7 7. Nd6+ Kg7
1:19	5/10	0.00	6276981		1...Be7 2. Qd4+ Bf6 3. Qxd5 Qxc2
					4. Nd6 Rf8 5. Qxh5 Qg6 6. Nf5+
					Kf7 7. Nd6+ Kg7

>
>This one is an opening trap sprung by the program
>"Postmodernist":
>
>[D] rn1qk1nr/ppp3pp/5p2/2bP1bB1/3p4/1Q3N2/PP2PPPP/RN2KB1R w KQkq -
>
>Most programs will play Qxb7, but this loses material as the
>Queen can be trapped. There isn't really a good move here -
>White's mistake was earlier in the game, and he's already
>worse. Crafty eventually selects Bf4 (at ply 12)
>with a minus score.
>
>This is another example where grabbing material is the
>wrong choice. A human might well avoid Qxb7 on the general
>rule that Queen sorties in the opening are a bad idea,
>but most computers won't weight that factor heavily
>enough and must discover the badness of Qxb7 by search.

CM8000 discards Qxb7 after 20 seconds, and settles on Bd2 five seconds later.

Time	Depth	Score	Positions	Moves
0:00	1/4	0.38	4296		1. Qxb7 Nd7 2. Bf4 Rb8
0:00	2/5	-0.24	23874		1. Bf4 Ne7 2. Qb5+ Nd7 3. Qxb7 Rb8
0:01	2/6	0.03	81558		1. Qxb7 Nd7 2. Bf4 Rb8 3. Qxc7
					Qxc7 4. Bxc7 Rxb2 5. Nbd2
0:02	3/7	-0.40	157589		1. Qxb7 Nd7 2. Bf4 Rb8 3. Qxc7
					Qxc7 4. Bxc7 Rxb2 5. Nbd2 Ne7
0:13	3/8	-0.40	829712		1. Qxb7 Nd7 2. Bf4 Rb8 3. Qxc7
					Qxc7 4. Bxc7 Rxb2 5. Nbd2 Ne7
0:20	3/8	-0.36	1295458		1. Bc1 Ne7 2. e3 dxe3 3. fxe3 Qxd5
					4. Bc4 Qe4 5. O-O
0:25	3/8	-0.04	1558058		1. Bd2 Be4 2. e3 Bxd5 3. Bc4 Ne7
					4. exd4 Bxc4 5. Qxc4
0:51	4/9	-0.20	3223189		1. Bd2 Ne7 2. e3 Qxd5 3. Bc4 Qe4
					4. O-O dxe3 5. Bxe3 Nd7 6. Bxc5
					Nxc5
2:12	4/10	0.02	8824265		1. Bd2 Ne7 2. e3 Qxd5 3. Bc4 Qe4
					4. O-O Nbc6 5. Qxb7 Rb8
5:29	5/11	-0.14	23377967	1. Bd2 Ne7 2. e3 Qxd5 3. Bc4 Qe4
					4. O-O dxe3 5. Bxe3 Bxe3 6. fxe3
					Nd7

jm



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