Intermediate play - side example
Material here combined from probe and intermediate plays pages. Charles
Alain: The attachment under the small low enclosure is often given as an example of a probe move. Here is another one which, I hope, will make the concept clearer.
is an example of the probe technique. Before deciding how to continue the joseki on the lower left (a or b), Black probes White's intentions with
.
If White plays at , Black will play
and
. If Black had followed the joseki before playing at
, White would have played at the marked point, aiming at the invasion point a. This does not mean that playing the joseki without exchanging
for
before is worse than playing
(it was played in numerous professional games). Black
is just a way to resist White's plan.
If White plays the large low extension, Black plays this variation of the joseki and, again, is not ideally placed for invading at a.
Charles Matthews Variation 2 may have been taught to us; but in current pro practice Black invades the corner at b immediately, for a quite different kind of result.
Uberdude: In a gobase search in April 2007, there are 13 games following this diagram, and 42 with the invasion as Charles describes.
White cuts
Silly me, but what happens when White cuts? You could answer that Black can treat the stones lightly, but that's a fairly large gain for White locally anyway with the corner now secured. That's the only thing keeping me from studying and using this probe. -- lavalyn
I have tried working on that in 3-4 point high approach, inside contact, tenuki variation. A problem might be that it's too high-level, I don't know about that. - Andre Engels
Charles Matthews This has happened at least three times in pro games: in a game Cho Chikun-Tozawa Akinobu 1977-05-26, and in games of Cho Hun-hyeon as Black. In each case I've seen, Black plays as the double kakari, and White initiates a classic joseki by playing a or b.
Clearly White already has taken a significant profit in the lower left corner. But it isn't easy to win the game with just one corner territory.
What happens if White cuts?
It's not clear to me that answering the approach in the upper left is better for White than this (which is almost certainly not best play for either side, but looks distinctly plausible at my level (8 kyu)). As such, I'm not sure that the low approach is really a forcing move - a probe, yes, but...
Is there some reason the pros invariably answer (at ) as White in this diagram?
In Andrew's diagram the good style play for Black is b rather than anything else, in the upper left. But it is often better to do nothing at all in an unsettled position.
To try to answer Andrew's question (as corrected by me): this is an orthodox position, and White at now is or was the main line. Various fighting options have been tried. The main alternative is to play one line higher. They have mostly stopped doing that, as one can find by searching a database. This is the usual situation of seeing stuff and wondering if it can be made to yield some reasons. If you use the large knight's move enclosure after the approach to 4-4, the 3-3 invasion tends to come very soon. Here White would end up with strength mainly facing up the left side - a difference from the small knight's move enclosure, which yields better influence along the bottom. You have to look at least that deep.
Bill Spight: I think that Andrew's suggestion has merit. The cut seems playable to me. We can get there by an alternate route:
The enclosure at look fine. But then
-
seem questionable to me. All of which means that the cut should be playable. :-)
Hmmm. I spoke too soon. looks too passive, since White has a ladder to capture
. But the exchange in the top left corner probably balances out. I still think that the cut is playable.
Charles Matthews Sure, the cut is playable - made in a number of pro games.
Andre Engels: From my collection: Position occurs 193 times, amongst which white plays some kind of answer down the upper left 121 times, pincered the black stone 20 times, plays around the middle of the left side 13 times and cuts 4 times. If we extend the search by disregarding the right half of the board, the numbers get to 405 occurences, with 323 extensions in the upper left, 45 pincers, 23 plays around the middle of the left side, 10 cuts and 4 times where white plays on the right and black gets the next move in this area.
Bill: Thinking of as a probe makes sense, but there are other factors. First, it is likely that
is a bit larger than a connection in the bottom left. It has been known for a long time that continuing this joseki is inferior for Black too early in the game. Second, and more telling, the relation of
to the nirensei on the right is very significant strategically. This relationship is , IMO, more important than its role as a probe for the play in the bottom left. Black has prevented a White enclosure in the bottom left with sente. Now,
is the natural strategic extension of the nirensei. In this I am influenced by the recent writings of Go Seigen, in which he recommends leaving other joseki in an early stage to make this kakari.
Bill: Having invoked Go Seigen because of his comments on what I thought were similar positions, I took a look and found three places in 21st Century Go vols. 3 and 4 where he comments on this fuseki. He does not like it much.
Instead of , if Black plays a kakari in the bottom left, he prefers
. He does not like
. He thinks
is on the wrong side (See next diagram). And he thinks
is bad. After
he thinks that Black has a winning advantage.
Go Seigen prefers the approach from the left side instead of the top, and gives this possible continuation. Instead of connecting in the bottom left, he says, Black takes big points.