Alisadora—CRT 48 (dirección eléctrica)

Dg327: Black to move

It is important to visualize such sequences and consider what would be possible on the board as it would look afterwards. Picture 1.

…Nxd4, 2. NxN; QxN. The implications of the resulting position are clear if you notice the kernel for a discovered attack that White has on the d-file all along. That kernel is rea-son for Black to act with great care in any operations on that file; taking the d-pawn is asking for trouble, because it creates a target for White’s queen after it is unmasked. In this case the bishop on d3 would end up able to give check with Bxb5, winning Black's queen on d4 next move. So Black dares not play Nxd4 in the first place after all.

Notice how those quick exchanges on d4 ended up leaving White with a new way to check Black's king and also with a great new target for his queen to take once it's un-masked. An earlier point repeats: when a con-tested pawn lies in the center, don't just ask who has more pressure against it. Ask what the board would look like after those pres-sures are spent.

3.1.8. Horizontal Discoveries.

Thus far we have been considering positions based on a single root idea: a bishop masking an attack by a queen or rook on the same file.

The masked piece travels vertically up the board after the bishop vacates its square. But of course bishops also can unmask attacks by pieces on the same rank—attacks that are horizontal, with the unmasked piece running sideways across the board. These are

some-what less common than vertical bishop coveries; it is easier to arrange a vertical dis-covery because it's easy for a queen or rook to move from their starting positions on the back rank onto open files where bishops sit—and then to travel up the files once the bishops move out of the way. A horizontal discovery usually requires that a rook or queen get out toward the middle ranks of the board first so that it can then travel sideways productively.

At any rate, the logic and mechanics here are no different than in the positions we already have studied. The main new challenge lies just in spotting a new kernel: the rook or queen alongside the bishop on the same rank, rather than behind it.

Dg328: White to move

Dg328: In the example, where does White have the makings of a discovered attack? His bishop on c2 masks nothing on its file, but on the second rank it masks an attack by the White queen against Black’s rook. From here the thinking is familiar. The bishop must va-cate the rank violently, and this it does with Bxh7+. After Black fends off the check with KxB, the way is clear for White to play QxR.

White wins the exchange and a pawn with a simple discovered attack turned on its side.

Dg329: Find the kernel of a horizontal dis-covery for White. He has his rook "behind"

(i.e., masked by) his bishop on the fourth rank; he has a good target for the rook in the Black queen on h4; and he has a check to give with his bishop—two of them, in fact: Bh6+

and Be5+. Which is better?

Dg329: White to move

Bh6+ doesn’t work because the queen can both dissolve the check and take itself out of danger with QxB. Be5+ is better because it threatens Black’s king from a square the queen can’t reach, so the queen is lost one way or the other. If Black plays f7-f6, White replies RxQ; if Black plays Qf6, White has BxQ.

Dg330: White to move

Dg330: This time the search for the basis of a discovery leads you to the first rank. Black’s queen appears to have pinned White’s bishop to his rook; but if the bishop can vacate the rank forcefully enough, White can turn the tables and play RxQ. Indeed, everything is in place for a discovered attack except a suitable threat for White’s bishop to make. It can’t now threaten Black’s king; the bishop travels on dark squares and the king is on a light one.

But you see that by moving to h6 the bishop could line up behind the White queen already aimed into the king's territory. This cries out for consideration of QxR, both as a climax later and as a preliminary table-setting move now. Or you might come at the position from the other direction by just looking for checks you can use to move the king into a

vulner-able position. White has two: Qxf7 and QxR.

Qxf7 still leaves the king on a light square after KxQ. But if White instead plays QxR, the recapture KxQ leaves the king on f8. Now the c1 bishop would be able to give check with Bh6+; White next plays RxQ, taking the queen and netting a rook with the sequence.

Dg331: Find the kernel of a discovered attack for Black. He has the queen-behind-bishop pattern horizontally on the sixth rank. He has a target, too; he could play QxQ for free if the bishop on b6 were out of the way.

Dg331: Black to move

Again we have a clear view of the problem;

we need something violent and distracting for the bishop to do—probably a check, but at the moment the bishop can’t threaten White’s king, which is on a light square. We need to move the king. We even can see where: if it could be forced onto g1, Black could play BxB+ and win the queen. The methodical way to pursue this is by experimenting with checks using Black’s other pieces. There is just one to consider: Rxh2+. How would White respond? He has two legal moves:

Kg1, which is what we want, or KxR, which is more likely and doesn’t immediately help us. Okay; but imagine the position after KxR;

look for you next check. The only piece that would have the power to check would be the queen. Qh6+ gives check while still staying on the sixth rank and preserving the kernel of the discovery. White’s only legal move this time is Kg1, and then the discovered attack BxB+ works to win White’s queen.

Dg332: Black to move

Dg332: Where does Black have the makings of a discovered attack? On the fourth rank.

