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Probe

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Enclosure
KawabataSMasterOfGo
BeginnerStudySection
3453Enclosure
MiddlegameJoseki
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ShinFuseki
KikashiAndInfluence
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Timing
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44PointLowApproac...
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Yosu-Miru
  Difficulty: Advanced   Keywords: Strategy, Go term

A probe (Japanese: yosu-miru) is a play made in order to see how the opponent reacts. After a probe, the opponent must choose between one of two or three options. You should have planned your game so that none of these options are beneficial to your opponent. -- Morten Pahle

Dieter Verhofstadt (1k) starts with a classic example of a probe given by Goran Siska and continues.

[Diagram]
Possible answers for Black

Possible local answers for Black range from a to d. I'm less sure about d, so I'll discuss the other three here in more detail.


[Diagram]
Block the probe from the outside

White crosscuts with W3 and plays kikashi with W5 and 7. Then White jumps out lightly with a, if this was a reducing manoeuver. Alternatively White leaves the situation for the moment and plays tenuki. Later in the game, the stones at 3, 5 and 7 will affect events at the top and center.



Charles B4 here isn't usally correct by pro standards, even though it appears in a number of books: see probe popular misconceptions.

[Diagram]
Reinforcing the outside

If Black thinks the outside is important, all outward aji will be removed by playing at 2. Naturally, this leaves the aji of White living in the corner with a. See the Tripod Group. With Black's territory reduced from the inside, White can now play a gentle reducing move, in case Black builds a moyo at the top.

Dave Sigaty: White may also push more aggressively at b. If Black answers at c, White plays a threatening to live with a better result than the tripod group. If Black answers instead at d, White plays c and escapes on the outside. This is discussed in The 1971 Honinbo Tournament, chapter 13.


[Diagram]
Blocking the probe from the inside

Black 2 chooses to protect the corner. Either White continues with a, probably reverting to answer 1, or plays tenuki. The aji of 1 enables White now to invade deeper than if Black had answered with 2 at a.

Dave Sigaty: Another continuation for White is the clamp at b. In Strategic Concepts of Go Nagahara gives the continuation Black c, White d, Black a, and White e. By removing the stones at 1, 2, c, and b, Nagahara shows by tewari analysis that Black has played at a in answer to White's probe at d - an unfavorable exchange (in the position shown in the book).

Charles Matthews In fact the common answer from the pros to White now at a is Black at b.



[Diagram]
The usual probe

This is the commonly-used probe in the small high enclosure.


[Diagram]
A continuation

This allows White to get two useful moves W3 and W5 and start to build on the outside; there is another common way to play with W3 at B4.





This is a copy of the living page "Yosu-Miru" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.