Energy is connected to physical fitness. One of the reasons I stayed at the top so long is that I was tremendously fit. At 36, I was fitter than most opponents ten years younger.

It was an impressive achievement, of course, and a human achievement by the members of the IBM team, but Deep Blue was only intelligent the way your programmable alarm clock is intelligent. Not that losing to a $10 million alarm clock made me feel any better.

With this mistake I deprived myself of the possibility to make a contribution to the treasury of chess art.

We know that the governments in most of the successor states formed after the collapse of the Soviet Union are replaced through a process of regular elections.

[Vladimir] Putin wants to keep [Bashar] Assad in power and expand his own military base in Syria, whatever the cost. I even believe he has an interest in more and more people fleeing the country. The flow of refugees improves his negotiating position toward the West, including the German chancellor.

The sanctions and travel restrictions would have to be far more comprehensive to be truly painful for [Vladimir] Putin and his inner circle. And the new middle class should also feel the effects of what he is doing. For instance, we should ask those who wish to enter the EU whether they have visited illegally occupied Crimea in the last few months and, if the answer is "yes," deny them a visa.

It's not enough to be talented. It's not enough to work hard and to study late into the night. You must also become intimately aware of the methods you use to reach your decisions.