BQM 471

3rd game of the BCcard World Championship  

tapir here was really surprising to me, and I don't understand it. In the following fight, while I see some meaning in those moves I like to explore the hidden variations that escape me.

Velobici: , move 63, is the local response to , move 54. Move 54 limits Black's development on the right side and helps the white group on the bottom. Imagine a black play in this area before move 54, perhaps at a which develops the right side for Black....mind the openness of the side to the white stones in the upper right is bothersome. Might be good to consider the prospective territories at this point. White 68 (left side 44, top right 12, bottom 12) vs Black 63 (top left 10, top 10, bottom right 28, left center 15)...this count must be off. Adding komi makes it more than 10 points difference. Does not answer your question, but estimating possible territory is a good way to start inquiring about direction of play questions.

I didn't say it clearly above. When playing, one must estimate the score from time to time. Those estimates are based upon prospective borders between the territories. As play proceeds from that point, the prospective borders may change, indeed they often change, as tapir points out regarding the bottom right corner where White lives inside the prospective borders drawn above, but at the cost of Black moving the prospective border on the right side from the ninth line to the thirteenth line in sente. The player that is behind will strive to force different borders upon the opponent, ones that are more favorable to the person that is behind so that he might catch up or even win. A resignation in the middle game or early end game is a declaration that the prospective borders can not be changed sufficiently to change the prospective result of the game.

tapir: Positional judgement is not my strongest skill, but after the peep and the white connection the side isn't closed at all.

tapir: Well, touching the opposing stone with a kosumi don't occur to me since I started reading pages about shape on SL :) Btw. in the game Black split the left side, the white stones in the lower right corner (here still unsettled) will be alive.

Velobici: Touching strong stones is okay. Its touching weak stones that should be avoided...perhaps the reason is that play alternates, so one's great advantage is at the beginning of a sequence when the difference in number of stones involved is greatest. As stones are added, one at a time by each player, the ratio approaches 1:1. So, unless you are killing the stone immediately, best not to touch a weak stone because in touching one loses the advantage. Agreed that the lower right is unsettled at this time and that white does live there in the end. Black also breaks up the left side compared to the current configuration. One has to make some assumptions in estimating the score during a game. The assumptions should be reasonable and applied equally to both sides.

White can live in the corner  

unkx80: I may be stating the obvious, but White leaves behind two stones in the corner that can live later on. See Tripod Group.

Game Sequence through B108  

Velobici: This is the sequence from the game, after Black played at , a sente move (at least White responded), away from the lower right corner, to close the right side against incursion from the upper right despite the fact that the lower right corner can be killed. See Tripod Group with Extra Leg. Does this mean that and keeping sente is larger than killing the corner (about 20 points) and losing sente?

Black lives  

unkx80: A quick partial answer to your question. Firstly, for the standard tripod group with extra leg, Black can only kill by a ko. Secondly, later in the game White makes the and exchange, this ensures unconditional life (as proven in the diagram sequence). I haven't checked what happens when is played without the and exchange though, but probably White at , Black at , White at .

What if?  

tapir: What if ? (Since this is the first move which comes to my mind.) ends as good forcing move, white overconcentrated?