Chess is a game for two players (we shall call them White and Black) using an 8×8 board of 64 squares. The squares are alternately white and black (or any pair of light and dark colours). The board is placed between the players in such a way that each one has a light square in front of him in the right-hand Corner.
Notation of squares
Each square has, so to speak, a “name”. This is especially important because you will need this notation for playing with your talking chess partner. The computer displays each move by naming first the departure square, then the destination square.
On the chessboard there are eight vertical files (i.e. columns of squares) and eight horizontal ranks. The files are designated by the letters a-h, the ranks by the numbers 1-8. Each square is situated on one rank and one file, and is thus has a unique identity – there is only one “a2” square on the whole board, one “c5” and one “g3”. On your computer’s chessboard, you will see that every square has its notation marked on it.
The Pieces and the Starting Position
Each player begins with 16 pieces: one king, one queen, two rooks, two bishops, two knights and eight pawns. In this book they are represented by the following symbols:
The starting position of the pieces always looks like this:
Experience shows that the king and queen, or the bishop and knight, get placed the wrong way round particularly often. For the former case, note that the queen goes on a square of its own colour. For the bishop and knight, unfortunately, there seems to be no such convenient memory aid.
The starting position gives rise to an important pair of concepts. The right-hand half of the board, where the kings are placed (consisting of the files e-h), is called the kingside. The files a-d are the queenside.
A game always begins with White making the first move. Then Black moves, then both continue to move alternately. An important point is that on your turn, you must move – you are not allowed to “pass”. In fact, in some situations (which are by no means rare), a player would be better off if he did not have to move, because any move he makes will worsen his own position! Such a situation is known as Zugzwang (in German, “compulsion to move”). You will find plenty of examples in later chapters.
This is the most important of the chess pieces, since the object of the game is to take the king prisoner (that is, “checkmate” it – we will come back to this). On the other hand the king is by no means the strongest fighting unit, and it generally needs to be kept well guarded in a safe place – at least as long as there are many other pieces on the board. It can move in any direction, but only one square at a time:
The two kings can move to the squares indicated. The first thing to strike you is that the white king has many more squares available, namely eight. The black king has only three, one of which happens to be occupied by a white knight. Most of the pieces are much more mobile in the middle of the board (the so-called centre) than on the edge, let alone in the corner. Nonetheless, for the more valuable pieces it can be dangerous to plunge into the midst of the fray from the very start, and this is especially true of the king, as we have said already
If an enemy piece is within the field of movement of one of your own pieces, it can be captured. This is carried out just like a normal move – in other words if the black king captures the white knight here, it occupies the knight’s square and the latter is removed from the board.
You may not capture your own pieces. If the knight on h7 were black, it would be depriving its king of this square. In general, the king actually likes to have a protective wall of its own pieces. However, when your own pieces get in each other’s way, this can do more to hamper their co-ordination than anything the enemy does!
As an overall rule, any piece may capture any other; however, the king is the only piece which can not itself be captured. Hence one king can never move into the other king’s field of action; there must always be at least one square separating them. Of course the king is also unable to move onto a square threatened by any other enemy piece. For what happens when an enemy piece attacks the king, see below, under “Check and Checkmate”.
This is the most powerful piece in the game. It can move any distance in any direction.
Here the queen can move to any of the indicated squares. It too has less choice when placed on the edge or in the corner. As we know, it can capture enemy pieces within its field of action; it may not, however, jump over any piece. If we place a black pawn on d7, then the queen can move in that direction to d5 or d6, or capture the pawn; but it cannot go to the square beyond, i.e. d8.
This is the second strongest piece, after the queen. It can move any distance in a straight line horizontally or vertically. Note that the rook has the same number of possible moves from any square (at least on an open board) – so it is not affected by being placed on the edge or in the corner
The Bishop only moves diagonally, though it too can go any distance in a particular direction. Placed in the centre, as here, it has almost as many moves as the rook; but on the edge or in the corner it has distinctly fewer. For this reason the bishop is on the whole somewhat weaker than the rook.
Throughout the game the bishop remains on squares of one colour. Thus, at the start, each player has a “light-squared” bishop and a “dark-squared” one. Both together (the bishop pair) can be an especially powerful force, since they complement each other effectively and can control the whole board.
Comparing the last three diagrams, we can see that the move-ments of rook plus bishop equal the movements of the queen. The queen is nevertheless stronger than a rook and bishop combined, since unlike the bishop it can switch between both colours of squares; and anyway, at each turn it has the choice of moving either like a bishop or like a rook.
The knight’s move is generally the most difficult to learn, as it makes such “crooked” jumps. There are two ways of visualizing it: either as an L-shape (two squares in a straight line, then one at right-angles), or else as a “Y” (one square straight forward, then one diagonally right or left). In the diagram, all the squares the knight can move to are marked. Furthermore, the knight is the only piece that can jump over others (of either colour)! We can see that none of its moves leads to a directly adjacent square; the knight could therefore be completely surrounded by pieces with-out losing any of its mobility at all.
