by Steve Lopez

In last week's issue we created an "empty" opening key, added a root key to it, and then added two additional subkeys to it. This week we'll add deeper subkeys to one of them and look at a few extra tricks that will come in handy when you create your own opening keys.

You'll recall that the root key was for the Ruy Lopez Exchange Variation (1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Bxc6) and we added two main subkeys to it (4...bxc6 and 4...dxc6). Let's go back to our opening tree and look at what follows after 4...dxc6:

[If you make your own opening tree for the Ruy Exchange, you will likely see a different game total and different stats in your tree. I've been playing the Ruy Exchange for nearly ten years and started a separate database on it back in 1994. My games come from a variety of sources, so that's why my totals and stats are likely to be different from yours.]

First off, we note that White has eleven responses to 4...dxc6 based on the games in the database. We'll need to decide how much of this is important enough to warrant the creation of individual subkeys. It's certainly possible to create keys for every single move as deeply into the opening as you'd like to go, but this is a lot of work. There comes a point at which you have to decide whether or not it's worth the effort to try to capture every individual game into a key. In the tree above, we see that the first six moves on the list have been played more than a hundred times, while the seventh move (5.b3) has been played twenty-seven times. If we create subkeys for only these seven moves, games in which the remaining four moves were played will be "loose" games; that is, they'll appear as individual games at the bottom of the list when we look at the key for 4...dxc6. This isn't critical in a database this size: there will be just fifteen loose games at this point. So we decide it's not worth the effort to create individual keys for the last four moves on this list.

The next determination to make is the order of the moves in your key list. If you've used the opening keys that come with Big Database, Mega Database, the ChessBase Opening Encyclopedia, etc., for any length of time you've probably already noticed the "standard" for move ordering ChessBase GmbH uses when creating these keys: the least commonly-played moves typically appear at the top of the list, followed by the more commonly-played ones near the bottom. A corollary of this is that the more commonly-played moves typically lead to further subvariations and are also seen near the bottom of the list. The idea is that when you click on moves near the top of a list, you're more likely to get individual games, while moves nearer the bottom are more likely to lead to further subkeys.

So when we create subkeys for moves that follow 4...dxc6, we should start at the bottom of the tree list in the diagram above and work our way up. What we should ideally see is 5.b4 as the first subkey on our list (at the top of the list) and 5.0-0 as the last key (down at the bottom). Following the instructions given last week for creating keys, we should end up with something like this:

It should look exactly as described: 5.b3 is at the top and 5.0-0 is at the end. If your key is in the wrong order, it's because you forgot a suggestion I gave last week: before adding a new key, always click once on the last key on your list to highlight it -- then ChessBase will place the new key after it on the list (e.g. at the bottom of the list).

If you messed this up, don't worry -- this is actually a good thing at this point, because it leads right to another tip. If you decide that you want to move a key up or down in your list, right-click on the key you want to move. A popup menu will appear; select "Define key memo" in this menu. You've just told ChessBase that this is the key you want to move. Click once on the key that appears immediately above the position where you want the moving key to appear. Right-click on it and select "Insert key memo" from the popup menu. ChessBase will then move the first key to the new spot on the list. Once in a while, particularly when you try moving a key to the very top or bottom of a list, ChessBase will insert it above the key you've highlighted, so it may take a bit of tweaking on your part to get the list just right -- but it's certainly "doable".

Note the zeros in parentheses at the far right of our key list. This is where the program will show you the number of games that are classified into each key. Why are these zeros? Because we haven't yet classified the games. To classify them (that is, make ChessBase sort the games into the proper indexing classifications), go to the Tools menu, select "Classification", and then "Whole database" from the submenu. You'll see a dialogue that asks the game number in the database where it should start. Go ahead and use the default of "1" and you should end up with something like this:

You'll note some unusual things about this list. First, we have more than the expected fifteen "loose" games at the bottom of the list. This is because there are a bunch of games that ended after 4...dxc6 (you can pick these out by the dashes where moves would normally appear), so these appear as extra games beyond the expected total of fifteen (since the games ended after Black's fourth move, they didn't appear in the tree list for White fifth moves). Also, the number of games for some of the keys don't exactly match what we saw in the tree; this is because of transpositions that are picked up in the tree that don't appear in the keys. This ultimately gets sorted somewhat as you create further subkeys (or higher branch keys) in your opening keyfile. (You'll also notice that I haven't killed the doubles in this database for a while -- shame on me).

