(AP) -- He said nyet to $1 million. Grigory Perelman, a reclusive Russian mathematics genius who made headlines earlier this year for not immediately embracing a lucrative math prize, has decided to decline the cash.

Perelman's decision was announced Thursday by the Clay Mathematics Institute in Cambridge, Mass., which had awarded Perelman its Millennium Prize.

The award honors his solving of the Poincare (pwan-kah-RAY) conjecture, which deals with shapes that exist in four or more dimensions.

Jim Carlson, institute president, said Perelman's decision was not a complete surprise, since he had declined some previous math prizes.

Carlson said Perelman had told him by telephone last week of his decision and gave no reason. But the Interfax news agency quoted Perelman as saying he believed the prize was unfair. Perelman told Interfax he considered his contribution to solving the Poincare conjecture no greater than that of Columbia University mathematician Richard Hamilton.

"To put it short, the main reason is my disagreement with the organized mathematical community," Perelman, 43, told Interfax. "I don't like their decisions, I consider them unjust."

Attempts by The Associated Press to reach Perelman, a resident of St. Petersburg, were unsuccessful.

Carlson said institute officials will meet this fall to decide what to do with the prize money. "We have some ideas in mind," he said. "We want to consider that carefully and make the best use possible of the money for the benefit of mathematics."

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