From: Manabu Terao <Manabu.Terao <at> JAPAN <dot> SUN <dot> COM>
Date: 8 jan 1999
Subject: Shogi strength drill - #10

Dear Shogi Fans,

Here is Problem #10.

Manabu Terao(on behalf of ISPS)



Problem #10

This position sometimes appears when two Rooks are
aiming the King from the upper and the lower sides.
In this case the common sense of endgame is to sacrifice
an either Rook and to promote up an another Rook.
Which Rook do you sacrifice?


The answer line is bRx2a+, wK3c, bG*5d



   9    8    7    6    5    4    3    2    1
+--------------------------------------------+       White in hand:
|    |    |    |    | bR |    |    | wN | wL |  a   +------------------+
+--------------------------------------------+      |GP                |
|    |    |    |    |    | wS | wK |    |    |  b   |                  |
+--------------------------------------------+      +------------------+
|    |    |    |    |    | wP |    | wP | wP |  c
+--------------------------------------------|
|    |    |    |    |    |    | wP |    |    |  d
+--------------------------------------------+
|    |    |    |    |    |    |    |    |    |  e
+--------------------------------------------+
|    |    |    |    |    |    |    | bR |    |  f
+--------------------------------------------+
|    |    |    |    |    |    |    |    |    |  g
+--------------------------------------------+      Black in hand:
|    |    |    |    |    |    |    |    |    |  h   +------------------+
+--------------------------------------------+      |G                 |
|    |    |    |    |    |    |    |    |    |  i   |                  |
+--------------------------------------------+      +------------------+



Answer #10

The answer line is Rx2a+, K3c, G*5d



   9    8    7    6    5    4    3    2    1
+--------------------------------------------+       White in hand:
|    |    |    |    |    |    |    |+bR | wL |  a   +------------------+
+--------------------------------------------+      |GP                |
|    |    |    |    |    | wS |    |    |    |  b   |                  |
+--------------------------------------------+      +------------------+
|    |    |    |    |    | wP | wK | wP | wP |  c
+--------------------------------------------|
|    |    |    |    | bG |    | wP |    |    |  d
+--------------------------------------------+
|    |    |    |    |    |    |    |    |    |  e
+--------------------------------------------+
|    |    |    |    |    |    |    | bR |    |  f
+--------------------------------------------+
|    |    |    |    |    |    |    |    |    |  g
+--------------------------------------------+      Black in hand:
|    |    |    |    |    |    |    |    |    |  h   +------------------+
+--------------------------------------------+      |N                 |
|    |    |    |    |    |    |    |    |    |  i   |                  |
+--------------------------------------------+      +------------------+

Point : How to sacrifice your Rook

  R5b+ (Approx. 50 kyu)

Promoting the Rook for the survival of the Rook loses
the chance of attack with the defending move of G*5a.

  Rx2c+ Kx2c Rx2a+ P*2b P*2d (Approx. 40 kyu)

This is a line to chase the King with a Rook of lower
side ascrificing a Rook of upper side. This line also
frequently appears in a game but not so good in this
case.

Rx2a+ is a fine move. If Kx2a, then Rx2c+, (Any
piece in hand)*2b, G*3b results mate.

Accordingly the King has no choice except K3c. Then
brinkmate comes with G*5d which is an excellent move
cutting off the escape route of the King. Next, no
simultaneously defending move is left against N*4e
and Rx2c+.