Positional chess, as opposed to tactical chess, involves a situation in which there are no clear objectives on the board, no obvious squares to be commandeered, no threats to be made. It is a kind of jockeying, with the two sides maneuvering for position, from which to begin long-term plans. It is the kind of chess that grandmasters generally say they play better than machines, because the power of individual moves is subtle, deeply resonant, rather than calculable.
[Frederic] Friedel tried to explain it with an anecdote about the development of Fritz. He once asked grandmaster Walter Browne about a particular position in which each side had the same number of pawns and pieces and the same number of controlled squares.
"Any amateur would have said the position was a draw," Friedel said. "I said, 'Walter, who is better here?' And he said, 'White is winning.' I said, 'Why?' and he said white controls more space." When Friedel pointed out that in fact each side controlled exactly the same number of squares, Browne continued, "Oh, these squares here don't count. They aren't important."
How to tell important squares from unimportant squares? Friedel didn't understand.The intuition of grandmasters is not mystical. But it's difficult to put into words, let alone program.
"But two years later," he said, "I was driving with the former world champion, Max Euwe, and I had the position in my pocket, and I asked him, and he said: 'White's winning. White's better. It controls more squares.' I counted them for him. And he said, 'Oh, these squares are not important.' "