In view of this peculiar way of moving, you might suppose it would be hard to compare the knight’s value with any other piece. In practice, though, the knight and bishop prove to be almost equal in strength! One other feature may be noted: the knight moves to the very squares which a queen cannot reach from the same departure square. Hence queen and knight often work well together as a pair.
This is the weakest of the pieces, yet its way of moving has a few peculiarities. The pawn’s ordinary move is just one square forward (never backwards). From its starting position on the second rank, however, it may also advance two squares. You have the choice of moving it one square or two at once, but if it only goes one square, the double advance cannot be reserved for later.
The pawn’s capturing move differs from its ordinary move. When capturing, it goes one square diagonally forward to the right or left. This is no different if the pawn is still on its starting square.
All the pawn’s possibilities of moving and capturing are incorporated in the diagram. The white pawn can move one or two squares forward, or else capture the black knight. The black pawn has already taken one step from its original square, so now it may only go one square forward; alternatively it may capture the white rook.
It is quite rare for a pawn to keep advancing right to the far end of the board (usually it will be captured on the way); if however it does so, it is promoted, i.e. it changes into a different piece of the same colour! The only restriction is that it cannot become a king or remain a pawn; you therefore have the choice between a queen, rook, bishop or knight. Almost always, of course, the queen is chosen, being the strongest piece. There are, however, exceptions, when (say) promotion to a knight is better, as the knight can reach different squares from the queen.
A promotion is carried out by removing the pawn from the board and inserting the new piece on the promotion square. It doesn’t have to be a piece previously captured. In other words, a player may have two queens or three knights on the board – even though no provision is made for this in the starting position!
This special rule contributes much to the peculiar charm of chess, for at a late stage, with few pieces left on the board, hardly any game could be won if there were no promotions.
Capturing en passant
This rule resulted from the pawn’s double advance. The diagram illustrates what is involved.
If the black pawn were to go just one square forward, the white one could capture it. But is it possible to slink past the danger zone by the double advance d7-d5…? It was in order to eliminate this possibility that the en passant rule (French for “in passing”) was introduced:
If a pawn’s double advance places it alongside an enemy pawn, the latter may capture it as though it had only moved one square.
The move is carried out in just the same way as a capture following a single advance. The white pawn goes from c5 to d6 and removes the black one from the board.
NB: An “en passant” capture is only possible as an immediate reply to the pawn’s double Advance!
Another special rule – but don’t worry, this is the last one! It results from the fact that early in the game (as we have said), the king needs to be brought to a safe place, if possible with pawns in front of it. If it simply moved towards the corner, however, it would be constricting the rook. Castling solves both problems at once.
Here is how the move is carried out. The king moves two squares towards the rook with which it wants to castle. The rook jumps over the king to the square on the other side.
Here we see the position after both possible castling moves. White has castled “short”, Black has castled “long”.
According to the rules, castling counts as a move of the king; hence the king should always be moved first, and this is the only way your computer allows you to castle. If you move the rook first, the computer will take this to be a simple rook move, and won’t let you follow by jumping with the king.
For castling to be possible, certain conditions must be met:
- The king, and the rook with which it wants to castle, must not have moved before. Even if the king or rook has moved and then returned to its starting square, castling is no longer possible. If only one rook has moved, but the king has not, castling is still possible with the other rook.
- The squares between the king and the rook must be vacant.
- The king must not be under attack (i.e. “in check” – see the section “Check and Checkmate”). If only the respective rook is under attack, castling is permitted.
- The square the king is moving to, and also the square it crosses over, must not be under threat.
Here’s an illustration of these rules. Black cannot castle on either side. To castle short, the king would have to cross the f8 square, which is controlled by the white bishop. After castling long, the king would be on c8, which the white queen on h3 has in its sights.
White on the other hand can castle on either side. At first sight, the bishop on e4 might seem a hindrance. However, on the “short” side, the bishop only attacks the rook; the squares f1 and g1, required for the king’s leap, are free. On the “long” side, things are similar – the bishop threatens b1, but if White castles long, that square is only crossed by his rook; neither of the crucial squares for the king (c1 or d1) is under fire
Check and Checkmate
If a player attacks a piece and his opponent overlooks this, the piece is lost. With the king the matter is not so simple, because, as we know, it can never be captured. You can attack the king just like any other piece, but it is essential for your opponent to parry this attack on the very next move. Since such an attack is called a check and the king is then said to be in check, a player will often say “Check” to draw his opponent’s attention to it, especially in games among novices. Your computer does this too, although it isn’t strictly necessary.
