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Subject: Re: A hard test position

Author: John Merlino

Date: 10:28:19 09/29/03

Go up one level in this thread


On September 28, 2003 at 06:49:32, ludicrous wrote:

>Ludek Pachman's Book, Attack and Defense in Modern Chess Tactics, Page 97, game
>of Ravinsky vs Panov, 1947.
>
>Can any program see White's move?
>
>1)P-K4 P-QB4
>2)N-KB3 P-K3
>3)P-Q4 PxP
>4)NxP N-KB3
>5)N-QB3 P-Q3
>6)P-KN3 N-B3
>7)B-N2 B-Q2
>8)O-O P-QR3
>9)B-K3 R-B1
>10)Q-K2 P-QN4
>11)P-QR3 N-K4 (Pachman gives this a "?", B-K2 was in order)
>12)QR-Q1 N-B5
>13)B-B1 NxRP (Again, Pachman gives this a "?"; he suggests B-K2 instead)
>14)P-K5! PxP
>15)N-B6 Q-B2
>16)NxKP N-B5 (Pachman says the pawn grab cost Black two tempi, and now he wil
>pay for them)
>17)NxB NxN
>18)N-Q5 Q-R2 (...W-K4 is more natural, so says Pachman)
>19)N-B4! QN-K4?
>20)RxN!! ("The prelude to a beautiful combination.  By sacrificing a Rook White
>destroys the Black King's pawn cover and obtains an irresistable attack down the
>open K-File")
>20)...NxR
>21)NxP! PxN
>22)QxP ch B-K2
>23)R-K1 Q-B4
>24)P-QN4! N-B1?
>25)Q-N4! Q-B6
>26)RxB!!! and white soon won...

There's one problem with the game as it was played.

First of all, here's the posiition and the suggested line in Algebraic, for
anybody who needs it:

[D]2r1kb1r/q2n1ppp/p3p3/1p2n3/5N2/6P1/1PP1QPBP/2BR1RK1 w k - 0 20

20.Rxd7 Nxd7 21.Nxe6 fxe6 22.Qxe6+ Be7 23.Re1 Qc5 24.b4 Nf8 25.Qg4 Qc3 26.Rxe7+

However, there is one very bad move by Black in this line -- 25...Qc3. This move
loses instantly, as shown above, to 26.Rxe7+.

25...Qc4 appears to give Black a much better fighting chance. This is likely why
programs do not choose 20.Rxd7, as they do not see 25...Qc3 as forced....

Here is the position:

[D]2r1kn1r/4b1pp/p7/1pq5/1P4Q1/6P1/2P2PBP/2B1R1K1 b k - 0 24

And here is what Chessmaster 9000 (default), on a P4-2.4, says:

Time	Depth	Score	Positions	Moves
0:00	1/3	-1.63	2214		24...Qc3 25.Bd2 h5 26.Qg5
0:00	1/4	0.00	6486		24...Qc3 25.Rxe7+ Kxe7 26.Bg5+
					Ke8 27.Qe4+ Kf7 28.Qf5+ Ke8 29.Qe4+
0:00	1/5	0.00	21554		24...Qc3 25.Rxe7+ Kxe7 26.Bg5+
					Ke8 27.Qe4+ Kf7 28.Qf5+ Ke8 29.Qe4+
0:00	1/6	0.00	60789		24...Qc3 25.Rxe7+ Kxe7 26.Bg5+
					Ke8 27.Qe4+ Kf7 28.Qf5+ Ke8 29.Qe4+
0:00	1/7	3.65	142605		24...Qc3 25.Rxe7+ Kxe7 26.Bg5+
					Kd6 27.Qd1+ Kc7 28.Bf4+ Kb6 29.Qd6+
					Ka7 30.Qe7+ Nd7 31.Qxd7+ Rc7 32.Qxc7+
					Qxc7 33.Bxc7
0:00	1/7	2.68	278969		24...Qc7 25.Qxg7 Qd6 26.Bg5 Ne6
					27.Qxh8+ Kd7 28.Bxe7 Rxh8 29.Bxd6
					Kxd6
0:01	1/7	0.26	385114		24...Qc4 25.Qxg7 Qxb4 26.c3 Rg8
					27.Qxg8 Qxc3 28.Kf1 Rc4
0:02	1/8	0.00	808796		24...Qc4 25.Qxg7 Qxb4 26.c3 Rg8
					27.Qxg8 Qxc3 28.Kf1 Qd3+ 29.Kg1 Qc3
0:06	1/9	0.00	2017931		24...Qc4 25.Re4 Qxc2 26.Rxe7+ Kxe7
					27.Qxg7+ Ke8 28.Qe5+ Kd7 29.Qd4+
					Ke8 30.Qe5+
0:16	1/10	0.00	5227803		24...Qc4 25.Re4 Qxc2 26.Rxe7+ Kxe7
					27.Qxg7+ Ke8 28.Qe5+ Kd7 29.Qd4+
					Ke8 30.Qe5+
0:36	2/11	0.54	12151710	24...Qc4 25.Qxg7 Qxb4 26.c3 Rg8
					27.Qxg8 Qxc3 28.Rd1 Qc2 29.Bf3
					Qxd1+ 30.Bxd1 Rxc1 31.Qb3
2:01	3/12	0.48	42508006	24...Qc4 25.Qxg7 Qxb4 26.c3 Rg8
					27.Qxg8 Qxc3 28.Rd1 Qc2 29.Qg4
					Qxc1 30.Qh5+ Ng6 31.Rxc1 Rxc1+
					32.Bf1 Kd7 33.Qxh7

jm



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