p.7-8“The most important single feature of a chess position
is the activity of the pieces. This is absolutely fundamental in all phases of the game (opening, middlegame and especially
endgame)... The primary constraint on a piece's activity is the Pawn structure...The job of the chessplayer must therefore
be to use his skill to create a Pawn set-up which will allow his own pieces the optimum freedom and stability, while denying
his opponent's similar scope.”
Holes in the attacking power of the pawn structure, which only can be determined by examining
future pawn mobility, allow the identification of squares which can be used as outposts.
p.17"In general a successful attack can only be launched from a position of strength in the
center of the board. This 'position of strength' can take various forms, the simplest being an outpost.
As the name suggests, an outpost is a square at the forefront of your position which you
can readily support and from where you can control or contest squares in the heart of the enemy camp. To be useful, an outpost
must be firmly under control and so should ideally be protected by a Pawn. Conversely your opponent should not be given the
opportunity to deny you access to your outpost, so in particular it must be immune to attack by enemy pawns.
This last condition is far and away the most important and can indeed be taken as the defining
property of an outpost."
Outposts near the enemy's king are especially valuable.
p.24"an outpost in the vicinity of the enemy King is an excellent platform from which an offensive
can be launched."
Pieces must be able to move freely within the structure of pawns. Moving freely should not mean
that we consider only possible moves for the piece at its next turn. We should consider visualizing what each
piece can do a few moves into the future.
p.38"The lesson to be learned here is that structure alone is not quite everything. The pieces must
be able to coordinate with the pawn structure. After all, what use is a body without a soul?"
Pawns become weak by being unsupportable by neighboring pawns, and by being attackable by the enemy.
Potentially weak pawns that are not attackable by the enemy require no defensive support from friendly pieces. Giving points
in our evaluation function for doubled or isolated pawns without considering how attackable they are can cause incorrect
(1) focus in our search and (2) evaluation of winning chances.
p.39,42"If the defending forces can be reduced to the menial task of protecting Pawns, they will
not be able to offer much opposition to a full-scale offensive.
So what exactly is a weak Pawn and how is it recognizable? The answer is both simple
and logical. A weak Pawn is one which cannot be protected by another Pawn and so requires support from its
own pieces. Note that the criterion is the ability to be protected by another Pawn, not the existence of such protection.
Take the example of two adjacent Pawns on, say, d4 and e4. Neither protects the other but each as the ability to be guarded
by the other, by advancing. We must therefore say that the weakness or strength of two adjacent Pawns depends on whether or
not they are able to advance if the necessity arises... The most common form of Pawn weakness encountered in practical play
is the isolated Pawn - one which has lost its neighbors and stands alone in face of the enemy. Such a Pawn has two basic deficiencies:
firstly it requires defense, and secondly the squares immediately in front of it make ideal outposts for the other player."
Here we see evidence that to effectively evaluate pawns, we need to consider 1) the restrictions they impose on the mobility
of pieces (friendly and enemy), and 2) how attackable they are.
p.51"the White Pawns provide a very effective barrier against the enemy Bishop without any way impeding
their own Bishop. Above all there is no question of White having any weak Pawns [in the game being discussed] - they
all protect each other, except for the 'base' at c2 which is completely unassailable."
Traditional chess programs that give a bonus to rooks for sitting on open files are likely to award
this bonus without checking to see that there is an entry point for such a piece after a potential movement down
the file in question. Stean thinks that without an entry point that there is no value to such a positional rook move.
p.66-67,78-79" 'Put your rooks on open files' is a piece of advice every beginner receives, and
a very sound piece of advice it is. But like all pieces of sound advice, it can prove to be inadequate, or worse... Occupation
of an open file is of no value unless there is a chance of penetration... It must be stressed that open files only have a
value as a means of feeding Rooks (or [possibly] Queens) into the enemy position, so that a file has no value unless
there is somewhere along it an entry point, i.e., an advanced point on which a Rook can safely land... To summarize, the use
of open files can be broken down into three parts: (i) Take control of the file. (ii) Find a point of entry (this is the important
part; without an entry point a file has no value). (iii) Penetrate via the entry point."
In order to properly evaluate the strengths of the pieces, it seems that we need to find a way to
estimate how a piece 'pulls its weight' in a position by exerting pressure on objectives.
p.71"Chess is very much a team game. The pieces rely heavily on each other's help and cooperation,
so if one does not pull its weight it lets the whole side down."
Mobility and space are important, but how do we define space? It is not a stretch to suggest that
space allows pieces to trace future mobility towards objectives. Future mobility is a measure of space and the first step
in forming plans to attack enemy weaknesses. It seems that tactical opportunities multiply as we focus our search efforts on
(1) ways to move pieces towards weaknesses in the enemy position and (2) ways to restrict the enemy's ability to resist the
advances.
p.132"The essence of simple chess is mobility. Pieces need to be kept active and used economically.
All the objectives of simple chess can be traced back to this underlying notion... weak Pawns hamper mobility because they
require protection... However, the single most important factor in determining mobility must be space, but what is space?
...space is not an easily definable or recognizable concept... The following is nearer the truth. 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."
This is how Stean would exploit a space advantage. Note that one measure of 'counterplay' is the
future mobility of the pieces, modified by the limiting factors which exist on the board and which conspire
to restrict this mobility.
p.140"The strategy behind playing to exploit a space advantage is twofold:
(i) Deprive the opponent of any counterplay, avoiding exchanges whenever possible.
The psychological pressure of being permanently hemmed in may well induce him to weaken himself in order to gain some freedom.
(ii) If no weaknesses are forthcoming you must be prepared to attack on either wing.
Greater space control gives you better communication between flanks, so you naturally want to exploit this fact to build up
against the adversary's weaker front."
According to Stean's definition of space advantage below, it is difficult to determine
whether or not this condition exists unless your evaluation function takes into account the restrictions placed on the mobility
of the pieces by the pawn structure (and of course other pieces)
p.157"The real criterion [for a space advantage] is whether your opponent has more pieces than can
comfortably fit in with his Pawn structure"
