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 Post subject: Re: This 'n' that
Post #241 Posted: Wed May 25, 2016 9:54 pm 
Judan

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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

Click Here To Show Diagram Code
[go]$$B Example 1
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | . . . X X X X O .
$$ | . 1 . X X X X O .
$$ | . . X O X O O O .
$$ | . . X O O O . . .
$$ ------------------[/go]


Area scoring. White komaster.

OC, :b1: prevents an effective invasion.

Evaluate the corner before :b1:.

Enjoy! :)

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 Post subject: Re: This 'n' that
Post #242 Posted: Thu May 26, 2016 7:21 pm 
Judan

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mongus asks how to play this kind of position. See viewtopic.php?f=11&t=13222

Click Here To Show Diagram Code
[go]$$B Inside the box
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O . . . X .
$$ . . X . . . O . . . X .
$$ . . X . . . . . . . X .
$$ . . X . . . . . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


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! :)

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 Post subject: Re: This 'n' that
Post #243 Posted: Thu May 26, 2016 8:58 pm 
Lives in gote

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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

Click Here To Show Diagram Code
[go]$$B Example 1
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | . . . X X X X O .
$$ | . 1 . X X X X O .
$$ | . . X O X O O O .
$$ | . . X O O O . . .
$$ ------------------[/go]


Area scoring. White komaster.

OC, :b1: prevents an effective invasion.

Evaluate the corner before :b1:.

Enjoy! :)


Here's the first thing that comes to mind, but it doesn't work for white. Black wins after capturing in a snapback.

Click Here To Show Diagram Code
[go]$$W 6 at 1
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | . . 4 X X X X O .
$$ | 7 2 1 X X X X O .
$$ | 8 3 X O X O O O .
$$ | . 5 X O O O . . .
$$ ------------------[/go]


So let's try a different move for 5:
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | . . 4 X X X X O .
$$ | 5 2 . X X X X O .
$$ | . 3 X O X O O O .
$$ | . . X O O O . . .
$$ ------------------[/go]


Black can't answer with 6, since he can't connect after 7
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | 6 . 4 X X X X O .
$$ | 5 2 . X X X X O .
$$ | . 3 X O X O O O .
$$ | . 7 X O O O . . .
$$ ------------------[/go]


But this 6 works for black.
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | . . 4 X X X X O .
$$ | 5 2 . X X X X O .
$$ | . 3 X O X O O O .
$$ | . 6 X O O O . . .
$$ ------------------[/go]


So let's try 1 where black defended:

This leads to a ko where white takes first:
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | 7 3 . X X X X O .
$$ | 6 1 2 X X X X O .
$$ | 5 4 X O X O O O .
$$ | 8 . X O O O . . .
$$ ------------------[/go]


But this 4 leads to seki after a or b:
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . .
$$ | O O O . . . . . .
$$ | O X O O O O O O .
$$ | X X X X X O X O .
$$ | b 3 . X X X X O .
$$ | 6 1 2 X X X X O .
$$ | 4 5 X O X O O O .
$$ | . a X O O O . . .
$$ ------------------[/go]


Since white is komaster, seki seems like a good result for black. 3 and 5 are forced to prevent black getting 2 eyes, so I don't think white can do better with this 1.


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 Post subject: Re: This 'n' that
Post #244 Posted: Wed Jun 01, 2016 2:45 pm 
Gosei
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My first instinct for the box:

Click Here To Show Diagram Code
[go]$$B Inside the box
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O . . . X .
$$ . . X . . . O 2 3 . X .
$$ . . X . . . 4 1 . . X .
$$ . . X . . . . . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]





Click Here To Show Diagram Code
[go]$$Bcm5 Inside the box
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O 6 4 . X .
$$ . . X . 9 8 O O X 5 X .
$$ . . X . . 7 O X 2 . X .
$$ . . X . . . 1 3 . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


Seems like white made a mistake here since black comes away with 11 points. Maybe this way:

Click Here To Show Diagram Code
[go]$$Bcm5 Inside the box
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O 6 7 . X .
$$ . . X . 3 . O O X . X .
$$ . . X 5 2 4 O X . . X .
$$ . . X . 8 . 1 . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


This time black only comes away with 8.

