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Subject: Re: Interesting Position (Tactics and King Safety)

Author: Robert Hyatt

Date: 15:36:04 07/07/01

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On July 07, 2001 at 15:51:46, Peter McKenzie wrote:

>[D]2r2rk1/1p2bppp/1qn1p3/p2pPn2/1P1P1P1P/P2Q1NP1/1B2N3/2R1K2R w K -
>
>This position was reached in a game on ICC, with LambChop black and a human
>white.  LambChop just played a5, which allows the opponent to attack on the king
>side with g4 Nh6 Ng5 g6 h5 and white is winning I think.
>
>I was a little surprised that it takes Chop 11ply to play g4 (initially it
>preferred b5), and even after a 13ply search the score is still slightly
>negative (0.2 in black's favour).
>
>So I'm wondering how other programs do here?
>
>I think that black has some chances to muddy the waters with sacrifices on b4 at
>various points.  While I don't think these are any good, they do have some merit
>and could push the horizon out a bit.
>
>Any suggestions of what sort of evaluation terms or extensions might help here
>would be welcome :-)
>
>cheers,
>Peter
>
>p.s. Now I see that there is another possible defence: g4 axb4 gxf5 bxa3, not
>sure if this works but it's interesting.  The position after g4:
>
>[D]2r2rk1/1p2bppp/1qn1p3/p2pPn2/1P1P1PPP/P2Q1N2/1B2N3/2R1K2R b K -
>
>In this position, Chop needs 12ply to switch to axb4, score is +0.44.  I
>wouldn't treat that score as gospel, but I think axb4 is a much better try than
>Nh6.


g4 is about all I get.  Crafty finds this at the 5 second mark on my PIII/750
notebook...  depth=8.  Scores don't look overwhelming however:

                7->   1.08  -0.88   1. b5 Na7 2. g4 Nh6 3. g5 Ng4 4. Nc3
                8     1.80  -1.12   1. b5 Na7 2. Rxc8 Rxc8 3. g4 Nh6 4.
                                    g5 Ng4 5. Nc3 <HT>
                8     3.24  -1.06   1. g4 Nh6 2. g5 Nf5 3. b5 Na7 4. Rxc8
                                    Rxc8 5. Nc3 <HT>
         (2)    8->   3.75  -1.06   1. g4 Nh6 2. g5 Nf5 3. b5 Na7 4. Rxc8
                                    Rxc8 5. Nc3 <HT>
                9     6.69  -1.03   1. g4 Nh6 2. Ng5 g6 3. h5 Bxg5 4. fxg5
                                    Nxg4 5. Qh3 gxh5 6. Qxh5
                9->   7.97  -1.03   1. g4 Nh6 2. Ng5 g6 3. h5 Bxg5 4. fxg5
                                    Nxg4 5. Qh3 gxh5 6. Qxh5
               10    13.96     ++   1. g4!!
               10    21.20  -0.46   1. g4 axb4 2. gxf5 bxa3 3. Bc3 Nb4
                                    4. Bxb4 Rxc1+ 5. Nxc1 Qxb4+ 6. Qd2
                                    exf5 7. Qxb4 Bxb4+
               10->  22.51  -0.46   1. g4 axb4 2. gxf5 bxa3 3. Bc3 Nb4
                                    4. Bxb4 Rxc1+ 5. Nxc1 Qxb4+ 6. Qd2
                                    exf5 7. Qxb4 Bxb4+
               11    39.31  -0.61   1. g4 axb4 2. gxf5 bxa3 3. Bc3 Nb4
                                    4. Bxb4 Rxc1+ 5. Nxc1 Qxb4+ 6. Qd2
                                    Rc8 7. Qxb4 Bxb4+ 8. Kf2 exf5
               11->  43.32  -0.61   1. g4 axb4 2. gxf5 bxa3 3. Bc3 Nb4
                                    4. Bxb4 Rxc1+ 5. Nxc1 Qxb4+ 6. Qd2
                                    Rc8 7. Qxb4 Bxb4+ 8. Kf2 exf5
               12     1:24  -0.75   1. g4 axb4 2. gxf5 bxa3 3. Bc3 Nb4
                                    4. Bxb4 Rxc1+ 5. Nxc1 Qxb4+ 6. Nd2
                                    Rc8 7. Na2 Qb2 8. f6 gxf6
               12->   1:38  -0.75   1. g4 axb4 2. gxf5 bxa3 3. Bc3 Nb4
                                    4. Bxb4 Rxc1+ 5. Nxc1 Qxb4+ 6. Nd2
                                    Rc8 7. Na2 Qb2 8. f6 gxf6



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