Nolot's 11 difficult positions (possible spoilers)

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Feng-Hsiung Hsu

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Jul 28, 1994, 2:19:37 PM7/28/94
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Sometime ago, the following 11 positions collected by Pierre Nolot were
posted to rgc. Pierre claimed that no computers can solve any of them
in reasonable time (and no micros in even a few weeks). A long while back, he
might be right. At this point, a few of them are solvable even under
tournament time control. The ones that we tried overnight are all solvable
in a few hours. DT-2 was searching around 3 million nodes/sec during the
runs. The time probably would be reduced by 5-30 times for the harder
problems if the machine has a better quiescence search.

The comments below might be considered spoilers. The first line for
each position is in a computer-readable notation.

1 ;r3;q;b1;k/1;b4;p1/;p2;p;r2;p/3;n4/p;n;p1n1n1/6rp/1b3pp1/1b1qr1k1/40

white to move

8 R * - * Q B - K
7 * B * - * - P -
6 P * - P R * - P
5 * - * N * - * -
4 p N P * n * n *
3 * - * - * - r p
2 - b - * - p p *
1 * b * q r - k -

a b c d e f g h

Source: Kasparov-Karpov, Lyon 1990.

Kasparov played Nh6 here. DT-2 agreed with Kasparov's analysis after
going down the line given in Informant, but could not find the move
on its own in one hour time. When letting it run overnight, it produced
Nh6 after 8 hours (but would play it with a 6 hours/move time control; that
is, it got first indication that the combination might work after about 6
hours), with the variation 1. Nh6! c3 2. Nf5 cb2 3. Qg4 ... which wins for
white.

2 ;r4;r;k1/;p;p1;n1;p1;p/1;n;qP2;p1/2;b1p1b1/4nq2/1b3p2/pp2k2p/2r5/40

White to move

8 R * - * - R K *
7 P P * N * P * P
6 - N Q p - * P *
5 * - B - p - b -
4 - * - * n q - *
3 * b * - * p * -
2 p p - * k * - p
1 * - r - * - * -

a b c d e f g h

Source: Bronstein-Ljubojevic, Petropolis 1973.

Solution is 1. Rc5! Nc5 2. Nf6 Kh8 3. Qh4... Solved under tournament
time control (3 minutes/move, plus extra time if the value for the move
is unstable). Plays it after 2 minutes. Actually spent 4.5 minutes before
the value stabilized to about a piece up.

3 ;r2;q;k2;r/;p;p;p1;b1;p;p/2;n1;p3/3;pp1;n1/3p2;b1/2pb1nn1/pp4pp/r1bqk2r/40

White to move

8 R * - Q K * - R
7 P P P - B - P P
6 - * N * P * - *
5 * - * P p - N -
4 - * - p - * B *
3 * - p b * n n -
2 p p - * - * p p
1 r - b q k - * r

a b c d e f g h

Source: Smagin-Sahovic, Biel 1990.

Solution move is 1. Ng5!. Verified that the move is sound by following
the published analysis, but could not play it within one hour time. This
is more a positional sac than what would be normally called tactics.

4 ;r1;b1;k;b1;r/1;p1;n1;p;p;p/;p2;p;p;n2/6bb/2;qnp3/2n5/ppp2ppp/r2q1rk1/40

White to move

8 R * B * K B - R
7 * P * N * P P P
6 P * - P P N - *
5 * - * - * - b b
4 - * Q n p * - *
3 * - n - * - * -
2 p p p * - p p p
1 r - * q * r k -

a b c d e f g h

Source: Keres-Kotov, Budapest 1950.

Solution: 1. Ne6 Qe6 2. Nd5 Kd8 3. Bg4. Plays it after 3.8 hours, would play
it under 2.5 hour/move time control.

5 ;r2;q;r;b1;k/1;p1;b2;p1/;p2;p;p;n1;p/8/3np3/1bn5/ppp3qp/1k3rr1/40

White to move

8 R * - Q R B - K
7 * P * B * - P -
6 P * - P P N - P
5 * - * - * - * -
4 - * - n p * - *
3 * b n - * - * -
2 p p p * - * q p
1 * k * - * r r -

a b c d e f g h

Source: Spassky-Petrosian, Moskow 1969.

Took 4 hours to find e5!. 1. e5! de5 2. Ne4 Nh5 3. Qg6... More than a
piece up. The minimum time control needed to play it is around 2 hours/move.