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 Post subject: Re: This 'n' that
Post #245 Posted: Wed Jun 01, 2016 3:53 pm 
Dies with sente

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emeraldemon wrote:
My first instinct for the box:

Click Here To Show Diagram Code
[go]$$B Inside the box
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O . . . X .
$$ . . X . . . O 2 3 . X .
$$ . . X . . . 4 1 . . X .
$$ . . X . . . . . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]





Click Here To Show Diagram Code
[go]$$Bcm5 Inside the box
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O 6 4 . X .
$$ . . X . 9 8 O O X 5 X .
$$ . . X . . 7 O X 2 . X .
$$ . . X . . . 1 3 . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


Seems like white made a mistake here since black comes away with 11 points. Maybe this way:

Click Here To Show Diagram Code
[go]$$Bcm5 Inside the box
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O 6 7 . X .
$$ . . X . 3 . O O X . X .
$$ . . X 5 2 4 O X . . X .
$$ . . X . 8 . 1 . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


This time black only comes away with 8.

It seems to me that black can create a miai by playing:
Click Here To Show Diagram Code
[go]$$B
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O . . . X .
$$ . . X . . a O b . . X .
$$ . . X . . . 1 . . . X .
$$ . . X . . . . . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]



Click Here To Show Diagram Code
[go]$$B Result: 9 points for B
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O 4 5 . X .
$$ . . X . . 2 O 3 . . X .
$$ . . X 8 . 6 1 . . . X .
$$ . . X . . . 7 . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


Click Here To Show Diagram Code
[go]$$B (Variation) 10 points for B
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O . . . X .
$$ . . X . . 3 O 2 8 . X .
$$ . . X . . . 1 4 6 7 X .
$$ . . X . . . . 5 9 . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


Click Here To Show Diagram Code
[go]$$B (Variation) 10 points for B
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O . 4 . X .
$$ . . X . . 5 O . 2 . X .
$$ . . X . . . 1 3 6 8 X .
$$ . . X . . . . . 7 . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


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 Post subject: Re: This 'n' that
Post #246 Posted: Thu Jun 23, 2016 3:26 pm 
Judan

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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. ;)

Click Here To Show Diagram Code
[go]$$B Black first
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O 4 5 . X .
$$ . . X . . 2 O 3 . . X .
$$ . . X . . 6 1 . . . X .
$$ . . X . . . 7 . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


Black to play makes the nose attachment, which was mongus's play, I believe. :) After :b7: Black has 9.75 points of territory.

Where is the 0.75 point?

Click Here To Show Diagram Code
[go]$$B Black follow-up
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O O X . X .
$$ . . X . 1 O O X . . X .
$$ . . X 3 2 O X . . . X .
$$ . . X a . . X . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


:b1: - :b3: make one point of territory plus 0.5 point at "a".

Click Here To Show Diagram Code
[go]$$W White follow-up
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O O X . X .
$$ . . X . 1 O O X . . X .
$$ . . X . . O X . . . X .
$$ . . X . . . X . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


:w1: keeps Black from making any more territory here.

Black has 9 pts. of territory plus half of 1.5, or 9.75 points.

Click Here To Show Diagram Code
[go]$$B Local play, Black first
$$ . . . . O O O O O O . .
$$ . , . . O X O X X X X .
$$ . . X X X X O 4 5 . X .
$$ . . X . 8 2 O 3 . . X .
$$ . . X . . 6 1 . . . X .
$$ . . X . . . 7 . . . X .
$$ . . X X X X X X X X X .
$$ . , . . . . . , . . . .[/go]


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! :)

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 Post subject: Re: This 'n' that
Post #247 Posted: Tue Jul 19, 2016 5:54 am 
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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.

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 Post subject: Re: This 'n' that
Post #248 Posted: Tue Jul 19, 2016 7:29 am 
Judan

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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. :)

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 Post subject: Re: This 'n' that
Post #249 Posted: Wed Jul 20, 2016 6:07 am 
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Bill Spight wrote:
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. :)


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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 Post subject: Re: This 'n' that
Post #250 Posted: Sat Oct 22, 2016 12:28 am 
Judan

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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.

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 Post subject: Re: This 'n' that
Post #251 Posted: Sat Oct 22, 2016 3:59 am 
Dies in gote

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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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 Post subject: Re: This 'n' that
Post #252 Posted: Sat Oct 22, 2016 8:24 am 
Judan

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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.


