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Once beginners reach a certain level of performance, they realize
that there are many situations where they would have benefited from making 'positional' moves. There are several good books
on positional chess that are somewhat easy to understand and this is one of them. Unfortunately, the chess teachers seem to
teach primarily by presenting chess games and insisting that you set up the pieces and play along on a board of your own.
The basic principles they add 'here and there' between the games. This can be very tiresome and the books themselves never
seem to be able to stay open on the table as you play along. Additionally, the analysis presented (while insightful) often
does not hold up to computer analysis. The analysis is good enough to present the principle being discussed. The only alternative
to becoming stronger at positional chess (other than reading these books) seems to be watching chess videos, a private tutor, or
playing a few years of competitive chess.
In any case, it is absolutely essential that we understand the basics
of positional chess if we are going to write a computer program that attempts to play a strong positional game. We look to
books of this nature to suggest the foundations for our positional evaluation function and for any selective search we might
decide to perform. The ideas we decide to use in our computer program will be the time-tested ideas of chess teachers
and grandmasters.
p.1"In the beginning, I, like many others, found chess to be a simple
game... Suddenly my next plateau was reached - my more experienced opponents wouldn't fall for any of my tricks anymore. Worse
than this, they were slowly but surely grinding me down to defeat with something called 'positional chess'... This book is
aimed as an introduction to positional chess"
Piece activity is important, and even more so if our pieces can threaten multiple objectives at
once and put pressure on our opponent to respond. Additionally, pieces that are not participating in the game need to be activated
or else our opponent will view the situation as similar to a 'power play' in hockey and take advantage of a situation where
we cannot balance his threats in all places on the board at once. Our chess program should recognize these situations and
take advantage of them if the opportunity presents itself. A traditional chess program will have no idea of how forceful its
pieces are positioned and might even accept positions with trapped pieces if they happen to be on good squares.
p.7"Assuming we have a material balance in a position, then one of the most important features is
the relative activity of the pieces. There can be an advantage for one side if he has one piece which is performing several
useful functions at the same time. On the other hand, a side can be severely disadvantaged if one of his pieces is not pulling
his or her weight."
In this example [which featured some sloppy play on both sides], we see that the knight on b7 is
constrained by the white pawns and cannot participate effectively in the game. A traditional computer chess
program will not be able to understand this concept.
p.30"On this occasion, however, there is one overriding feature of the position - the awful placement
of Black's knight on b7.
| Miralles |
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| Emms, black to move |
In this respect the white pawns on b4 and d5 are doing a grand job, not allowing the knight to re-enter
the game... With the knight on b7, Black has a long-term positional disadvantage. Such small positional details can be vitally
important when assessing positions."
Emms teaches two basic weaknesses of doubled pawns, which are usually
penalized in all cases by traditional chess programs. Unfortunately, these principles are not understood by the machine because
it does not consider how attackable the pawns are or how mobile the pawns are in the evaluation function. But the proposed
heuristic allows us to measure and reward these principles. We might therefore choose to accept positions with doubled
pawns if 1) our opponent cannot attack them 2) they are mobile or 3) they constrain the movement of the enemy pieces.
p.63"doubled pawns... can be weak in two different ways. The first
of these is that they can be vulnerable to attack... The second weakness is that they can decrease the mobility of a pawn
formation."
Here is another example where white's doubled pawns are a liability.
p.64"The main problems for White, however, [diagram below, Black to move] are his static weaknesses,
including the miserable set of doubled and isolated c-pawns.
| Parker |
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| Shneider |
Not only are they vulnerable to attack, they are completely immobile
and they also leave gaps around the white king. Added to this, Black's knight has already found itself a great outpost on
c5, where it is completely invulnerable to white pawns."
Emms teaches that each position involving doubled pawns must be judged on its own to see if the
doubled pawns are a weakness, a strength, or neither. A traditional computer chess program penalizes doubled pawns without
determining this.
p.67"So far we've only looked at the negative side of [doubled] pawns, but there are some positives
too. Doubled pawns, especially ones... in the center, can control vital squares... Another positive feature is that the creation
of doubled pawns automatically produces an open file for the possessor of the doubled pawns. This can be good news for the
activity of the rooks.
Naturally each position has to be considered on its own merits, before deciding
whether the doubled pawns are a weakness, a strength, or just plain irrelevant."
Isolated pawns that cannot be attacked represent less of a weakness. This feature can be included
in our evaluation function if we wish, while a traditional computer chess program would just add a penalty.
p.70"isolated pawns are much more easily attacked if they stand on a half open file as the attacker
can simply move his rooks to this file and the pawn is under threat. Even when the pawn can be adequately defended, the fact
that the possessor of the isolated pawn has to use pieces to defend it means that he will be passively placed for operations
on other parts of the board."
Emms agrees with the position of Michael Stean with regard to the restrictions that pawns place
on piece mobility. Looking at the future mobility of the pieces, as well as the restrictions on piece mobility placed by the
lower value enemy pieces, helps us to determine the capacity of the present board position and allows us to effectively estimate
how promising the position is, both for further searching, and for winning chances.
p.125"In Simple Chess [a different book by a different author with the same name
as this book], Michael Stean talked of 'space' and 'capacity' in a way that was quite enlightening to me. His words were,
'Any given pawn structure has a certain capacity for accommodating pieces efficiently. Exceed this capacity and the pieces
get in each other's way, and so reduce their mutual activity. The problem of overpopulation is easy to sense when playing
a position - it 'feels' cramped.' "
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