I am taking examples based on the lower left corner from this game of Fllecha's: viewtopic.php?f=4&t=13209
Area scoring. White komaster.
OC,
prevents an effective invasion.Evaluate the corner before
.Enjoy!
This 'n' that
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Bill Spight
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Re: This 'n' that
Endgame corner invasion examples
I am taking examples based on the lower left corner from this game of Fllecha's: viewtopic.php?f=4&t=13209
Area scoring. White komaster.
OC, prevents an effective invasion.
Evaluate the corner before.
Enjoy!
I am taking examples based on the lower left corner from this game of Fllecha's: viewtopic.php?f=4&t=13209
Area scoring. White komaster.
OC,
prevents an effective invasion.Evaluate the corner before
.Enjoy!
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
-
Bill Spight
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Re: This 'n' that
mongus asks how to play this kind of position. See viewtopic.php?f=11&t=13222
I have simplified it slightly. Experienced players don't often get into such positions, so this may be unfamiliar.
Help mongus out. Evaluate the region inside the box. (Assume that all stones currently on the board are immortal.)
Enjoy!
I have simplified it slightly. Experienced players don't often get into such positions, so this may be unfamiliar.
Help mongus out. Evaluate the region inside the box. (Assume that all stones currently on the board are immortal.)
Enjoy!
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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jeromie
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Re: This 'n' that
Bill Spight wrote:Endgame corner invasion examples
I am taking examples based on the lower left corner from this game of Fllecha's: http://www.lifein19x19.com/forum/viewto ... =4&t=13209
Area scoring. White komaster.
OC,
Evaluate the corner before
Enjoy!
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emeraldemon
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Bill Spight
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Re: This 'n' that
I see that it has been almost one month since I last updated this thread. My apologies. Life happens. 
I asked people to help out mongus with play in a Black box which White has penetrated.
No guarantee that I have analyzed the position accurately, OC, but I'm pretty close, I think.
Black to play makes the nose attachment, which was mongus's play, I believe. After 
Black has 9.75 points of territory.
Where is the 0.75 point?
- 
make one point of territory plus 0.5 point at "a".
keeps Black from making any more territory here.
Black has 9 pts. of territory plus half of 1.5, or 9.75 points.
If the rest of the board is settled, leaving only this region for play, if Black plays first she gets 9 pts. Since there are no kos, we can take that as the maximum value for the Black territory before either side makes a play.
Similarly, we can find the minimum value for the Black territory by finding the result of local play when White plays first. What is it?
Enjoy!
I asked people to help out mongus with play in a Black box which White has penetrated.
No guarantee that I have analyzed the position accurately, OC, but I'm pretty close, I think.
Black to play makes the nose attachment, which was mongus's play, I believe.
After Black has 9.75 points of territory.Where is the 0.75 point?
- make one point of territory plus 0.5 point at "a". keeps Black from making any more territory here.Black has 9 pts. of territory plus half of 1.5, or 9.75 points.
If the rest of the board is settled, leaving only this region for play, if Black plays first she gets 9 pts. Since there are no kos, we can take that as the maximum value for the Black territory before either side makes a play.
Similarly, we can find the minimum value for the Black territory by finding the result of local play when White plays first. What is it?
Enjoy!
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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mongus
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Re: This 'n' that
Sorry, only just noticed this. Many thanks for analysing this for me.
So I think the general approach is to essentially realise that roughly half the territory has been lost and the play then focuses on building up a wall to preserve your half whilst white takes the other half. The problem with the way I was playing was that I refused to accept that I should lose any territory at all, and rather than building a barrier protecting my half, I built some swiss cheese that allowed my opponent to to infiltrate a very large majority of the space.
Very enlightening, thank you.
So I think the general approach is to essentially realise that roughly half the territory has been lost and the play then focuses on building up a wall to preserve your half whilst white takes the other half. The problem with the way I was playing was that I refused to accept that I should lose any territory at all, and rather than building a barrier protecting my half, I built some swiss cheese that allowed my opponent to to infiltrate a very large majority of the space.
Very enlightening, thank you.
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Bill Spight
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Re: This 'n' that
Hi, mongus.
Sorry it took me so long to post that.
And I see that almost another month has gone by. {sigh} But I will revive this thread, and say a bit more about your position.
Sorry it took me so long to post that.
And I see that almost another month has gone by. {sigh} But I will revive this thread, and say a bit more about your position. The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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mongus
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Re: This 'n' that
Bill Spight wrote:Hi, mongus.
Sorry it took me so long to post that.
No problem at all! My understanding of the game has progressed since I posted the initial thread. I don't seem to be falling into such situations quite as much as I used to.
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Bill Spight
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Re: This 'n' that
Another sporadic post, I am afraid.
The logic of discovery
Often a subject is taught in a "logical" manner, by starting with its elements and building up to more complex aspects. Go lends itself to such pedagogy, where beginners may learn about ladders and about living (or killing) by playing in the middle of a three point eye. But often you see learners making leaps of understanding (or sometimes misunderstanding) skipping over logical or pedagogical steps.