Yes, you get to see how the ideas are tested and refined, or even rejected. :)

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Post #253 Posted: Sun Oct 23, 2016 2:00 pm 
Judan

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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.

Click Here To Show Diagram Code
[go]$$Wc Keima approach, ogeima response
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . 3 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . 2 . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


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. :w3: is still joseki, albeit rarely seen. It is obviously not territorial, but aims at the bottom left corner.


Click Here To Show Diagram Code
[go]$$Wc Wedge
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 4 . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:b4: 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.

Click Here To Show Diagram Code
[go]$$Wc Each side makes a base; Black approaches the White corner
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . 9 . 0 . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . 7 . . . . . . . . . . . . . . . . |
$$ | . . 6 8 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . 5 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w5: approaches :b4:, making a base at the same time. Then :b6: makes a base. The kick, :w7:, 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. :b10: 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.


Click Here To Show Diagram Code
[go]$$Wcm11 Moves 11 to 14
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . X . . 4 . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 3 O . O . . . . . . . . . . . . . . |
$$ | . 2 . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . 1 . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w11: takes aim at the Black corner, and Black defends with sente. (The corner is still a bit thin, though.) Then :b14: makes a base on the top side.

Click Here To Show Diagram Code
[go]$$Wcm11 Surprising wedge
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . X . . X . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . 5 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . 7 . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . . 6 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O O . O . . . . . . . . . . . 8 . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . O . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w15: approaches the top right corner. Then :b16: is another wedge. That surprised me. Why not a pincer? :b16: gives White the opportunity to make a base with :w17:, and with sente, as :b18: makes a base, too. The miai seems to me to favor White.

Click Here To Show Diagram Code
[go]$$Wcm19 Sacrifice
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 8 6 7 . |
$$ | . . . . . . O . X . . X . 1 . 4 3 . . |
$$ | . . . O . . . . . , . . . 2 . X 5 . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O O . O . . . . . . . . . . . X . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . O . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w19: is a rather nice sacrifice, don't you think? As a result, White invades the corner and connects his stones with sente.


Click Here To Show Diagram Code
[go]$$Wcm27 The last play of the opening
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . . . . . O . X . . X . O . X O . . |
$$ | . . . O . . . . . , . . . X . X O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O O . O . . . . . . . . . . 2 X . . |
$$ | . X . . . . . . . . . . . . . . 1 . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . O . . . 3 . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


With sente in hand, White plays the kick, :w27:, and then plays the ogeima response. :w29: 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 :w15:, 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, :b16:, is slack by today's standards, but guaranteed a base for Black on the right side. :)

Click Here To Show Diagram Code
[go]$$Wcm27 Bases
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . . . . . W . B . . B . O . X O . . |
$$ | . . . W . . . . . , . . . X . X O . . |
$$ | . . W . . . . . . . . . . . . . . . . |
$$ | . . B B . . . . . . . . . . . . W . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . B . . . . . . . . . . . . . W . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . W . . . . . . . . . . . . . B . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O W . O . . . . . . . . . . B B . . |
$$ | . X . . . . . . . . . . . . . . W . . |
$$ | . . . B . . . . . , . . . . . W . . . |
$$ | . . . . . . B . O . . . W . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I have marked the bases made by each player in this opening.

_________________
"Drooling Banjos"


This post by Bill Spight was liked by: dfan
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Post #254 Posted: Mon Oct 24, 2016 10:13 am 
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Another very old game record. :D Dated 280 A.D.

Click Here To Show Diagram Code
[go]$$Wc Moves 1 to 4
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 4 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . 2 . 3 . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


After the usual ogeima response, :w3: aims at the Black corner. Black does not reply passively, but plays a pincer with :b4:.

Click Here To Show Diagram Code
[go]$$Wcm5 Counterpincer, base
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 3 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . W . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . O . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White plays a counterpincer with :w5:, and after :b6: prevents the underneath connection and hems in :wc:, White makes a base with :w7:.