6 ;r;n;b;q;k2;r/1;p3;p;p;p/;p7/1n;pp;p3/qpp1p1;n1/p4n2/4k;bpp/r1b2b1r/41

Black to move

8 R N B Q K * - R
7 * P * - * P P P
6 P * - * - * - *
5 * n P p P - * -
4 q p p * p * N *
3 p - * - * n * -
2 - * - * k B p p
1 r - b - * b * r

a b c d e f g h

Source: Melaniuk-Ivanchuk, USSR 1988.

Ivanchuk played 1. ... ab5! which appears to be a sound positional sacrifice.
Calling this position a tactical one, however, is a little unfair on Pierre's
part. Ivanchuk, by the way, could not find the best continuations over the
board, but won it anyway due to Melaniuk's inaccurate defence. Could not
solve it in one hour. Probably a home preparation. The same move was
replayed 3 years later in some random tournament.

7 1;r1;b;k2;r/2r2;p;p;p/;p3;p3/1;b2p2;q/4qp2/4n3/1b4pp/3r2k1/40

White to move

8 - R - B K * - R
7 * - r - * P P P
6 P * - * P * - *
5 * B * - p - * Q
4 - * - * q p - *
3 * - * - n - * -
2 - b - * - * p p
1 * - * r * - k -

a b c d e f g h

Source: unknown.

This one we left the machine ran overnight. It found that 1. Rd8! wins.
1. Rd8! Kd8 2. Ra7 and if 2. ... Qe2 3. Qd4 Ke8 4. h3... Took 12 hours
to get the value back, but would have played it if the time control
is 6 hours/move.

8 ;r3;r;b;k1/;p;p;q2;p;p;p/2;b1;pb2/8/6q1/1p1b3p/p1p2pp1/r2r2k1/40

White to move

8 R * - * R B K *
7 P P Q - * P P P
6 - * B * P b - *
5 * - * - * - * -
4 - * - * - * q *
3 * p * b * - * p
2 p * p * - p p *
1 r - * r * - k -

a b c d e f g h

Source: Gufeld-Osnos, USSR 1978.

The move played was 1. Bh7, but as it turns out 1. Bh7 might not be the
best move. Osnos defended poorly and got slaughtered. With best black
defence, white only maintains a positional edge after 1. Bh7 Kh7 2. Qh5
Kg8 3. Rd4 Bf3! (with the idea of Qxc2, and then Q to king side to defend
the king). DT-2 prefers to play c4, which threatens Bh7 for real.

9 ;r4;r1;k/4;b;p;p;b/2;n1;p2;p/;p1;n1p3/1;p1;p1bnp/3p1np1/;qp2qpb1/2rr2k1/40

White to move

8 R * - * - R - K
7 * - * - B P P B
6 - * N * P * - P
5 P - N - p - * -
4 - P - P - b n p
3 * - * p * n p -
2 Q p - * q p b *
1 * - r r * - k -

a b c d e f g h

Source: unknown.

After 9 minutes, it played 1. Nf6, expecting 1. ... Rfc8 2. Nh7 Kh7 3. Ra1 ...
The score was slightly nagative for white. On longer searches, it went up
to half a pawn and creeping up.

10 ;r1;b2;r;k1/1;p1;n;b;p;p;p/;p;q1;p4/3b4/p2np3/2n1;p3/1pp3pp/r2q1r1k/40

White to move

8 R * B * - R K *
7 * P * N B P P P
6 P Q - P - * - *
5 * - * b * - * -
4 p * - n p * - *
3 * - n - P - * -
2 - p p * - * p p
1 r - * q * r * k

a b c d e f g h

Source: Van der Wiel-Ribli, Amsterdam 1980.

Solution is 1. Rf7 Rf7 2. Bf7 Kf7 3. Qh5. Plays it in less than 2 minutes,
score stablized within 5 minutes to a pawn plus.

11 ;r1;b3;k1/;p2;p1;np1/2;p;q;r1r;p/1;p2;p2p/2b1p;nq1/1p6/p1pp4/1k4r1/40

White to move

8 R * B * - * K *
7 P - * P * N p -
6 - * P Q R * r P
5 * P * - P - * p
4 - * b * p N q *
3 * p * - * - * -
2 p * p p - * - *
1 * k * - * - r -

a b c d e f g h

Source: unknown

Be6 appears somewhat worse for white, but 1. Rh6 Nh6 2. Qg5 Nf7 3. Qd8 appears
to be a repetition draw or slightly ahead for white. Plays 1. Rh6 after
5 minutes, thought white was slightly ahead, but going down the line, it
appeared that black had enough pressure for a draw.

