Kasparov-Deep Junior draw after stunning sacrifice

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HAL or Tal? Junior Stuns Kasparov in Game Five

Game five of the Kasparov-Deep Junior match was the shortest game so far, just 19 moves. It ended in a draw after Junior played an amazing bishop sacrifice on move 10 that led the game to a perpetual check draw. A stunned Kasparov found the best moves to survive the black attack and declined to play a risky attempt to continue the game on move 16. The match is tied 2.5-2.5, setting up a high-stakes battle in Friday's game six.

When Deep Junior played 10...Bxh2+ it smashed Garry Kasparov's kingside and many of our conceptions about computer chess with a single spectacular move. I haven't heard a chess audience make as much noise since the Great Pea Soup Riots of Wijk aan Zee '94.

If we needed any further proof that Deep Junior is something beyond what we have come to think of as computer chess, game five provided it. From a quiet opening in a standard-looking position, the Israeli brainchild of Amir Ban and Shay Bushinsky sacrificed a bishop out of a clear blue sky to drag Kasparov's king out into the open. Attacking with only a queen and knight, Junior put the white king under heavy fire.

When a machine plays something like 10...Bxh2+ against you, one thought goes through your mind. Unfortunately this is a family website and I can't print that thought here. Your second thought is, "So should I just resign?" You could tell from Kasparov's always-expressive face that he, like everyone in the room, was having painful flashbacks to game six against Deep Blue in 1997, when he was blown off the board after a piece sacrifice by the machine.

Kasparov collected himself, realized he wasn't being mated, and played the next few forced moves quickly. He captured the bishop and played his king from the frying pan into the fire on g3. Junior feinted with its queen, keeping it close to Kasparov's king. The climax was reached on move 16, when it was becoming clear that Kasparov could allow a perpetual check draw or play a dangerous line and continue the game with his king in the center.

As the strongest human chessplayer in the world sank into thought, the commentators and our computers were frantically analyzing the consequences of his options. 16.Bxh7+ and 16.Ng3 both allowed Black to force a repetition. 16.g3 was the only move to continue the game. Junior would have many attacking options, and could Kasparov be computer-perfect in his defense? Might the position be lost anyway?

Those questions will only be answered in the notes. Kasparov thought for over half an hour and allowed the perpetual check after 16.Bxh7+. The game was agreed drawn on move 19. A short draw with black against Kasparov cannot be called anything other than a tremendous success for Junior, and the spectacular method in which it was achieved is an extra feather in Junior's yarmulke.

Although most programs we've checked with at first say that White had good chances after 16.g3, it was not a move for a human to play against a computer. Black gets good compensation for the piece both in pawns and/or in attacking chances. How much Junior actually saw and how much Junior estimated based on subjective factors we do not yet know.

After less than eight hours since the game ended, it seems that everyone and their CPU has sent me analysis proving white was winning, or losing, after 16.g3. Kasparov was worried about 16...Qh2, cutting off his king's escape and leaving his king vulnerable for the rest of the game. Most analysis has focused on 16...Nh2+, chasing the king to apparent safety on e1.

No matter how many trillion nodes are counted by all the computer chess fans out there, it would have been incredibly hard for Kasparov to play this position against Junior. (Grandmaster John Nunn has written that Junior had sufficient attack for the material.) Less than perfect play would have been rewarded with a speedy execution. What is clear is that 10...Bxh2+ was a speculative sacrifice more in the spirit of Tal than HAL.

That leads me to something that bothers me about this match: the public's lack of access to the thoughts and opinions of one of the players. Kasparov comes out to the press conference after every game and talks about what he was thinking. He writes analysis on the web. Meanwhile, the Junior team has been very tight-lipped about what Junior was thinking during the games. Even when the position was far from the opening and irrelevant to preparation, they have declined to give any information about Junior's evaluations. This has been frustrating for reporters covering the match and we have heard complaints about the "cageyness" of the programmers. "They should just say, "we can't tell you that" instead of giving these evasive non-answers," said one newspaper writer.

This is a stark contrast to the Fritz-Kramnik match in Bahrain, when the commentators sat next to Fritz programmer Frans Morsch looking at the actual Fritz readout. We knew what lines Fritz was looking at, when it changed its mind, and how it evaluated the position. We shared this information with the fascinated web audience. Everyone keeps talking about how this match is for science, so how is science being served if we don't know what Junior was thinking? Junior's logs are being archived by the organizers in case of problems, but there is no provision for their release or publication.

Since there doesn't seem to be any competitive reason for Ban and Bushinsky to be so guarded about middlegame positions, we might surmise that they plan to publish the logs, or excerpts and articles based on them. Otherwise why the secrecy? Everyone wants to know what Junior did or didn't see and the most we've gotten are vague comments like, "Junior was happy with its position."

A direct and interesting question about game five from New York Times writer Paul Hoffman, "at which move in the game was Junior's evaluation lowest?" received no concrete answer. What harm could there be in answering this and similar questions?

One of the reasons everyone wants to know is because Deep Junior's play so far has been quite unlike that of any other program. Every program gives white the advantage all through game five; Junior felt differently. Bushinsky's post-game comment about Junior always having been "happy" with its position confirms this. Deep Junior is a commercial product and we can't expect them to give away the secret formula, but some data and eval info would be nice.

This sets up a game six showdown that also echoes 1997. The match is tied and Kasparov has black in the final game. Could this déjà vu be what Ban and Bushinsky had in mind when they chose to have black in game one and white in the final game?

Replay the game and analysis here

Previous reports

• Game one: Junior in Deep against Kasparov
• Pictures from the Big Apple
• Game two: Kasparov's 'fingerfehler' lets the computer off the hook
• Real Chess against a Virtual Opponent
• Game three: Deep Junior strikes back
• Game four: Kasparov, Deep Junior draw
• Amir Ban: Facing Garry Kasparov
• Picture gallery: It's up to you, New York, New York

Picture Gallery

Amir Ban and Shay Bushinsky prime the machine

May the negotiations begin: Garry Kasparov and Amir Ban before the start of game five

The glare: what have they cooked up against me?

Digging in, getting to work, mustering the forces of the human brain

The house was pack, again. The glasses are used to view the X3D projection of the game

Ex women's world champion Susan Polgar with X3D glasses

And then came the sacrifice on h2. Commentators Maurice Ashley and Yasser Seirawan cannot believe what is happening in this game.

After the game is over Amir Ban and Shay Bushinsky try to explain Junior's thinking

Then Garry Kasparov arrives on the stage to tell of his feelings during this fateful game

Garry Kasparov in the press conference after game five