Side Pawn Capture, Bishop*45

In shogi, Side Pawn Capture, Bishop*45 variation or Side Pawn B*4e (横歩取り☖４五角 yokofudori yon-go kaku) is a Rapid Attack Side Pawn Capture variation in which White drops their bishop on the 45 square after the bishops are traded attacking Black's rook.

B*45 variation
☖ pieces in hand: 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
     角   5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 歩歩歩歩

Rapid Attack development


Rapid Attack Variation
up to move 17
☖ pieces in hand: 角 歩歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
         5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金      8
香桂  玉金銀桂香9
☗ pieces in hand: 角 歩歩歩

The ☖Bishop*45 Side Pawn variation is one of the Rapid Attack (急戦 kyūsen) subvariations of Side Pawn Capture that starts with bishop trade initiated by White (that is, 8...Bx88+ 9.Sx88). It is named after the bishop drop position – the 45 square – that White makes three moves after the bishop trade.[1] This Side Pawn Capture substrategy was popular in the early 1980s.[2] Much of the theory was advanced from the games (in 1978-1979) and analysis of Koji Tanigawa.[3] After much research, this variation is thought to be unsound at the professional level since perfect play by Black leads to an unfavorable position for White. However, at the amateur level, the complex variation may be difficult for both sides to navigate giving winning chances for either player.

The position is reached by the following the Side Pawn Capture opening with 1.P-76 P-34 2.P-26 P-84 3.P-25 P-85 4.G-78 G-34 5.P-24 Px24 6.Rx24 P-86 7.Px86 Rx86 8.Rx34 and, subsequently, veering into the Rapid Attack lines with 8...Bx88+ 9.Sx88 to reach the position shown in the adjacent digram. (See: Side Pawn Capture for discussion of these preceding moves, especially §White's bishop trade variations.)

☖B*45
up to move 18
☖ pieces in hand: 角 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
         5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金    歩 8
香桂  玉金銀桂香9
☗ pieces in hand: 角 歩歩歩
9...P*28

9...P*28. The variation starts with this move.

Main line: ☗10.Sx28
☖B*45
up to move 19
☖ pieces in hand: 角 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
         5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金桂香9
☗ pieces in hand: 角 歩歩歩歩

10.Sx28.

☖B*45
up to move 20
☖ pieces in hand: 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
     角   5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 歩歩歩歩

10...B*45.

☗11.R-24
☖B*45
up to move 21
☖ pieces in hand: 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛 4
     角   5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 歩歩歩歩
11.R-24

11.R-24. Considered the best reply for Black.

☖11...P*23
☖B*45
up to move 22
☖ pieces in hand: –
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩 歩歩3
       飛 4
     角   5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 歩歩歩歩
11...P*23
☗12.B*77
☖B*45
up to move 23
☖ pieces in hand: –
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩 歩歩3
       飛 4
     角   5
 飛歩      6
歩 角歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 歩歩歩歩
12.B*77
☖B*45
up to move 27
☖ pieces in hand: 飛 銀
987654321 
香桂銀金王 銀桂馬1
      金  2
歩 歩歩歩歩  歩3
       歩 4
     角   5
  歩      6
歩  歩歩歩歩 歩7
  金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 香 歩歩歩歩
12...Rx88+ 13.Bx88 Px24 14.Bx11+
☖14...N-33
☖B*45
up to move 28
☖ pieces in hand: 飛 銀
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香桂銀金王 銀 馬1
      金  2
歩 歩歩歩歩桂 歩3
       歩 4
     角   5
  歩      6
歩  歩歩歩歩 歩7
  金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 香 歩歩歩歩
14...N-33
☖14...S*87
☖14...R*25
☗12.P*87
☗12.R-26

☖11...Bx*67+

☗11.B*77
☖B*45
up to move 21
☖ pieces in hand: 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
     角   5
 飛歩      6
歩 角歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 歩歩歩歩
11.B*77

11.B*77. The old joseki move but now considered not as strong as 11.R-24.

☗11.R-35
☖B*45
up to move 21
☖ pieces in hand: 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
        4
     角飛  5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 歩歩歩歩
11.R-35

☗11.P*87
☖B*45
up to move 21
☖ pieces in hand: 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
     角   5
 飛歩      6
歩歩 歩歩歩歩 歩7
 銀金    銀 8
香桂  玉金 桂香9
☗ pieces in hand: 角 歩歩歩
11.P*87

☗10.B*77
☖B*45
up to move 19
☖ pieces in hand: 角 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
         5
 飛歩      6
歩 角歩歩歩歩 歩7
 銀金    歩 8
香桂  玉金銀桂香9
☗ pieces in hand: 歩歩歩
10.B*77

☖10...Rx88+
☖B*45
up to move 20
☖ pieces in hand: 飛 角 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
         5
 歩      6
歩角歩歩歩歩 歩7
 龍金    歩 8
香桂  玉金銀桂香9
☗ pieces in hand: 歩歩歩
10...Rx88+

☖10...Rx76
☖B*45
up to move 20
☖ pieces in hand: 角 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
         5
 飛      6
歩 角歩歩歩歩 歩7
 銀金    歩 8
香桂  玉金銀桂香9
☗ pieces in hand: 歩歩歩
10...Rx76

Without ☖9...P*28
☖B*45
up to move 18
☖ pieces in hand: 歩
987654321 
香桂銀金王 銀桂香1
      金  2
歩 歩歩歩歩  歩3
      飛  4
     角   5
 飛歩      6
歩  歩歩歩歩 歩7
 銀金      8
香桂  玉金銀桂香9
☗ pieces in hand: 角 歩歩歩
9...B*45

9...B*45. Dropping the bishop to 45 without playing 9...P*28 10.Sx28 first is considered a blunder for White.

gollark: Fiiiiine.
gollark: Sure, why not.
gollark: Anything people have lots of: so far, it's storm and frilled.
gollark: How about we resolve to have everyone with a *lot* of commons massbreed tomorrow at some specific time?
gollark: Aren't frills discontinued?

See also

References
  1. Aono 1983, p. 101–150.
  2. Aono 1983, p. 105.
  3. Hosking 1997, p. 141–149.
  • Aono, Teruichi (1983). Guide to shogi openings: Unlock the secrets of joseki 将棋定跡のカギ: 和英 定跡問題集. Translated by Fairbairn, John. 山海堂. ISBN 4-381-00598-8.CS1 maint: ref=harv (link)
  • Hosking, Tony (1996). The art of shogi. The Shogi Foundation. ISBN 978-0-95310-890-9.CS1 maint: ref=harv (link)
  • Kitao, Madoka (2011). Joseki at a glance. Translated by Kawasaki, Tomohide. Nekomado. ISBN 978-4-9052-2501-0.
  • Sawada, Takio (1983). Translated by Murphy, David. "Side pawn capture: B*4e system part 5". Shogi (41): 4–6.
  • 所司, 和晴 [Shoshi, Kazuharu] (2002). 横歩取り道場. Vol. 3 (4五角戦法). 毎日コミュニケーションズ.
  • Tanigawa, Kōji (1982). Translated by Murphy, David. "Side pawn capture: B*4e system". Shogi (36): 12–15.
  • Tanigawa, Kōji (1982). Translated by Murphy, David. "Side pawn capture: B*4e system part 2". Shogi (37): 4–7.
  • Tanigawa, Kōji (1982). Translated by Murphy, David. "Side pawn capture: B*4e system part 3". Shogi (38): 14–16.
  • Tanigawa, Kōji (1982). Translated by Murphy, David. "Side pawn capture: B*4e system part 4". Shogi (40): 14–16.


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