Also, if you take a historical view of a subject, you can see ideas be discovered and usually tested against other ideas. Sometimes the new ideas prevail, sometimes they lose against traditional ideas, often they survive in modified form. This is a process of discovery and dialectic, in which the subject makes progress over time. This dialectical process is a way of learning at the level of the community of those who are interested in the subject. This history of discovery and dialectic can provide a good way for individuals to learn a subject, although it does not seem to be as popular among pedagogues as the analytical approach.
The logic of discovery
Often a subject is taught in a "logical" manner, by starting with its elements and building up to more complex aspects. Go lends itself to such pedagogy, where beginners may learn about ladders and about living (or killing) by playing in the middle of a three point eye. But often you see learners making leaps of understanding (or sometimes misunderstanding) skipping over logical or pedagogical steps.
Also, if you take a historical view of a subject, you can see ideas be discovered and usually tested against other ideas. Sometimes the new ideas prevail, sometimes they lose against traditional ideas, often they survive in modified form. This is a process of discovery and dialectic, in which the subject makes progress over time. This dialectical process is a way of learning at the level of the community of those who are interested in the subject. This history of discovery and dialectic can provide a good way for individuals to learn a subject, although it does not seem to be as popular among pedagogues as the analytical approach.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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globulon
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Re: This 'n' that
I heartily agree with you. I really like to learn about the history of ideas and I often feel I understand something much better when I can see the historical iterations it passed though. It's harder to learn this way though because as you noted it's much less popular as an approach so there doesn't tend to be books or stuff teaching in this manner. We tend to have a division between teaching and history.
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Bill Spight
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Re: This 'n' that
Yes, you get to see how the ideas are tested and refined, or even rejected.globulon wrote:I really like to learn about the history of ideas and I often feel I understand something much better when I can see the historical iterations it passed though.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
I thought it would be interesting to go back and look at ancient games, courtesy of GoGoD, and try to ascertain ancient ideas in the opening and see how they were modified or discarded. OC, this will involve some interpretation, and, hence, the possibility of error.
Here is a partial game record dated 196 A.D. OC, it may be a later reconstruction or forgery. It illustrates some ideas that are still around.
The game was played with setup stones, and White played first. It seems that the keima approach to the 4-4 stone has always been popular. And the ogeima response was popular well into the 20th century. We do not see it so much these days, but that does not mean that it is bad, or even inferior. It gives the opponent a lot of play, however.
is still joseki, albeit rarely seen. It is obviously not territorial, but aims at the bottom left corner.
is a wedge, a play that is still with us, too. The wedge tells us that the ancients had the concepts of miai and of a base, as Black can form a base with a play at either "a" point.
approaches , making a base at the same time. Then 
makes a base. The kick, 
, makes Black slightly overconcentrated, but we know that there was no concept of overconcentration until the 17th century. The kick offers some protection for the White corner. 
is neither territorial nor moyo building, but takes aim at the White corner. We still have this kind of play, as well, and not just against the ogeima response, but against the one space jump and the keima, as well.
takes aim at the Black corner, and Black defends with sente. (The corner is still a bit thin, though.) Then 
makes a base on the top side.
approaches the top right corner. Then 
is another wedge. That surprised me. Why not a pincer? gives White the opportunity to make a base with 
, and with sente, as 
makes a base, too. The miai seems to me to favor White.
is a rather nice sacrifice, don't you think? As a result, White invades the corner and connects his stones with sente.
With sente in hand, White plays the kick,
, and then plays the ogeima response. 
is the last play of the opening, but I doubt if that concept had any significance to players of that time. OTOH, if White had made a base on the bottom side with , Black could have gotten the last big play of the opening with an extension on the right side.
Looking at this game, and other ancient games, I think that the concept of the base had great importance then. It is still important, OC, but not so much, I think. In particular, the wedge,, is slack by today's standards, but guaranteed a base for Black on the right side.
I have marked the bases made by each player in this opening.
Here is a partial game record dated 196 A.D. OC, it may be a later reconstruction or forgery.
It illustrates some ideas that are still around.The game was played with setup stones, and White played first. It seems that the keima approach to the 4-4 stone has always been popular. And the ogeima response was popular well into the 20th century. We do not see it so much these days, but that does not mean that it is bad, or even inferior. It gives the opponent a lot of play, however.