There are three types of move by which a check can be parried:
- The king moves to a square where it is no longer in check.
- The piece giving check is captured.
- A piece places itself between the king and the enemy piece which is checking.
Here we see all three possibilities in a very simple example. It is White’s move, and he is in check from the bishop on d5.
- The king can move to h2 or g1 (but not g2, where it would still be in check).
- The rook can capture the black bishop.
- The rook can move to g2, which again terminates the check.
If a check cannot be parried in any of these ways, the king has been checkmated (i.e. it would unavoidably be captured next move). In later chapters you will be shown numerous checkmate positions and how they can be brought about
Winning a game
A player who checkmates his opponent’s king wins the game. Checkmate – generally abbreviated to “mate” – terminates the game no matter what else is happening on the board. Even if the player who has been mated has several pieces more, or possesses any other kind of advantage, he loses.
In actual fact, among stronger players and especially in tournament games, the mating move is hardly ever carried out. A player will usually resign when he realizes that his position is hopeless. It may be that he is threatened with unavoidable mate by a forced sequence of moves, or his opponent may have so much extra material that the rest is a so-called “matter of technique”.
In tournament chess there is also one other way of winning, which is not all that rare; this is when your opponent oversteps the time limit.
However, these last two possib-ilities need not concern you when playing with the computer, as you may always carry on until one side is mated and are also allowed to take more than the stipulated thinking time.
The normal type of draw occurs when neither side has enough material left to force mate. As to what sort of advantage you need in order to win, this is explained in Chapter 2 (“Checkmating the King”).
A second type of draw is stalemate. That means that the player to move has no legal moves available, yet his king is not in check (as it would be in a checkmate position).
Such things quite often happen to inexperienced players when they are trying to mate the opponent but get a little careless. Here White has penned the black king in and deprived it of all its squares. The queen controls c8, d7 e7 and e8, while the king controls c7. Black to play has only his king left, but can’t make any more moves with it – and he is not in check. Though White is a whole queen up, the game is a draw.
A draw may also come about in any of the following ways:
- The same position, with the same player to move, occurs for the third time.
- Both sides play a sequence of 50 moves each, in which no piece is captured and no pawn is moved.
- The players agree a draw (which in principle they are free to do at any time).
In fact, a special case of (1) might very well come about in play with your Computer:
Black has a rook and pawn less, but if it is his move, he can force what is known as perpetual check. He moves his queen to h4, checking the king. White can neither take the queen nor interpose a piece on h3, so he must move his king – which only has the square g1. Now the queen returns to e1, giving check again. White has to go back to h2, and the shuttling back and forth continues. White can’t make use of his material advantage because he can never escape the checks. The game ends in a draw.
Material value of the pieces
Material isn’t everything in chess, yet most games are won by the player who has more pieces or more valuable ones. In presenting the individual pieces, we have already learnt something about their value. In numerical terms, the following table has proved its worth as a basic guide.
- Pawn = 1 Point
- Knight = 3 points
- Bishop = 3 points
- Rook = 5 points
- Queen = 9 points
The king has no material value, as it can never be captured.
Some important chess terms can now be explained. If both sides capture material of equal value, we speak of an exchange. It also frequently happens that a player will deliberately give up material to in return for other advantages; this is called a sacrifice.
The term the exchange is also used to denote the difference in value between a bishop (or knight) and a rook. Thus, if a player deliberately gives up a rook in return for a for bishop or knight, he is said to be “sacrificing the exchange”.
When you have an opportunity to capture enemy pieces, you often have to calculate a little further ahead. Sometimes a whole series of captures or exchanges will be set in train. Then you will need to keep track of who wins more or loses more at the end of it all!
Captures and recaptures are the theme of the next diagram and some adaptations of it. In each case it will be White to move, and we shall ask whether it will pay him to capture on e8.
In this basic form, the matter is simple. White can take the rook with his queen, gaining 5 points. Black can do nothing about it, as he only has his king left.
Now let us add a black bishop on f7. If White now takes the rook with the queen, the queen will be taken by the bishop. White would be gaining 5 points before losing 9 – a bad deal. He will therefore avoid capturing the rook. In such positions we say that the bishop is protecting the rook, i.e. preventing White from capturing it.
The next stage is to give White one more piece, a rook on e3. Now this rook captures the black one, the bishop takes the white rook, and finally the white queen takes the bishop. The balance sheet is 5 points for White, then 5 for Black (in other words a rook exchange), but afterwards 3 more for White, who thus gains material worth three points out of the whole transaction.
Next, one further alteration – we place White’s new rook not on e3 but on e1, behind the queen. Now the queen can capture on e8 (5 points), but will be taken by the bishop (minus 9 points), after which the bishop will be taken by the white rook (3 points). White will have captured two pieces to Black’s one, but will nonetheless have lost one point (8 against 9).
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