This pattern is easy to overlook during a game because of the pawn that lies between the Black queen and bishop. It's still important to see the kernel; teach your eyes to hop over pieces or pawns in the way of the pattern, since it may be possible to get rid of those obstructions, as is our challenge here. Black has a target in White’s queen on a4, and he has a check for the bishop in BxN+. All the ingredients are in place save one: the pawn on c4 must be removed. The usual way to clear an enemy pawn from a line you need is to capture something it protects, forcing it to move to recapture. Black does this with Nxd5.

White can’t recapture with his c3 knight be-cause it’s pinned; and if he plays c4xN, the way becomes clear for BxN+, discovering the fatal attack QxQ. Of course White should prefer just to forfeit the pawn.

There remains one complexity to consider:

White could reply to Nxd5 with QxB. (Don’t automatically assume that a capture will pro-voke a recapture; it might propro-voke a fresh capture by your opponent elsewhere.) Of course this would leave White’s queen open to capture by the knight now on d5, but it also would unpin the knight on c3 and thus ready it to capture Black’s queen next move. So does White’s QxB ruin Black’s plans? Not quite. Imagine it playing out: 1. …Nxd5; 2.

QxB, NxQ; 3. NxQ. When considering a little sequence like this that would reposition either or both of your knights, pause to consider whether there might be a kicker at the end in the form of a knight fork. Here the exchanges just described would leave a Black knight on

b4—and able to drop next move to c2, where it forks White’s king and rook.

Dg333: Black to move

Dg333: Here is a demanding position. A ha-bitual scan for discovery kernels for Black makes the lineup on the d-file obvious, but nothing productive can be made of it because the target (the d4 knight) is secure. Less obvi-ously, though, Black has a kernel of sorts in attack once it is unmasked. How might Black somehow force or attract a White piece onto a6, b6, or c6? Consider Black’s other pieces and what moves they can make that might help. The rook can’t force anything useful, but now have a look at the bishop on c8. One way to attract an enemy piece onto a square is to put one of your pieces there in a manner sufficiently threatening to make your oppo-nent capture it. Here Black can put the c8 bishop onto the sixth rank with Ba6, where it attacks White’s queen. What response could White make? Moving the queen seems out, because that would expose the rook on f1 to capture; and letting the queen be captured likewise is out. Another option would be Nb5, where White interposes a piece between his queen and Black’s bishop. But then Black has c7-c6, attacking the knight and winning a piece. (Once on b5 the knight is pinned to the queen.)

That leaves White with one other reply to Ba6: capturing the bishop with QxB. But this completes the three-piece kernel of a

discov-ery on the sixth rank, setting up the board for Bxh2+—a discovered attack that takes White’s queen. Black ends up exchanging two bishops for a queen and a pawn. (Moving the queen, and enduring the loss of the exchange with BxR, would have been better after all for White.)

Seeing this idea will be easier after you have studied skewers, for then your attention would be attracted from the beginning by the align-ment of White’s queen and f1 rook. You imagine running a piece through them with Ba6, see that this results in QxB, and then recognize the three-piece pattern for a discov-ery that would result on the sixth rank.

Notice what has been involved in each of the positions we recently have considered: (a) Identification of the basic kernel for a discov-ered attack by the bishop. (b) A precise grasp of the elements of a discovery that are in place and those that aren’t—a suitable target for the unmasking piece, a suitable target for the unmasked piece, and clear lines between all the relevant pieces. (c) Methodical thought about how any obstacle or missing element might be remedied. If the problem is that the unmasking piece lacks a good target, we con-sider ways of drawing the king into its range:

checking the king with other pieces, some-times repeatedly, or capturing something next to the king and thus forcing it to move to re-capture. If the problem is that the unmasked piece lacks a good target, we consider ways of creating one: if there are unsuitable targets already in place, we might capture them with other pieces and invite recapture by more valuable enemy pieces; if there is no target in place, we think about putting our own pieces

Finally, if the problem is that there are pieces blocking the needed lines to make the discov-ery work, we have methods for dealing with that as well. If the obstructing pieces are our own, we look for ways to vacate them from

their squares that are violent and time-consuming for our opponent: checks, cap-tures, and threats. If the obstructing pieces belong to our opponent, we may be able to capture them and cause them to be replaced by the targets themselves. Or we may be able to draw them out of the way by capturing pieces they protect, or by making threats from squares they protect.

That is not a complete catalogue of problems that arise in creating discoveries and options for dealing with them, but it is a summary of the most common types. You want the thought processes involved in those sorts of sequences to become second nature so that you see them right away and can spend your tactical time thinking about more complicated things: how these ideas might be combined, or combined with other tactics; and how they might come into view after a series of pre-liminary threats or exchanges. We will return to all of these patterns, and explore and rein-force them further, when we examine discov-eries by other pieces in the following chap-ters.