This maneuver looks questionable to me. If White already had the extension, :w7:, would the exchange, :w5: - :b6:, be worth it? Besides which, would White want to play :w7: as an extension after :b4:, anyway? But I think that at the time the base, :w5: - :w7:, was appealing. :)

Gotta run. More on this game in the next note. :)

_________________
"Drooling Banjos"


Last edited by Bill Spight on Tue Oct 25, 2016 12:02 am, edited 1 time in total.
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 Post subject: Re: This 'n' that
Post #255 Posted: Mon Oct 24, 2016 11:58 pm 
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Click Here To Show Diagram Code
[go]$$Bcm8 Pincer, counterpincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 3 . . . . . . . . |
$$ | . . . X . . . . . , . . . . . O . . . |
$$ | . . . . . . X . O . 1 . 2 . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black now plays the pincer, :b8:, and White plays :w9:, a counterpincer which also makes a base.

Click Here To Show Diagram Code
[go]$$Bcm24 Extension?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:b24: 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.

Click Here To Show Diagram Code
[go]$$Bcm24 Black makes a base
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . 3 . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


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 :b26:.

Click Here To Show Diagram Code
[go]$$Bcm24 Black makes a base
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . B . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . 3 . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The problem is that, by leaving six spaces between :b24: and the :bc: stone, Black leaves enough room for White to make a base, as well. Today Black would only extend as far as R-10.

Click Here To Show Diagram Code
[go]$$Bcm24 Black makes a base
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . 2 . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


In the actual game White approached with :w25: 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 :b24: seems to be that Black has miai for a base, and not that it sketches out a sphere of influence with the :bc: stone.

Click Here To Show Diagram Code
[go]$$Wcm27 Another surprising wedge
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 9 8 0 . . . . . . . . . . . . . |
$$ | . . . . 7 6 . . 4 . 5 . . 1 2 . . . . |
$$ | . . . O . . . . . , . . . 3 . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w27: 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. :b30: - :b34: is one joseki, even today.

This game, like the other one, illustrates the significance of the base in these ancient games. :b24:, 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?

Click Here To Show Diagram Code
[go]$$Wcm37 Reduction
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O X X . . . . . . . . . . . . . |
$$ | . . . . O X . . X . O . . O X . . . . |
$$ | . . . O . . . . . , . . . O . X 6 . . |
$$ | . . . . . . . . . . . . . . . 5 . . . |
$$ | . . . . . . . . . . . . . . . 1 2 4 . |
$$ | . . O . . . . . . . . . . . . . 3 . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w37: is a reducing play. :w39:, a different kind of wedge, is quite nice, isn't it? Black has nothing better than the descent. White continues the reduction with :w41:.

Click Here To Show Diagram Code
[go]$$Wcm43 White pushes Black down
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O X X . . . . . . . . . . . . . |
$$ | . . . . O X . . X . O . . O X . . . . |
$$ | . . . O . . . . . , . . . O . X X . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . O . . . . . . . . . . . 5 4 W 2 . |
$$ | . . . . . . . . . . . . . . . 1 X 8 . |
$$ | . . . . . . . . . . . . . . . . 3 6 . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:w49: takes ko ( :wc: )

:w43: is also quite good. Through :b50: White forces Black into a low posture on the right side.

Click Here To Show Diagram Code
[go]$$Wcm51
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O X X . . . . . . . . 1 2 . . . |
$$ | . . . . O X . . X . O . . O X . . . . |
$$ | . . . O . . . . . , . . . O 3 X X . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . O . . . . . . . . . . . O . O X . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X X . . . . . . . X . O . . . . . . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . . . . . |
$$ | . . . . O . . . . . . X O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


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.

Click Here To Show Diagram Code
[go]$$Bcm60 Black lives in the White corner
$$ ---------------------------------------
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . X X O X X . . . . . . . . O X . . . |
$$ | . O O O O X . . X . O . . O X . . . . |
$$ | . . . O . . . . . , . . . O O X X . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . O . . . . . . . . . . . O . O X . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . 2 . . |
$$ | . X X . . . . . . . X . O . . . . 1 . |
$$ | . O X X . . . . . , . . . . . O . . . |
$$ | . O O O X X X . O . X . O . . 4 3 . . |
$$ | . . . . O . . . . . . X O . . 6 5 . 7 |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

_________________
"Drooling Banjos"


Last edited by Bill Spight on Tue Oct 25, 2016 10:17 pm, edited 2 times in total.
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Post #256 Posted: Tue Oct 25, 2016 9:43 pm 
Dies in gote

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I'm really enjoying your commentaries on these games. It's interesting that they are more concerned to make a base than today's players.

