A ChessBase report for the ongoing Cairns Cup gives this paragraph:

The first game to finish was Humpy Koneru versus Ju Wenjun. Out of an English Opening, Humpy quickly found herself out of book with the white pieces. The Indian was on the back foot but managed to keep things under control until a repetition took place starting on move 19. Later on, she explained that it is difficult to face someone who comes from preparing for a world championship match, as their level of preparation is particularly impressive after such an important contest.

The implication is that Ju Wenjun is likely to be very "booked up" for a while after the world championship match, but only for a while, and she'll be easier to face some time in the future.

  1. How long does it take until Ju Wenjun is no longer very "booked up"?
  2. Why doesn't Ju Wenjun stay very booked up for as long as she's playing professionally?

4 Answers 4


As Brian noted, theory can move on quickly, but that does not remotely mean that everything that was prepared is lost in a short period of time. I think that the biggest issue was just that prepping for the world championship was much more intense, and rigorous, so Ju is going to be that much more prepared, and thus, a much more dangerous opponent than usual for while, but not just because of opening preparation.

On the other hand, I disagree that just because they have outstanding memories, that they do not forget much...virtually all memories do fade, and it can take a long time to use some prep. There is also the enormous volume that they have to memorize compared to a club player. They certainly do not forget the basics, but it is easy to transpose a couple of moves when you are already deep into the opening. I have read about this happening many times, and in the first round of Tata Steel 2020 just last month, it happened to Vladislav Kovalev in the first round versus Alireza Firouzja, and Kovalev went down without a fight (he played 16...c4? when he needed 16...Nd7 17.Ra3, and only then 17...c4). It can happen to the very best: Here is a tweet from Caruana talking about Magnus forgetting his prep. They memorize SO much that it is still human to forget things that they have not looked at for a while.

It can also take years sometimes to be able to use an opening surprise. I remember reading on at least one occasion, it took Kasparov years to use some prep, and I have heard numerous such stories about top players in my 40 years of tournament chess. Here is a link to a story about Kaspy waiting years, and using some prep against Michael Adams. That game can be found here, and 14.Qh4 was the novelty.

I also think that there is another huge factor that Humpy did not touch upon, and that is that when you play a major round robin (relative to your rating), or in this case, a world championship match, it is so intense, and the level of play is so high, that you usually come out much sharper than normal. I played a couple of round robins against all strong masters, and I felt like I was better than ever when I was done each of them.

Of course, professional players at this level continue to work on their openings, maybe daily, but it is doubtful that it is quite as intense as when she was preparing for the match. In essence, she still stays fairly booked up at all times.

  • 1
    P.S. I would also swear that at Tata 2020, I saw an interview with Caruana, where he mentioned that he forgot his prep. If I can find that, I will add it to my answer. Feb 12, 2020 at 1:04
  • Re memory of super-GMs: I've heard claims that Carlsen remembers a ridiculous amount of games. However, all examples I have actually seen have been some advertising videos which contain famous classic games or Carlsen's own games from childhood, which isn't really enough for opening theory. I wonder if there's any quantified studies on how well GMs remember old games.
    – JiK
    Feb 12, 2020 at 15:10
  • 1
    @JiK There is no question that he has a phenomenal memory, but short of having a truly eidetic memory, everyone forgets some things. One of my closest friends is an IM, who has the best memory of anyone I have ever encountered, but now in his late 40's, even he has started to forget things, but just relative to his memory. He used to be able to periodically walk around the World Open, and remember virtually all the games that were played. Once, 20 years after the fact, he referenced a game I played where he had just been playing on the board next to mine. :) Feb 12, 2020 at 15:25

How long does it take until Ju Wenjun is no longer very "booked up"?

Top players have outstanding memories so it takes a very long time for the actual memories of the booking up to fade.

However, theory moves on quite fast. When you "book up" you are essentially bringing yourself up to date with the latest theory and ideally coming up with some new (computer tested) ideas that will give you an edge. Once your novelty is played it is no longer a novelty and the value of the "booking up" diminishes. Even worse, an earlier move may be superseded by an improvement by another player. When that happens that "booked up" knowledge is essentially worthless at the top level because players will be diverging from your booked up knowledge.

Why doesn't Ju Wenjun stay very booked up for as long as she's playing professionally?

At the top level players try and stayed "booked up" but as pointed out that knowledge goes stale quite quickly and so the booking up process has to be continuous. There is an enormous amount of work involved and so that work tends to be targeted for maximum benefit.


Since I play the same openings, I'm always booked up, although I still need to refresh some of the side lines. Just like I will always know addition, but need to refresh the higher math functions.

At higher levels, the GMs have to changes openings to surprise their opponent and hope for some advantage. Once this line is played and the surprise is spent, the player, especially against that opponent, is considered to no longer be booked up.

As one of the classic exceptions is the 2000 Championship. Kasparov was known to be booked up on six to nine main line openings. Kramnik was booked up on only versed in three, but his knowledge was deeper (more moves) and more familiar. Many commentators that Kasparov's arrogance prevented him from switch to a system he knew better [between the two of them] instead of trying to defeat the "Berlin Wall", and that lost him the championship. HOW do GMs play a man not the board? gives a better explanation of this match.


Depends what you mean by booked up. Normally top GMs prepare for the openings they will play and also those that the opponent will likely play.

The normal lines in those openings the will always know.

The problem is the special surprises and prepared lines they 'booked up' on. Once they have been used the opponent will also be prepared and often come up with counter surprises.

So they will always be booked up on their openings. They will never catch up with new theory and moves in their openings. And especially surprises/prepared_variations will be old news after they are used.

How long depends on how long it is until they actually use the new surprise or someone else finds it and uses it.

There are many opening surprises in book lines. I know of two that I use often. One is known but apparently not widely enough. The other seems to be a total bug in the analysis as it always works and nobody else seems to be playing it. But it does depend somewhat on the level you play at. Not many magazines printing my games for others to find out. When a top GM has a surprise the word should get out fast and many others will be analyzing it so the surprise value is gone. And they may have new surprises in the follow ups.

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