Marc-Francois Baudot

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Jul 29, 1994, 7:44:00 AM7/29/94
to
f...@watson.ibm.com (Feng-Hsiung Hsu) writes:

>Sometime ago, the following 11 positions collected by Pierre Nolot were
>posted to rgc. Pierre claimed that no computers can solve any of them
>in reasonable time (and no micros in even a few weeks). A long while back, he
>might be right. At this point, a few of them are solvable even under
>tournament time control. The ones that we tried overnight are all solvable
>in a few hours. DT-2 was searching around 3 million nodes/sec during the
>runs. The time probably would be reduced by 5-30 times for the harder
>problems if the machine has a better quiescence search.

I just phoned Pierre, and he admits he is very impressed by DT-2'sresults!
So am I, and we thank you for the time you have spent on these positions.
I'll post the solutions according to Pierre as given in Gambisco
separately, but first I'll just give you his comments on DT's outstanding
results (much much better than the best micros)


>1 ;r3;q;b1;k/1;b4;p1/;p2;p;r2;p/3;n4/p;n;p1n1n1/6rp/1b3pp1/1b1qr1k1/40

>Source: Kasparov-Karpov, Lyon 1990.

>Kasparov played Nh6 here. DT-2 agreed with Kasparov's analysis after
>going down the line given in Informant, but could not find the move
>on its own in one hour time. When letting it run overnight, it produced
>Nh6 after 8 hours (but would play it with a 6 hours/move time control; that
>is, it got first indication that the combination might work after about 6
>hours), with the variation 1. Nh6! c3 2. Nf5 cb2 3. Qg4 ... which wins for
>white.

Very good. This is not an easy one!

>2 ;r4;r;k1/;p;p1;n1;p1;p/1;n;qP2;p1/2;b1p1b1/4nq2/1b3p2/pp2k2p/2r5/40

>Source: Bronstein-Ljubojevic, Petropolis 1973.

>Solution is 1. Rc5! Nc5 2. Nf6 Kh8 3. Qh4... Solved under tournament
>time control (3 minutes/move, plus extra time if the value for the move
>is unstable). Plays it after 2 minutes. Actually spent 4.5 minutes before
>the value stabilized to about a piece up.

Excellent!! and this is not supposed to be an easy one. Your score proves
you found it for the good reasons.

>3 ;r2;q;k2;r/;p;p;p1;b1;p;p/2;n1;p3/3;pp1;n1/3p2;b1/2pb1nn1/pp4pp/r1bqk2r/40

>Source: Smagin-Sahovic, Biel 1990.

>Solution move is 1. Ng5!. Verified that the move is sound by following
>the published analysis, but could not play it within one hour time. This
>is more a positional sac than what would be normally called tactics.

Well, Pierre still calls it tactics!

>4 ;r1;b1;k;b1;r/1;p1;n1;p;p;p/;p2;p;p;n2/6bb/2;qnp3/2n5/ppp2ppp/r2q1rk1/40

>Source: Keres-Kotov, Budapest 1950.

>Solution: 1. Ne6 Qe6 2. Nd5 Kd8 3. Bg4. Plays it after 3.8 hours, would play
>it under 2.5 hour/move time control.

Very good!

>5 ;r2;q;r;b1;k/1;p1;b2;p1/;p2;p;p;n1;p/8/3np3/1bn5/ppp3qp/1k3rr1/40

>Source: Spassky-Petrosian, Moskow 1969.

>Took 4 hours to find e5!. 1. e5! de5 2. Ne4 Nh5 3. Qg6... More than a
>piece up. The minimum time control needed to play it is around 2 hours/move.

Very good, but 3.Qg4 is even stronger (spassky played Qg6)
Hiarcs also finds this one, and also gives 3Qg6

>6 ;r;n;b;q;k2;r/1;p3;p;p;p/;p7/1n;pp;p3/qpp1p1;n1/p4n2/4k;bpp/r1b2b1r/41

>Source: Melaniuk-Ivanchuk, USSR 1988.

>Ivanchuk played 1. ... ab5! which appears to be a sound positional sacrifice.
>Calling this position a tactical one, however, is a little unfair on Pierre's
>part. Ivanchuk, by the way, could not find the best continuations over the
>board, but won it anyway due to Melaniuk's inaccurate defence. Could not
>solve it in one hour. Probably a home preparation. The same move was
>replayed 3 years later in some random tournament.

All this is perfectly right, except that Pierre still thinks this is tactics.
Very deep tactics.

