Dwingende zetten

Forcing Chess Moves: The Key to Better Calculation

Brute Force combinations
Study material
In the introduction, we defined the two core aspects of developing
powerful computer eyes. The first task was accurate brute force analysis of
variations, and the second was overcoming human bias in order to become
more objective, and creative, in our ability to find unusual winning forcing
moves.
The term ‘brute force’ refers to the way machines ‘think’. While
computers analyze scores of variations and then try to draw conclusions,
humans have a tendency to conceptualize positions first, with concepts
like ‘weak pawn’, ‘open file’, ‘better development’, etc. This is natural and
okay, but the problem comes when we make decisions based on such
generalizations, without first testing their validity with concrete analysis.
Developing computer eyes means learning to analyze essential forcing
moves first, and always basing our final decisions on well-considered
analysis.
When the supercomputer Hydra crushed the incredibly strong English
GM Michael Adams in a 2005 match, an age-old debate was put to rest.
Many had believed that positional judgment or ‘grandmaster intuition’
could overcome brute force calculation of scads of variations, but we now
know that accurate brute force analysis is the single most important chess
skill.
In Chapters 1 and 2 we began by training your computer eyes to become
aware of recurring stock sacrifices, helping you recognize critical attacking
positions and get in the habit of examining the most forcing moves first.
At the same time, we began to examine the crucial role of brute force
analysis and creativity in unearthing these powerful combinations.
Having gained a basic knowledge of stock themes, you are now ready to
learn how to better calculate the original, uncharted ‘bread and butter’
situations which occur most often in tournament play.
Even ‘straightforward’ brute force variations can be very difficult to
calculate accurately, because this analysis requires three essential skills:
1. Accurate ‘board sight’ – the ability to correctly envision where
the pieces are, and what they can do, even deep in the midst of a long
calculation.
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2. Accurate ‘selection’ – the ability to hone in on the key options, and
avoid two key pitfalls at the opposite ends of the spectrum: failure to
consider unexpected, but crucial ideas; or wasting huge amounts of time
analyzing ‘dead ends’.
3. The raw ability and effort needed to calculate variations.
Fortunately, these skills can be developed through practice, problemsolving, the study of master games, and by gaining a deeper understanding
of forcing moves.
In this chapter we examine three types of brute force combinations:
A) ‘Bread and Butter’ Brute Force combinations
Most tactics books concentrate only on mating positions like the stock
forcing moves found in Chapter 2. But these positions are relatively
unusual in club play, compared with ‘bread and butter’ tactics: 2-4 move
deep combinations winning material. Some of these combinations may
utilize stock ideas in one or two side variations, but the primary focus is
on accurate brute force calculation.
B) Mating and ‘Hybrid’ Brute Force combinations
This section is devoted to mating combinations which are too unique, or
require too much original brute force analysis, to be considered ‘stock’
ideas; and ‘hybrid’ sequences in which both mate and/or win of material
figure in the calculation of different variations.
C) Promotion-based Brute Force combinations
Combinations involving actual pawn promotion, or the achievement
of mate or material gain via the threat of promotion, could constitute
a worthwhile book by themselves. A strong awareness of these motifs
is certainly a key aspect of developing your computer eyes, and we will
revisit them many times, as they relate to different chapters of the book.
A) ‘Bread and Butter’ Brute Force combinations
FCM 3.1
Karthikeyan-Vachier-Lagrave
Gibraltar 2019
._._._T_
_J_.jMt.
J_Sj.j.l
_._N_I_.
._._BbSj
_.i._._.
Ii._.iI_
_._Rr.k. †
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Chapter 3 – Brute Force combinations
The critical position has arrived in this tense queenless middlegame.
White is clearly better after 1.♗xh6 ♘xh6 2.♘f4 ♖b8, but as a practical
matter he must calculate a long forcing sequence which may knock off his
famous opponent decisively:
1.f3! ♗xf4
The other messy try also required bold calculation: 1…♘ge5!? 2.♗xh6
♖xg2+ 3.♔h1! (surprisingly 3.♔f1 only draws: 3…♖g1+ 4.♔e2 ♖1g2+ 4.♔e3
♘c4+ with a perpetual) 3…♖2g3! (threatening mate; inadequate is 3…♖xb2
4.♖b1 ♖xa2 5.♘c7! with the crushing fork threat 6.♗d5+) 4.♘f4! (better
than 4.♗f4 ♖h3+ and 5…♘xf3) 4…♖h8 5.♘h5 ♘xf3 6.♘xg3 ♘xe1 7.♘e2,
winning.
2.♘xf4 ♘ge5 3.♗d5+ ♔e8 4.♗xg8 ♘xf3+ 5.♔f2 ♘xe1 6.♗d5!
White had to visualize all this, as well as Black’s last-ditch next move, to
choose the right line. If 6…♘c2 7.♘g6! snuffs out all counterplay before
corralling the knight with ♖c1.
6…♖g5 7.♔xe1 ♖xf5 8.♘g6 and 1-0.
Similarly here, evaluation of the critical position turns on a brute force
shot.
FCM 3.2
Gostisa-Robatsch
Ptuj 1995
T_D_._T_
j._LmJ_.
Sj.j.s._
_.jIj.j.
I_I_I_._
_._N_QiI
.i.n._Bk
† rR_._._.
If Black had one more move, he could establish a fortress with …♖g6 or
even take the initiative with …g5-g4. But White strikes first, destroying
the integrity of Black’s set-up:
1.♘xe5! dxe5
White has a solid extra pawn and more after 1…♖h8 2.♖f1, while on 1…g4,
2.♕f4! gxh3 3.♖f1 is very strong.
2.d6+! ♔xd6
2…♔e6 3.♕f5+.
3.♕xf6+ ♗e6 4.♘f3 Black is in tatters: 1-0.
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Forcing Chess Moves
In messy, wildly complicated positions the only way to deduce that a
position is ‘critical’ is often to find the winning line! In tactical minefields,
every position is essentially critical:
FCM 3.3
Short-Zagrebelny
Dhaka 1999
._._._._ ._._._._
_.tL_M_J
._.s.d._
_._I_J_.
.j._.i._
_._._.qI
._._._Rk
_R_._._. †
The old coffee-house saying ‘Always check, it might be mate!’ could be
usefully amended as follows: ‘When many checks are available, computer
eyes carefully calculate each one, mining every line for potentially
winning brute force sequences’.
Four succinct and accurate checks bring home the point here:
1.♕g8+ ♔e7 2.♖g7+
The quickest and most efficient, although here or on the next move,
2/3.♖e1+ would also have won.
2…♘f7 3.♖xf7+! ♕xf7 4.d6+ Prying king from queen – 4…♔e6 5.♖e1+; 1-0.
Even in relatively ‘simple’ positions, calculating one move deeper or more
precisely often makes the difference: