Forum for Horse Head

Understanding more about this jump [#382]

erislover: Understanding more about this jump (2006-04-04 19:31) [#1373]

I did not wish to clutter the main page here with these questions. We could always move any content over if it becomes worthy (or create a new page).

Here is the diagram provided on the main page:

The following text reads: "White succeeds in creating several cutting points at a, b and c but creates a very ugly shape."

My question here: is B10 necessary? I do not understand this shape except as an efficient jump. Would it not be better to simply let one of the black stones go? I know these are context-dependent questions, but that is why showing any cutting sequence out of context is particularly puzzling.

It seems to me (though I hardly know and am really asking) that there are two places where the horse head is a good idea: getting ahead (i.e. an actual jump) or a convenient block.
For instance, perhaps we see this in a handicap game:

It could hardly be said that white had a base in the first place. Can someone help increase my understanding of this move more? Does make more sense at a, b, or c? It seems to me that black has enough bad aji floating around to make trying to cut this jump a lot of work for nothing, even if anything gets cut off there are enough problems in black's shape to let it all settle anyway. Perhaps it is much like cutting the one point jump, there are times when it may be right...?

Using the other sequence:

This is heavily ladder dependent if we want to connect all stones. And it seems very likely that no ladders are good for white (certainly the ladder to catch and is broken).

I saw one other use of this move in a recent handicap game that might be of note:

Cutting through here is not really going to solve much of anything for white. But what about shifting directions with a? (Actual play on the bottom was more involved than just immediate jumping, but in any case white had to run.)

For the one-point jump, there is a separate page about cutting it. Perhaps we could do that here if people have some good examples? Or perhaps just an examples page? This seems like a fairly common "good shape" in practice and understanding its broader implications would be very helpful. I am very surprised that nothing has been mentioned since 2002!

Unkx80: Re: Understanding more about this jump (2006-04-04 20:13) [#1374]

This is quite a mouthful to reply.

Cutting through the horse head

My question here: is necessary?

If you don't play B10 , then White at B10 will cause Black to be in a split shape. Blocking at B10 should be a basic instinct.

For instance, perhaps we see this in a handicap game:

Getting a(horse)head

It could hardly be said that white had a base in the first place. Can someone help increase my understanding of this move more? Does make more sense at a, b, or c? It seems to me that black has enough bad aji floating around to make trying to cut this jump a lot of work for nothing, even if anything gets cut off there are enough problems in black's shape to let it all settle anyway. Perhaps it is much like cutting the one point jump, there are times when it may be right...?

This is a negative example of cutting, and also illustrates why the horse head is said to be a good shape. After , I find that there is no satisfactory move for Black. Most likely I will play at either c or d, but then the , , and stones have become a heavy burden.

Using the other sequence:

Cutting through the horse head

This is heavily ladder dependent if we want to connect all stones. And it seems very likely that no ladders are good for white (certainly the ladder to catch and is broken).

Even with a White response from onwards, the result may not be good for Black.

If and cuts, then is a net.

I saw one other use of this move in a recent handicap game that might be of note:

Jump? Block!

Cutting through here is not really going to solve much of anything for white. But what about shifting directions with a? (Actual play on the bottom was more involved than just immediate jumping, but in any case white had to run.)

is a possible attacking technique, but leaves behind the weakness of Black b, White c, Black d. I don't have time to analyze whether this is possible. On the other hand, White a seems okay.

By the way, page churn is good!

erislover: Re: Understanding more about this jump (2006-04-04 20:45) [#1375]

Hi unkx80, thanks for the quick reply (wow). Yes, I agree that B10 prevents the split shape. I was not very clear (as you note I am really asking a lot), but it seems that saving such a stone is very context-dependent. If the point was to get the heck out of a situation with a jump in good shape, then creating more cutting points with that B10 smells like the "save every stone" bad habit. I am sorry I was not clear... I certainly agree, absent anything else around the jump, B10 should definitely be a basic instict.

When we do life and death, we have an area of interest and assume many things that, in fact, make sense in actual play (outside stones tactically alive for example). However for dealing with good shapes (wedge weakness of the table shape for example), it seems so context-dependent that a simple cutting sequence and preventing the split shape is more angels on pins than solid go. I say this as someone who is trying to understand why the horse head is good shape, not as someone complaining! If I knew better I would certainly add the content myself. :)

Unkx80: Re: Understanding more about this jump (2006-04-04 21:20) [#1376]

If White is allowed to play , then all the White stones is a chain, which by all means cannot be cut at all, and so White is very strong. Then the black+circle stones lies smack against the White wall and has no aji at all.

Lets say we want to sacrifice the black+circle stone. Here, Black will still block at , but retreat with . Then can capture the stone. However, the stone leaves some aji. For example, Black can atari at a to expand the influence, or push at b (aiming for making a dumpling with the next move at c).

However, in this example, the black+square stones are so strong. Therefore, there is actually no need to sacrifice the black+circle stone. So it is entirely possible to pull out with and have a fight. In this fight, it is very likely that Black will have the upper hand.

Minue: Re: Understanding more about this jump (2006-04-04 22:44) [#1377]

erislover wrote:

I did not wish to clutter the main page here with these questions. We could always move any content over if it becomes worthy (or create a new page).

Here is the diagram provided on the main page:

Cutting through the horse head

My question here: is necessary?

-> Yes, As unkx80 explained well, it is definitely necessary.

variation (1)

let's assume Black decided to sacrifice its marked stone. Then ~ B10 is one of expected common variations. after B10 , white connects at a.

now, trace how white and black stones flow. Black stones is working well to surround white stones(making white stones to be more closer to atari pos in broad meaning), driving them backward and bended into narrow area. And, Flow of stones in this diaram is essentially same with a simplfied case in the following diagram. see below.

As we can see, W stones are moving in a very ugly style. So, bad for white.

variation (2)

simplfied pos

This result can be even more simplfied as follows.

even more simplfied.

In conclusion, W's plays in variation(1) is just non-sense, or Non-Go moves, in the sense that white helped black to drive White stones to be closer to being in atari position.

erislover: Re: Understanding more about this jump (2006-04-04 23:54) [#1379]

Heh! Yes, I absolutely agree. I am very sorry for not being more clear. Connecting under with B10 in that diagram is just common go sense.

I think my issue is that cutting the horse head in absence of a context is a totally insane move in the first place, so of course connecting under with B10 is correct. That is...

Black will clearly dominate in this situation. That is most likely true whether or not the horse head is good shape. But some more realistic scenarios might mean sacrificing black+circle without even attempting to save it. I guess that's what I'm wondering about.
Consider:

The table shape has a "wedge weakness." But what sense does this diagram make of that?

Unkx80: Re: Understanding more about this jump (2006-04-05 04:04) [#1380]

Maybe I can guess or clarify what minue meant by "making White stones to be closer to atari position". I think he simply mean "reduction of White's liberties". For this, erislover, you can see don't take away your own liberties and five liberties for tactical stability.

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