Taisha five-way junction
This occurs some way into the main variation of the taisha joseki and may even be a six- or seven-way junction. The point of this page is to sort out which variations are attested as pro plays, and which are presumed just hamete (joseki tricks). The latter are perpetuated by joseki books.
For the hardcore enthusiast, this is position is the source of the major taisha variations. We'll look at Black a, less difficult than b or c.
Instead of the push of , the descent at d is also possible. The "Descent Variation" section below covers this. d is more often seen in a similar position that arises from three-space white pincer (at one of the circled points) to a low approach to a 3-4 stone. See 34PointLowApproachThreeSpaceLowPincerTaisha and 34PointLowApproachThreeSpaceHighPincerTaisha for these.
Black 1 here has been played by some top players down the years (Shusai, Sekiyama Riichi, Hashimoto Utaro). The line continues with and
, and is thoroughly analysed in Ishida.
Black here is a pro play, though perhaps not recently (any advance on Kubomatsu-Kitani in 1934?) This is a pushing battle with a hamete in it. Black
may look as if it's easy to refute - but beware the two-stone edge squeeze!
That leaves these plays a and b from Ishida unaccounted for; they may be outright tricks. Analysis is given there for a; for b too but that was played differently 1974-06-06 by Hashimoto Utaro against Magari Reiki (game on Gobase).
Gobase also has a game 1973-10-31 between 1 dan pros Inoue Hatsue and Kimura Yoshio in which Black tries c.
Sazn: A and B are Trick Plays
Descent Variations
The descent of is an alternative to the push of a. It seems to be most common in 3-4 point joseki in which White has played either a three-space low or high pincer (marked points). See 34PointLowApproachThreeSpaceLowPincerTaisha and 34PointLowApproachThreeSpaceHighPincerTaisha for these.
The descent of can also be played without a white stone at one of the circled points, though it is not common. Note that the Taisha is not to be recommended when there is a white stone closer to the corner than the marked points. The result is too good for White in such cases.
This continuation appears in NieWeipingOnGo. creates a target for White so something lighter might be worth considering. White can begin the attack on the Black center stones with a or b.
Notice that in the "normal" Taisha continuation (shown above), White c is exchanged for . In this descent variation, instead
is exchanged for
. Thus, with respect to the center attack, White has gained a tempo. At the expense of solidifying Black's corner, White gets to initiate the attack on Black's center stones. Locally, this seems to be the main difference between this variation and the more common one.
--SnotNose