Tuesday, May 06, 2008

Roman (2)

We have already said that in the Roman theme a black piece, that can defend adequately, is relocated in a position, from where it can defend again, but not quite successfully.

(Problem 75)
A. E. Plesnivy,
First Prize, ”Narod. Politika”, 1928
White plays and mates in 3 moves
#3 (7+14)

Tries: {1.Bg7+? Rxg7!}, {1.Qxc5+? Bxc5!}, {1.Qg3? Bd4!}
We write the next two tries apart, because they reveal that in this problem there is a double application of the Roman theme :
Tries: {1.Sf6? [2.Sxd7#] Rd2!}, {1.Bf6? [2.Be7#] Bh4!}

Key: 1.Qe3! [2.Qxh6#]
1...Rxe3 2.Sf6 Rd3 3.Sh7#
The Rook Re2 has adequate defense Re2-d2, but when it is relocated to e3 its defense Re3-d3 closes the line of the Bishop Bc2 and allows mate on h7.
1...Bxe3 2.Bf6 Bg5 3.Bg7#
The Bishop Bf2 has adequate defense Bf2-h4, but when it is relocated to e3 its defense Be3-g5 closes the line of the Rook Rg2 and allows mate on g7.

Let us see the next problem-76 with Roman theme, a more-mover by Rehm, in which problem we observe pericritical moves.

(Problem 76)
Hans – Peter Rehm,
First Prize, ”Leipzig Olympiad”, 1960
White plays and mates in 7 moves
#7 (9+11)

There are some checking tries, but they do not lead to mate in seven moves.
Tries: {1.Bxe7+? Rxe7!}, {1.Rd6+? Ke5!}, {1.Rxf5+? Bxf5!}, {1.Sg4+? fxg4!}.

This try, which is written separately, is the one containing the general plan. The plan may be refuted, but with the application of a pre-plan, the general plan leads to the solution.
Try: {1.Kg8? Rg2+! 2.Sg4+ Rxg4+ 3.Kf8 Re3!}

Key: 1.Ke8! Ba4+
2.b5 Bxb5+
3.Kf8 Bd3 (because there is 4.Sg4+ fxg4 5.Rf5#)
4.Kg8! (with the black Bishop now on d3, there is no Ra3-e3 move anymore)
4...Rg2+ 5.Sg4+ Rxg4+ 6.Kf8 Re4 (an obstacle for the Bishop Bd3) 7.Rxf5#

The Rook Ra3 may be played to e3 to inhibit mate on e7. The Bishop Bc2 holds f5 to inhibit mate by the white Rook there. Bc2 is relocated to d3 from where it guards f5, but closes the line of Ra3.
The Rook Re2 is relocated to g4. Again a threat on e7 appears and only Rg4 can act, it goes to e4, closes the line of Bd3, allows mate on f5.
The moves Bc2 – a4 – b5 – d3, Re2 – g2 – g4 – e4 are called pericritical moves.

[This post in Greek language].

No comments: