(Furi-bisha niwa Kaku koukan wo nerae.)
Vocabulary: Furi-bisha=ranging Rook, niwa=against, Kaku=Bishop, koukan=exchange, nerae (imperative)=to aim
(1)
This applies when you plan a quick attack against ranging Rook.
White in hand: nothing 9 8 7 6 5 4 3 2 1 +---------------------------+ |wL wN * wG * * * wN wL |a | * wK wS * wG wR * * * |b | * wP wP wP wP wS wB wP wP |c |wP * * * * wP wP * * |d | * * * * * * * bP * |e |bP * bP * bP * bP * * |f | * bP * bP bS bP * * bP |g | * bB bK * bG bS * bR * |h |bL bN * bG * * * bN bL |i +---------------------------+ Black in hand: nothing Diagram 1. Up to ..... S4c.Diagram 1 is just an ordinary position you are likely to see when playing static Rook against ranging Rook. Just for the sake of argument, suppose both Bishops are in each other's hand instead of on board (Diagram 2).
White in hand: B 9 8 7 6 5 4 3 2 1 +---------------------------+ |wL wN * wG * * * wN wL |a | * wK wS * wG wR * * * |b | * wP wP wP wP wS * wP wP |c |wP * * * * wP wP * * |d | * * * * * * * bP * |e |bP * bP * bP * bP * * |f | * bP * bP bS bP * * bP |g | * * bK * bG bS * bR * |h |bL bN * bG * * * bN bL |i +---------------------------+ Black in hand: B Diagram 2.From Diagram 2, the static Rook side has a very good move to play: P2d. This is why the ranging Rook side has to avoid Bishop-exchange. After Px2d, Rx2d, White may drop a Pawn on 2b for defense, but Black can drop his on 2c to get a favorable position.
(2)
We will look into another one.
White in hand: nothing 9 8 7 6 5 4 3 2 1 +---------------------------+ |wL wN * wG * * * wN wL |a | * wK wS * wG wR * * * |b | * wP wP wP wP wS wB wP wP |c |wP * * * * wP wP * * |d | * * * * * * * bP * |e |bP * bP * bP * bP * * |f | * bP * bP bS bP * * bP |g | * bB bK * bG bS * bR * |h |bL bN * bG * * * bN bL |i +---------------------------+ Black in hand: nothing Diagram 1. Up to ... S4c. From Diagram 1 there will follow: P4f P6d P4e --->Diagram 2. White in hand: nothing 9 8 7 6 5 4 3 2 1 +---------------------------+ |wL wN * wG * * * wN wL |a | * wK wS * wG wR * * * |b | * wP wP * wP wS wB wP wP |c |wP * * wP * wP wP * * |d | * * * * * bP * bP * |e |bP * bP * bP * bP * * |f | * bP * bP bS * * * bP |g | * bB bK * bG bS * bR * |h |bL bN * bG * * * bN bL |i +---------------------------+ Black in hand: nothing Diagram 2. Up to P-4e.After Black's P4e, if White responds with Px4e, Black will next play Bx3c+, followed by Nx3c, P2d, Px2d, Rx2d (Diagram 3), a favorable position for Black.
White in hand: B P2 9 8 7 6 5 4 3 2 1 +---------------------------+ |wL wN * wG * * * * wL |a | * wK wS * wG wR * * * |b | * wP wP * wP wS wN * wP |c |wP * * wP * * wP bR * |d | * * * * * wP * * * |e |bP * bP * bP * bP * * |f | * bP * bP bS * * * bP |g | * * bK * bG bS * * * |h |bL bN * bG * * * bN bL |i +---------------------------+ Black in hand: B P Diagram 3. Up to Rx2d.Therefore, White cannot let that happen.
Moves after Diagram 2: ..... P7d N3g P5d --->Diagram 4 White in hand: nothing 9 8 7 6 5 4 3 2 1 +---------------------------+ |wL wN * wG * * * wN wL |a | * wK wS * wG wR * * * |b | * wP * * * wS wB wP wP |c |wP * wP wP wP wP wP * * |d | * * * * * bP * bP * |e |bP * bP * bP * bP * * |f | * bP * bP bS * bN * bP |g | * bB bK * bG bS * bR * |h |bL bN * bG * * * * bL |i +---------------------------+ Black in hand: nothing Diagram 4. Up to .....P-5d.What if, instead of playing Px4e, White plans to get his King more breathing room by P7d? In this case, Black does not have to hurry: By N3g he can strengthen his attacking force an wait for the right time.
Moves after Diagram 4: P2d Px2d P4d Sx4d P*4e S5c B3c+ Nx3c Rx2d --->Diagram 5Strictly speaking, the position is even in Diagram 5, but Black initiated the sequence of moves and now has the position exactly as he had planned. Black should have nothing to complain here.