The positions are presented twice, one without commentary if you would like to attempt 10 minutes thought on them, and once with a comment cherry-picked from Simon's much more detailed discussion.
I have also added two famous examples of master's thinking.
[Comment from DR: I might add, that a
misjudgement of this sort might lead to much fruitless searching for a
winning line if you think you are better. Blumenfeld used to advise
trying to look again with a fresh eye at a position to see if you
haven't overlooked some simple tactical point, but no less important
to make sure you don't overlook some important positional point. I
have known players ignore really key features of a position (a Pawn
majority, and open file) because they thought they knew what the
position was 'about'. Positions in books are selexcted to be 'about'
one clear theme. Positions in most games are usually more
complex!]
2
Black to play: analyse your way to success
"A striking example of the different depths to which the players analysed
was provided by the move 1...P-QB4. GJ[112] considered this for about five
minutes, but in general terms, without actually mentioning a reply for White.
JW[155] and IC[149] got as far as 1...P-QB4 2. Q-B2 R-R7 3. QxBP Q-KB3 4. Q-KB5
before giving the line up, but RW[208] continued with 4...Q-N7 5. R-Q8 R-R8 6.
Q-B8 Q-N8 7. RxNch K-R2 8. Q-KB5ch and mates. I had always thought that strong
players don't analyse much deeper than weaker players, but this is a clear
example to the contrary." -- Webb
[Comment from DR: This belief is rather
widespread. de Groot's research certainly
seemed to argue more for the importance of judgement than calculation,
but there has been a lot of work since which shows the importance of
seeing ahead.]
2/78
Black to play: what is the point at issue?
"They all settled fairly quickly on a king move so as to be able to get the
rook into play with ...R-QB1 (...) The main problem in this position is whether
to play ...K-R1 or ...K-R2. (...) Although having ten minutes to use up, two
of the panel (of four -- DR) gave scarcely any consideration to which
was the better king move." -- Webb
[Comment from DR: de Groot's
research is also relevant here. What his tests seemed to show was
not that masters analysed very much deeper, but they homed in on the
critical lines and issues much more quickly than non-masters.
]
6/78
White to play: candidate moves?
"Korchnoy played 12. N-KN5! (-K4-B5), a move not considered by any of the
panel...
"JN[236] thought almost exclusively in terms of concrete variations, whereas GJ[112] went to the opposite extreme... RW[208] and SJ[165] also gave very few concrete variations, and this may be more a question of style than strength...
"IC[149]... seemed to have the best-organised thought processes (...) It is not clear, however, whether this logical approach is necessarily all that effective, for it could be argued that if IC had adopted the RW approach of looking at moves twice he might have spotted 1. P-K4 B-N5 2. P-Q5 N-Q5! which seems good for Black" -- Webb
[Comment from DR: This position illustrates for
me quite nicely Kotov's notion of 'candidate moves': Korchnoi's actual
choice wasn't even considered by the panellists. Korchnoi may even have
reviewed, and rejected, other moves that were not considered by
them.
Kotov expands his approach to analysis by saying once the list of
candidate moves is drawn up, each branch should be considered once and
once only. IC has clearly read and believed, and this player may be
more efficient because of it, but at least while we are improving this
may be at the cost of accuracy. de Groot used to describe an approach
of 'progressive deepening', and this may not just a more common
approach but a more appropriate one for positions which are not highly
tactical.
7/78
White to play: begin at the end
"JN[236] and RW[208] had far more idea what they ought to be doing than the
others, and this supports the widely held supposition that the greatest
difference between stronger and weaker players is in the endgame." --
Webb
[Comment from DR: Howard Staunton complained that
only the 'magnates' of the game were really skilled at endgame play,
and this remains true!
But Capa advised, that chess study really should begin with the
endgame.
10/78:
playing by analogy
"...Although experience is an advantage in telling a player what to look
for, it can also restrict you into considering only 'normal' moves.
"JM [237] 's idea of meeting 1. P-B5 with ...PxP and ...P-K5 (was) difficult to spot, because ...PxP is an abnormal way of meeting the thrust P-B5. This also applied to RY[160] and RN [165], who didn't consider ...PxP because it would have looked anti-positional to them. To AP [ungraded player], however, ...PxP was the obvious reply...
[Comment from DR: I like this observation. It
may be that stronger players actually consider more 'stupid' moves than
wekaer ones - dismissing most of them, but not ruling them out without
a glance! It may be that this is the only possible explanation for,
say, some of Tal's moves...]
White
(de Groot ) to play: what makes a difference?
Chess master and psychologist de Groot gave this position to Alekhine, Keres,
Euwe and other GMs at the 1938 AVRO tournament, as well as to a number of
weaker, but still expert, players.
All the GMs except Flohr quickly found the win with 1. Bxd5 (1...exd5 2. Qf3 Qd8 3. Rfe1 Kg7 4. Ng4 Nxg4 5. Bxe7). They also analysed other forcing continuations like 1. Nxc6, which Alekhine considered just as strong and which Flohr actually preferred.
Hardly any of the other players suspected there was a forcing solution (even after 15-20 minutes, much longer than the GMs. For the most part, they opted for safe positional moves like 1. Rfe1 or 1. Bh6; nothing alerted their antennae to a concrete solution.
Every solver thought: White has an isolated d-pawn, so endgame problems, so attack now. But only the GMs chased it down to a line 4/5 moves deep. The lesser masters seemed unable to overcome two barriers to seeing the tactic: the safe appearance of the Black position, and the anti-positional appearance of 1.Bxd5.
"It is by no means easy to detect these chance factors which are not based on obvious strategic factors", conclude Pfleger and Treppner, rather gloomily.
Oh, Flohr's idea? Looking for something even better than Bxd5, he hatched 1.Nxc6 bxc6 2.Bxd5 cxd5 3.Bxf6 Bxf6 4.Nd7, winning the exchange... but it is only the ghost of the knight that goes to e7!
Lasker-Capablanca
#10 1921; White to play: masters at fault?
This is a similar case, where the GMs may have got it wrong: Breyer analysed a
win starting 15.Bxf6!
It looks anti-positional to gove up the Bishop, but Breyer claims an advantage in all lines:
17...Bxf6 18. Bxd5 exd5 19. Ng4 Bg5! (19...Bd8 20. Qf5) 20. f4 exf4 21. Qf5 Bc7 (else 22. Qxd5 a6 23. a4) 22. Nxd5 Kh8 23. Nxh6 gxh6 24. Nf6 Kg7 25. Nh5+ with mate in two.
I have seen this analysis "busted", and I don't feel qualified to judge: but if Lasker didn't overlook something important, then Breyer did!
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This document (webb2.html) was last modified on 30 Jul 96 by
Dr. Dave