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Jul 29, 1994, 7:55:22 AM7/29/94

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Solutions to the 11 difficult tactical positions published in the chess

mag Gambisco.

mag Gambisco.

Solutions, comments and analysis by Pierre Nolot, published in the July issue

of Gambisco

# Position: 1

# Move: W

r...qb.k Kasparov-Karpov, 20th game 1990

.b....p. 26.Nxh6!! c3 (26... Rxh6!? is not sufficient:

p..pr..p 27.Nxd6 Qh5 (best) 28.Rg5! Qxd1 29.Nf7+ Kg8 30.Nxh6+ Kh8

...n.... 31.Rxd1 c3 32.Nf7+ Kg8 33.Bg6! Nf4 34.Bxc3 Nxg6 35.Bxb4 Kxf7

Pnp.N.N. 36.Rd7+ Kf6 37.Rxg6+ Kxg6 38.Rxb7 +-) 27.Nf5! cxb2

......RP 28.Qg4 Bc8 (if 28... g6!? 29.Kh2! wins : 29...Qd7 30.Nh4 Bc6

.B...PP. 31.Nc5! dxc 32.Rxe6 Nf6 33.Nxg6+ Kg7 34.Qg5 Nbd5 35.Ne5 Kh8

.B.QR.K. 36.Nxd7 +-) 29.Qh4+ Rh6 30.Nxh6 gxh6 31.Kh2! Qe5 32.Ng5 Qf6

33.Re8 Bf5 34.Qxh6 (pretty, but there was a mate in 6 :

34.Nf7+ Qxf7 35.Qxh6+ Bh7 36.Rxa8 Nf6 37.Rxf8 Qxf8 38.Qxf8+ Ng8

39.Qg7#) 34...Qxh6 35.Nf7+ Kh7 36.Bxf5+ Qg6 37.Bxg6+ Kg7 38.Rxa8 Be7

39.Rb8 a5 40.Be4+ Kxf7 41.Bxd5+ 1-0

A very deep combimation, that Tasc R30 or Genius 2 running on a pentium would

take between a few months and a few years to find.

The best Novag computer, the Diablo 68000, finds 26.Nxh6 after 7 months

and a half (Pierre Nolot has let it run on the position for 14 months and one

day, until a power failure stopped an analysis of over 80 000 000 000 nodes!)

but for wrong reasons : it evaluates white's position as inferior and

thinks this move would enable it to draw.

# Position: 2

# Move: W

r....rk. Bronstein - Ljubojevic, Petropolis itz 1973

pp.n.p.p 22.Rxc5!! Nxc5 23.Nf6+ Kh8 24.Qh4 Qb5+ (Now computers have

.nqP..p. a problem here : they think there is perpetual check, but...)

..b.P.B. 25.Ke3! wins 25... h5 26.Nxh5 Qxb3+ and Bronstein won in 41 moves.

....NQ.. If black plays 26... d5+ 27.Bxd5 Qd3 28.Kf2 Ne4+ 29.Bxe4 Qd4+

.B...P.. 30.Kg2 Qxb2+ 31.Kh3 +-

PP..K..P The best programs should be able to find 25.Rxc5!! in a few weeks.

..R.....

# Position: 3

# Move: W

r..qk..r Smaguine - Sahovic, Bienne 1990

ppp.b.pp White wins with a queen sac but black has several ways to defend

..n.p... 12.Nxg5!! Bxd1 13.Nxe6 Qb8 14.Nxg7!! Kf8 15.Bh6! Bg4 16.0-0+

...pP.n. 17.Kg8 17.Rf4 +-

...P..b. It should take between a few months and a few years for a program

..PB.NN. to find 12.Nxg5!!

PP....PP

R.BQK..R

# Position: 4

# Move: W

r.b.kb.r Bronstein - Kotov, candiates, Budapest 1950

.p.n.ppp 10.Nxe6!! Qxe6 11.Nd5 Kd8 12.Bg4 Qe5 13.f4 Qxe4 (13...Qxb2

p..ppn.. was stronger but not sufficient : 14.Bxd7 Bxd7 15.Rb1 Qa3

......BB 16.Nxf6 Bb5 17.Qd4 Qc5 18.Rfd1 +-) 14.Bxd7 Bxd7 15.Nxf6 gxf6

..qNP... 16.Bxf6+ Kc7 17.Bxh8 and Kotov resigned on move 27.

..N..... Tasc R30 (The King), the strongest program for this

PPP..PPP kind of combination, would need a few weeks here.

R..Q.RK.

# Position: 5

# Move: W

r..qrb.k Spassky - Petrossian, w ch (19), Moscow 1969

.p.b..p. 21.e5!! dxe5 22.Ne4! Nh5 23.Qg6!? (This is allright, but

p..ppn.p 23.Qg4!! Nf4 24.Nf3 Qc7 25.Nh4 +- was even stronger) 23...exd4?

........ 24.Ng5 1-0

...NP... Although No program finds 21.e5!! after 8 days, this might well

.BN..... be the first of the 11 positions to be solved by computers in

PPP...QP reasonnable time...

.K...RR.

Well... He sould have said : No program I have tested... as we now know!

# Position: 6

# Move: B

rnbqk..r Malaniouk - Ivantchouk, Moscow 1988

.p...ppp 13... axb5!! offers a rook to keep the white queen out of

p....... play. 14.Qxa8 Bd4 15.Nxd4 cxd4 16.Qxb8 0-0! 17.Ke1 Qh4

.NpPp... 18.g3 Qf6 19.Bf4 g5? (Ivantchouk would have won much faster

QPP.P.n. had he found 19...d3!, a move he found during the analysis.