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Post #257 Posted: Thu Oct 27, 2016 7:47 am 
Judan

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globulon wrote:
I'm really enjoying your commentaries on these games. It's interesting that they are more concerned to make a base than today's players.


Well, I guess that's just the result of not having more advanced thinking about the opening. Making a base with miai was one of the best things they could see to do. In the second game White punished Black for playing a wedge on the top side instead of a pincer, but did either player see it that way?

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Post #258 Posted: Thu Oct 27, 2016 8:57 am 
Judan

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We have seen that the ancients understood the importance of making a base in the opening, although they gave it too much importance. By the logic of discovery, it should be one of the first things taught about the opening. :)

The idea of a base is still quite important. When I was learning go, other amateurs explained the saying, Corners, sides, center, by pointing out it was easier to make territory in the corner than on the side, and easier to make territory on the side than in the center. However, Takagawa, in his Go Reader (IIRC), said that the reason was not so much about territory as that it is easiest to make a base in the corner and hardest to make one in the center.

What is a base? Like a lot of go terms, it does not seem to have a precise, generally accepted definition. The prototypical base is the two space extension on the side.

Click Here To Show Diagram Code
[go]$$ Base
$$ . . . . . . . .
$$ . . X . . X . .
$$ . . . . . . . .
$$ . . . . . . . .
$$ ---------------[/go]


In Contemporary Go Terms Nam Chihyung says that a base can make two eyes if attacked. Obviously that is so for the two space extension on the side if the board is otherwise empty. And we would not call it a base if it were surrounded so that it was dead on arrival. I think that there are intermediate or unclear cases where we would still want to call it a base. :)

Now, one of the Nihon Kiin booklets that I bought when I was 4 kyu said that a base could not be cut in two (otherwise empty board assumed). That is obviously true for the two space extension.

Click Here To Show Diagram Code
[go]$$W Underneath connection
$$ . . . . . . . .
$$ . . X 1 3 X . .
$$ . . . 2 4 . . .
$$ . . . . . . . .
$$ ---------------[/go]


I don't remember all the variations in the booklet, but Black can easily connect underneath, as this diagram shows. Here is another variation.

Click Here To Show Diagram Code
[go]$$W Underneath connection, ii
$$ . . . . . . . . .
$$ . . . 5 . . . . .
$$ . . X 1 4 X 9 . .
$$ . . 6 2 3 7 8 . .
$$ . . . . 0 . . . .
$$ -----------------[/go]


However, the underneath connection may be too passive, and the booklet showed connecting over the top.

Click Here To Show Diagram Code
[go]$$W Over the top connection
$$ . . . . . . . . . . .
$$ . . 9 . . . . . . . .
$$ . 8 7 2 4 . 6 . . . .
$$ . . X 1 3 X . . . . .
$$ . . 0 . . 5 . . . . .
$$ . . . . . . . . . . .
$$ ---------------------[/go]


:w7: is necessary if White is to cut Black in two.

Click Here To Show Diagram Code
[go]$$Wm11 Connection, continued
$$ . . . . . . . . . . .
$$ . . O . . . . . . . .
$$ . X O X X 2 X 9 . . .
$$ . . X O O X 1 5 8 . .
$$ . . X . 3 O 4 6 7 0 .
$$ . . . . . . . . . . .
$$ ---------------------[/go]


If Black plays at 17 she easily wins the semeai.

There are other variations, OC, but the message is clear. On an otherwise empty board a base cannot be cut in two.

Unfortunately, I assumed that, because a base could not be cut in two, I should never allow a base to be cut in two. That sometimes led to heavy play. The ancients knew better, as I will illustrate in the next post. :)

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This post by Bill Spight was liked by: globulon
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Post #259 Posted: Sun Oct 30, 2016 1:48 pm 
Judan

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This is the famous game played in the Tang dynasty for a pair of gold petaled bowls.

Click Here To Show Diagram Code
[go]$$Wc Kosumi
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 6 7 . . . . . . . . . . . . . . |
$$ | . . . . . 1 . 2 . . . . . . . . . . . |
$$ | . . . X . . 3 4 . , . . . . . O . . . |
$$ | . . . . . . . 9 . . . . . . . . . . . |
$$ | . . . . . . 5 . . . . . . . . . . . . |
$$ | . . 8 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w3: is unusual these days, but I suppose that the sequence up to :b16: was joseki back then.

