by Steve Lopez

There seems to be a great deal of recent confusion on the subject of opening books in our playing programs. This is due to the proliferation of chessplaying programs that we now offer (Fritz5.32/Hiarcs7.32/Junior5/Nimzo99). Each of these programs comes with its own opening book, and quite a few people are confused about their usage and some other related issues. In this week's ETN, we'll take a look at the various opening books and a couple of side issues pertaining to opening book use.

First of all, an opening book is the same thing as an opening tree -- different terminology, same thing. So, for example, you can use the opening tree that's included on an Informant CD as an opening book for any of our playing programs.

How do you know what opening book is currently loaded? This is displayed on the main screen in the analysis window:

Note the upper left corner of the analysis window -- you'll see the filename "power.ctg". This shows me that I have the Powerbook 99 opening book loaded.

If you see "newbook.ctg" in this box, this will explain why your playing prigram plays the same opening over and over and over. "Newbook" is the default name for an empty opening book that you've created yourself. The "New tree" command in the Book menu does not allow you to switch from one previously-existing tree to another -- it instead allows you to create a brand-new (empty) opening book for your playing program. To switch from one opening book to another, use "Load book" in the Book menu. This was previously covered for Fritz5.16 in the November 8, 1998 ETN and will be further amplified in this article you're now reading.

If you select "New tree" and then just click the "Save" button, a new empty tree is created on your hard drive. If you then start playing a game against one of your engines the moves of this game are saved into the tree. This then becomes the opening tree and the moves therein are thereafter the only opening moves your program "knows". This is the primary cause of your program playing the same opening repeatedly.

When you want to load an opening book, select "Load book" instead of "New tree". In the new window that appears, select the "Load" button, which will bring up the standard Windows file selector box (this is the same box that you see in any Windows program, whether it's a chess program, a spreadsheet, a word processor, a sports game, etc.). Use this box to go to your CD drive and load the opening book you'll find on that CD. If you don't know how to use this file selector, you'll need to learn -- this is a vital skill for the use of any Windows program. Your best bet for learning is a good basic book on your version of Windows; I recommend either the for Dummies book or the Complete Idiot's Guide book for whichever version of Windows you're running. These are the best and most painless beginner books on the market.

Once you've selected the opening book and clicked "OK", you be taken back to the "Load book" window. Just click "OK" in that window and your new opening book will be loaded. Click the "New" button to start a new game and you'll see the name of the opening book you just loaded appear in the analysis box.

Many people with larger hard drives want to copy the opening book from the CD to the hard drive. This can be done quite easily directly in the program. Be aware, however, that each opening book is about 100 megabytes in size -- be sure you have enough hard disk space to put the opening tree on your drive.

To copy the tree to the hard drive, just hit [F11] on your keyboard (you'll find it in the row of "F" keys along the top of the keyboard; this does not mean hit the [F] key followed by the [1] key twice). Hitting the [F11] key opens the tree so that you can see the moves therein. Click the Book button and select "Copy tree to disk" from the menu. You'll see that Windows file selector box again, which will allow you to designate what folder you want to place the opening tree files into. I'm frequently asked, "Does it matter where I put the tree?". Not to me and not to your program. It's totally up to you. If you're going to put more than one opening tree on your hard drive, you'll want to know where you put them so you can switch between them using "Load book", so it's helpful if you copy them to a folder you'll remember.

Once you've selected a folder and clicked "Save", the program will copy the tree to the hard drive. When it's finished, it will also automatically switch to that tree and remove the "read-only" attribute from the files. At that point, you're done -- the tree is on the hard drive and your playing program will happily use it.

So which tree should you use in which program? Let's take a brief look at the opening trees that come with the various programs.

Fritz5.16 only has one opening tree: it's called f5book.ctg and it's found on both the installation CD and the Talk CD. However, Fritz5.32 comes with two opening books. The one on the Talk CD is still the old f5book.ctg, but the installation CD has a newer book called general.ctg. Which one should you use?

If you're running the opening book off of the CD and you want Fritz to speak in English, your choice is made for you: you must use f5book.ctg on the Talk CD. However, if you're using your hard disk to store the books, you have the choice of either book. The one on the Talk CD (f5book.ctg) is a special opening book geared toward Fritz' unique style of play; it's intended to maximize the program's strength and minimize its weaknesses. The book on the installation CD (general.ctg) is a good generalized opening book geared to overall computer play. The reason that the "general" book is included with the program is so that it can be used with the other engines that are included with Fritz5.32 (Comet, Crafty, Doctor?, ExChess).

The choice of opening book is not so critcial in typical human vs. computer games (i.e. in games you play against the program, unless you're a top grandmaster). Fritz5.32 is very content to use either opening book. However, in engine vs. engine matches and tournaments, you'll probably want to use the f5book for Fritz and the general book for other playing engines included with the program.

The same advice holds true for the other opening books that come with the various chess programs we sell. Hiarcs7.32 comes with an opening book called hiarcs.ctg -- this is an opening book tuned to Hiarcs' strengths and weaknesses. The same holds true for Junior5 and its junbook.ctg and Nimzo99 with its nzbook.ctg. You should use these with the program in question when you play matches and tournaments against other chess engines.

We offer other opening trees on some of our other disks. Chief among these is the Powerbook 99. This comes with 5 opening books: the overall power.ctg and four opening books covering Kasparov and Anand's opening repertoires. The Kasparov and Anand books are there for you to have fun with: just load Garry's opening repertoire as White, you take the Black pieces, and imagine yourself sitting across the board from the world champion.

But what about the power.ctg? Won't this make your playing program stronger? Actually, it will probably weaken it somewhat. The Powerbook tree is a compendium of all major opening theory. Consequently, it contains openings that are positional in nature in which long-term strategic planning is the key to success. Computers can't plan and execute long-range ideas; this is why they stink at closed positions. Computers are strongest at tactics, which is why they prefer wide-open positions. By using the power.ctg opening tree, you're allowing the computer to play openings that lead to positions unfavorable to the computer's style of play. This will consequently weaken the program somewhat over the long haul. The benefit of using this opening tree is to allow you, the human player, to face a wider range of openings than what are provided in the program's preferred opening book. This makes the Powerbook an excellent training tool for you to use to help you become familiar with a wide range of openings.

Another tree is the gambit tree on our Gambit Lexicon CD. Loading this book allows your program to play a large number of gambits against you (or gives the program the necessary knowledge to face your gambit play). The Informant 1-70 CD contains a tree made up of the games from the first 70 volumes of the Chess Informant. The individual Informant CDs also contain trees of the games from those particular issues. Many of our training CDs also contain specialized opening trees for your use.

Of course, it's pretty easy to create your own opening trees for use in your playing programs. This was discussed in ETN on February 7, 1999. The issue for September 14, 1997 discusses creating an opening book to make your program play the openings in the style of a specific player -- just use the general ideas from the September issue with the specific procedures from the Feb. 7, 1999 issue to discover a unique (and fun) way to use our playing programs.

I hope that this week's ETN has answered some of the nagging questions you might have about opening trees and increases the usefulness of your program. Until next week, have fun!

You can e-mail me with your comments, suggestions, and analysis for Electronic T-Notes. If you love gambits, stop by the Chess Kamikaze Home Page and the Yahoo Chess Kamikazes Club.