P....N.. Tasc R30 inds 19...d3! in 2 1/2 hours. But to find 13...axb5

....KbPP it would probably need a couple of centuries...) 20.Rc1 exf4

R.B..B.R 21.Qxf4 Qd4 22.Rd1 bxc4 23.e5 Qc3+ 24.Rd2 Re8 25.Bxd3 cxd3

26.0-0 Nxe5 -+

Last minute info from Pierre, 19...Bf5!! is even stronger than d3

What does DT think about move 19 for black, and in how much time, asks Pierre.*

# Position: 7

# Move: W

.r.bk..r Todorovic - Tosic, Arandjelovac, 1993.

..R..ppp A nice exchange sacrifice to keep control of the 7th rank :

p...p... 1.Rxd8+!! Rxd8 (if 1...Kxd8 2.Ra7! Qe2 3.Qd4+ e8 4.h3 Qe1+

.b..P..q 5.Kh2 Rd8 6.Qc5 Qh4 7.Ba3 Rd7 8.Ra8+ Rd8 9.g3 1-0)

....QP.. 2.Ba3 Qe2 3.h3! Bd7 (better but still losing was 3...Qe1+

....N... 4.Kh2 Qa5 5.Re7+ Kf8 6.Rd7+ Kg8 7.Bb4 Rxd7 8.Bxa5 +-)

.B....PP 4.Nf5! Qd1+ 5.Kh2 f6 6.e5xf6 1-0

...R..K. Genius 2 does better than the R30 on this one, but

needs more than a month to find 1.Rxd8!! even on a 90 MHz

Pentium.

# Position: 8

# Move: W

r...rbk. Goufeld - Osnos, Koutaissi 1978

ppq..ppp After the obvious 24.Bxh7+!! you stil have to find the right

..b.pB.. attacking moves as black has some serious defensive

........ resources. 24...Kxh7 25.Qh5+ Kg8 26.Rd4! gxf6 27.Rg4+ Bg7

......Q. 28.Qh6 Kf8 29.Rxg7! Rac8 (computers prefer 29...Be4 which

.P.B...P also loses after 30.Rg4+ Ke7 31.Rxe4 Rad8 32.c4 Qa5 33.Rae1+-)

P.P..PP. 30.Qh7 b5 31.Rd1 Bd5 32.c4 bxc4 33bxc4 1-0.

R..R..K. It should take the best micros a few months to find 24.Bxh7+!!

As Deep Thought found out, 26 ... gxf6 seems to be a mistake.

More on that later, but this one is dubious now!

# Position: 9

# Move: W

r....r.k Weinstein - Elyoseph, Israel 1992

....bppb This one is really beautiful and should resist computers

..n.p..p for quite a long time, maybe until next century?

p.n.P... 1.Ng5!! hxg5 2.hxg5! Rac8 3.Nf6!! Nb8 (black can also

.p.p.BNP try 3...gxf6, which loses if white play precisely : 4.gxf6

...P.NP. 4...Rfe8 (best defense) 5.Qh5 Rg8 6.Rxc5! Bg6! 7.Qh4 Bxc5

qP..QPB. 8.Be4 Ne7 9Kg2 Qd5 10.Bxd5+-)

..RR..K. 4.Qh5 Bxf6 5.gxf6 gxf6 6.Rxc5 Rxc5 7.Be4 f5 8.Kg2 Rg8 9.Rh1

9...Rg7 10.Bh6 Nd7 11.Bxg7+ Kxg7 12.Qxh7+ 1-0

In fact, Pierre is not sure this one is 100% correct. Any improvements

are wellcome!

# Position: 10

# Move: W

r.b..rk. Van der Wiel - Ribli Amsterdam 1980.

.p.nbppp Ribli is a solid player, but he didn't see this one

pq.p.... coming :

...B.... 15.Rxf7!! Rxf7 16.Bxf7 Kxf7 17.Qh5+ Kg8 16.Qe8+ Bf8

P..NP... 19.Nd5 Qxd4 20.Nxe7+ Kh8 21.Rf1 Qf6 22.Rxf6 and white on

..N.p... on move 29.

.PP...PP This is propably the easiest one, with number 5.

R..Q.R.K

# Position: 11

# Move: W

r.b...k. Teichmann - NN, Zurich 1920

p..p.nP. This was a trap, as the game was spectacularly won because

..pqr.Rp of black's weak play. Several authors have published this game

.p..p..P without checking anything. For instance, Neishtadt in his

..B.PnQ. excellent book "Lecons de tactique" (sorry, I don't know

.P...... the title of the english version) gives :

P.PP.... "1.Rxh6!! the g pawn will be helped by the h pawn 1...Nxh6

.K....R. (1...Rxh6 2.Bxf7+ Rxf7 3.g8Q+) 2.Qg5 Nf7 3.Qd8+!! Nxd8

4.h6 and there is nothing to prevent h6-h7+ 1-0"

Right, nothing can prevent h6-h7+, but it is not decisive!

4...Qd4!! 5.h7+ Kf7 6.g8Q+ Ke7 7.h8Q Kd6 8.Rg7 Qxd2!! 9.Qxd8 Rc5

10.Rxd7 Bxd7 11.Qxa8 Rb4 12.Qxa7 Qe1 13.Kb2 Qc3 1/2 as white cannot

escape the black checks.

Marc-Francois Baudot.

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