An interesting tesuji problem?
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kvasir
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An interesting tesuji problem?
I encountered this tesuji problem the other day. I guess it could be said to be from a (middle game) joseki gone wrong. I was perplexed that I didn't think I understood the shape and then I disagreed with the provided solution.
Maybe checking it with the computer has the risk that the answer may fit one position and not others, but I did check in the two positions that follow. It turned out I was right to reject the solution as given and for the right reason but it is an interesting puzzle (I maybe I shouldn't confuse people by copying the incorrect solution here). I do find it to be easier to see the solution in the real game positions, which is maybe the real reasons why those positions are provided. It just seem too abstract somehow without a whole board diagram.
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Knotwilg
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Re: An interesting tesuji problem?
The suji that is for everyone to see, is this one:
I'm pondering the forcing moves of A or B prior to this basic line of play, or leaving that as aji.
This is probably kvasir's solution and not the tesuji as challenged.
If White exchanges
first then she can apply the same cut and capture suji but without losing the two stones in the corner.
But then Black can go this way and it's not clearly better for White than the first diagram. Next, Black can further reduce White with a-b-c/d
I'm pondering the forcing moves of A or B prior to this basic line of play, or leaving that as aji.
This is probably kvasir's solution and not the tesuji as challenged.
If White exchanges
first then she can apply the same cut and capture suji but without losing the two stones in the corner.But then Black can go this way and it's not clearly better for White than the first diagram. Next, Black can further reduce White with a-b-c/d
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Knotwilg
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kvasir
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Re: An interesting tesuji problem?
Yeah, you got it.
In both whole board position the main line is something like what follows
And in the first position it appears to be equally good for black to play in another way instead. I'd say the second way has some appeal, but it does look a little bit like a handicap joseki.
The solution in the book was odd. It is like some moves were misplaced by a zealous copy editor.
In both whole board position the main line is something like what follows
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ez4u
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Re: An interesting tesuji problem?
This position is in Ishida vol 3, with the comment, "(tricked) Black 2 is just what White wants. If Black makes a second hane at 4, White has the troublesome move at 5. Letting White connect is awful, but if Black plays 'a', white captures with 'b' and 'c'." See the diagram below for the numbering used here. No alternatives to 'a' are considered.kvasir wrote:Yeah, you got it...
...
The solution in the book was odd. It is like some moves were misplaced by a zealous copy editor.
Dave Sigaty
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kvasir
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Re: An interesting tesuji problem?
ez4u wrote:The same diagram appears in the Igo Daijiten with the exception that the marked extension is missing. These seem like untested lines, however, not actual joseki. There are no sample games given or mentioned. Are the reference positions from actual games?
I think the joseki is to play a keima a little bit earlier (or a large keima). All of the pro games I could find had this way of playing. As a tesuji problem it doesn't matter that the moves leading there aren't good.
BTW if you remove the star point on the side then the large keima was played by alpha zero.
You can take a look at the examples games and the alpha zero game if you are curious how they were played.