>> WALLS

Surrounding territory in the centre normally has the major drawback of requiring walls on at least three sides. But if you butt two territories together, you can eliminate one wall.

Cho Hun-hyeon as Black here (in 1988) spotted the chance to merge two areas and so won by 2.5 points against Seo Pong-su, though he did need Seo to help by making a mistake.

White 80 should first have been a probe at 119. Black 115 was better at 199. Black 117 should have been 162 to take sente. White 120 is a tesuji to win sente. After 124 White has a sure win even though it is a close game, but he spoiled it by playing 190 - he should have responded on the left side. Black 191 ~ 199 was enough to turn the tables.

The full game in sgf form:

© John Fairbairn & T Mark Hall (GoGoD), London 2007.