White to move. A little bit different this time, and harder. This time, the question is not what function does the move actually have (some of them have practically no function), but what might White be thinking, AND, more importantly, does the move actually fulfill that function? Options:
1) Invade opponent's prospective territory.
2) Save a weak stone and destroy territory.
3) Secure territory.
4) Create a moyo.
5) Attack weak stones.
6) Kikashi (a forcing move)
I'm a bit less certain about the direction of play for this problem as for previous ones. Among these options, I think I'd choose d as my next move. White is falling behind in potential (and real) territory and this move would help. If Black responds by protecting around b, then White can play a to take control of the center. Note, even with a Black move around b, Black's moyo is thin enough (at top and bottom) for invasion later.
If, instead, Black plays around a to help the center stones, White can jump in at b.
If White plays a (instead of d) first, I think, as Black, I'd not run away with the center stones, but play around d, to establish a base toward which those stones might run. White will have to add several more moves to surround the center, while black can make territory in many places.
If White plays at b (instead of d or a) first, black can attack this stone to build influence and then use that influence to help the center stones and/or push white around on the left.
So, all in all, I feel that White's undeveloped left side is the biggest problem for White and should be delt with first. But, I'm not 100% sure on this.
Lastly, a question. looks like a funny move to me. Is it joseki? The upper-left 3-3 point is still open and White has not yet developed from . This is another reason why d seems most urgent. What is the thinking behind playing and then not developing down the left? Is it to aim at Black's thin top position? Who tenukied first in this area? It seems a premature tenuki has occurred by someone.
Alex Weldon: Almost full marks, as usual. I'd say the moyo is most urgent, d. Black has several invasion points as you mentioned, so White will get a chance to invade somewhere, no matter what. You're right that f and c don't accomplish anything (I was thinking f was a pure wasted move in gote, as you say, but what you say about san-san is interesting. Someone better than me at reading these things out want to comment as to whether White can do something there if Black ignores f?). What you're wrong about is e securing the corner, I think. I believe that Black can get a ko by invading san-san once he's made the obvious response of extending up from the marked stone. In any case, e is a bad move (and what White actually played, ugh...), because when Black stretches up, he has the perfect extension from his two-stone wall.
I was Black in this game. White played really strangely, which is why Black is way ahead now. I already had the K14 stone in place when I played the kakari in the upper left. I have no idea what White's intention was when he played the marked kosumi. In any case, I tenukied.
Sadly to say, I actually lost this game. It was a case of Black being way ahead, White trying a bunch of wacky stuff in desperation, Black making mistakes, White killing something. From that, and White's bad play up to this point, I'd say White is one of those "Internet-style" people who have no theoretical backing, but a large amount of playing experience, so good fighting skills.
SnotNose: Indeed Alex is right, Black can get a ko in the usual way in the lower left. I was too lazy to work it out earlier. The only way (I know of) that White can resist is as follows (but it doesn't work in this case).
The key, I think, is that White has to have enough strength in the surrounding area so that defense of or the cut at b is not needed when Black plays a. That is, when Black plays a, White needs defense at b and c. If White already has one of these points defended (directly or indirectly), then Black dies. That's how I read it, though I'm sure there are nuances I don't appreciate.
If I'm right about this, then an easy way to remember when a ko is possible is if the two points diagonal from in the corner (points b and c) both need defense, then White cannot play as shown and must allow the ko.
Alex Weldon: This is the sort of stuff that, as 1 dan, I should know at a glance... but these standard corner situations are always my weak point. That said, I probably could have read it out if it arose in a game. And I do know enough to know that the kosumi-tsuke is a bad move in that situation, regardless.
SnotNose: As a 1 dan wannabe, this is the sort of stuff that I sort of know but not well. What I've done by developing and commenting the above diagram is to move the idea from "I've heard it's ko" to "Now I know it's ko except when..." That is, I now see the two key points (b and c) and can easily remember which they are. Thus, I now know how to check quickly if another move by White eliminates the ko. Very handy. I've been systematically doing this kind of "knowledge of shape" building recently and it has greatly improved my game. Thanks, Alex, for pushing me to nail this one.
Imagist: So what is the best order of plays here? I personally would play a, b, and then d (trying to end in sente from each of the first two sequences). Depending on how b played out, I might even play g before d. While d is important, I think that it allows too much time for black to prevent invasions that would otherwise set up for even larger plays by white.
xela: As you say, there are two possible invasion points at the bottom (b and g). Therefore I think b isn't urgent, as black can't defend both those points with a single move.