The new master is Samuel Sevian. He set the record on Dec. 11, at the age of 9 years, 11 months and 11 days by tying for first in a small tournament at the Mechanics Institute in San Francisco. He broke the record held by Nicholas Nip, a San Francisco resident, by 11 days.

Nip set the record in March 2008, but at the time there were some questions about how he did it. He had played matches against opponents who had volunteered to play him.

Some masters criticized this practice. Hikaru Nakamura, the record-holder before Nip, was one of them. Nakamura, who is now ranked No. 10 in the world, said, “If he goes on and does great things, then it doesn’t really matter.”

But Nip has done very little. He played one tournament nine months after setting the record and has not played since.

Sevian did not rest on his laurels; he played in a tournament the next day.

Magnus Carlsen of Norway won the second London Chess Classic, which ended Wednesday. Round-by-round coverage is at The New York Times’s chess blog, There is also coverage of the Women’s World Championship, which is being played in Turkey.

Carlsen clinched first with a victory in the last round over Nigel Short of England. Short’s strategy was to try to trade pieces early in the game to make it hard for Carlsen to attack. But Carlsen was able to take the initiative and then constrict Short’s position until it crumbled.

Carlsen’s 6 Bc4 was rarer than 6 Bd3, partly because it makes it easier for Black to exchange pieces.

After 11 Rd1, Short’s position was not all that easy, despite the absence of the queens, because it was hard for Black to develop his queen-side pieces.

Short should have played 14 … Rd8; 14 … h6 was too slow. And 15 … a5 was a mistake, as it created a hole at b6 that Carlsen quickly exploited.

It would not have helped Short to play 25 … e4, as after 26 Be4 Rd2 27 Kf3 g5 28 Bf5 Bf5 29 Rf5 Rc2 30 Rb5, White would soon have won Black’s b pawn and his pawns would have been unstoppable.

Though it made no difference, Carlsen could have shortened the game a bit with 29 Nd5, as after 29 … Bd5 30 ed5 e4 31 Bf1, Carlsen would soon win the b pawn.

Short resigned, as there was no longer any way to stop Carlsen from promoting his pawn to a queen.