Round 4 of the 2011 World Amateur Go Championships (WAGC) began at 1:30p on May 30 with referee Yasuhiro Nakano giving the signal to start. With only seven undefeated players remaining, the competition was beginning to tighten up. Two of the three games among those undefeated players ended quickly. Choltit Rattanasetyut of Thailand made an early and serious mistake against Baoxiang Bai of China, and Morten Ofstad of Norway made a major mistake in the middle game against Tsung-Han Wu of Chinese Taipei, giving Bai and Wu easy wins. Wu, who said he had never played a European opponent before this tournament (“except possibly on the Internet”), rated Ofstad as fairly strong. Rattanasetyut was rated as considerably stronger than the Thai player who finished with four wins last year by Yuan Sun, a Chinese 3P player who had been a referee at the WAGC in Hangzhou last year and is assisting the Ranka staff this year.
The third game between undefeated players, 
Woo-soo Choi of Korea against Eric Lui of the US (left in photo at right), proceeded much more slowly but ended without an upset. Choi said he was satisfied with having won a difficult game, and rated his opponent’s level as not much different from his own. Another undefeated player who won what he described as a difficult game was Poland’s Kamil Chwednya, who had been paired down against Belgium’s Jan Ramon. For the first time in this tournament, the Polish player played conventional opening moves. “Every opening has its own logic,” he said.
In the next round, the undefeated Chinese and Korean players will face each other in what is generally expected to be the deciding game of the tournament. Shortly after round 4 ended, Baoxiang Bai was seen to be going over the game record of Woo-soo Choi’s victory with Choi’s defeated opponent Eric Lui (U.S.). In a different room, Choi was being interviewed for Japan’s Go & Shogi TV channel. When asked how he intended to play against Bai, Choi said he had no special plan: “I’ll just do my best, same as always.”
Undefeated Tsung-han Wu and Kamil Chwednya are also paired against each other in the next round. Eric Lui, Choltit Rattanasetyut, and Morten Ofstad join eleven other players with three wins, including Japan’s Hironori Hirata, who redeemed his honor this afternoon by defeating Jun Fan of Canada by 9.5 points, and Aliaksandr Suponeu of Belarus, who so far is having the best World Amateur Go Championship of his long career.
Round 5: A light rain was still falling on the morning of May 31 as the players made their way, some on foot but most by bus, to the Shimane Prefectural Assembly Hall. First to take his seat in the main playing room, ten minutes before the 9:30 starting time, was China’s Baoxiang Bai (below), arguably the favorite to win the tournament. He has been making 
his mark on the Chinese national tournament scene since 2006, when he took second place in the Huanghe (Yellow River) Cup at the age of 13. The next year he won the amateur Qiwang (King of Go) tournament, in 2009 he won the amateur Dujuanha (Azelia) Cup, and in 2010 he won the Wanbao (Evening News) Cup. Those last two triumphs earned him the right to represent China at this year’s Korean Prime Minister’s Cup and the 32nd World Amateur Go Championship. At age eighteen he is already recognized as one of the four top amateur players in China.
Five minutes later Woo-soo Choi took the seat facing Bai. Choi is less well-known, having had no national triumphs until he won the Korean amateur Kooksu in 2010. In that tournament, however, he defeated Hong-suk Song, who had beaten Chen Wang, another of China’s top four, to become last year’s world amateur champion. The Kooksu victory made Choi this year’s Korean player at the World Amateur. Soon after Choi sat down, Chinese Taipei’s Tsung-Han Wu took his seat at the adjacent board, and at 9:30 on the dot Poland’s Kamil Chwedyna ambled into the main playing room and sat down facing Wu. Referee Yasuhiro Nakano then gave the signal to start.
On the top board Baoxiang Bai correctly guessed that Woo-soo Choi’s hand held an even number of stones and quickly played the first black stone on the four-four point in the top right corner. Choi took his time before replying on the four-four point in the top left. On the second board Kamil Chwedyna produced another unusual opening, positioning white stones on the 8-8, 8-10, and 8-12 points.
The game on the second board ended within an hour and a quarter. Black carved white’s position into pieces and captured two of them. Kamil Chwedyna manfully resigned and stepped out of the playing room, to be swarmed by a group of uniformed girls from the go club at the Okuizumo Choritsu Takada Primary School, who collected his signature on their programs. A rather older group of spectators had gathered around the board where Japan’s Hironori Hirata was playing Czechia’s Radek Nechanicky. This game ended with the Czech player’s resignation at 11:36.
Some of the spectators now moved over to watch Bai and Choi play out the endgame of their crucial encounter. White had started well in the opening, but in the middle game white let black capture two stones in the center in a classic turtle-shell shape. The territory white took in return did not compensate for the power black gained in the center. Bai’s expression revealed nothing, but he said later that once he took those two stones he had felt confident of winning, and win he did, by 3.5 points, just before noon, as a crowd of close to thirty onlookers thronged around the board.
At this point the only game still going was the one between Eric Lui of the US and Xiang Zhang of Singapore. It continued until nearly 12:40, with Eric Lui winning safely by 5.5 points. In the meantime France’s Thomas Debarre, Ukraine’s Mykhailo Halchenko, Spain’s Joan Flos, Thailand’s Choltit Rattanasetyut, and Vietnam’s Kanh Binh Do had also won their games to join Woo-soo Choi, Kamil Chwedyna, Hironori Hirata, and Eric Lui in the group with four wins. These nine will be fighting to stay in contention while the two remaining undefeated players, Baoxiang Bai and Tsung-han Wu, battle it out it in the afternoon round.
In parallel with all this action in the playing room, the three referees, together with other professional players in attendance, had been kept busy reviewing the completed games, assisted by a capable staff of interpreters. The weather was also cooperating. The rain lifted during the break between rounds 5 and 6, and several players took advantage of this interval to stretch their legs and visit Matsue Castle.
– James Davies, Ranka Online; edited by Jake Edge
THE “IMPOSSIBLE” TIAN YUAN TOWER PROBLEM, SOLVED
Monday June 7, 2010
The “Impossible” Tian Yuan Tower problem (5/27 EJ) is “Far from impossible,” writes John Fairbairn, “especially once
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you know the name of the problem, Shenlong Guotu, or Divine Dragon Shedding Its Bones. The Daoist phrase ‘shedding bones,’ or variants such as ‘shedding a skin’, always signify it’s an under-the-stones problem,” says Fairbairn, a longtime go writer and co-author of the Games of Go on Disk encyclopedia (GoGoD). Fairbairn was one of just eight readers to correctly solve the problem: Steven Burrall, who also knew it was an ishi no shita, or “under the stones” problem; Daniel Gourdeau, Jimmy Guo, Marek Kamiński, Carlo Metta, Solomon Smilack and our very own weekly AGA go problem-meister Myron Souris. We won’t mention the name of the reader who wanted to know “is the problem black to play and kill or white to play and live?”