Entries in computer chess (27)
Martin Thoresen has been running computer-computer events for some years now, and the super-final of the eponymous Thoresen Chess Engines Competition (TCEC) is nearly at an end. After four elimination stages the programs Komodo and Stockfish (not Houdini!) made the final, and after 44 of 48 games Komodo leads 22.5-21.5. Game 45 is nearly over now and headed for a certain draw, leaving Stockfish just three games to catch up.
There is a bit of a "human interest" aspect to the story. (Granted, that's an incredibly stupid phrase, as all stories are presumably of some interest to humans - why else report them?) Komodo's main programmer, Don Dailey, passed away from leukemia on November 22*, early in the super-final. While programming surely wasn't his highest priority at the very end of his life, it still must have afforded him some satisfaction to have reached the final, ahead of Houdini, the previously recognized top program.
* This November 22 marked the 50th anniversary of the deaths of not only John F. Kennedy, but authors Aldous Huxley (best known for Brave New World) and C. S. Lewis (the Narnia books, Mere Christianity) as well.
TCEC is holding its second unofficial world computer chess championship, and it has just gotten underway. There's always a live game going there, and will be for about three months' time for anyone truly desperate for a chess fix. Last year Houdini won in the "super-final" against Stockfish; those two should be in the mix this year as well, with Komodo another favorite.
HT: Chess Today
If you're looking for a strong, free engine and already have a GUI for it, Stockfish 4 is available. Stockfish 3 was a very strong #3 on this rating list (the other two are certainly worthy but not free), so one would expect its successor to be at least as strong. My quick impression is that its evaluations may be a little bloated early in the game, so don't be in a rush to accept its evaluations of your favorite opening as gospel truth. Clearly it does a great job of finding moves though, so again, if you're looking for a very strong and free engine and have a GUI for it, you may wish to give it a try.
Remember the second match between Deep(er) Blue and Garry Kasparov? This is the one where computers supposedly proved their superiority to human beings in chess. Kasparov had defeated its predecessor the year before by a relatively comfortable 4-2 score, but the rematch in 1997 went differently. Kasparov opened with a comfortable win, but then lost game 2 in what turned out to be controversial style, drew the next three games (though coming close to victory in games 4 and 5), but then had a complete breakdown in the last game, getting crushed in just 19 moves. Thus Kasparov lost the match 3.5-2.5, and the popular media widely broadcast that this was the end of humanity's reign over the royal game. This was almost surely false, but like the old joke goes, we're just haggling over the price; there's absolutely no doubt at this point that decent programs running on decent home computers are far stronger than even the best humans on their best day.
But back to the match. Game 2 was a huge turning point, and not just because the computer won. Kasparov was playing the Closed Ruy - not exactly one of his main openings with the black pieces - and was getting impressively outplayed. A first move that shook up Kasparov was 37.Be4. To human eyes, it's really obvious. Black has no counterplay anywhere, but would if he could play ...e4. Prevent it, and the world is White's oyster. The problem was that 37.Qb6 seems like a simple win of material. The standard view of computers was that they would take free material in all but the most obvious cases where doing so would be wrong, but here it didn't.
But if that bothered Kasparov a bit after the game, that was nothing compared with what happened later. The computer apparently continued rolling along with its positional masterpiece, and when Deep Blue played 45.Ra6 Kasparov threw in the towel. Anyway, analysis later that night seemed to show that in the final position Kasparov missed a draw with 45...Qe3, with an inevitable perpetual check. As the line wasn't even too terribly long, especially for a computer calculating 300 million positions per second, it really seemed to Kasparov that the hand of human intervention was at work. If 37.Be4 was the sort of move where typically human judgment is better than that of a materialistic computer's, then 44.Kf1 is a moment where human judgment falls short relative to the computer's. The engine can work things out to the bloody end; humans can't.
And yet...Deep Blue didn't. How was this possible? After and even during the match, Kasparov requested - or rather, demanded - the logs displaying the computer's evaluation. (Unless I'm badly mistaken, the Deep Blue team claims that they were given shortly after the match, as promised (and even published publicly), but for some reason I haven't been able to ascertain Kasparov continued to insist on their release.) Logs or no logs, it still seemed surprising that Deep Blue missed the perpetual.
But did it? There has been a lot of analysis of the ending since then, and if anything has become clear it's that if there is a draw, it isn't a trivial one. Whether it's a draw at all is an interesting question in its own right, but it's a very different issue from that of the alleged perpetual check. Also, importantly, this non-perpetual line is also relatively obvious for the computer; that is, it's plausible and well within its search horizon. It's clear that White - Deep Blue - is better in the resulting position, but this doesn't settle all the doubts either.
Did Deep Blue spot the perpetual check variations? IF it did, then it would have had to assess the non-perpetual variations as better for it than the endgame after 44.Kh1 Rb8 45.Qc6 Qxc6 46.dxc6. Contemporary engines prefer 44.Kh1, but did Deep Blue?
I've culled material from various Web sources: Ken Regan recently addressed the topic, Wikipedia has a decent introductory survey on the issue, and there are various analytical suggestions in the thread devoted to the game on ChessGames.com. For a historical look back readers may wish a look at this ChessBase article. Finally, I've amassed the analysis from the listed sites and added some of my own here, which you can replay and download. Doubtless there are mistakes in my analysis - I ran it on an older computer, for one thing - so I hope that those of you with access to souped-up hardware will find some improvements.
(And more.) The blog's favorite computer scientist with an IM title, Ken Regan, offers some reflections on draws in relation to the world championship match and in comparison with computer chess, in this recent blog post. As usual with his work - when it's accessible to laypeople (and in this case, it is), it's worth your time.
In early 2011, Vasik Rajlich was accused by the International Computer Games Association (ICGA) of plagiarism in writing his famous chess program Rybka, he was stripped of the world championship titles won with Rybka from 2007 to 2010, and banned for life from ICGA events. (Other than that, I think they liked him.)
It has been quite a while now, but there's a new and vigorous defense of Rajlich by one Dr. Søren Riis against what the author considers ICGA overreach. Two parts are out now (there's a third part coming soon), and they can be read here and here. He makes some interesting points, and it's good that Rajlich has someone defending him.
Some time ago I mentioned the accusations that Vas Rajlich, Rybka's programmer, had based his program on the chess engine "Fruit". Since then the International Computer Games Association (ICGA) has investigated the claims, and concluded in a 5-0 decision that Rajlich was guilty not only of improperly taking code from Fruit but from Crafty as well. They write that
We are convinced that the evidence against Vasik Rajlich is both overwhelming in its volume and beyond reasonable question in its nature. Vasik Rajlich is guilty of plagiarizing the programs Crafty and Fruit, and has violated the ICGA’s tournament rules with respect to the World Computer Chess Championships in the years 2006, 2007, 2008, 2009 and 2010.
As a result, Rajlich is banned for life from the World Computer Chess Championship and all other ICGA events, and Rybka's championships in 2007-2010 are vacated, along with the Rybka predecessors's =2nd finish in 2006. Strong punishment, but appropriate if they are right about the evidence.
Much more, here.
For fans of computer-computer matches, the third season of Martin Thoresen's TCEC (Thoresen Chess Engines Competition) is underway. Information on how this season's competition is arranged is here, while the live broadcast (and a list of the participating computers, their ratings and their scores) is here.
For those who like to follow computer vs. computer matches, Rybka and Houdini will have a match to close the second season of engine competitions on Martin Thoresen's TCEC website. The fun starts Tuesday at 14:00 Central European Time.