Author: Robert Hyatt
Date: 20:20:09 04/30/04
Go up one level in this thread
On April 30, 2004 at 23:04:24, Andrew Wagner wrote:
>Here's the position:
>
>[d] 8/7p/5k2/5p2/p1p2P2/Pr1pPK2/1P1R3P/8 b - -
>
>The move to find here is Rxb2. My question is...what ply does your program find
>the solution on?
Takes Crafty reaching depth=13 to see this:
13 5.11 -1.88 1. ... Ke6 2. h3 c3 3. bxc3 Rxc3 4.
Ra2 Kd5 5. h4 Kc4 6. h5 Rc2 7. Ra1
Kc3 8. Rb1 (s=2)
13 8.50 +1 1. ... Rxb2!!
13 8.72 +3 1. ... Rxb2!!
13 9.45 -4.11 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7
4. Rc6 c2 5. Kf2 d2 6. Rxc2 d1=Q 7.
Rc5 Kd6 8. Re5 Qd2+ 9. Kf3 Qd3
13-> 9.73 -4.11 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7
4. Rc6 c2 5. Kf2 d2 6. Rxc2 d1=Q 7.
Rc5 Kd6 8. Re5 Qd2+ 9. Kf3 Qd3 (s=7)
14 10.51 -4.18 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7
4. Rc6 c2 5. Kf2 Kd7 6. Rc5 d2 7. Rxc2
d1=Q 8. Rc5 Kd6 9. Re5 Qh5 10. Kg3
Qg4+ 11. Kf2 <HT> (s=6)
14-> 16.78 -4.18 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7
4. Rc6 c2 5. Kf2 Kd7 6. Rc5 d2 7. Rxc2
d1=Q 8. Rc5 Kd6 9. Re5 Qh5 10. Kg3
Qg4+ 11. Kf2 <HT> (s=10)
15 18.64 -4.18 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7
4. Rc6 c2 5. Kf2 Kd7 6. Rc4 d2 7. Rxc2
d1=Q 8. Rc5 Kd6 9. Re5 Qh5 10. Kg3
Qg4+ 11. Kf2 <HT> (s=9)
15-> 35.63 -4.18 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7
4. Rc6 c2 5. Kf2 Kd7 6. Rc4 d2 7. Rxc2
d1=Q 8. Rc5 Kd6 9. Re5 Qh5 10. Kg3
Qg4+ 11. Kf2 <HT> (s=12)
16 39.54 -4.18 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7
4. Rc6 c2 5. Kf2 Kd7 6. Rc4 d2 7. Rxc2
d1=Q 8. Rc5 Kd6 9. Re5 Qh5 10. Kg3
Qg4+ <HT> (s=11)
> To tactically work it out to see that you can force queening
>requires something like 13 or 14 ply. This is an interesting knowledge vs.
>search position...can you special-case this somehow to find it sooner? The
>problem is, as an FM friend of mine pointed out, if the king were just a bit
>closer, the sac is losing. E.g. In this position:
>
>[d] 8/7p/5k2/5p2/p1p2P2/Pr1p1K2/1P1R3P/8 b - - (white pawn missing on e3)
>...the sac would be losing because the king is close enough to stop the pawns.
>So my first inclination to somehow make the static eval see that the pawns were
>worth being down a pawn seems to be bad. Any thoughts?
Black is already winning in position 2:
12 1.21 +1 1. ... Ke6!!
12 1.34 -3.49 1. ... Ke6 2. Ke3 Kd5 3. h3 h5 4. Kf3
Kd4 5. Kf2 c3 6. bxc3+ Rxc3 7. Kf3
Rxa3 8. h4 <HT>
12-> 1.36 -3.49 1. ... Ke6 2. Ke3 Kd5 3. h3 h5 4. Kf3
Kd4 5. Kf2 c3 6. bxc3+ Rxc3 7. Kf3
Rxa3 8. h4 <HT> (s=6)
13 1.75 -3.59 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. Kf3
Kd4 5. h4 h5 <HT> (s=5)
13-> 2.63 -3.59 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. Kf3
Kd4 5. h4 h5 <HT> (s=4)
14 3.15 -3.59 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. h4
h5 <HT> (s=3)
14-> 5.08 -3.59 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. h4
h5 <HT> (s=5)
15 6.11 +1 1. ... Ke6!!
15 7.27 -4.12 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. h4
h5 5. Kf3 Kd4 6. Kf2 c3 7. bxc3+ Rxc3
8. Kg3 Rxa3 9. Kf3 Rc3 (s=4)
15-> 10.42 -4.12 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. h4
h5 5. Kf3 Kd4 6. Kf2 c3 7. bxc3+ Rxc3
8. Kg3 Rxa3 9. Kf3 Rc3 (s=4)
16 12.56 +1 1. ... Ke6!!
16 15.59 -4.89 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. h4
h5 5. Kf3 Kd4 6. Kf2 Ke4 7. Ke1 Kxf4
8. Kf2 Ke4 9. Kg3 (s=3)
16-> 22.36 -4.89 1. ... Ke6 2. Ke3 Kd5 3. h3 h6 4. h4
h5 5. Kf3 Kd4 6. Kf2 Ke4 7. Ke1 Kxf4
8. Kf2 Ke4 9. Kg3 (s=4)
Nothing wrong with a good eval term.. I do this myself. You just have to be
sure the king is not close enough to stop the pawns...
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