Let's go up one level in the key (to Black's fourth move) to illustrate another point:

Have a look at what's in the parentheses at the far right after 4...dxc6. You'll see a couple of dots following the number of games. This indicates that there are subkeys as part of that key. As you create subkeys and classify the games, you'll always see these dots for any key that has additional subkeys.

Now for a couple of additional tips concerning move ordering and move display within a key list. You might come to a point in a game where an opponent's reply is forced. Pulling an example out of my head (that is, I'm just making this up), you might have a selection of three moves, one of which leads to a forced reply:

8.Ne5
8.Bxh7 Kxh7
8.b3

Instead of creating a key for 8.Bxh7 and then making 8...Kxh7 (the only move in that position) a subkey of it, you can save a step by creating a key for the position after 8.Bxh7 Kxh7. This saves you time later when using your keys: instead of double-clicking on 8.Bxh7 and getting a single subkey (8...Kxh7) that you'll also need to double-click on to proceed deeper into the keys, you create a key for the position after both 8.Bxh7 and 8...Kxh7 have been played. Then when you double-click on 8.Bxh7 Kxh7 you'll immediately get any further subkeys and games, instead of a useless extra subkey for a move that was forced anyway.

As a matter of aesthetics, you might also want to put 8.Bxh7 Kxh7 as the bottom key on your list, so it'll look like this:

8.Ne5
8.b3
8.Bxh7 Kxh7

This prevents your key from having a "ragged" look. (And, if you want to be really picky, you could put 8.b3 at the top, followed by the Knight move, and then the Bishop capture, for an even "smoother" look).

Another tip concerns the font you'll want to use in your key displays. You'll want to use a Courier font (which is a "fixed pitch" font), rather than one of the others -- this will ensure that your keys will line up properly. A fixed pitch font is one in which any character takes up the same amount of space on a line as any other. With most fonts, smaller letters (such as i) take up less room than larger letters (such as m). With a fixed pitch font, i's will take up the same amount of space as m's; this creates a uniform spacing of characters and the moves on each line of your key list should line up properly with the moves on the lines above and below it. To change the font, right-click on an empty space in your key display (instead of directly on a key), choose "List format" from the popup menu, select "Font" from the submenu, and choose the font from the list. You'll want a font that starts with the word "Figurine" and has "Crr" (for Courier) elsewhere in the name (if you have some of the older ChessBase fonts) or else use the font "FigurineCB LetterSP" if you're working with the newer ChessBase fonts.

Here's one more aesthetic consideration. As you get deeper into the keys, you might wind up with a situation like this:

9.Nd2
9.Bb3 Ne7
9.Bb3 Nf6

There are two Black responses to 9.Bb3 and, to save later clicking, you might want to have them appear in the list for White's ninth move. But the appearance of 9.Bb3 twice in the same list is a bit confusing. Here's how you handle it. Make 9.Bb3 Ne7 the first key on your list. Then, when you create the second key (for 9.Bb3 Nf6) and come to the display that lets you edit how the key will display, delete the characters for "9.Bb3" and instead just put six spaces in the box prior to the "N' in "Nf6":

9.Nd2
9.Bb3 Ne7
      Nf6

And you wind up with a better looking display. Since there's empty space before "Nf6", the move from the previous line is assumed. (And this is another reason why you want to use a fixed pitch font, so that everything lines up properly. Also, you can just count characters from the previous key and see how many spaces you'll need in order to make it line up properly).

One last point concerns transpositions. If you try to create a key for a position that already exists somewhere in the keyfile for that database, ChessBase will alert you to this. Go ahead and create the key; ChessBase will "link" the two keys. Stepping down through the key to that position will get you to the same set of subkeys/list of games no matter which of the two "paths" you take to get there. But things might get quirky as you move upward through the hierarchy of keys and you'll often find yourself in a totally different part of the opening key than where you started. Such is the nature of chess transpositions.

Over these three articles, we've looked at the basics of creating opening keys. We certainly haven't looked at everything (and can't cover every situation that might arise), but this should be enough to get you started; more info can be found in the Help files. I've created a lot of opening keys for my own use (and a bunch of keys for some soon to be released electronic books) and I still find the process to be full of surprises (especially due to transpositions). Creating good opening keys is almost an art -- you get to use both halves of your brain in sorting the technical aspects of the chess moves and in making a useful key that also appears good to the eye. You'll also learn a lot about the opening in question, too. Go ahead -- give it a try and, as always, have fun!

© 2003, Steven A. Lopez. All rights reserved.
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