Click Here To Show Diagram Code
[go]$$Bcm10 Black base
$$ ---------------------------------------
$$ | . . . 6 . . . . . . . . . . . . . . . |
$$ | . . 4 X O . . . . . . . . . . . . . . |
$$ | . 7 . 5 . O . X . . 3 . 8 . . . . . . |
$$ | . . . X . . O X . , . . . . . O . . . |
$$ | . . . . . 1 2 O . . . . . . . . . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 9 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:b12: makes a base. :w17: approaches it. Since White is so strong in the area, you or I might have jumped out, but Black did not.

Click Here To Show Diagram Code
[go]$$Wcm19 Sacrifice
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . 5 4 . . . . . . . . |
$$ | . X . X . O . B . 3 X . O . . . . . . |
$$ | . . . X . . O B . 1 2 . . . . O . . . |
$$ | . . . . . X O O . 7 6 . . . . . . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w19: attacks the Black group. :b20: at 21 would have been heavy. Instead, Black sacrificed the :bc: stones.

Click Here To Show Diagram Code
[go]$$Bcm26 Counter invasion
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . 4 8 6 . . . . |
$$ | . X . X . O . X . O X . O 3 1 2 . . . |
$$ | . . . X . . O X . O X . 5 . . O . . . |
$$ | . . . . . X O O . O X . . . 7 . . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black uses the thickness built up by the sacrifice to invade White's base. White connects underneath while Black builds more thickness.

Click Here To Show Diagram Code
[go]$$Bcm34 Black thickness
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . O O O . . . . |
$$ | . X . X . O . X . O X . O X X O . . . |
$$ | . . . X . . O X . O X . X 3 . O . 6 . |
$$ | . . . . . X O O . O X . 2 . X 1 5 4 . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . 7 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The local skirmish continues. :w35: plays kikashi, forcing Black to make an empty triangle. :w37: is tesuji, as well.

Click Here To Show Diagram Code
[go]$$Wcm41 A vulnerable base
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . O O O . . . . |
$$ | . X . X . O . X . O X . O X X O . . . |
$$ | . . . X . . O X . O X . X X . O . O . |
$$ | . . . . . X O O . O X . O . X X X O . |
$$ | . . . . . . O . . . . . . . . . . 2 . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . 4 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White makes a base on the right side, but, since it is so close to Black's thickness, it is vulnerable to attack.

Click Here To Show Diagram Code
[go]$$Bcm70 Attack
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . O O O . . . . |
$$ | . X . X . O . X . O X . O X X O . . . |
$$ | . . . X . . O X . O X . X X . O . O . |
$$ | . . . . . X O O . O X . O . X X X O . |
$$ | . . . . . . O . . . . . . . . . . X . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . X , . . . . . , . . . . . , 3 1 . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . . . . O . . |
$$ | . X O O . . . . . . . . . . . . 2 . . |
$$ | . X X . O . O . . . . . . . . . X . . |
$$ | . . O . . X O . . . . . O . . . . . . |
$$ | . . . O O O X . . , . . . . . X . . . |
$$ | . . . . O X X . X . X . O . X . . . . |
$$ | . . . . O X . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The attack comes with :b70:. White counters with :w71:, allowing :b72:.

Click Here To Show Diagram Code
[go]$$Wcm73 Counterattack
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . O O O . . . . |
$$ | . X . X . O . X . O X . O X X O . . . |
$$ | . . . X . . O X . O X . X X . O . O . |
$$ | . . . . . X O O . O X . O . X X X O . |
$$ | . . . . . . O . . . . . . . . . . X . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . X , . . . . . , . . . . . , X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . . . . O . . |
$$ | . X O O . . . . . . . . . . . . O . 7 |
$$ | . X X . O . O . . . . . . . . . B 1 . |
$$ | . . O . . X O . . . . . O . . . 2 3 6 |
$$ | . . . O O O X . . , . . . . . B . 4 . |
$$ | . . . . O X X . X . X . O . B . 5 . . |
$$ | . . . . O X . . . . . . . O . . 8 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White plays a counterattack against the Black corner. Will we ever look at the :bc: stones the same way again? :b80: is tesuji.