>7 1;r1;b;k2;r/2r2;p;p;p/;p3;p3/1;b2p2;q/4qp2/4n3/1b4pp/3r2k1/40

>8 - R - B K * - R

Feng-Hsiung Hsu

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Jul 29, 1994, 8:26:29 AM7/29/94
to
In article <31aqbp$5...@sheckley.cnam.fr> m...@cnam.cnam.fr (Marc-Francois Baudot) writes:
>>9 ;r4;r1;k/4;b;p;p;b/2;n1;p2;p/;p1;n1p3/1;p1;p1bnp/3p1np1/;qp2qpb1/2rr2k1/40
>>Source: unknown.
>
>>After 9 minutes, it played 1. Nf6, expecting 1. ... Rfc8 2. Nh7 Kh7 3. Ra1 ...
>>The score was slightly nagative for white. On longer searches, it went up
>>to half a pawn and creeping up.
>
>This is the hardest of them all, and Pierre has not been able to
>prove it is correct, so any further analysis is wellcome!
>Proposed move is Ng5 I think, see my post with the solutions
>for more information.

From possibly faulty memory, the Nf6 line traps black queen for a rook and
bishop, winning a pawn in the process. Will check on Ng5, but Nf6 does
appear to be winning. If black refuses to give up the queen, his king
gets caught without pants.

Marc-Francois Baudot

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Jul 29, 1994, 7:49:13 AM7/29/94
to
Newsgroups: rec.games.chess
Subject: Re: Nolot's 11 difficult positions (possible spoilers)
References: <CtnxK...@hawnews.watson.ibm.com>

f...@watson.ibm.com (Feng-Hsiung Hsu) writes:

>Sometime ago, the following 11 positions collected by Pierre Nolot were
>posted to rgc. Pierre claimed that no computers can solve any of them
>in reasonable time (and no micros in even a few weeks). A long while back, he
>might be right. At this point, a few of them are solvable even under
>tournament time control. The ones that we tried overnight are all solvable
>in a few hours. DT-2 was searching around 3 million nodes/sec during the
>runs. The time probably would be reduced by 5-30 times for the harder
>problems if the machine has a better quiescence search.

I just phoned Pierre, and he admits he is very impressed by DT-2'sresults!


So am I, and we thank you for the time you have spent on these positions.
I'll post the solutions according to Pierre as given in Gambisco
separately, but first I'll just give you his comments on DT's outstanding
results (much much better than the best micros)

>1 ;r3;q;b1;k/1;b4;p1/;p2;p;r2;p/3;n4/p;n;p1n1n1/6rp/1b3pp1/1b1qr1k1/40

>Source: Kasparov-Karpov, Lyon 1990.

>Kasparov played Nh6 here. DT-2 agreed with Kasparov's analysis after
>going down the line given in Informant, but could not find the move
>on its own in one hour time. When letting it run overnight, it produced
>Nh6 after 8 hours (but would play it with a 6 hours/move time control; that
>is, it got first indication that the combination might work after about 6
>hours), with the variation 1. Nh6! c3 2. Nf5 cb2 3. Qg4 ... which wins for
>white.

Very good. This is not an easy one!

>2 ;r4;r;k1/;p;p1;n1;p1;p/1;n;qP2;p1/2;b1p1b1/4nq2/1b3p2/pp2k2p/2r5/40

>Source: Bronstein-Ljubojevic, Petropolis 1973.

>Solution is 1. Rc5! Nc5 2. Nf6 Kh8 3. Qh4... Solved under tournament
>time control (3 minutes/move, plus extra time if the value for the move
>is unstable). Plays it after 2 minutes. Actually spent 4.5 minutes before
>the value stabilized to about a piece up.

Excellent!! and this is not supposed to be an easy one. Your score proves


you found it for the good reasons.

>3 ;r2;q;k2;r/;p;p;p1;b1;p;p/2;n1;p3/3;pp1;n1/3p2;b1/2pb1nn1/pp4pp/r1bqk2r/40
>Source: Smagin-Sahovic, Biel 1990.

>Solution move is 1. Ng5!. Verified that the move is sound by following
>the published analysis, but could not play it within one hour time. This
>is more a positional sac than what would be normally called tactics.

Well, Pierre still calls it tactics!

>4 ;r1;b1;k;b1;r/1;p1;n1;p;p;p/;p2;p;p;n2/6bb/2;qnp3/2n5/ppp2ppp/r2q1rk1/40
>Source: Keres-Kotov, Budapest 1950.

>Solution: 1. Ne6 Qe6 2. Nd5 Kd8 3. Bg4. Plays it after 3.8 hours, would play
>it under 2.5 hour/move time control.

Very good!

>5 ;r2;q;r;b1;k/1;p1;b2;p1/;p2;p;p;n1;p/8/3np3/1bn5/ppp3qp/1k3rr1/40

>Source: Spassky-Petrosian, Moskow 1969.

