Bill: is too slow. Even though Black's play is weak and slow, it is not that bad. White needs to challenge Black in a handicap game.
With White develops his position while restricting Black's development. Even in an even game this is better than sanrensei. is the right point against Black's enclosure. White looks forward to an extension at a, threatening Black's corner. A Black extension to b still leaves weaknesses in the corner.
Taking the open corner may be marginally bigger than playing an approach to Black's bottom right corner, but allowing Black a second enclosure allows him a relatively easy game. In a handicap game White cannot afford that. An approach to the bottom right corner is called for, for instance, .
With two open corners, White can regard them as miai. Black wants to make an enclosure in the bottom left because it faces his stone in the bottom right. Therefore, White should prevent that with an approach to the bottom left corner.
Charles I wouldn't consider those corners miai. , , Black can take the initiative in the lower left. With at ,
it is really not the same.
Bill: They do not have to be the same to be miai. You just have to expect that one player will get one and the other player the other.
Gronk: From the miai page : "Note that equivalence is an important aspect of miai. In miai positions, both the points are about the same in value, but they may not be exactly the same." Some grey area here. One can't say that any two open points are miai, of course. Are the two open corner points under discussion here "about the same in value?"
Bill: If White does not treat the top corners as miai, but makes sure of getting the top left one, can make a good enclosure facing the bottom right corner.
Charles Well, I've looked into related openings, and I just think White's idea is impatient and brings no advantage.
Bill: Playing a Shusaku opening is an interesting idea.
is then a good move for White.
Charles Honto? It invites a simple joseki that is excellent for Black in this position. Actually I prefer at 4-4 in the upper right, especially if this is going to happen. (Of course can still be a good play, but the low approach makes it harder for Black to find the right plan, I believe.)
Velobici: Dont tease us Charles ;) Which joseki are you thinking of here?
Charles But everyone knows this one. Up to Black has an excellent development, because neither of White's chances to approach on the right side is really attractive. (If is the pincer at b, Black invades at 3-3 and has all four corners.)
Velobici: White can choose between this joseki and the avalanche. Would the small avalanche work out better for White in taking the bottom and creating thickness facing the right? Or perhaps the large avalanche?
Charles It is unlikely that the avalanche is best, with a black stone lower right. With the colour of the stone changed, then, yes.
Bill: It is well known that the joseki in the previous diagram is advantageous for Black early in the game. (Besides White ends up too concentrated on the left side.) So White does not play it, but switches to the bottom right corner with .
Bill: White's tenuki in the bottom left corner after is not, I think, rare. (Although continuing is usual.) As for the sides, I don't know which one you are talking about, Charles, but I expect that both the left side and bottom side are unusual in even games. (Unfortunately, I do not have any game records of pros giving free handicaps.)
Charles We could take this up over at 3-4 point high approach, inside contact, tenuki variation. There it rightly says that the tenuki is not uncommon. For this left side my database suggests tenuki about 5% of the time. I was referring to this lower side as a rare pattern (pro games). Since I don't really believe there are handicap joseki (except as a pejorative), and I'm committed intellectually to treating side patterns qua joseki, I don't really admit Bill's point about data from pro free placement games. Put it another way, playing a combative opening has a lot to do with making your opponent's orthodox replies look poor in context.
Bill: is played with an eye to in the top right corner. As you indicated, Charles, it is somewhat problematic to play this after B a in the left bottom corner. My remark about handicap vs. even games has to do with two things. First, in an even game you are most unlikely to get the Shusaku setup for Black with Black to play when White approaches the bottom left corner. Second, because of Black's extra stone in the top right, White faces the problem of concentration on the left where he would not in an even game. For instance, in an even game White could tenuki and play in the open top right corner. So the circumstances that might lead White to tenuki in the bottom left to approach the bottom right are rare in an even game, but not so rare in a free handicap game. In any event, cannot be understood only looking at the bottom side.
Charles is thoroughly orthodox looking at the right side alone. It is most unorthodox looking at the lower side alone. That's the observation. I have no way of evaluating the combination.
Bill: Instead of a double enclosure, looks interesting, a la mode Chinoise.
Vs. Kitani style, after Black can continue with . After Black has two enclosures and a framework. Now the top and left sides are miai. This is an easy opening for Black.