Click Here To Show Diagram Code
[go]$$Wcm81 Run, run
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . O O O . . . . |
$$ | . X . X . O . X . O X . O X X O . . . |
$$ | . . . X . . O X . O X . X X . O . O . |
$$ | . . . . . X O O . O X . O . X X X O . |
$$ | . . . . . . O . . . . . . . . . . X . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . X , . . . . . , . . . . . , X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . 9 . . O . . |
$$ | . X O O . . . . . . . . . . . . O . O |
$$ | . X X . O . O . . . . . . 8 . . X O . |
$$ | . . O . . X O . . . . . O . . . X O X |
$$ | . . . O O O X . . , . . . . . X . X . |
$$ | . . . . O X X . X . X . O . X 6 O 4 . |
$$ | . . . . O X . . . . . . . O 2 1 X 3 . |
$$ | . . . . . . . . . . . . . . 5 . 7 . . |
$$ ---------------------------------------[/go]


Both sides run out into the center.

Click Here To Show Diagram Code
[go]$$Bcm90 Twining attack
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . O O O . . . . |
$$ | . X . X . O . X . O X . O X X O . . . |
$$ | . . . X . . O X . O X . X X . O . O . |
$$ | . . . . . X O O . O X . O . X X X O . |
$$ | . . . . . . O . . . . . . . . . . X . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . X , . . . . . , . . . . . , X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . O 2 4 O . . |
$$ | . X O O . . . . . . . 7 . 1 . 3 O . O |
$$ | . X X . O . O . . . . . . X . . X O . |
$$ | . . O . . X O . . . 0 . O . . . X O X |
$$ | . . . O O O X . . , . 5 6 . . X . X . |
$$ | . . . . O X X . X . X . O . X X O X . |
$$ | . . . . O X . . . 8 9 . . O X O . O . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ ---------------------------------------[/go]


:b96: pushes out in a twining attack against both White groups. :w97: is tesuji, an excellent sacrifice that allows the White corner group to escape.

Click Here To Show Diagram Code
[go]$$Bcm130 The battle ends
$$ ---------------------------------------
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . O X . O O O . . . . |
$$ | . X . X . O . X . O X . O X X O . . . |
$$ | . . . X . . O X . O X 3 X X . O . O . |
$$ | . . . . . X O O . O X . O . X X X O . |
$$ | . . . . . . O . . . O 2 . . . . . X . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . 4 . . . . . . X O O O X . . . . . |
$$ | . . . . . . . . 1 . X X O . X X O X . |
$$ | . . X , . . . . . , . . O O O O X X . |
$$ | . . . . . . . . . . . X X . . . . . . |
$$ | . X . . . . . . . X . X O O O O O . . |
$$ | . X O O . . . X X O . X . X . X O . O |
$$ | . X X . O . O O O O . X . X . . X O . |
$$ | . . O . . X O . . . O O O . . . X O X |
$$ | . . . O O O X . . X . X O . . X . X . |
$$ | . . . . O X X . X . X . O . X X O X . |
$$ | . . . . O X . . . O X . . O X O . O . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ ---------------------------------------[/go]


The battle finally ends at move 132. Then White opens a new front with an invasion of the left side.

The ancients had excellent reading and fighting skills. :D

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 Post subject: Re: This 'n' that
Post #260 Posted: Mon Oct 31, 2016 2:13 pm 
Judan

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A quick note today about my discovery of the theme of the base in ancient openings.

Everyone these days knows about corners, sides, center, but it is really a modern idea, and one that was challenged by the New Fuseki. Also, it is plain that ancient players often valued sides more than corners at various points in the opening, although it has nearly always been rare to place the first stone on the side. In the games we have looked at (with the corners already occupied by setup stones) one of the first things players did was to make a base on the side.

It has seemed to me that players today are stressing the sides more than they did when I was learning go. With that in the back of my mind I noticed that players in the early modern era (17th century) often made a specific base on the side, on the 3-8 and 3-11 points.

Click Here To Show Diagram Code
[go]$$W Common base (17th century)
$$ -----------
$$ . . . . . .
$$ . . . . . .
$$ . X . . X .
$$ . . . , . .[/go]


I have not done a study of that base, but it still occurs today, although not very frequently. We have seen it in these very ancient games when a player played on the 3-11 point with the 3-8 point as a miai point to make a base. In the early modern era players often made the base with no provocation at all. OC, making this base would usually be slow by today's standards. :)

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