Interview by Arvind Aaron with author of REBEL10 Ed Schröder on Italy after the match Rebel vs Anand in 1998. The interview was published first in the sports weekly The Sportstar (India's largest sports weekly news paper) and the chess magazine Chess Mate.

REBEL Not To Play Other Computers
By Arvind Aaron

Finally there is a specialist chess programme which works good specifically against Humans. It is called REBEL, the Dutch programme which shocked World No.2 Viswanathan Anand 5-3 in an eight game match at Ischia, an island near Naples in Italy last month.

REBEL's victory in this three day contest held July 21-23 confirms the machines' superiority in quick time chess leaving the hope to humans in classical time controlled games only.

The programme was superior due to its human-like playing style and the new feature "Anti-Grandmaster Style," said its bearded 48-year old programmer Ed Schroder in an exclusive interview to Arvind Aaron.

REBEL 10 will be soon in the production line and in the market from September-October this year.

Excerpts:
Q: Your programme REBEL won. With four blitz games of out eight, what percentage of chance does a grandmaster have (for winning)?
A: This is a difficult question. In my opinion it depends on which programme you are playing. One programme will do good against humans completely different from another programme. Speaking for my own programme, REBEL has always been on top playing against humans. If you look at the Human versus Computer tournament at Aegon you see in statistics from 1991-97 REBEL is overall clearly on top playing against humans. So, I also think that Mr. Anand has estimated REBEL in that respect. You cannot compare REBEL and FRITZ. If you let them play against each other, it is equal. REBEL against human is truly stronger than REBEL against FRITZ.

Q: Why this difference?
A: Because of the playing style. If you take the REBEL, FRITZ example, FRITZ is programmed based on speed and tactical things, e.g., deep combinations, REBEL is of course also good in tactics but it is positionally based. It tries to play the human style, positional moves. That is my personal opinion. When you have a good position tactics come by itself. So, REBEL tries to play good positional chess like a human.

Q: How much of the victory was attributed to the powerful and fast hardware. Would REBEL had done the same had it taken place on a Pentium-2 400 MHz processor as was promised to Anand?
A: I think on a P-2 400 the result would have been the same. If you go lower, then the result will be less. I think the difference between the P-2 400 and the AMD which played here is about 25%. It is nice to have. In Elo it is not so much.

Q: REBEL 9 had an Elo rating of 2580 which you printed on your CD ROM. What is the estimated strength of REBEL 10?
A: The big problem is to say something about this. If you say in computer to computer, I would say it is about 20-30 Elo points stronger. If you use the new future of REBEL, with the anti-human and anti-grandmaster style, then it is a major step up. Maybe fifty of even hundred Elo points stronger.

Q: How do you define the anti-grandmaster style?
A: This is based on my experience in the Aegon tournaments playing against grandmasters. I have played all kinds of people. Against people rated till say 2200, REBEL always wins. Almost without an exception.

If you go one step higher to say 2400-2450, you see another pattern. You see that REBEL mostly wins, the struggle is closer for the iniative. If REBEL wins the game, it has happened because the player in that area makes a minor positional mistake or big blunders. But in the fight for the initiative you can see that the human player had the positional understanding than the computer on the long term but still REBEL mostly manages to win the games.

Then if you come to the point, it is against the grandmasters. It is always that a grandmaster gets the initiative. It is good strong position. Anti-grandmaster style is about having the initiative. Don't lose it. It is important.

It will not always play the best moves in respect to the normal REBEL. It will play moves that will confuse the grandmaster and keep the initiative. It is the first time for it. It has never been practised before against humans.

If you look at all eight games, I can see it works. Because REBEL always got chances in the games against Mr. Anand. It wasn't locked in a position where it had no chance. But I have seen so many times that when you play a game, after it you say you lost to a grandmaster I had no chance at all.

In these games, it always had chances. Also in the two tournament games, it could play. This is anti-grandmaster. Create chances, don't let yourself get slaughtered by a grandmaster.

Q: How do you compare this match with the one against Artur Yusupov last year?
A: I cannot answer this because I was not present here. My co- operator did it last year. So I do not know the atmosphere of the games.