>Took 4 hours to find e5!. 1. e5! de5 2. Ne4 Nh5 3. Qg6... More than a
>piece up. The minimum time control needed to play it is around 2 hours/move.

Very good, but 3.Qg4 is even stronger (spassky played Qg6)
Hiarcs also finds this one, and also gives 3Qg6

>6 ;r;n;b;q;k2;r/1;p3;p;p;p/;p7/1n;pp;p3/qpp1p1;n1/p4n2/4k;bpp/r1b2b1r/41
>Source: Melaniuk-Ivanchuk, USSR 1988.

>Ivanchuk played 1. ... ab5! which appears to be a sound positional sacrifice.
>Calling this position a tactical one, however, is a little unfair on Pierre's
>part. Ivanchuk, by the way, could not find the best continuations over the
>board, but won it anyway due to Melaniuk's inaccurate defence. Could not
>solve it in one hour. Probably a home preparation. The same move was
>replayed 3 years later in some random tournament.

All this is perfectly right, except that Pierre still thinks this is tactics.
Very deep tactics.

>7 1;r1;b;k2;r/2r2;p;p;p/;p3;p3/1;b2p2;q/4qp2/4n3/1b4pp/3r2k1/40
>Source: unknown.

>This one we left the machine ran overnight. It found that 1. Rd8! wins.
>1. Rd8! Kd8 2. Ra7 and if 2. ... Qe2 3. Qd4 Ke8 4. h3... Took 12 hours
>to get the value back, but would have played it if the time control
>is 6 hours/move.

Right!

>8 ;r3;r;b;k1/;p;p;q2;p;p;p/2;b1;pb2/8/6q1/1p1b3p/p1p2pp1/r2r2k1/40

>Source: Gufeld-Osnos, USSR 1978.

>The move played was 1. Bh7, but as it turns out 1. Bh7 might not be the
>best move. Osnos defended poorly and got slaughtered. With best black
>defence, white only maintains a positional edge after 1. Bh7 Kh7 2. Qh5
>Kg8 3. Rd4 Bf3! (with the idea of Qxc2, and then Q to king side to defend
>the king). DT-2 prefers to play c4, which threatens Bh7 for real.

Pierre is chacking his analysis right now, and it seems DT is right!
Excellent! (he did not see Bf3!)

>9 ;r4;r1;k/4;b;p;p;b/2;n1;p2;p/;p1;n1p3/1;p1;p1bnp/3p1np1/;qp2qpb1/2rr2k1/40

>Source: unknown.

>After 9 minutes, it played 1. Nf6, expecting 1. ... Rfc8 2. Nh7 Kh7 3. Ra1 ...
>The score was slightly nagative for white. On longer searches, it went up
>to half a pawn and creeping up.

This is the hardest of them all, and Pierre has not been able to

prove it is correct, so any further analysis is wellcome!
Proposed move is Ng5 I think, see my post with the solutions
for more information.

>10 ;r1;b2;r;k1/1;p1;n;b;p;p;p/;p;q1;p4/3b4/p2np3/2n1;p3/1pp3pp/r2q1r1k/40

>Source: Van der Wiel-Ribli, Amsterdam 1980.

>Solution is 1. Rf7 Rf7 2. Bf7 Kf7 3. Qh5. Plays it in less than 2 minutes,
>score stablized within 5 minutes to a pawn plus.

Really excellent. Some programs find this one after a few hours
(Frits 2...) but with an equal score, and then they switch to
another move. DT sees at least a pawn, so it has really found it.
It should go up to about a piece up. Could you give the variations
it saw?

>11 ;r1;b3;k1/;p2;p1;np1/2;p;q;r1r;p/1;p2;p2p/2b1p;nq1/1p6/p1pp4/1k4r1/40

>Source: unknown

>Be6 appears somewhat worse for white, but 1. Rh6 Nh6 2. Qg5 Nf7 3. Qd8 appears
>to be a repetition draw or slightly ahead for white. Plays 1. Rh6 after
>5 minutes, thought white was slightly ahead, but going down the line, it
>appeared that black had enough pressure for a draw.

This was the "trap" for the readers of Gambisco.
What you say is the expected solution! Rh6 only draws even though
it is said to be winning in some books!

Well, we are impressed. Pierre would be interested in figures like
number of nodes, depth, and exact variations.

He would also be very much intersted in the results of Hitech and
B* Hitech, Cray Blitz, *Socrates and all the others! (Botvinnik's
program should score well on these positions :-)!)

Thanks a lot!
Marc-Francois Baudot

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