Handicapping Rybka 3

1/7/2009 – Chess programmers have for many years been finding unique means of "handicapping" their chess engines to make them play a weaker chess game should the human user desire one. The reason for this should be obvious: not everyone enjoys getting his or her head torn off by a 2700+ Elo player on a daily basis. Learn all about Rybka's handicap playing features in the newest ChessBase Workshop.

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The challenge for programmers over the past ten or twelve years is to find a means of making such handicapping essentially transparent to the user. The paradox is that a person using a chessplaying program as a practice tool wants the option of "dumbing down" the chess engine, but he doesn't want to feel like he's playing said engine under handicap conditions.

In my opinion, the problem for a chess programmer is that it's difficult to find a really elegant solution for this paradox (or even just a passable solution which will please a majority of users), and searching for one simply takes time away from what are arguably more crucial programming concerns. The programming team for Rybka3 has opted for the direct approach; instead of offering a "transparent" solution, they've gone straight for the bare-bones approach with two new handicap forms for their software.

People who have read previous ChessBase releases about Rybka may have received the wrong impression about the two handicap modes which we're going to discuss in this column. The two modes are not designed to work together; they are, in fact, two distinctly separate modes for handicapping a chess game.

The first of these modes is a truncated opening book. There are two schools of thought regarding opening libraries for chess computers. The first is that a larger opening book is good for training purposes, because the human user will see a broader array of openings which he's likely to encounter when facing human opposition. The second school of thought is that a larger opening book gives the chess engine some kind of "unfair advantage" over a human opponent.

I've been in the chess software business for a decade and a half, and I find that second school of thought to be quite curious, given the sheer number of chess opening books, disks, and reference materials I've sold (and provided support for) over those years. Chessplayers spend far too much of their study time on the opening; in light of this, the idea that a computer program shouldn't have access to a detailed opening book is like saying one's opponent in a sprint should have his feet tied together.

However, that having been said, I can understand why a novice chessplayer might voice that particular opinion. In such a case, a player who doesn't know a King's Indian from a Ruy Lopez might well feel overwhelmed by playing a chess engine which references an opening book containing hundreds of thousands (even millions) of moves/positions. Rybka3, in addition to an opening book designed for normal play, also contains a second "handicap" book which goes just three moves deep. Note that by "three moves" I mean three move pairs (six plies, in "chess computerese"). This opening book, incidentally, can be used by any chess engine running within the ChessProgram11 interface; it's not limited to just Rybka3's use alone.

Another use for this handicap book is as an opening library for engine vs. engine games, matches, and tournaments. Since the book is a mere three moves deep and contains no "weighting" factors based on results of human games, it will provide a certain level of variety to games pitting engines against each other without unduly affecting the end result(s).

Note that the filename for this opening book is handicap.ctg; it's copied to your hard drive when you install Rybka3. The exception occurs if you selected a "Custom" installation and opted to not install the opening books. In this case, you'll find the book on your Rybka3 DVD:

If you need to copy the opening book manually, please be sure to copy all three of the tree files shown above (the file extentions are .ctb, .ctg, .cto) into the same hard disk folder, otherwise the tree won't work. Also be sure to remember which folder you've copied them to; after launching Rybka3, you can go to "File/Open/Openings book" and use the File Select dialogue to "point" the software to the proper opening book.

Another time-honored handicapping tradition is the "Material" or "Material+Move" handicap. This is often used today when teaching a novice chessplayer; the more experienced player removes a certain amount of material from the board (and may also give the less experienced player the White pieces; hence the "+Move" aspect). I've used this technique extensively when teaching children or teenagers to play. I'll remove my Queen from the board at the start of each game until they reach a point at which they regularly win games. Then I'll give "Rook odds" until they progress to a "minor piece odds" level, and so on.

Although this technique is primarily used as a teaching device today, there was a time in the 1800's when the technique of "giving odds" to the weaker player was a standard practice. It helped give the less experienced/less accomplished player a fighting chance while providing a more challenging game to the stronger/more experienced player (one of my favorite games I ever played was one in which I gave Queen odds to a teenager who'd just learned the game, and it was a challenging game for us both; the game is briefly described in my column "The Crossroads" [published in the year 2000 and which has been reprinted in various places around the Internet]).

For some reason, this tradition of offering "odds" has died off (at least among adult players); apparently many people find the concept to be somehow "insulting". However, if a player is willing to swallow a bit of that unreasonable pride and wishes to play that type of "odds" game against his Rybka3 software, that handicap mode is offered by going to the File menu, selecting "New", and then "Handicap position":

The dialogue offers a variety of "odds game" forms, all of which were traditionally used in the 19th Century. You can simply select one, click "OK", and the board will automatically be set up with the proper odds given (i.e. with the proper material missing). If you've selected "Material+Move" odds, that will also be automatically taken into account. If you've selected an option which gives Rybka the White pieces (you'l know this because the Black pieces will be at the bottom of the screen), just hit the spacebar on your keyboard to have the engine start the game by making a move.

And by no means should you be "embarassed" by playing an odds game against a computer program. It's just between you and your software; nobody else will ever know about it (unless you tell them). Best of all, it's actually fun and, if you're blessed with a bit of imagination, it's easy to picture yourself playing a game against a world-famous player in a Paris opera box sometime in the mid-1800's.

Until you return to the 21st Century, have fun!



© 2008, Steven A. Lopez. All rights reserved.


Topics: rybka3
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