is still joseki, albeit rarely seen. It is obviously not territorial, but aims at the bottom left corner. is a wedge, a play that is still with us, too. The wedge tells us that the ancients had the concepts of miai and of a base, as Black can form a base with a play at either "a" point. approaches , making a base at the same time. Then makes a base. The kick, , makes Black slightly overconcentrated, but we know that there was no concept of overconcentration until the 17th century. The kick offers some protection for the White corner. is neither territorial nor moyo building, but takes aim at the White corner. We still have this kind of play, as well, and not just against the ogeima response, but against the one space jump and the keima, as well. takes aim at the Black corner, and Black defends with sente. (The corner is still a bit thin, though.) Then makes a base on the top side. approaches the top right corner. Then is another wedge. That surprised me. Why not a pincer? gives White the opportunity to make a base with , and with sente, as makes a base, too. The miai seems to me to favor White. is a rather nice sacrifice, don't you think? As a result, White invades the corner and connects his stones with sente.With sente in hand, White plays the kick,
, and then plays the ogeima response. is the last play of the opening, but I doubt if that concept had any significance to players of that time. OTOH, if White had made a base on the bottom side with , Black could have gotten the last big play of the opening with an extension on the right side. Looking at this game, and other ancient games, I think that the concept of the base had great importance then. It is still important, OC, but not so much, I think. In particular, the wedge,
, is slack by today's standards, but guaranteed a base for Black on the right side. I have marked the bases made by each player in this opening.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Another very old game record. 
Dated 280 A.D.
After the usual ogeima response, aims at the Black corner. Black does not reply passively, but plays a pincer with .
White plays a counterpincer with, and after prevents the underneath connection and hems in 
, White makes a base with .
This maneuver looks questionable to me. If White already had the extension,, would the exchange, - , be worth it? Besides which, would White want to play as an extension after , anyway? But I think that at the time the base, - , was appealing.
Gotta run. More on this game in the next note.
Dated 280 A.D.After the usual ogeima response,
aims at the Black corner. Black does not reply passively, but plays a pincer with .White plays a counterpincer with
, and after prevents the underneath connection and hems in , White makes a base with . This maneuver looks questionable to me. If White already had the extension,
, would the exchange, - , be worth it? Besides which, would White want to play as an extension after , anyway? But I think that at the time the base, - , was appealing. Gotta run. More on this game in the next note.
Last edited by Bill Spight on Tue Oct 25, 2016 12:02 am, edited 1 time in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
-
Bill Spight
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Re: This 'n' that
Black now plays the pincer, 
, and White plays 
, a counterpincer which also makes a base.
stakes a claim on the right side. It follows one heuristic for extensions that is still followed today, but violates another modern heuristic.
Note that it leaves four spaces between it and the White corner. That is usual for extensions today. The reason is shown in the next diagram.
The reason for leaving four spaces is that if White invades, either right away or in a fight, Black has room to make a base by extending to
.
The problem is that, by leaving six spaces between and the 
stone, Black leaves enough room for White to make a base, as well. Today Black would only extend as far as R-10.
In the actual game White approached with
and Black made a base. This exchange is good for Black, OC, as White is overconcentrated in the bottom right corner. Note that the main consideration for seems to be that Black has miai for a base, and not that it sketches out a sphere of influence with the stone.
approaches the top right corner. Black plays the kick and then . . . plays a wedge on the top side. White makes a base and Black does, too. 
- 
is one joseki, even today.
This game, like the other one, illustrates the significance of the base in these ancient games., like the wedge, was chosen so that Black had miai for a base.
I want to present a bit more of the game record, to highlight the reading ability and fighting skill of these ancient players.
Black is thin in the top right. How does White take advantage of that?
is a reducing play. 
, a different kind of wedge, is quite nice, isn't it? Black has nothing better than the descent. White continues the reduction with 
.
takes ko ( )
is also quite good. Through 
White forces Black into a low posture on the right side.
Next, White solidifies his position in the top right. Black's play, starting with the kick, has been a failure.
Later, Black shows his prowess by invading the White stronghold in the bottom right corner.
, and White plays , a counterpincer which also makes a base. stakes a claim on the right side. It follows one heuristic for extensions that is still followed today, but violates another modern heuristic.Note that it leaves four spaces between it and the White corner. That is usual for extensions today. The reason is shown in the next diagram.
The reason for leaving four spaces is that if White invades, either right away or in a fight, Black has room to make a base by extending to
.The problem is that, by leaving six spaces between
and the stone, Black leaves enough room for White to make a base, as well. Today Black would only extend as far as R-10.In the actual game White approached with
and Black made a base. This exchange is good for Black, OC, as White is overconcentrated in the bottom right corner. Note that the main consideration for seems to be that Black has miai for a base, and not that it sketches out a sphere of influence with the stone. approaches the top right corner. Black plays the kick and then . . . plays a wedge on the top side. White makes a base and Black does, too. - is one joseki, even today.This game, like the other one, illustrates the significance of the base in these ancient games.
, like the wedge, was chosen so that Black had miai for a base.I want to present a bit more of the game record, to highlight the reading ability and fighting skill of these ancient players.
Black is thin in the top right. How does White take advantage of that?
is a reducing play. , a different kind of wedge, is quite nice, isn't it? Black has nothing better than the descent. White continues the reduction with . takes ko ( ) is also quite good. Through White forces Black into a low posture on the right side. Next, White solidifies his position in the top right. Black's play, starting with the kick, has been a failure.
Later, Black shows his prowess by invading the White stronghold in the bottom right corner.
Last edited by Bill Spight on Tue Oct 25, 2016 10:17 pm, edited 2 times in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.