Q: How many people are involved in programming REBEL?
A: Me, of course and I work on the chess engine. You know Jeroen Norman who was the operator and a chess player. He is also the book editor. We have others who do the graphics, the database, one for the website, one to respond to the E-mails and one for the Windows versions. It is about seven or eight people.

Q: What is the commercial worth of this victory?
A: It is two-sided. First, it is of course promotion. The second, as a chess addict I want to find out what is the state of art of my programme against the top of the chess world.

Q: Are you going to sell more?
A: Yes. Of course. I have no idea. I think because of the good result I will be able to sell ... no idea. I think what I spent on this match I will earn it back. Apart from the money paid to Mr. Anand to play the match which we will not disclose, our investment was 30,000 dollars.

Q: If you had seen game four and game eight, the machine went for material and could not assess the rook for two pieces value. Is it easy for the programmers to eliminate this or is it habitual for the machines to fall for this in the years ahead?
A: I can speak about the eighth game. The fourth game is not in my head now. That was an exceptional case because REBEL had four connected passed pawns. Normally it is worth a lot. In reality it was worth nothing. That was the big problem for REBEL. It didn't judge the position good. It thought four connected pawns is fine. Normally it is. Not in this position.

This is the main problem for chess programmes. Yesterday was such an exception. It was kind of bad luck that it ended in this kind of position.

Q: I think this is a pattern for most computers?
A: In this game of yesterday, every computer would have lost. Because the four connected pawns are evaluated too high. Black can easily halt them. That was the difficult point of yesterday's game.

Q: What was said new about REBEL in this match?
A: I think only anti-grandmaster chess.

Q: How do you hope to fare in the next world computer championship? How did your programme do in the world PC and blitz championships at Paris, and the overall world computer championship in Hong Kong?
A: I am not in any mood to spend my time and money in Computer- Computer events. Maybe in the future but for the moment no. In a Computer-Computer match you are also commercial which means everybody can get your programmes. I want to win against humans.

In Computer-Computer events other programmers have told me that they have worked two months on one opening to catch me. (laughs) Of course it works. They can open the programme and see the holes in the REBEL opening books and shoot on that. They practise it in tournaments. To play in Computer-Computer tournaments I have to escape from all those book attacks and other programmers. I need three months preparation. I need totally new lines but I don't have that time. Besides of that, I think in Computer-Computer chess tournaments are losing interest from people. They are not so important any more as the days before.

Q: Why?
A: I don't know. I see it from the number of visitors in the website. I see it in the attention it gets in the press. It is not so attractive any more. Things like this, and REBEL playing Yusupov, that's what people want. People believe that computers are strong and want them to play strong grandmasters. It is a matter of attention it gets which matters.

Q: How many man-hours have been spent on REBEL this far and how many hours were spent on this match with Anand?
A: Incredible amount of hours. Days, months, about three-four months on this match. Let's say four-five hours a day. On REBEL this far is impossible to say. I need a calculator for this! Full time is atleast eight hours a day since 1985. In the last few years I had more people to do it and I do not spend as much time as in the early days. I do not spend so much time on the chess engine as I have so much in my head for other things. In the past I only had to do the chess engine and for the other things I went to other people. Now I have to do all the promoting stuff myself, being in charge for the packaging, the manual and so on.

Q: Why the name "REBEL"?
A: I started programming it in 1981 as a hobby. Then there was no literature at all. It was very difficult to write chess programmes. Those days you had to figure out all by yourself. It was so complicated and confusing, you programme something and it didn't work.

I asked the programme to do something and he didn't do it. So I said "you are a REBEL". You are rebelling against me. These days I am the rebel and he listens to me. Besides it is a good name. It sounds good in every country.

Q: What do you have in future for REBEL?
A: Keep on improving the engine. We decided a few years before that we don't play Computer-Computer any more. Let's play good chessplayers instead. I think this was a good decision. In principle we decide to play in such an event every year. Last year it was Mr. Yusupov, this year it was Mr. Anand and next year some one else.

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